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Uncovering the infamous shroud over biological control

HUMANnature - Tue, 04/17/2018 - 10:49am

Written by Dhaval Vyas, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Bioagricultural Sciences and Pest Management.

The next time you’re peeling an orange, squeezing a lime over some tacos or enjoying a glass of lemonade, take some time to thank the vedalia beetle (Rodolia cardinalis).  This little insect was the hero in one of our country’s first successful attempts at introducing one organism to control another organism (i.e., biological control).  Since then, land managers have used an assortment of animals and germs to control unwanted visitors.  Some of these efforts succeeded, others were disastrous; nonetheless, biological control remains a valuable tool for ensuring food security, public health and conservation of endangered species.

Why pay homage to the vedalia beetle?  In the late 19th century, hordes of people moved into California with dreams of striking it rich in the gold mines.  As the demand for food increased, several crops were brought from the eastern US and grown, for the first time, in California.  Citrus fruits were one of many imported crops and, like these other crops, the citrus trees were attacked by insects that the plants had never experienced.  Any defenses that the plants had evolved to combat insect pests from the eastern US were useless in California.  One particular insect, the half-inch long cottony-cushion scale (Icerya purchasi), decimated citrus groves and brought California’s fledgling citrus industry to its knees.  The cottony-cushion scale’s origin was traced to Australia and researchers traveled down under to see what kept this insect from destroying crops in its home range.  They found that the vedalia beetle, a type of ladybug beetle, devoured cottony-cushion scales and helped prevent the scale from overcoming plants1.  Unbeknownst to most people, ladybug beetles and their young are voracious predators!  The vedalia beetles were brought by boat to California and these beetles saved the citrus industry, which today gives us tasty breakfast beverages and helps makes a certain Mexican beer drinkable.

Thanks to the domestication of plants, humans must intervene to save crops from their enemies. Domestication does two things to plants: it makes them tasty and it weakens their defenses2.  The two outcomes can be intertwined because many of the plant chemicals used for defense against being eaten are the same chemicals that produce nasty tastes.  For example, let’s take the beloved cabbage.  The round heads of red and green cabbage are all domesticated types of wild cabbage (Brassica oleracae), which is in the family of plants known as the Brassicaceae.   Nearly every type brassica plant is armed with glucosinolates, a family of chemicals that can be toxic and disgusting when eaten3.  Glucosinolates are the plant’s way of saying, “The first bite’s free, but afterwards, you’ll pay dearly!”.   With the power of domestication on our side, we bred out these nasty chemicals so that the plants could please our taste buds.  Domestication of cabbage gave rise to crop varieties including broccoli, cauliflower, Brussel’s sprouts and kale; all of which are actually different parts of a cabbage plant!  There still exist some brassicas that have kept their chemical defenses and you can actually taste them, just grab a mouthful of some raw mustard greens!

The majority of our food comes directly or indirectly from plants that have had their chemical defenses weakened from domestication.  This is one of the reasons why we rely so heavily on chemical pesticides.  If we’re going to feed six billion (and growing) humans, we can’t share our food crops with pests!  However, we’re also concerned with the harm caused by pesticides to environmental and human health.  Integrated Pest Management (IPM) is becoming a more common alternative to “spray and pray” approaches for reducing food loss from crop pests.  The key to IPM is that it aims to control the pests, not necessarily to eradicate them from the environment.  Social, ecological and economic outcomes are all in consideration for managers that use IPM, which is often guided by ecological and evolutionary principles (e.g., food web interactions and evolved resistance to pesticides).  One of the IPM strategies is biological control, which reduces the harm caused by pests by introducing the pests’ natural enemies.  Enemies can be predators, pathogens (viruses, fungi or bacteria) and parasitic insects.  Ecologists are often tasked with finding the most effective and safest natural enemy based on its natural history, biology and potential for pest control.  Once one or more biological control agents have been identified and tested for effectiveness, the species are released in the area affected by the pests.

Most people cringe at the notion of introducing an organism from one place into another.  This reaction is likely from hearing about biological control efforts that failed to resolve the pest problem and ended up creating a worst-case scenario.  The kingpin of such examples is the cane toad (Rhinella marina).  Its original habitat is found along riverways in Central and South America.  However, in the 1930s, the cane toad was introduced throughout the Caribbean and some Pacific islands, including Hawaii, to reduce damage to sugar cane caused by beetles4.  The cane toad introductions were successful, and as the toads gorged on beetle grubs, sugar cane farmers saw the desired reduction in losses from beetle damage.  Australian officials were smitten with the success observed in these smaller islands, so they decided to bring the cane toad to Australia to control beetle problems in their cane fields.  Unfortunately, the Australian beetle grubs fed high atop the sugar cane plant where the toads failed to reach.  The cane toads, hungry and unable to feed on the beetle grubs, satisfied their appetites by turning their attention to a diversity of Australian species, leading to declines in several species found only in Australia.  Mongooses introduced to control rabbits and cats brought to control rats are some additional failures peppered throughout the history of biological control. 

The lessons learned from fiascos have guided contemporary biological control efforts, and it continues to be a valuable tool for managing natural resources.  There are numerous success stories where introductions of natural enemies to pests have saved entire agricultural industries and helped conserved endangered species5.  Given the complex process of getting food from seed to our plates, we need creative and responsible solutions that are informed by responsible science.  Federal and state agencies are now in charge of overseeing all organisms proposed for use in biological control.  Gone are the days when you could release animals or other organisms without any regulations.  Strict review procedures, quarantine periods and rigorous testing all precede the release of any biological control agent.  The unforgettable disasters are a constant reminder that successful biological control requires a tempered approach.

Most people are unaware that many economically important crops are highly vulnerable to being wiped out by a single threat.  Inbreeding and monocultures have made many crops defenseless against attack from pests.  Skeptical?  Try stomaching the current state of bananas: http://www.bbc.com/news/uk-england-35131751.  Rubber, coffee and chocolate all share a similar fate.  International traffic allows us to crisscross the globe and this movement guarantees the continued spread of organisms between countries.  One unintentional benefit of biological control is that it allows us to study how organisms react after arrival into a new region.  To make biological controls effective, it’s critical to know what enables an immigrant species to establish or causes it to perish after its arrival.  Controlled introductions can reveal answers to these questions and help us understand the growing phenomenon of transcontinental movement of species.   

As I write this blog post, citrus farmers in the US are nervously awaiting the start of the 2018 growing season.  The country’s citrus industry is once again under attack, this time by a bacterium that’s spread by an insect: the Asian citrus psyllid (Diaphorina citri).  The bacterium causes citrus greening disease, also known as Huanglongbing or yellow dragon disease, which makes citrus trees produce green and bitter tasting fruits6.  Once infected, trees die within a few years.  The disease was discovered in 2004 in Brazil, and in 2005, it arrived in southern Florida.  Citrus greening has affected over a million acres of citrus orchards in eight US states and in several African and Asian countries.  The cure continues to evade scientists. 

In the meantime, the vedalia beetle has left six big shoes to fill. 


  1. Caltagirone, L.E. & Doutt, R.L.  1989.  The history of the vedalia beetle importation to California and its impact on the development of biological control.  Annual Review of Entomology, 34: 1-16.
  2. Chen, Y.H., Gols, R. & Benrey, B. 2015.  Crop domestication and its impact on naturally selected trophic interactions.  Annual Review of Entomology, 60: 35-58.
  3. Lewis, J. & G.R. Fenwick.  1987.  Glucosinolate content of brassica vegetables: Analysis of twenty-four cultivars of calabrese (green sprouting broccoli, Brassica oleracea L. var. botrytis subvar. cymosa Lam.).  Food Chemistry, 25: 259-268.
  4. Lampo, M. & De Leo, G.A.  1998.  The invasion ecology of the toad Bufo marinus: from South America to Australia.  Ecological Applications, 8: 388-396.
  5. Fessl, B., Heimpel, G.E. & Causton, C.E.  2017.  Invasion of an avian nest parasite, Philornis downsi, to the Galapagos Islands: colonization history, adaptations to novel ecosystems, and conservation challenges.  In: Parker P. (eds) Disease Ecology. Social and Ecological Interactions in the Galapagos Islands. Springer, Cham., 213-266.
  6. Bové, J.M.  2006.  Huanglongbing: A destructive, newly emerging, century-old disease of citrus. Journal of Plant Pathology, 88:7-37.

Rethinking Wood in Rivers to Ensure Ecological Health and Human Safety

HUMANnature - Wed, 04/11/2018 - 4:25pm

Written by Dan Scott, a 2017-2018 Sustainability Leadership Fellow and PhD Studentin the Department of Geosciences.

Picture a healthy river: one that is teeming with life, supporting an array of plants, insects, fish, and animals. Such a river also supports you, providing beautiful views, opportunities to play outdoors, and clean water. When you pictured this river, did it have wood in it? Was it complex, with patches of different types of vegetation, some logs and brush, deep pools in some places and shallow reaches in other places? Or, was it a well-kept river that looked like it would be right at home next to a perfectly manicured lawn? It turns out that most people prefer simplified, manicured rivers and see things like wood as harming streams, and needing to be cleaned out1. In fact, wood is almost as important to the organisms living in and around rivers as the water that flows in the channel.

Historically, the default perspective regarding wood has been that it endangers humans, increases flood risk, makes rivers harder to navigate, and acts as debris2. That has led to the widespread removal of wood from streams, with severe consequences for the things that live in and around rivers, including us.

Wood comes in many forms. Small bits and pieces, dispersed logs, and large accumulations known as jams all play an essential role in the physical and ecological function of rivers. When it breaks down, wood provides food to in-stream organisms like insects and material on which plants such as algae can grow. Log jams commonly create cover for fish, which allows them to grow to maturity. One of the most important functions of wood is in changing flow patterns, which in turn move sediment and nutrients across the land surrounding the river. This scours new surfaces so that trees can sprout and grow, brings older patches of forest into the river, and creates a mosaic of diverse vegetation across the valley bottom. Diverse vegetation supports a diverse array of animals that depend on that vegetation for habitat and food. Wood generally makes rivers messier, which is exactly how fish and other animals tend to like them.

That said, wood can also pose a danger to people and property, giving it a bad reputation in the eyes of society. Flooding is essential to nourishing floodplain soil, as floods deliver sediment and nutrients over river banks and onto floodplains. However, the presence of wood in a river slows down the flow of water, which, during a flood, pushes more of that water up and over the banks, onto floodplains that may host roads and houses. Wood can also accumulate around bridge piers, causing flooding and exerting enough force to damage the bridge structure. This is especially true for bridges that aren’t built with enough space underneath them for wood to pass through. To boaters, anglers, and hikers, wood can pose a significant risk by trapping swimmers underwater. The same log jam that hosts dozens of happy fish one day could drown a whitewater kayaker the next. When we remove wood from rivers to mitigate these risks, we often simplify the river, reducing fish populations that we might depend on as a food source, or reducing how often the river floods and delivers essential nutrients to vegetation on its banks. Unhealthy ecosystems around rivers lead to decreases in native animal and insect populations, which ultimately harm surrounding agriculture, hunting, fishing, and other human activities.

This presents a challenge: we know that wood is essential for the health of streams, but we need to ensure that wood is compatible with human needs. None of the dangers posed by wood are inherent to wood itself: wood jams don’t hunt down anglers and drown them. Managing the risks wood poses is a matter of managing how we build, act, and live around rivers. Some solutions are obvious: educate recreationalists about how to be safe around rivers, engineer bridges to be able to pass wood underneath them (i.e., make them taller), and avoid building near rivers to lessen flood damage. These solutions can be very difficult to implement, however. People like living near rivers, where their homes may flood; taller bridges are more expensive; and public education doesn’t necessarily reach all recreationalists, whereas a single death or injury can lead to drastic management actions like removing most or all of the wood along a river.

River scientists’ research will help balance the risks wood poses to humans with the benefits it provides to ecosystems. Currently, we are implementing a collaborative tool to study wood and create a large database of how wood behaves in rivers, called the Wood jam Dynamics Database and Assessment Model (WooDDAM). This database and the research that comes out of it will allow managers to make the most informed decision possible when considering whether to retain, remove, alter, or even reintroduce wood to rivers. How wood changes over time, especially during floods, determines the risk it poses to humans and property. By quantifying how wood behaves in rivers (e.g., moves downstream, accumulates other pieces of wood), managers can identify and retain low-risk wood and know when to remove or alter wood that poses a high risk to people or property.

Public policy and urban planning also serve an important role in managing wood. The city of Fort Collins, for instance, has instituted a policy of buying land near the Poudre River and converting that land to flood-resilient uses, like parks, sports fields, and natural areas. This reduces the need to pull wood out of the river, since floods don’t do as much damage as they used to. Education campaigns focused on informing recreationalists of the ecological importance of wood can help prevent people from manually removing wood, especially from small, sensitive streams that harbor insects and fish.

Next time you see a messy, wood-rich river, think about the important ecological functions that wood is performing. It might not be well-manicured, but a messy river system tends to be a healthy one, and wood is usually at the heart of that mess.


  1. Chin, A. et al. Perceptions of Wood in Rivers and Challenges for Stream Restoration in the United States. Environ. Manage. 41, 893–903 (2008).
  2. Wohl, E. A legacy of absence: Wood removal in US rivers. Prog. Phys. Geogr. 38, 637–663 (2014).



Surviving Day Zero: What plants can teach us about enduring drought

HUMANnature - Wed, 04/04/2018 - 10:51am

Written by Ava Hoffman, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Biology and Graduate Degree Program in Ecology.

Just opposite the Rocky Mountains, the fiery sun paints the prickly pears red with long shadows and promises an unbearably blazing hot day. I step out of my reliable old field truck in northeastern Colorado and a tumbleweed races by, crisp and bouncing. My spurs jingling like a couple of quarters and my cowboy hat drawn low, I take in the orange and red sunrise. Next to my boot lies a perfectly bleached bison skull, lying on cracked, parched soil. I am a scientist in a drought-prone landscape.

Well, that’s not entirely accurate. I wear ill-fitting tennis shoes and zip-off cargo pants and work in a water-limited grassland conspicuously lacking bison bones and cowboy hats. I count drought adapted grasses and quantify their genomes. I see plants wilting with, dying from, and adapting to droughts. Yet, the droughts I study rarely disrupt day-to-day life.

Nearly halfway around the world, Cape Town, South Africa, is embroiled in a water crisis. “Day Zero”, the day the city must shut off plumbing and water to 4 million people, is fast approaching. Authorities have prepared hundreds of emergency water stations [1] and have cracked down on surging prices for bottled water [2]. Locals are banned from watering lawns or washing cars and are being urged to recycle “greywater” (sink and shower water). Even Cape Town’s thriving tourism industry is calling for each visitor to “save like a local”, urging limited shower time and fewer toilet flushes [3]. Divides between the haves and have-nots are more obvious than ever as only some residents can afford to stockpile bottled water. Other cities globally are likely to face similar drought-related crises in the coming decades [1]. However, drought is far removed from daily life for many Americans — it mostly exists in movies, Steinbeck’s Grapes of Wrath, or on bad dating apps. Water is close to being cut off in Cape Town, but taps coughing air when turned on is unthinkable to most of us.

Studies have shown that droughts are happening more and are becoming worse [4]. This prediction might be surprising given recent flooding by hurricanes in Texas and elsewhere, but these two natural disasters are opposite sides of the same coin. The key similarity is extreme climate. Gentle thunderstorms scattered throughout the year provide small amounts of water that nourish plants slowly, giving them time to soak up what they need. But if most rain falls in a strong storm, followed by longer and longer droughts, plants will die. Some types of plants may disappear from their current ranges if the extreme weather pattern holds. Longer and harsher droughts are likely to affect agriculture and intensity of wildfires. The American Midwest may be particularly hard hit by unprecedented drought in coming decades [5]. The effects of climate change are here, and they are not good. It’s time for the American people and drought to get acquainted.

Yet, plants have been surviving droughts for millions of years. How is this possible? The first strategy is to shift the abundance of species. In communities of plants, certain environmental conditions favor certain species. Shrubs with deep taproots become more common during droughts in drylands - including deserts and steppes - while grasses and herb species can become abundant when rain is available. Usually these two coworkers tolerate each other, but recent droughts are already increasing shrubs in grasslands [6]. Declining grasses could also mean loss of grazing resources for cattle and other animals. Human communities will benefit from learning to extract hard-to-reach water. But adopting water-saving strategies may mean giving up water-hungry amenities. Plant communities show us that certain strategies may come with costs in a drought-prone future.

The second strategy is adaptation. Plants in drought-prone areas have special tools at their anatomical disposal developed over thousands of years of evolution. Researchers have recently learned that xylem vulnerability to embolism – or how easily an air bubble can appear in plant water vessels – is an important factor determining plant survival during droughts [7]. Other aspects of plant hydraulics besides vulnerability to embolism are common adaptation strategies. For example, timing of leaf wilting depends on where a species comes from and is closely tied to drought resistance [8]. While modifying human genomes to use less water seems unlikely, we can learn to modify our behavior. Depending on where we are living, we should adopt the best practices to conserve water.

The third strategy I will mention here is plasticity, the ability to change with the environment. Not all traits are fixed. In fact, plant growth, leaf structure, and even color can change depending on resources. When drought is sensed, some grassland species change their leaves to become smaller and thicker, thus conserving water in the short-term [9]. Photosynthetic activity and the rates of exchange for water and carbon dioxide also tend to be flexible [10]. Plants must exchange water for carbon dioxide, and some plants shift this exchange to early morning hours. This minimizes the evaporative power of the sun, saving water with time-based plasticity. The capacity for plasticity can even be passed along across generations like an adaptation. For humans, plasticity is perhaps the most intuitive. Save water, especially when it’s in short supply. If water stores are running dangerously low, set aside any stubborn predispositions and try a different strategy as quickly as possible.


Despite these water savvy strategies, droughts are still having enormous impacts on plants, such as widespread mortality of trees weakened by drought [11]. So, next time you turn on your faucet, think about Cape Town and think about plants everywhere. Droughts will get worse, but we can prepare ourselves by practicing best water conservation practices and developing long term goals. If we learn a little bit from the plants around us, we can better respond to drought.

[1] https://news.nationalgeographic.com/2018/02/cape-town-running-out-of-wat...

[2] https://www.timeslive.co.za/news/south-africa/2018-01-31-call-to-halt-bo...

[3] http://www.capetown.travel/visitors/plan/save-like-a-local-how-visitors-...

[4] Cook et al., 2014: http://link.springer.com/10.1007/s00382-014-2075-y

[5] Cook et al., 2015: http://advances.sciencemag.org/cgi/doi/10.1126/sciadv.1400082

[6] Schlaepfer et al., 2017: https://www.nature.com/articles/ncomms14196

[7] Anderegg et al., 2016: http://www.pnas.org/content/113/18/5024.short

[8] Bartlett et al., 2012: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1461-0248.2012.01751.x

[9] Wellstein et al., 2017: https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.13662

[10] Puglielli et al., 2017: https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.3484

[11] Young et al., 2016: https://onlinelibrary.wiley.com/doi/full/10.1111/ele.12711

Is forest bioenergy really a climate change solution?

HUMANnature - Wed, 03/21/2018 - 11:47am

Written by Tony Vorster, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Ecosystem Science and Sustainability and Graduate Degree Program in Ecology.

It’s -3°F, yet I’m roasting – nearly to the point of singeing my eyebrows!

As I watch pile after pile of wood burn, I think to myself – there must be a better use for this wood than simply burning it for disposal. Half of a tree’s biomass is carbon. The growing trees sucked this carbon out of the atmosphere over many decades and stored it. Now, it is returning to the atmosphere as each pile goes up in smoke. In a world working to address climate change by reducing atmospheric CO2 levels, there must be a better use for this wood.

Forest bioenergy refers to using woody materials for energy production. These uses range from burning wood for heat and electricity generation to converting wood into liquid fuel through a process called pyrolysis. Forest bioenergy is often considered carbon neutral, meaning it has net zero carbon emissions with any emissions being offset by removal of CO2 from the atmosphere. If truly carbon neutral, forest bioenergy would hold a clear advantage over fossil fuels for battling climate change. The rationale for calling forest bioenergy carbon neutral, however, is somewhat misleading. The idea is that carbon released from burning wood for energy is recovered from the atmosphere when the forest regrows.

The reality is not that simple—forest bioenergy often emits more CO2 than fossil fuels. The carbon neutrality logic ignores the continued forest growth, and associated reductions in atmospheric CO2, if the forest were not harvested. It also does not account for the fossil fuel emissions released during harvesting, transportation, and conversion of wood to energy or fuel. Lastly, burning wood for energy releases a pulse of CO2 to the atmosphere— in the time between this pulse of CO2 and the much slower recapture of CO2 with forest regrowth, the CO2 is having a warming effect in the atmosphere.

Forest bioenergy’s carbon benefit (or lack of it) compared to fossil fuels depends on the particular forest of interest as well as the methods used to assess the carbon footprint. Is the forest being harvested solely for bioenergy, or are harvest by-products being used? Is the wood from a plantation or a natural forest? What is the source of the energy displaced by bioenergy? Replacing dirtier energy sources like coal is more likely to be beneficial than replacing cleaner energy sources. How quickly will your particular forest recover? This is an increasingly difficult question to answer with climate change effects on forest regeneration and growth. Furthermore, there are a variety of approaches to quantifying forest bioenergy’s carbon footprint—different approaches can give different answers.

Forest bioenergy influences climate in more ways than just changing atmospheric CO2 levels. For example, harvesting wood can change the reflectivity of the Earth’s surface, or albedo. Harvested sites with seasonal snow cover reflect more of the Sun’s energy than do forested sites, having a cooling effect. This offsets some of the warming from the CO2 released to the atmosphere. The increase in Earth’s reflectivity after harvest plays less of a cooling role in the tropics because harvesting tropical forests also reduces cloud cover, which is highly reflective. Thus the difference in reflectivity between forested and harvested sites is reduced.

Forest bioenergy may be a sustainable alternative to fossil fuels in certain scenarios. For instance, the slash piles that were singeing my eye brows could be put to good use. If we are burning wood simply to dispose of it, why not use it for bioenergy instead? In the northwest U.S., progress is being made to convert unused limbs and branches from logging operations to jet fuel. Alaska Airlines even flew across the country with a portion of the jet fuel made from this leftover material. Another potential bioenergy source lies in the vast number of trees killed by bark beetles throughout the western U.S. I am on a team researching the environmental, economic, and social sustainability of using this dead wood for forest bioenergy. The approach taken by this team highlights an important point. I’ve only touched on one aspect of the sustainability of forest bioenergy in this article—social and economic sustainability must also be considered.

Is forest bioenergy climate-friendly? It depends. This answer is difficult to build policy and industries around compared to the too-good-to-be-true blanket statement that forest bioenergy is carbon neutral. However, the many contingencies surrounding this issue must be considered if forest bioenergy is to actually contribute to the fight against climate change.

Food for thought: Carbon

HUMANnature - Tue, 03/06/2018 - 12:08pm

Written by Robert Griffin-Nolan, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Biology and Graduate Degree Program in Ecology

Without photosynthesis, humans would not be here. Photosynthesis is arguably the most valuable biochemical process on Earth. Without it we would have no food. Plants “eat” carbon dioxide (CO2) from the atmosphere and use the Sun’s energy to convert it into sugars. When tending to your house plant, you probably do not consider CO2 concentrations. You focus on proper lighting or adequate watering, factors you can control. However, the amount of CO2 in the atmosphere can have huge implications for plant function. It likely drove the evolution of several plant adaptations we observe today. For plants, carbon is food – and some plants are better than others at using it. Improving the carbon use efficiency of plants has caught the attention of a global community of plant breeders interested in increasing crop yields to feed the expected 9.8 billion people that will share this planet in 2050.1

Why do plants differ in their ability to use carbon? With all the CO2 we’ve been pumping into the atmosphere, one would think plants should be saturated in a carbon feast! In fact, photosynthesis is riddled with inefficiencies which are revealed in light of evolution. Plant life has its origins in the ocean, an environment that provides structural stability and plentiful hydration yet has very little CO2 (i.e. plant food). One of the environmental drivers of plants moving onto land over 400 million years ago was the high amount of CO2 in the atmosphere, approximately 10x higher than today’s atmospheric concentrations – truly a plant feast!2 The enzymes, or proteins, plants use to reorganize carbon into sugars were saturated in CO2. Thus, there was no “enzymatic incentive” to use it efficiently. In this carbon rich world, terrestrial plants thrived and conquered much of Earth’s land surface. However, as photosynthetic rates soared, CO2 concentrations dropped, revealing a lethal flaw in the photosynthetic pathway.

Ribulose-1,5-bisphosphate carboxylase/oxygenase, more commonly referred to as RuBisCO, is the most abundant protein on Earth.3 It is responsible for catalyzing the carbon fixing step of photosynthesis. RuBisCO is not a loyal servant of carbon, however, and has an affinity for another molecule, oxygen. When oxygen interacts with RuBisCO, in a process called photorespiration, there is less RuBisCO available to grab onto CO2, and thus less sugar is produced.

In a CO2 rich world, this was not an issue for plants; however, around 30 million years ago, CO2 concentrations dropped to the point where photorespiration became problematic.4 There was not enough ‘plant food’ to go around! Around this time, however, a more efficient form of photosynthesis emerged in the paleo-botanical record: C4 photosynthesis. This new biochemical pathway compartmentalized RuBisCO in specific plant cells that were then pumped full of CO2 to essentially remove any chance of RuBisCO interacting with oxygen. Variations of this particular carbon concentrating mechanism evolved not once, but more than 45 times in different plant lineages. The process of natural selection was hard at work.

Scientists are still debating what truly drove the evolution of C4 photosynthesis.5 The emergence of C4 photosynthesis was geographically isolated to some of the warmest and periodically dry regions of the world – tropical grasslands. Why didn’t it happen in other parts of the world? This is likely because the carbon concentrating mechanism of C4 photosynthesis allows plants to use water more efficiently.

CO2 is not freely available to plants but must be purchased. The currency for buying CO2 is water. Most plants are extremely inefficient at using water. For every molecule of CO2 gained by a plant, up to 400 molecules of water are lost! By preventing CO2 and O2 from fighting over RuBisCO, C4 plants can close the microscopic pores in their leaves used for exchanging gases, prevent excessive water loss, and survive in arid climates. Whether it was changing CO2 concentrations, climate or other factors (e.g. increased fire frequency4) that drove the evolution of C4 photosynthesis, the success of this new photosynthetic pathway was clear – C4 plants, and largely C4 grasses, spread rapidly throughout the world creating our warm savannas and grasslands. While C4 plants comprise a mere 3% of vascular plants species, they make up 25% of global photosynthesis6 – and it is this that has caught the attention of plant breeders.

In 2008, the Bill and Melinda Gates foundation awarded the International Rice Research Institute a grant of $11.1 million to begin the C4 Rice Project (http://c4rice.irri.org/), a 15-year collaborative research effort including 12 institutions with the goal of genetically modifying rice to use C4 photosynthesis. Rice, a staple food source for much of the world, is a C3 plant meaning it uses the relatively ‘carbon inefficient’ photosynthetic pathway that evolved over 2.8 billion years ago (named after the three-carbon sugar initially produced, C4 photosynthesis makes a four-carbon sugar). Indeed, many of our crops are C3 plants. The C4 Rice Project aims to identify relevant genes that code for proteins involved in C4 photosynthesis and eventually re-engineer the entire cellular structure and biochemistry of rice to mimic the C4 pathway, allowing rice to use water, light, and nutrients more efficiently. The end result is potentially a 50% increase in crop yield!7

There are multiple benefits of having C4 crops (some researchers remain skeptical of this increase in yield). C4 plants use nitrogen, or the building block of proteins, much more efficiently than C3 plants. Given that RuBisCO is saturated in CO2 in C4 plants, there is less need for RuBisCO production, and thus less need for nitrogen (i.e. fertilizer). Conversion of crops to C4 plants would greatly reduce our need for synthetic fertilizer with their attendant greenhouse gas emissions and resulting widespread eutrophication of our water bodies. Additionally, C4 crops would require less irrigation, given the higher water use efficiency of the pathway. Droughts are expected to become more common with climate change, a trend that is already apparent in California and even here in Colorado (see map). There is a reason why C4 grasses rapidly dominated the most arid regions of the world – they are masters of environmental stress.

If you’re concerned about genetic modification of crops, think about one number – 9.8 billion. That’s how many people we’ll have to feed by 2050. C4 photosynthesis has already evolved multiple times over the course of evolutionary history, one of the most amazing examples of convergent evolution. Scientists are now trying to make it happen just one more time. 


  1. United Nations, Department of Economic and Social Affairs, Population Division (2017). World Population Prospects: The 2017 Revision, Key Findings and Advance Tables. ESA/P/WP/248.
  2. Ehleringer, J. R., & Cerling, T. E. (1995). Atmospheric CO2 and the ratio of intercellular to ambient CO2 concentrations in plants. Tree Physiology, 15(2), 105-111.
  3. Ellis, R. J. (1979). The most abundant protein in the world. Trends in biochemical sciences, 4(11), 241-244.
  4. Sage, R. F. (2004). The evolution of C4 photosynthesis. New phytologist, 161(2), 341-370.
  5. Edwards, E. J., Osborne, C. P., Strömberg, C. A., Smith, S. A., & C4 Grasses Consortium. (2010). The origins of C4 grasslands: integrating evolutionary and ecosystem science. science, 328(5978), 587-591
  6. Still, C. J., Berry, J. A., Collatz, G. J., & DeFries, R. S. (2003). Global distribution of C3 and C4 vegetation: carbon cycle implications. Global Biogeochemical Cycles, 17(1).
  7. “C4 Rice Project”. http://c4rice.irri.org/

The ‘alternative [true] facts’- Reasons even climate change skeptics should support renewable energy development

HUMANnature - Wed, 02/21/2018 - 11:48am

Written by Kerry Rippy, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Chemistry

If you’re reading the SoGES Human Nature blog, chances are you’re already a proponent of renewable energy development. Why? Probably because you’re worried about climate change. That’s a great reason to advocate for sustainable energy, but it’s also a controversial and politicized topic that doesn’t always lend itself to reasonable discussion. To be unambiguously clear, this post is not meant to trivialize the importance of climate change or imply that we should shy away from discussing it. However, we live in a world of ‘alternative facts.’ There’s plenty of rhetoric out there to give generally reasonable people grounds to disagree with you about climate change. Fortunately, as a researcher devoting my career to sustainable energy, I think there are plenty of reasons, besides climate change, that my field is important and, frankly, exciting!

Let’s think of these reasons as a new type of ‘alternative facts,’—alternative not in the sense of being wildly unsubstantiated claims, but rather, in the sense that they’re based on validated scientific data that are not as polarizing as climate change. Just maybe, even if we can’t agree about the impact of fossil fuels, we can agree to take action and support renewable energy development. It’s important, because, as this MIT study points out, developments in the oil and gas sector mean that they aren’t going to run out or become unfeasibly expensive anytime soon.

The first, and probably least controversial alternative fact I think we can all agree on is that we should really be funding more battery research. While this would have a major impact on the field of renewable energy, there are plenty of other reasons to want better batteries as well. Everybody wants faster-charging, longer-lasting batteries for their smartphones and laptops, right? And battery research is also humanitarian cause. Read this, and that lithium cobalt oxide battery in your cell phone might feel a little heavier. Cobalt used in many batteries is almost entirely sourced from hand-dug mines in the Congo that, among other atrocities, utilize child labor. Better batteries that are faster, longer lived, and aren’t the root of a humanitarian crisis is something we can all agree on wanting, right?

And better batteries would really be a huge leap for renewable technologies. Right now, the energy density of a battery is less than a hundredth that of gasoline, so you need a 100-pound battery, or 1 pound of gasoline, to go the same distance, as reported here in APS physics news. Better batteries would also address the problem of storing energy generated by renewable sources like solar and wind. Electricity isn’t like liquid or gas fuels–you need technology a bit less rudimentary than a big tank to store it.

Alright, so we can agree on funding ways to store renewables. What are some alternative facts to get us all excited about generating it? Well, two of the primary sources are wind and solar. Let’s talk about some developments happening in those fields.

Let’s start with solar panels. You’re probably thinking of big heavy black panels stuck on the roof. But solar technology has is developing into so much more than that! Funding solar research could open up avenues of power generation that we have never before conceived. My own research is focused on organic solar cells. These solar cells are made of a lightweight, cheap material based on carbon molecules. We can make molecules that absorb most of the sun’s spectrum, but not visible light. We can also make molecules that are flexible. That means we can make solar windows, solar fabric, solar paint, Elon Musk’s solar roof tiles—you name it. And organic solar cells are just one of many exciting technologies. Perovskite solar cells are another up-and-coming inexpensive and efficient competitor for silicon solar cells, and silicon solar cells themselves are becoming less expensive and more efficient every day. There’s so much potential here. The market for things like this is there—we just need to develop the technology. Who doesn’t want to be the Rockefeller of the renewable era, with the foresight to see (and profit from) the way new energy sources could totally revolutionize our world?

What about wind technology? Well, one active research topic in this area is magnets. Every windmill requires about 2 pounds of an element called neodymium, which happens to be an incredibly strong magnet. (Check out this video.) The problem is neodymium is a rare earth metal. Actually, it is pretty abundant in certain places on earth, but those places happen to be in China. No problem, you say, make trade agreements with China. But wouldn’t it be better to have a solution that wasn’t dependent on tenuous international relations?

Speaking of international relations leads us to another alternative fact we can consider, that has nothing to do with climate change. Renewable energy development is a global problem, and much of the rest of the world is committed to addressing it. We should join them. Funding for renewable energy has continued increasing in non-OECD countries, recently matching and, in some cases, surpassing OECD commitment to renewables.

Even oil-rich countries like Saudi Arabia are enthusiastically pursuing renewables. A strong commitment to renewables is part of Saudi Arabia Vision 2030, an initiative intended to reduce their dependence on oil, diversify their economy, and develop public service sectors. As a renewable energy scientist, the plethora of jobs available to me in Saudi Arabia offer perks that no other location in the world comes close to matching. These perks reflect goals that have nothing to do with climate concerns and everything to do with economic dominance. The King of Saudi Arabia has confirmed that “attracting leading American companies in the renewable energy sector to invest in the Kingdom will highly contribute to the transfer of American expertise and techniques to the Kingdom and adding high and qualitative return to the Kingdom's renewable energy sector.” It sounds to me like the Kingdom of Saudi Arabia thinks it’s onto something, and is trying to take advantage of the fact that we aren’t.

Let me make one thing clear here. Discussing other countries’ investment in renewable technologies is not a fear-mongering tactic on my part. Of course, if the idea of diminishing American dominance strikes fear into someone’s heart and inspires them to renewable energy fanaticism, by all means, champion the cause! I’d say they’re right for the wrong reasons, but I’m not going to squabble about the purity of their motivations if we’re working to achieve the same thing. However, the reason I am discussing this topic is to emphasize that forward-looking perspectives see renewable energy as the most feasible avenue, even disregarding climate change.

And, a final alternative fact for you: In matching much of the rest of the world’s commitment to developing renewable energy, we can do good things for our own country. According to the recently published Department of Energy 2017 U.S. Energy and Employment Report, energy efficiency employers project the highest growth rate over the next 12 months (about 9%) while the fuels sector projects a decline in employment of about 3% over the same period. As a recent New York Times article put it, today’s energy jobs are in solar, not coal.

There you have it: A set of ‘alternative facts,’ in support of renewable energy research that are all true, convincing, and have nothing to do with climate change.  In a world where confirmation bias and the bad sort of ‘alternative facts’ abound, lets try to find common ground.

Everyday experiences with particulate air pollution: Where there’s smoke, there’s…

HUMANnature - Tue, 02/13/2018 - 9:51am

Written by Jessica Tryner, a 2017-2018 Sustainability Leadership Fellow and Postdoctoral Fellow in the Department of Mechanical Engineering.

It’s Labor Day, and I’m driving home from the grocery store. I blink a few times. Is something wrong with my eyes? No. It’s hazy. It’s really hazy. It’s especially noticeable mid-day, when we’re used to seeing sunshine and clear blue skies in Colorado’s Front Range. The haze obscuring the afternoon sun means that the concentration of microscopic particles suspended in the air is high. “How bad is it?” I wonder. 50 µg·m-3? 100 µg·m-3?

The many small particles—generated by natural sources and human activities—that become suspended in the atmosphere are collectively referred to as “particulate air pollution.” The most extreme particulate air pollution on Colorado’s Front Range occurs when the region is affected by wildfire smoke (see Figure 1). On Labor Day 2017, the Front Range was blanketed in smoke transported from fires in states north and west of Colorado (1), and the concentration of particles smaller than 2.5 µm (abbreviated PM2.5) suspended in the Fort Collins air was more than 8 times the annual average. These elevated PM2.5 concentrations put our health at risk.

Particulate air pollution is all around us—literally! Although the highest levels occur when the Front Range is affected by wildfire smoke, more common sources of particle emissions include motor vehicles and wood stoves—technologies that many of us use daily. When we breathe, small particles penetrate deep into our lungs, and exposure to particulate air pollution has been linked to respiratory and cardiovascular disease (2). Globally, there are 4 million deaths associated with ambient particulate matter pollution each year. Children, the elderly, and people with existing cardiovascular or respiratory disease (e.g., asthma) are more susceptible to particle-related health impacts (3). Ensuring that all people have air that is safe to breathe, both now and in the future, is an important component of sustainability.

In the absence of wildfire smoke, levels of particulate air pollution in Fort Collins are generally below Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. Unfortunately, researchers have estimated that 87% of the global population lives in areas where the annual average concentration of PM2.5 in the outdoor air is above the WHO guideline of 10 µg·m-3 (4).

Each state in the U.S. maintains a network of instruments that monitor particulate air pollution at various locations (see Figure 2). If you are interested in air quality, you can access readings from monitors across Colorado here. These monitors take accurate measurements, but they are expensive and require scientific expertise to operate. As a result, measurements are only available for a limited number of locations. For example, Fort Collins is home to the only PM2.5 monitor in Larimer County (which is home to 300,000 people and covers an area of 2600 mi2). Particle sources and concentrations can vary on smaller spatial scales than that.

When I get home from work, I’m greeted with, “You smell like a campfire.” But I haven’t been sitting around a campfire. I just spent 15 minutes riding my bike through Old Town at 9pm on a winter evening (yes, 9pm—I’m a postdoc). As the name of the neighborhood implies, there are a lot of old homes in Old Town. Many old homes feature wood-burning stoves and fireplaces, and these stoves emit particles that impact our local air quality.

To complicate things further, the concentration of particulate air pollution to which we are exposed is not simply equal to the outdoor concentration in the city where we live (5). Outdoor air pollution contributes to our personal exposure, but we are exposed to different concentrations of particulate matter in different locations (e.g., at home, at work, during our commutes) and during different activities (e.g., sleeping, cooking, cleaning) (6). For example, a study of commuters in Fort Collins found that cyclists were exposed to higher levels of particulate air pollution than people who commuted by car (7).

To reduce our exposures, we need to know how particulate matter concentrations vary from one location to the next, where the particles in those different locations are coming from, and which of our daily activities result in the highest exposures. To characterize particulate air pollution in a greater number of locations, we need monitors that are affordable, portable, and accurate. We need unobtrusive wearable monitors that can measure an individual’s personal exposure to PM2.5 (8), and small stationary monitors that citizen scientists (that can be you!) can use to measure levels of particulate air pollution in their own backyards.

Sunshine poured into my living room. Did that mean that big cloud had gone away? I wandered out into my backyard and tried to look at the sun. “Ow,” I thought, “That’s why they told you not to look directly at the sun when you were a kid.” It looked like the big cloud was still there, though. The sunlight was peeking through it, but the sun itself was still obscured…Like most things in research, this was turning out to be more difficult than I expected.

As part of my research, I help develop and test backyard monitors (see Figure 3) that citizen scientists can use to measure particulate air pollution levels. Inside one of these monitors, air is pulled through a filter for 48 hours. Particles are trapped on the filter, and the filter is weighed to determine the average mass of particles per unit volume of air during that 48-hour period. The monitors also quantify the amount of sunlight that doesn’t make it through the Earth’s atmosphere due to particulate air pollution (a quantity called “aerosol optical depth”). That’s why I needed a clear view of the sun. Why measure aerosol optical depth? Because satellites circling the Earth also measure the amount of light attenuated by the atmosphere. The satellite measurements can be used to generate global maps of particulate air pollution, but, to do that, they need to be related to of the quantity of interest: the mass concentration of PM2.5 at ground level (9). By establishing a dense network of monitors that measure aerosol optical depth and PM2.5 mass concentration simultaneously, we can help improve these maps and gain a better understanding of PM2.5 concentrations in locations that lack ground-based monitors. The citizen scientists who take these measurements gain a better understanding of pollution levels in their own backyards and contribute to a better understanding of regional and global air pollution.

Particulate air pollution is a problem that we all contribute to and are affected by, but with researchers and citizen scientists working together—using accurate, affordable PM monitors—we can all be part of the solution.

  1. B. Ford, Labor day, a holiday up in smoke. Fort Collins Air Qual. (2017), (available at http://ftcollinsaq.blogspot.com/2017/09/labor-day-holiday-up-in-smoke.html).
  2. J. O. Anderson, J. G. Thundiyil, A. Stolbach, Clearing the Air: A Review of the Effects of Particulate Matter Air Pollution on Human Health. J. Med. Toxicol. 8, 166–175 (2012).
  3. J. D. Sacks et al., Particulate Matter–Induced Health Effects: Who Is Susceptible? Environ. Health Perspect. 119, 446–454 (2010).
  4. M. Brauer et al., Ambient Air Pollution Exposure Estimation for the Global Burden of Disease 2013. Environ. Sci. Technol. 50, 79–88 (2016).
  5. W. E. Wilson, M. Brauer, Estimation of ambient and non-ambient components of particulate matter exposure from a personal monitoring panel study. J. Expo. Sci. Environ. Epidemiol. 16, 264–274 (2006).
  6. L. Wallace, R. Williams, A. Rea, C. Croghan, Continuous weeklong measurements of personal exposures and indoor concentrations of fine particles for 37 health-impaired North Carolina residents for up to four seasons. Atmos. Environ. 40, 399–414 (2006).
  7. N. Good et al., The Fort Collins Commuter Study: Impact of route type and transport mode on personal exposure to multiple air pollutants. J. Expo. Sci. Environ. Epidemiol. 26, 397–404 (2016).
  8. J. Volckens et al., Development and evaluation of an ultrasonic personal aerosol sampler. Indoor Air. 27, 409–416 (2017).
  9. A. van Donkelaar et al., Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application. Environ. Health Perspect. 118, 847–855 (2010).

Shhh… reducing noise to save the voice of the natural world

HUMANnature - Tue, 02/06/2018 - 1:35pm

Written by Rachel Buxton, a 2017-2018 Sustainability Leadership Fellow and Postdoctoral Fellow in the Department of Fish, Wildlife, and Conservation Biology.

Imagine yourself in your favorite park, looking out over an expansive wilderness. You close your eyes and take in the natural quiet – the wind rustling the leaves, a nearby babbling brook, and birds singing from the trees. We’ve only now started to understand the importance of these natural sounds and the collective ‘soundscape’ they create.  For humans, natural soundscapes restore our senses: reducing stress, increasing our ability to concentrate, and improving mood1.  Most animals rely, at least in part, on sound to carry out essential activities such as finding and avoiding becoming food2. Unfortunately, these natural sounds are increasingly under threat.

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Listen: birds sing next to a mountain stream in Rocky Mountain National Park

What is a soundscape?

Each landscape has its own unique set of sounds. These soundscapes include a variety of geophysical sounds, such as ocean waves and thunder storms.  This is accompanied by the sounds that animals produce for communication, from wolves howling to frogs calling.  Animals produce and listen for these acoustic signals to defend territories, attract mates, deter predators, navigate, find food, and maintain social groups. In the same way that animals eat particular food and use specific habitat to avoid competition with other species in an ecosystem, animals use a specific part of the acoustic environment to avoid overlapping sound signals3.  For instance, birds with songs at a similar pitch will stagger their songs so as not to sing at the same time. Thus, each species occupies what is known as an ‘acoustic niche’.

A spectrogram (a visualization of sound) showing pitch (or frequency - in kHz) on the vertical axis, time on the horizontal axis, and loudness (or amplitude - in dB) in different shades of orange. Each animal's sounds in a distinct pitch is an example of species occupying an 'acoustic niche'4.


When habitats are disturbed, the acoustic environment is thrown off balance, altering the natural partitioning of acoustic space. For example, an invasive species that sings at the same pitch as a native species may cause ‘acoustic competition’, in which acoustic communication among native species is degraded by the sounds produced by an invader5. Also, human produced sound, such as traffic and machinery noise, has become widespread, causing disruption of the acoustic environment at enormous scales6.

What is noise pollution?

“Noise” is an unwanted or inappropriate sound. Human sources of noise in natural environments include sounds from aircraft, roads, machinery, or industrial sources. According to the Environmental Protection Agency, noise pollution is noise that interferes with normal activities, such as sleeping and conversation, and disrupts or diminishes our quality of life8.

How much of a threat is posed by noise pollution?

Noise pollution interferes with natural soundscapes by masking natural sounds. In other words, important natural sounds are either no longer audible or severely degraded by overlapping human produced sound.  For humans, noise pollution degrades the calming effect that we feel when visiting natural areas and listening to natural sounds.  For wildlife, the inability to hear acoustic signals can disrupt essential life processes and can mean the difference between life and death for many species9.  In turn, noise pollution alters ecological communities. For example, reduced hunting success of carnivores can result in inflated numbers of prey species such as deer.

As transportation networks, resource extraction, motorized recreation, and urban development continue to grow, human produced noise has become ubiquitous. In the United States, noise pollution has altered soundscapes in even the most remote protected areas. A recent study found that although wilderness areas – places that are preserved in their natural state, without roads or other development – generally experience near-natural sound levels, 12% experienced noise pollution that doubled sound energy6.  Noise pollution at these levels results in a 50% reduction in the distance at which natural sounds can be heard.  Wilderness areas are managed to minimize human influence, so most noise sources come from outside their borders.

How do we protect natural soundscapes?

Strategies to reduce noise in protected areas include establishing quiet zones where visitors are encouraged to quietly enjoy protected area surroundings, and confining noise corridors by aligning airplane flight patterns over roads. Thus, unlike less tractable threats, like climate change, we have the tools to take action and control noise pollution now.

Protecting natural acoustic environments is important to protect wildlife and so that people can still enjoy the sounds of birdsong and wind through the trees.


1Gould van Praag CD, Garfinkel SN, Sparasci O, Mees A, Philippides AO, Ware M, Ottaviani C, and Critchley HD. 2017. Mind-wandering and alterations to default mode network connectivity when listening to naturalistic versus artificial sounds. Scientific Reports 7:45273.
2Brumm H. 2013. Animal communication and noise. Springer-Verlag, Berlin, Germany.
3Pijanowski BC, Villanueva-Rivera LJ, Dumyahn SL, Farina A, Krause BL, Napoletano BM, Gage SH, and Pieretti N. 2011. Soundscape ecology: the science of sound in the landscape. Bioscience 61:203-216.
4Servick K. 2014. Eavesdropping on ecosystems. Science 343:834-837.
5Both C, and Grant T. 2012. Biological invasions and the acoustic niche: the effect of bullfrog calls on the acoustic signals of white-banded tree frogs. Biology Letters 8:714-716.
6Buxton RT, McKenna MF, Mennitt DJ, Fristrup KM, Crooks K, Angeloni LM, and Wittemyer G. 2017. Noise pollution is pervasive in U.S. protected areas. Science 356:531-533.
7Zwart MC, Dunn JC, McGowan PJK, and Whittingham MJ. 2016. Wind farm noise suppresses territorial defense behavior in a songbird. Behavioral Ecology 27:101-108.
9Simpson SD, Radford AN, Nedelec SL, Ferrari MCO, Chivers DP, McCormick MI, and Meekan MG. 2016. Anthropogenic noise increases fish mortality by predation. Nature Communications 7:10544.

Did Climate Change Cause Hurricane Harvey?

HUMANnature - Tue, 01/30/2018 - 2:47pm

Written by Alexandra Naegele, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Atmospheric Science.

This past summer, Hurricane Harvey rolled into west Texas and stalled, causing disastrous flooding. The National Hurricane Center just released their final report on Hurricane Harvey and the final numbers are in: Maximum recorded rainfall of over 60 inches. Widespread recorded rainfall of 36 to 48 inches (compared to the 50 inches of rainfall that Houston generally receives over the course of an entire year). Storm surge up to 10 feet. Over 300,000 structures flooded. An estimated 40,000 people evacuated. At least 68 direct deaths. Months later, Houston is far from being fully recovered.

If there is one thing that’s certain, it’s that Hurricane Harvey devastated the region. With such an impactful storm, it predictably received an onslaught of national media attention. What was less certain, however—at least from the public perspective—was if and how Hurricane Harvey was a result of climate change.

After Harvey hit, headlines—admittedly from sources with a wide range of credibility—ran the gamut, from “Hurricanes Harvey and Irma Can’t Be Blamed on Global Warming” to “Scientists Link Hurricane Harvey’s Record Rainfall to Climate Change.” Among those from the most reliable sources, the best headlines avoided sensationalism; the worst were rife with ambiguity. Thus, the question that was on everyone’s minds remained: Did climate change cause Hurricane Harvey?

As tempting as it may be to hastily draw conclusions and answer that question with a resounding “Of course!,” the answer is unfortunately far from straightforward. But perhaps the best place to start when thinking about the attribution of extreme weather events to climate change is with a helpful analogy, courtesy of Marshall Shepherd, a Meteorologist and Professor of Geography at the University of Georgia. As he explains it, “Think of bad storms like home runs in baseball’s recent steroid era. Sure, the big hitters have always hit home runs, and I can’t say that any one homer resulted from steroid use. However, I can make the argument that steroids made a lot more balls go over the fence than normal.”

Applying this line of thought to hurricanes, we know that hurricanes existed before humans first began emitting massive quantities of greenhouse gases (GHGs) into the atmosphere, and we know that hurricanes exist at present. But it is also true that such large-scale GHG emissions can lead to conditions favorable for hurricane formation and persistence. So although we cannot conclusively say that anthropogenic climate change is the clear cause of one particular hurricane, such as Hurricane Harvey, we can confidently say that there is a likely connection between the two. But perhaps a more important question is, what is the impact of climate change on extreme weather events in general?

Although it is misguided to attribute an event to climate change outright, it is entirely different to ask about the ways in which it might have been affected by climate change. It is questions like these that drive the emerging field of event attribution. A distinguishing aspect of this subfield is that they are making a point to ask the right questions, primarily: Is climate change affecting the likelihood of an event? And, is climate change affecting the intensity of an event? Additionally, these questions are accompanied by a deep understanding of the assumptions and uncertainties that are inherent in the data and the methodologies.

Perhaps the biggest takeaway from this growing body of research is that not all events are equal—at least in terms of event attribution. The factors that determine our ability to attribute an event to climate change are the capabilities of climate models, the data record, and an understanding of the mechanisms that would cause these events to change (National Academy of Sciences, 2016). As shown in the table and figure below, these three conditions are all well met for events related to extreme temperatures; the same cannot be said for severe convective storms (e.g. thunderstorms).

With these points taken into consideration, the Bulletin of the American Meteorological Society recently published their latest special issue on event attribution, Explaining Extreme Events of 2016 (Herring et al., 2018). Remarkably, this is the first year in which several events have been found to lie outside the bounds of natural variability. Perhaps somewhat unsurprisingly, each of these events were extreme heat events. To be clear, however, this is not the first time, by any means, in which the fingerprint of climate change has been detected on specific extreme weather events.

To some, it might be interpreted that by detaching Hurricane Harvey (or any extreme weather event) from climate change—even if only slightly, by saying that it is not a 100% cause and effect relationship—it serves either to trivialize the event, to trivialize climate change, or potentially, to do both. On the contrary, I would argue that by not dismissively answering these questions with a simple yes (or no), this opens us up to more nuanced consideration of the complexity of our dynamic climate system—and the ways in which we are intimately and actively connected to it. With that in mind, it’s in our own best interest to gain a more comprehensive understanding of the ways in which we are affecting the climate system, as well as the ways in which it will affect us in turn. Our improved understanding requires that we find the right answers, but to get the right answers we must first ask the right questions.


Herring, S. C., N. Christidis, A. Hoell, J. P. Kossin, C. J. Schreck III, and P. A. Stott, Eds., 2018. Explaining Extreme Events of 2016 from a Climate Perspective. Bull. Amer. Meteor. Soc., 99 (1), S1–S157.

National Academies of Sciences, Engineering, and Medicine, 2016. Attribution of Extreme Weather Events in the Context of Climate Change . Washington, DC: The National Academies Press.

Can soil save us? Unearthing the new ‘4 per mille’ soil health initiative

HUMANnature - Thu, 01/18/2018 - 2:44pm

Written by Erika Foster, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Graduate Degree Program in Ecology and Department of Soil and Crop Sciences.

Poor management and lost carbon. Since the dawn of agriculture, humans have cleared forested lands, razing all natural vegetation for the sake of food production. Land use change has now impacted over 40% of all land mass, upsetting natural global processes including the carbon cycle. Land use change causes carbon loss by removing plant biomass, causing the accumulation of CO2 in the atmosphere, and decreasing the soil carbon via lower inputs and exposed soil erosion. Forests naturally store carbon by pulling carbon dioxide (CO2) from the atmosphere for photosynthesis and storing it in their biomass. Tree roots and decaying leaf litter also add carbon into the soil, where organic carbon compounds stick to clay particles and remain there for decades to centuries.1 The reservoir of carbon in the soil, or soil carbon “pool,” accounts for 1500-2400 petagrams (Pg) of carbon globally (see global carbon figure).2 With agriculture and grazing, we have now lost 133 Pg of carbon from the top two meters of soil,3 resulting in more carbon in the atmosphere contributing to global warming.  Since soil naturally stores more carbon than the atmosphere and terrestrial biomass combined, soil plays a critical role in the global carbon balance. Despite its importance, soil only recently made a debut on the international climate policy stage, but not without controversy. 

Below, the global carbon cycle, as represented in the IPCC 2014 report , includes pools of carbon in the atmosphere, terrestrial biomass, and soils, measured in petagrams (Pg) of carbon.2 The red text indicates how humans have altered the carbon cycle. 1 Pg = 1 Gigaton = 1015 kg = 1 billion metric tons.(For a classic climate reference, a polar bear weighs 0.5 metric tons.)

Resetting the carbon cycle. International negotiations focused on reducing greenhouse gas emissions and rebalancing the carbon cycle have occurred at the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change for the last two decades. The most recent COP21 in Paris produced the Climate Agreement in which over 190 countries pledged to reduce their greenhouse gas emissions and keep global warming under 2°C. In conjunction with the primary agreement, a new French initiative proposed to mitigate climate change by storing carbon in non-atmospheric pools, particularly in soil.

This infographic from the 4 per mille initiative website, arguably, simplifies the concept that adding 0.4% carbon to soil annually will mitigate anthropogenic carbon emissions to the atmosphere. The numbers used here are also slightly different than reported in the literature 4,5,6

In 2015, the French minister of Agriculture, Stéphane Le Foll, introduced a unique international program: the “4 per 1000 Soils for Food Security and Climate.”4 The idea is simple. Human activities emit 8.9 Pg of carbon into the atmosphere annually; if we add an equivalent 8.9 Pg of carbon into the soil each year, we can offset our carbon emissions. The 8.9 Pg of C only is 0.4% of the total 2400 Pg of soil carbon. We can represent this tiny number either as 0.4% (using the ‘per cent’ symbol, out of 100) or 4‰ (using the ‘per mille’ symbol, out of 1000), hence the colloquial name of the ‘4 per mille’ initiative.

The initiative proposes that we add carbon at a rate of 4‰ annually in the top 30-40 cm of agricultural soils. At first this seems like a relatively small amount and an achievable goal, but opposition developed as soon as soil scientists began to crunch the numbers. Is ‘4 per mille’ possible?

The science behind ‘4 per mille’. While the ‘4 per mille’ initiative set a concrete goal, scientists quickly began to investigate and question its feasibility. In a collaborative international paper scientists Minasny et al. examined the possibility of adding 4‰ soil carbon in agricultural soils in 20 distinct world regions (Geoderma, 2017).5 Misany et al. calculate that we need to store carbon at a rate of 0.6 metric tons per hectare per yr. (One hectare (ha) equals roughly two football fields). To sequester or increase carbon storage in soils, we can use the following practices:

  • Plant forests (afforestation) (0.6 t/ha/yr),
  • Convert land to pasture (0.5 t C/ha/yr),
  • Add organic amendments (0.5 t/ha/yr),
  • Keep crop residues (0.35 t c/ha/yr),
  • Use reduced or no tillage (0.2 t C/ha/yr), and
  • Rotate crops (0.2 t C/ha/yr).5

Even after implementing all of these possible practices, Minasny et al. calculated sequestration rates fell in between 0.2-0.5 t C/ha/yr, shy of the target rate 0.6 t C/ha/yr.5 Since ‘4 per mille’ number was based on a global calculation, it does not account for certain soils that cannot store any more carbon, such as high carbon peat and bog soils. Also, Minasny et al. point out that smaller countries cannot do their part offset their own emissions. For example Belgium and South Korea do not have enough agricultural land available to offset their own greenhouse gas emissions at the ‘4 per mille’ rate. The scientists go on to explain that the initiative also ignores the ‘lifespan’ of the added carbon in the soil. In wet, hot, tropical environments the decomposition rates in soils are high, meaning that the soil critters (worms, beetles, bacteria and fungi) rapidly use the added carbon as food, breaking it down and releasing CO2 on a relatively short timescale. The research by Minasny et al. concluded that only 20-35% of global anthropogenic emissions could be sequestered in the top 1m of agricultural soils, due to initial high carbon content of some soils, the limited available agricultural lands, and climate factors.5 The authors include a positive note, stating that dry regions with degraded soil, like much of Australia, may sequester more than 4‰ , potentially even up to 10‰ annually. The researchers posit that the ‘4 per mille’ initiative, although aspirational, remains an important mechanism to put soils on the map and delineate goals for climate-smart management.

The discussion of ‘4 per mille’ heated up when scientists Baveye et al. submitted a Letter to the Editor of Geoderma: “The ‘4 per 1000’ initiative: A credibility issue for the soil science community?”6 The scathing pieces called out the initiative for being “deceptively simple,” having “considerable uncertainty,”

The per mille rate of carbon sequestration decreases over time since addition from several world regions reported by Minasny et al.5
Red diamonds = crops,green dots = grassland, blue stars = forest/plantation.

and misrepresenting farmers heroically as part of the solution, rather than the problem. Baveye et al. again question the ‘lifespan’ of new carbon addition in soils, stating that Minasny et al. glossed over their graph showing that new carbon may remain in soil for only a couple of years to decades,6 not exactly a long-lasting climate change mitigation strategy. Furthermore, Baveye et al. emphasize that governments need to calculate the cost of inputs and monitoring programs, before implementation. The authors reiterate that the initiative is “aspirational,” and add that “no matter how many times one tries...to say that the value of 0.4% should not be taken literally…there is a clear risk that policy-makers…will simply take the misleading message…at face value.”6 So, how can we discriminate between the aspirational global “4 per mille” initiative and the actual regional 4‰ soil carbon sequestration potential?

Can soil save us? The conversation continues between soil scientists in meetings, conferences, and peer-reviewed journals such as Geoderma and Environmental Science and Technology. We know that any blanket calculation will not hold true in every ecosystem, but quick estimates provide numbers necessary for strategy comparisons and decision making. Although the ‘4 per mille’ initiative boldly proposes that soils are the solution, the proposed management practices at least bring critical soil carbon into the discussion. Full understanding of nuanced soil processes, such as nutrient balance, temperature effects on decomposition, and uncertainty of global soil carbon estimates, proves challenging even for scientists. Policy-makers require concrete numbers on which to base decisions. The problem with ‘4 per mille’ lies in the fact that climate change is a global issue, but not all soils around the world are created equally; a single number will never be attainable. Scientists recognize the potential of agricultural soils to sequester carbon using a myriad of regionally-specific techniques. Climate change mitigation requires motivating global policies, such as the laudable ‘4 per mille’ initiative. However, lofty aspirational goals, in practice, require numerous local solutions. Shifting to climate-smart agricultural practices may mitigate climate change, but only in conjunction with improved practices in other sectors (e.g., transportation, industry, energy generation). Ultimately, can soil save us? Certainly not soil alone.


  1. Baveye, P.C., Berthelin, J., Tessier, D., Lemaire, G., 2018. The “4 per 1000” initiative: A credibility issue for the soil science community? Geoderma 309, 118–123.
  2. IPCC, 2014. Climate Change 2014: Synthesis Report, Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.
  3. Minasny, B., Arrouays, D., McBratney, A.B., Angers, D.A., Chambers, A., Chaplot, V., Chen, Z.-S., Cheng, K., Das, B.S., Field, D.J., Gimona, A., Hedley, C., Hong, S.Y., Mandal, B., Malone, B.P., Marchant, B.P., Martin, M., McConkey, B.G., Mulder, V.L., O’Rourke, S., Richer-de-Forges, A.C., Odeh, I., Padarian, J., Paustian, K., Pan, G., Poggio, L., Savin, I., Stolbovoy, V., Stockmann, U., Sulaeman, Y., Tsui, C.-C., Vågen, T.-G., Wesemael, B. van, Winowiecki, L., 2018. Letter to Editor: Rejoinder to Comments on Minasny et al. Geoderma 309, 124–129.
  4. “4 per 1000 Initiative.” Webpage, 2017. https://www.4p1000.org/. Accessed Jan 2018.
  5. Paul, E.A., 2016. The nature and dynamics of soil organic matter: Plant inputs, microbial transformations, and organic matter stabilization. Soil Biology and Biochemistry 98, 109–126.
  6. Sanderman, J., Hengl, T., Fiske, G.J., 2017. Soil carbon debt of 12,000 years of human land use. Proceedings of the National Academy of Sciences 114, 9575–9580.

Is the glass of orange juice half empty?

HUMANnature - Fri, 01/12/2018 - 1:11pm

Written by Stephen Cohen, a 2017-2018 Sustainability Leadership Fellow and PhD Candidate in the Department of Bioagricultural Sciences and Pest Management

What’s more American than a glass of orange juice in the morning? Last year, over 47 million boxes of Valencia oranges were produced in the United States [1], but this fundamental part of American breakfast is in danger of disappearing.

Huanglongbing (HLB), also known as citrus greening, is a disease of citrus trees that is wreaking havoc on worldwide production of oranges, grapefruits, lemons, limes, and more. Once infected, a tree will begin to produce green, oddly-shaped and bitter fruits before ultimately dying within five years. This incurable plant disease is caused by the bacterial pathogen Candidatus Liberibacter asiaticus, which is spread from tree to tree by insects called Asian citrus psyllids. These tiny jumping insects are invasive to North America.

HLB first appeared in the U.S. in 2005, when infections were detected in Florida orange groves. The disease spread, resulting in at least $4 billion of economic damage and the loss of 8,000 jobs over the ten years that followed. By today, HLB has been detected in most U.S. citrus growing regions, including California, Georgia, Louisiana, Puerto Rico, South Carolina, Texas, the U.S. Virgin Islands, and all citrus-growing counties in Florida.

The economic toll of the HLB outbreak has been devastating. In Florida, which is in the top three global regions for growing juice oranges, nearly all orange growing counties have lost oranges due to HLB [2]. HLB is not the only factor influencing orange production losses, but many experts speculate that it is the single greatest factor that has influenced the greater than 70% decline in Florida’s orange production over the last 12 years.

Since HLB is incurable, the recommended disease management solution is to prevent its spread by killing the insects that transmit it. To wipe out the psyllids, citrus growers use aggressive and repeated sprays of insecticide cocktails, but this solution is neither safe nor sustainable. Overuse of insecticides may present a health risk to orchard workers and consumers, while also allowing the insects to adapt to overcome insecticide treatments. For this approach to be effective, abandoned citrus groves would also have to be destroyed or treated, since both the bacteria and insects can survive on dying plants. However, treating abandoned orchards can be a total economic loss for farmers – so who would cover the expense?

In addition to insecticides, citrus growers are using other strategies to control the disease. Plastic enclosures called isolation tents protect trees from insects and raise the temperature to slow disease progression. Because HLB infection disrupts plant nutrient uptake, enriching the soil with extra nutrients prolongs the lives of trees. Limited trials have been approved for treating orchards with antibiotics. These solutions are only effective in the short-term, and no permanent solution has been found. As a result, many Florida farmers are switching from growing oranges to alternative crops, which is further contributing to the loss of juice orange production.

Many scientists are now advocating the use of biotechnology solutions, including the production of genetically modified (GM) trees, to solve the HLB crisis. For example, using transgenic technologies, a team of researchers at the University of Florida produced GM orange trees that were immune to HLB [3]. After three years, these trees remained disease-free, even when planted in areas with unmanageable levels of the disease.

While biotechnologies are helping scientists quickly develop efficient solutions to control HLB, the greatest challenge to widespread adoption of these technologies may be consumer acceptance. Historically, U.S. consumers are wary of GM foods, and there has been pushback against them. And in a recent survey of Florida citrus growers about the prospect of growing GM trees, the growers’ biggest concern was consumer reactions [4].

How will consumers react to the disappearance of the nation’s supply of homegrown oranges? Because the use of biotechnology is producing real, long-term solutions to HLB, perhaps the stubbornness to accept GM foods may decline in the face of rising cost and rarity of the nation’s supply of homegrown oranges disappearing. After all, can we live without our morning orange juice?


  1. United States Department of Agriculture National Agriculture Statistics Service. 2018. https://www.nass.usda.gov. Accessed: January 2018.
  2. Neupane D, Moss CB, van Bruggen AH. Estimating citrus production loss due to citrus huanglongbing in Florida. 2016 Annual Meeting, Southern Agricultural Economics Association. In: 2016 Annual Meeting, Southern Agricultural Economics Association, 6-9 February 2016, San Antonio, TX.
  3. Dutt M, Barthe G, Irey M, Grosser J. Transgenic Citrus Expressing an Arabidopsis NPR1 Gene Exhibit Enhanced Resistance against Huanglongbing (HLB; Citrus Greening). PLoS ONE. 2015;10(9): e0137134.
  4. Singerman A, Useche P. Florida Citrus Growers’ First Impressions on Genetically Modified Trees. AgBioForum. 2017;20(1):67-83.

Pathogens, People, and Pachyderms in Transfrontier Conservation

HUMANnature - Wed, 12/20/2017 - 12:06pm

Written by Laura Rosen, a 2017-2018 Sustainability Leadership Fellow and PhD candidate in the Graduate Degree Program in Ecology and Department of Clinical Sciences

“Jane” is 31, a mother of two working in international tourism, and weighs 6,000 pounds. Jane (name changed to protect her identity) is an African elephant, one of about 60 elephants working at ecotourism facilities in the Victoria Falls area of Zimbabwe and Zambia. These elephants live moments away from one of the seven natural wonders of the world, surrounded by a diversity of wildlife. But all is not perfect here, and one of the less visible problems that poses a threat is that of infectious diseases. Tuberculosis (TB) is still a major problem in humans in this part of the world, and can spread to animals as well.

We often think of zoonotic diseases as those we can get from animals, such as avian influenza, rabies, or Lyme disease. Animals can also get diseases from us – as with elephants and TB. Elephants have probably been getting TB from humans for at least 2000 years, and it has been diagnosed more frequently in the last 20 years in elephants cared for by humans. Elephants can also transmit TB back to humans and to other elephants. Given how common human TB is here, Jane and other elephants around the Victoria Falls area were tested to look for antibodies to the bacteria that cause TB. This collaborative project between researchers in the US and South Africa, and local veterinarians and conservationists in Zimbabwe was the first study looking at TB in working elephants in Africa.

While TB might be thought of as a disease from a bygone era in the United States, it has not been forgotten elsewhere in the world. One in four people in the world is infected with bacteria that cause TB. Most will never develop TB, which typically affects the lungs, and can cause general symptoms like cough and weight loss. Even so, every year more than 10 million new TB cases are diagnosed, and more than 1.5 million people die of the disease. Millions of dollars are spent around the world every year on efforts to test for, treat, and prevent TB.  Domestic animals like cattle also get TB, and in some cases, people can get sick if they have extended close contact with an infected animal or consume products like milk from an infected animal. TB affects species around the world, including wildlife such as rhinos, primates, and elephants like Jane.

We found that several elephants tested positive for TB antibodies. Antibodies are produced by the immune system when it encounters something foreign, like bacteria, and remain in the blood to allow for a quick response should that bacteria be encountered again. When antibodies to a specific pathogen are present, they indicate that the animal has been exposed to the bacteria at some point, but don’t tell us whether an animal is currently infected. These results do suggest that we should be monitoring animals in this area for TB and trying to minimize the spread of diseases like TB among humans, livestock, and wildlife.

TB can spread from working elephants to wild elephants when these elephants use the same areas and when people encourage mating of captive females and wild males. The spread of TB to wild elephants is a major concern, because TB is very difficult to eradicate in wild populations. Within the last 5 years, there have been reports of TB in wild elephants in Africa and Asia. Elephant populations are declining, so it’s vital to focus on their conservation to ensure that these iconic species remain a part of the landscape for generations to come.

Finding TB in wild elephants where Jane and the rest of her herd live would be alarming, because this area is home to Africa’s largest connected populations of elephants. Victoria Falls is at the center of the Kavango-Zambezi Transfrontier Conservation Area, which incorporates land from Angola, Botswana, Namibia, Zambia, and Zimbabwe into a region about the size of Colorado and Wyoming combined. As the name suggests, transfrontier conservation areas are designed to promote conservation and sustainable management of the rich natural resources of these areas, and benefit economic development of local communities through tourism. They combine large tracts of public, private, and communal lands across the borders of multiple countries in southern Africa. Historically, people built fences throughout this landscape to separate livestock and wildlife, but these fences disrupted migration paths for wildlife. Connecting land within a conservation area involves removing fences and joining fragmented habitat to allow wildlife to move freely. While unrestricted wildlife movement can benefit conservation, it can also increase disease transfer among wildlife, livestock, and people.

Southern Africa is home to many diseases of economic or public health significance, including TB, which must be considered in the management of these areas. Take an example from another transfrontier conservation area, which includes South Africa’s famed Kruger National Park. In the 1990s, African buffalo in the park began getting sick with bovine TB, a disease that came from cattle outside the park. The disease spread through the park, not just in buffalo but in other species like kudu and warthog. Carnivores like lions prey on the buffalo weakened by TB and then become infected themselves. Now TB appears to have spread across the Zimbabwean border to buffalo in Gonarezhou National Park. This real-life scenario serves as a warning for the potential for disease spread within a transfrontier conservation area.

Avoiding a similar outcome in Kavango-Zambezi is an opportunity to implement the One Health Initiative, which emphasizes the connections between human, animal, and environmental health. Preventing and managing TB in people and animals requires coordinated efforts in among multiple species. Routinely testing the elephants and their handlers for TB is important to recognize whether TB is present. Keeping the elephants away from livestock and wildlife minimizes the risk of disease transmission. Testing livestock and, when possible, wildlife as part of regular TB surveillance will allow for a more complete understanding of how much TB is present, and where. Keeping people and animals like Jane healthy means a healthier planet for all species, and a chance for successful conservation in places like Kavango-Zambezi.

See more from Laura at lerdvm.com or follow @LERDVM on Twitter

Balancing wildlands and Oil: Perspectives of working in Northern Alberta

HUMANnature - Mon, 12/18/2017 - 12:08pm

Written by Andrea Borkenhagen, 2017-2018 Sustainability Leadership Fellow and Ph. D. Candidate in the Graduate Degree program in Ecology and the Department of Forest and Rangeland Stewardship.

Ten years ago, I was paddling across a wetland in the boreal of Alberta. I had been contracted to survey for impacts from the oil sands mine across the road to make sure the wetland was healthy. Even though we were next to development, it felt like we were in the middle of wilderness.

A loon’s call echoed across the water as our canoe navigated past a beaver lodge and through the cattail marsh. We stopped to identify the plants and I dipped my hand in to have a closer look at the smaller species. There they were, Wolffia borealis (northern watermeal) and Riccia fluitans (liverwort), two rare plants in Alberta1.

I knew then that it was possible.

With thoughtful planning and monitoring, it was possible to have development while conserving biodiversity.

I know oil sands mining is controversial, but I have seen a lot of progress as well. The protection of rare plants and ecosystems, industry supporting novel restoration approaches, and passionate people who strive to mitigate impacts.

The boreal of Alberta is a beautiful place.

I worked for many years in Alberta to survey the land, identifying all the plants along our path. We would walk through upland forests of aspens and poplars rustling over willow, gooseberry, and rose thickets. The perfect place to cross paths with a bear or wasps nest. Drier forest sites had sandy soils with lodgepole pine and dense carpets of blueberries and puffy-white reindeer lichen. Descending from the hillsides, wetter depressions support paper birch trees with airy fields of horsetail2. River alders bushels entwine to buttress the soggy ground, hiding sink holes amongst cow-parsnip and sedge grass leaves. Further down still, the alder wall breaks to a view of scattered patches of larch, willows and bog birch over a blanket groundcover of moss3. Rubbers boots are necessary in these saturated fen peatlands as you float on mats of moss and sedges. In some areas moss mounds can grow into bog peatlands with pillows of red and green sphagnum and small gnarly black spruce4. Here, the horse flies and mosquitos viciously buzz and bump into your face looking for crevasses to burrow into for a chance to bite unprotected flesh5.

This pristine landscape hides underlying black gold.

Alberta has the third largest reserve of oil in the world. Millions of years ago, an inland sea existed on our continent where salty sand and marine organisms accumulated. Pressure and temperature transformed the organic matter into petroleum deposits we have today. Currently, the entire deposit is estimated to be under 142,200 km2 of the boreal forest, or about the land area of Illinois.

The vast majority of the deposit is deep underground (97%) and extracted by steam injection that separates the oil from the sand. The oil is brought up and saline water is pumped down in replacement. On the surface, these facilities are a network of roads and pipes connecting drill pads and refineries6. The surrounding land is continuously evaluated for impacts from disturbance. Routine monitoring tracks and prevents changes to water movement, water chemistry, plant communities, and wildlife habitat.

Mines are different.

Where the reserves are close to the surface, the deposit is open pit mined. The dense mixture of oil, sand, and water is scooped into enormous trucks and separated with hot water in extraction plants7. The oil is upgraded, the water recycled, and the remaining slurry is set out to dry in huge ponds so the sand can be used to rebuild the landscape. The minable surface area is estimated to cover 4,800 km2, about the land area of Rhode Island. As of a few years ago, the area of disturbance is over 750 km2, or 5 times the size of Fort Collins, Colorado. This means there is a lot of work that needs to be done, and this is where I come in as a reclamation scientist.

After days of training, we are certified to enter the facility and we drive up to the secure gate to swipe authorized passes. The drawbridge lowers, and we set course to meet with our coordinating personnel. We obtain a work permit, attend a safety meeting, drive on a pre-approved passage, don safety equipment, prepare for our daily tasks, and set foot onto our reclamation site.

We look across our site and get ready for a day of measurements, essential to assess condition and trajectory. How have we succeeded and what needs fixing?

Restoration is assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed

Reclamation is reconstructing the entire landscape that now lacks original topography, hydrology or biotic composition

At about two football fields in size, we have constructed one of two fen peatlands in the region. It was years in the making and supported by many government, industry, and academic institutions. Some of the strongest proponents where the industry leaders themselves. They coordinated with the government to tackle the huge gap in our understanding of how to rebuild peatlands in the oil sands region. Teams of researchers from Canada and the US worked to tackle problems that had never been assessed, develop methods that had never been tested, and implement a project that moved the bar of reclamation achievements.

Years ago, there was a pit. After hundreds of dump trucks, there was a hill and a basin. After careful placement, there was a peat soil surface ready for experimentation. And after planting and instrumentation by hordes of committed researchers, there has been intense evaluation of the site for the last five years. We experimented with different methods to figure out how to introduce desirable plants. We spread seeds and moss8, planting thousands of seedlings9, pulled weeds, and documented plant growth in wet and dry areas10.

Today, there is an upland forest of aspens, willows and rose thickets that transitions into a saturated fen peatland with a squishy mat of moss and sedges11.

The results are immensely encouraging. We were able to recreate plant communities similar to those found in natural areas of the region. There will always be more to test and aspects to refine, but we can confidently say that we have rebuilt a fen peatland.

We return every year. We reevaluate changes, we ask new questions, we change things that need changing, and we admire the work.

Our overall goal is to develop methods that improve reclamation outcomes and consider post-oil sands mining constraints. I want you to know that scientists are working closely with industry and government to improve the process. Over the last seven years, I have discovered how plants react to reclaimed systems, investigated patterns of change, and identified drivers that influence ecosystem health and function. This research forms that basis for which I can recommend avoiding disturbance to high-value ecosystems, propose strategies that minimize impacts, and develop methods that restore the pre-disturbance state.

This project is funded by oil sands organizations and the Canadian government. It is therefore our responsibility to facilitate their and your understanding of the issues and advances in reclamation ecology. We will continue to advance our ability to mitigate impacts of development and resource extraction on biodiversity in Alberta’s boreal. My hope to always be able to paddle across the water, listen to the birds, and take a closer look at the smaller things around me.

Beyond the narrative: For more information on our project, visit Andrea’s personal website.

Grasslands: The forgotten landscape

HUMANnature - Mon, 12/18/2017 - 10:49am

Written by Kate Wilkins, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Candidate in the Graduate Degree program in Ecology and the Department of Fish, Wildlife, and Conservation Biology.

At a dinner party, an important person (who shall remain anonymous) asked me, “Why do grasslands matter to people living in New York City?” I felt paralyzed by the question and began to fumble for a response: “Grasslands store carbon, which reduces greenhouse gasses that contribute to global warming.” The person looked thoroughly unimpressed, and I have made it my mission since that interaction to convey (to anyone who will listen) the importance of grassland ecosystems, and more specifically, the Great Plains of North America.

Grasslands, from North America’s Great Plains to Africa’s savannas comprise 40.5% of the land on Earth1, providing food for wildlife and livestock and rich soils for agricultural production. A recent study also found that strips of native prairie in Iowa help reduce run off into streams from agricultural fertilizers by slowing the flow of water and nutrients through the system3.

Human development, overgrazing from livestock, and deep-soil tilling from agriculture have threatened grasslands across the globe. In the United States and Canada, humans rely on farms located across the Great Plains to grow food, yet people seem to overlook this productive and beautiful landscape. The Great Plains of North America stretch from northern Canada to the tip of Texas and offer majestic, open spaces filled with grasses, flowering plants, shrubs, birds, lizards, prairie dogs, and pronghorn, in addition to domesticated crops and livestock. Amid the diversity of life in the Great Plains, the plains bison (Bison bison bison) stands out as a grassland icon with the potential to increase awareness and support for this forgotten landscape.

Elected as our national mammal4 in 2016, the bison, along with fire, helped shape the Great Plains that we see today. Before the late 1800’s, around 30-60 million bison grazed and wallowed in the Great Plains, which helped prevent trees and shrubs from growing, thus creating grassland habitat for various birds, mammals, reptiles, amphibians, and insects. The feces from these numerous bison herds also served as a rich, natural fertilizer for grassland soils5. However, Bison populations rapidly declined after European expansion westward, due to overhunting and the deliberate massacre of bison by the U.S. cavalry in a brutal attempt to destroy an important resource and cultural icon of Native Americans6.

The extirpation of bison, coupled with human development, agriculture, and livestock production, had devastating social and ecological consequences, including the marginalization of Native Americans and the loss of habitat for many wildlife and plant species across the Great Plains. Species such as black-footed ferrets, swift fox, burrowing owl, and Gunnison’s prairie dogs have not yet recovered from this massive habitat loss. In addition, grassland birds have experienced the largest and most rapid population declines of any other bird group over the past 25 years7. In an effort to restore grassland habitat and cultural connections, a wave of bison reintroductions have occurred across the Great Plains in Alberta (Canada), Colorado, Minnesota, Wisconsin, South Dakota, and Illinois to name a few. These reintroductions can be used as a tool to help reconnect people to grasslands and foster an appreciation for these systems.

So, why ARE grasslands important to people living in a city? To elaborate upon the paltry answer I provided at the dinner party, grasslands provide the ingredients for the food people eat every day, help to clean the water people drink, maintain a cooler climate, and provide critical habitat for various species, including our national mammal (bison). To better understand the benefits grasslands provide and how humans can preserve this disappearing landscape, scientists, such as myself, study interactions between bison, plants, and other grassland animals. Grasslands create a healthier, more biologically diverse planet in which humans, plants, and wildlife can thrive.

1. http://www.fao.org/docrep/008/y8344e/y8344e05.htm
2. https://www.nationalgeographic.com/environment/habitats/grassland-map/
3. http://harvestpublicmedia.org/post/strips-native-prairie-plants-could-re...
4. https://www.newyorker.com/tech/elements/bison-bison-bison-americas-new-n...
5. https://www.nps.gov/articles/bison-bellows-10-6-16.htm
6. https://www.theatlantic.com/national/archive/2016/05/the-buffalo-killers...
7. http://www.birds.cornell.edu/pifcapemay/vickery.htm

Thirsty to preserve: The Role of Women in Water Conservation Science

HUMANnature - Mon, 12/11/2017 - 2:57pm

Written by Carolina Gutierrez, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Student in the Graduate Degree program in Ecology and the Department of Biology.

“Everybody says women are like water. I think it's because water is the source of life, and it adapts itself to its environment. Like women, water also gives of itself wherever it goes to nurture life....” ― Xinran, The Good Women of China: Hidden Voices[1]

Life is not possible without water, that much is an irrefutable fact. Water is integral to all levels of biological organization. It supports normal cellular function by transporting materials and molecular machinery, it facilitates chemical reactions, it transports nutrients inside all living organisms, and it helps remove toxins and waste. Albert von Szent-Györgyi, Physiology or Medicine Nobel Laureate who partly discovered vitamin C, referred to water as “the matrix of life”[2].

It is no wonder then, that in a planet brimming with living organisms, water occupies most of its surface. On Earth, about 71% of the planet’s surface is covered with water. The oceans hold over 96% of all Earth’s water, while the vast majority of freshwater resources is locked up in ice caps, glaciers and underground storage[3]. Only around 1% of total water in our planet is in usable liquid form, mostly in rivers, streams and lakes. Thus, it would be logical to conserve these precious ecosystems, to make sure they are kept healthy and unpolluted, since our lives so heavily depend on them. However, it is estimated that 844 million people are currently living without access to safe, clean water, which means that around 1 in 9 people lack access to safe, drinkable water[4]. We need to design better strategies, that apply scientific knowledge to restore and preserve our freshwater ecosystems.

This is particularly critical in developing countries, where much of the world’s freshwater resources are concentrated and where access to clean water resources is most limited. It has been referred to as the world water crisis, and its impact is disproportionately stronger on women and children[4] (Figure 1). In remote rural areas, particularly in developing countries, women and children are often responsible for collecting water, which takes time away from attending school, working or caring for family. Reducing the time spent in collecting water increases chances of children having access to better education and play time, giving them opportunities for a brighter future.

The lack of access to clean water also has stronger effects on reproductive health for women, since childbearing and rearing becomes that much harder without appropriate water resources
(Figure 2).

In 2006 the United Nations developed a policy brief through their Task Force on Gender and Water (GWTF) recognizing the necessity of involving women on water conservation projects and stressing the fact that sustainable management of water resources requires more involvement from scientists, particularly female scientists, to increase chances of success. Women are in general under-represented in terms of careers and training in water science and management. Projects that address the science behind water conservation and the social and gender equality component of water access have greater chances of making a permanent change to improve quality of life for entire communities.

As a female Stream Ecologist from Colombia, I feel great passion and responsibility for this topic. I believe science has a duty to generate results that make a lasting impact on quality of life for all living organisms, and this resonates in many different contexts. A scientific understanding of the delicate interactions sustaining freshwater ecosystems will serve to conserve water for human consumption. For this, it is critical to work on all possible aspects of water conservation science, involving physics, chemistry, biology, physiology, ecology, statistics, management, policy and social sciences. So, if you have ever wondered: How does research by scientists studying water molecules or water force dynamics, or algae or aquatic insects, or ecosystem restoration affect me? The answer is: Each of these disciplines addresses a piece of the complex puzzle to preserve clean and sustainable water resources for the present and future, which affects every single living organism in this planet.

Several countries and regions have started projects and partnerships geared towards water sanitation and conservation, with special emphasis in training women for leadership roles in water resource management. Good examples of such projects are the Latin American Clean Water Initiative, which seeks to facilitate sustainable water solutions and improve the health and well-being of individuals living in extreme poverty in 13 countries in Latin America and the Caribbean. The project seeks to: 1) Provide access to potable water and sanitation systems, 2) Improve sustainable water supplies for productive activities and train individuals to manage the water systems effectively, and 3) Offer educational workshops in water conservation, hygiene and water-related illnesses. The program will be implemented in 13 countries: Argentina, Bolivia, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Peru and Venezuela[5].

The Nature Conservancy has created water funds, including 32 initiatives in various stages of development, which provide a steady source of funding for the conservation of more than 7 million acres of watersheds and secure drinking water for nearly 50 million people. Water users pay into the funds in exchange for the product they receive — fresh, clean water. The funds, in turn, pay for forest conservation along rivers, streams and lakes, to ensure safe drinking water for users[6].

These are just a few examples of actions for water conservation at the outreach and management level, however there are also efforts at the cultural level. In 2015 Nocem Collado directed and produced a documentary titled “Women and Water” that draws a parallel between cycles of life and water, analyzing the role women play in water management through the lives of four women. You can watch the full documentary on:


I believe we all must contribute our part in solving the water sustainability crisis in the best way we are able to. For me personally, that means using Stream Ecology Science to understand the interactions of living organisms inhabiting streams and rivers. My research focuses on aquatic insects and their roles and functions in bodies of freshwater, and how those roles change in the context of elevation gradients and more importantly, latitudinal gradients. I come from a tropical country, I have seen the life force that streams and rivers represent for those in and around them, but I also know how much of understanding exactly the balance of diversity and function of life inside these ecosystems we still lack, particularly in the tropics[7].

Although water conservation is an issue that disproportionately impacts women, we cannot reach the goal of preserving water resources on Earth unless we ALL get involved in educating ourselves about threats to water resources and supporting the empowerment of women through education and equality of opportunities, because as Sandra Postel once said:

For many of us, water simply flows from a faucet, and we think little about it beyond this point of contact. We have lost a sense of respect for the wild river, for the complex workings of a wetland, for the intricate web of life that water supports[8]

If you would like to know more about The Water Crisis and what you can do about it, you can visit:


[1] https://www.goodreads.com/quotes/337320-everybody-says-women-are-like-water-i-think-it-s-because

[2] https://www.nasa.gov/vision/universe/solarsystem/Water:_Molecule_of_Life.html

[3] https://water.usgs.gov/edu/earthhowmuch.html

[4] https://water.org/our-impact/water-crisis/

[5] https://sustainabledevelopment.un.org/partnership/?p=1567

[6] https://www.nature.org/ourinitiatives/regions/latinamerica/water-funds-of-south-america.xml

[7] https://www.researchgate.net/profile/Carolina_Gutierrez5

[8] Last Oasis: Facing Water Scarcity (1997), 184. 

The Perils of Ignoring Bad News: The Science-Policy Divide

HUMANnature - Wed, 11/29/2017 - 9:52am

Written by Jake Salcone, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Student in the Department of Human Dimensions of Natural Resources

In Deep Survival, through a series of gripping accounts of those who succeed or fail in life-or-death situations, author Laurence Gonzales concludes that the key to survival lies in admitting the possibility of not surviving.  Survivors acknowledge the reality of the perils they face. They do not waste time thinking about the situation they expected or wished they were in. Survivors address the reality of the situation at hand, no matter how dire.  In the 11th hour, denial is the kiss of death.

The majority of climate models used by the International Panel on Climate Change (IPCC) show that the Paris Accord commitments will not keep global temperatures from rising more than 2 degrees Celsius, the somewhat arbitrary threshold for catastrophic climate change effects. This is true even if the U.S. were to keep its pre-Trump commitments. World leaders continue to congratulate each other on their post-2020 “intended nationally determined contributions” (INDCs), but climate scientists tell us these commitments are not enough. In order to stay below the 2°C goal, we must use carbon markets to incentivize more radical changes to energy production, industry, agriculture, and transportation AND remove hundreds of billions of tons of CO2 already in the atmosphere. 

But the climate change dialogue remains focused mainly upon voluntary marginal reductions to emissions, and debate around who ought to volunteer to bear the burden.  Greenhouse gas (GHG) emissions are the product of business-as-usual economic activity. Generating energy, growing things, moving things, making things – the easiest (i.e. cheapest) ways of doing things tend to emit greenhouse gases.  This pollution comes at a cost to the global public, particularly future generations. Regulating emissions, through voluntary agreements and accords, is the most popular step towards avoiding the most catastrophic changes to the ecosystems and ecosystem services upon which our societies and economies are built. But these voluntary emissions reduction goals are just one leg of a three-legged stool.  If we keep all the 2020 voluntary agreements, the global climate is likely to warm 2.6 – 3.1° C by 2100, pushing our planet into the territory of ecological tipping-points and snowballing deleterious impacts upon the productivity of our oceans and agricultural systems.

Status-quo GHG emitting activities are cheap because dumping carbon in the atmosphere is free.  Full stop.  The atmosphere is currently un-regulated, like a giant landfill where you can dump as much GHG as you want.  Start charging for entrance to that dump, and behavior will change.  People respond quickly to prices.  Businesses respond even faster.  A price, any price, will decrease emissions and speed investment in renewals. The higher the price, the stronger the effect. Tradeable carbon credits reward creative and efficient firms and farmers, and incentivize conservation projects that can sell credits in exchange for proof of carbon storage. Price carbon, methane, and nitrous oxide and achieving the voluntary commitments of the Paris Accord becomes easy. 

The biggest obstacle to GHG prices and markets is that pesky old tenet, national sovereignty. Each country worries that if they agree to pay for their carbon disposal, but other countries do not, the “good” countries will suffer a massive competitive disadvantage.  Big players - China, the US and the EU - will have to take that risk, and bully the smaller players to get on board.  If most everyone joins, the playing field will be level and market prices will not distort capitalist competition. Letting the poorest countries abstain, for a while, will diminish the burden upon the poor and yes, give these chronically disadvantaged countries a competitive advantage in some GHG intensive agriculture and industry.  That’s a good thing.

Putting a price on carbon would give the emissions reductions a strong push, but we still have a two-legged stool.  The writing on the wall from the team of scientists who analyzed the expected impact of the Paris Accord is that reduced emissions alone will not keep warming below 2°C. The “emissions gap”, the gap between GHG levels that are likely with the existing commitments and what is necessary to keep global temperatures from passing the foreboding 2°C goal, will need to be filled by sequestration. We need to reduce emissions AND simultaneously remove billions of tons of GHGs from the atmosphere. Fortunately, this is possible, at least theoretically. Reforestation, improved agricultural practices, and sophisticated carbon capture and storage (CCS) technologies can reverse the GHG emissions imbalance that began with the industrial revolution.

Electricity generation and agriculture together make up nearly half of all GHG emissions. In addition to potential emissions reductions from these sectors, both sectors offer opportunities for significant carbon sequestration. Carbon sequestration is the process of pulling CO2 out of the air, converting it into carbon and oxygen, and storing the carbon in a stable “sink”, usually underground.

Climate smart agriculture practices can flip agriculture from a net emitter of GHGs to a net absorber of carbon. The Natural Resource and Ecology Laboratory (NREL) at Colorado State is a leader in monitoring agricultural GHG emissions and finding ways to flip ag from an emitter to an absorber.

For example, alternating the wetting and drying of rice paddies can reduce their methane emissions by 30 – 70%. Adding seaweed to livestock feed can drastically reduce cattle methane emissions, which account for almost 40% of agricultural GHG emissions.  Agricultural soils, depleted of natural carbon stores in many intensively farmed areas, offer the potential to store carbon on a massive scale by using carbon-rich amendments such as biochar combined with less plowing, and in doing so improve the health and productivity of the soil. Deforestation, often for agriculture expansion, causes about 10% of global CO2 emissions; reforestation could flip that statistic and contribute substantially to global carbon sequestration instead of emissions.

The energy sector can also contribute to carbon capture and storage using negative-emissions technologies. Futuristic power plants could burn biofuels, which pull carbon out of the air as they grow. Technology already exists to capture CO2 from smokestacks and inject it deep in the earth, effectively reversing the process of fossil fuel energy generation. These technologies are currently prohibitively expensive, but a carbon price will help bring the future closer, faster. Instead of paying to dump carbon, these plants could sell their positive credits to the dirty fossil fuel plants.

Signatories to the Paris Accord are eager to pat themselves on the back, despite warnings that they have not done enough. Like agriculture and energy, it seems politicians offer both the cure and the disease. At the recent Programme on Ecosystem Change and Society in Oaxaca Mexico, resource economist Erik Gomez-Baggenthun called on colleagues to stop arguing over how and why to put a value ecosystem services, such as carbon sequestration, and look instead at why economic valuation of nature’s benefits has not made substantive changes to the way we use resources. Traditional measures of economic growth, Gross Domestic Product (GDP) or Gross National Income (GNI), remain the central barometers of “successful” policies, despite years of acknowledgement that these measures completely neglect sustainability and long-term human well-being.  Instead, policies and politicians need held to natural capital and ecosystem service metrics. Economic valuation of ecosystem services is not “putting a price on nature”, it is revealing the true value of nature, value that has been taken for granted. Nature is the economy, stupid.

The amount of GHG already in the atmosphere has us imperiled. “Business-as-usual” belies our perilous state. The reality is that our ship has capsized, and we are adrift in great-white infested waters. Two scientists begin to argue about how soon a shark might strike or whether they will sooner drown from fatigue. A politician backstrokes coolly towards the center of the bobbing masses, saying there is insufficient evidence for dramatic actions that could threaten economic growth. A survivor, pray there be one amongst us, wastes no hot air, and moves to quickly inflate a raft.

A city runs through it: Growing up on an urban river

HUMANnature - Wed, 11/15/2017 - 4:26pm

Written by Rod Lammers, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Candidate in the Department of Civil and Environmental Engineering

A city runs through it: Growing up on an urban river

I grew up on an urban river – the White River that flows through Indianapolis. Indiana isn’t a state known for its natural beauty, and not without reason. We have no mountains or oceans, and just a sliver of a Great Lake. Like many places in the Midwest, we are more defined by our farm fields than our natural features. We do have rivers, but unfortunately, many are neglected, dirty, and often forgotten.

When I was nine, a state biologist came to my street to release fish into the river. I helped, carrying slippery, young catfish, bass, and bluegill from their buckets to the water. These fish had to repopulate the river after four million1 of their relatives were killed months earlier by a chemical spill. Luckily, fish kills are relatively rare but other pollution still plagues the White River. It receives all of our – mostly treated – waste. But, when it rains, the system is overwhelmed and raw sewage spills directly into the river. Oil and salt from roads wash in with every storm. Fertilizer from farms and lawns causes algal blooms; every summer there is a new outbreak of an invasive water weed that roots in the muddy river bed and thrives in the nutrient-rich water2. I’ve spent days pulling the plants to curb the epidemic, only to have them return weeks later. A sick system is hard to heal.

In my lifetime, I’ve seen many changes on the river. When I was younger, we used to skate on the ice when it froze. Lately, winters haven’t been cold enough. The river is also getting shallower. Water is slowed by a downstream dam, causing silt to settle and accumulate on the river bottom. The White River used to be called Wapahani (“White Sands”), a far cry from the muck-bottomed river today. Floods, too, seem more frequent, caused in part by the spread of the suburbs upstream. As more and more houses are built, the spongy ground is paved over and rain washes straight into the river. You don’t have to live within sight of a river to affect it. Rivers are often compared to the veins on a leaf; but rivers are really the whole leaf, because everything that happens on the leaf (the watershed) affects the river3.

After college – instead of looking for a job – I took a three day canoe trip down the White River. I paddled through several cities and drew some strange looks. I also portaged around at least ten dams, most of which had outlived their useful life. Dams have a lot of negative impacts4, but what struck me on this trip was just how boring they made the river. Behind a dam, the water was still and slow, the bottom mucky. Away from the dams, the river was free to move, make sand bars, trap trees, speed through riffles. This was much more fun as a canoer but – more importantly – it was better for the river and the fish, birds, and mammals who live there. I saw a beaver smack the water with his tail, a coyote stop mid-stream to stare me down, a fox dart up the river bank as I rounded a bend, and a snake resting on a partially submerged tree. Despite everything we have done to the river, nature was still hanging on.

Almost every city has a river. And almost every urban river has been neglected, polluted, and forgotten. But that is changing. We are starting to recognize that these are valuable resources – for drinking, for fishing, for swimming, and for enjoying. It has taken time but we are finally turning our attention back to our rivers. The White River fish kill spurred interest in protecting and restoring the river – not unlike the Cuyahoga River fires which galvanized the federal government to pass the Clean Water Act in 1970. Indianapolis is working to reduce the amount of sewage that flows into the river after every rain. Citizen action groups are engaged and working to improve water quality and river access. We are putting more sponges back into cities to slow and filter runoff. Most importantly, people are starting to return to their rivers, and they want to protect what they care about. The tides appear to be turning.

Every time I go home, I swim in the river. It’s partly nostalgia for my childhood but I think it’s mostly an affirmation of the river itself. I want it to know that I don’t think it’s too dirty, too polluted, too overgrown to love. I want to experience how it has moved, changed, shifted, flowed, and recovered since I was last home. And that is the best lesson it’s taught me. That urban rivers – if given the chance – can recover. They can be home to fish and birds and beavers and humans. So why don’t we give them that chance?


[1] Schneider, Justin. 2010. White River fish kill: 10 years of recovery. The Herald Bulletin. http://www.heraldbulletin.com/news/business/white-river-fish-kill-years-of-recovery/article_4db0b8f8-04b5-57db-a39d-154d30dd51d0.html

[2] Milz, Mary. 2012. Invasive weed clogging Indiana waterways. WTHR. https://www.wthr.com/article/invasive-weed-clogging-indiana-waterways

[3] Credit to fellow student and SLF fellow Dan Scott for this analogy.

[4] Read more about the impacts of dams by former Sustainability Leadership Fellow, Natalie Anderson: http://blog.sustainability.colostate.edu/?q=content/not-so-clean-hydropower-damming-us-all

Taking conservation to where the wild things are: farmlands and cities as the new frontiers for carnivore conservation

HUMANnature - Wed, 11/01/2017 - 4:08pm

Written by Rekha Warrier, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Candidate in the Department of Fish, Wildlife, and Conservation Biology and Graduate Degree Program in Ecology

Monarch of all it surveys

In popular conception, the tiger is painted as a creature of the jungle. A beast most at home in the shadows of dense woods and grasslands. Existing conservation measures for the species help perpetuate this imagery - most tiger reserves begin and end at the boundaries of jungles. Only when we look past these boundaries does a surprising image of the tiger unfold. My research in the sugarcane farmlands of the Terai region has revealed that the tiger is as much at home in a sugarcane field as it is in Kipling’s vividly imagined forests in the Jungle Book. Moreover, in the sugarcane farmlands of northern India, where I conduct my research, the presence of tigers on village lands is a commonly accepted social reality not different from our acceptance of raccoons or foxes as part of the Fort Collins cityscape.

The night is dark and full of terrors!

This surprising fact about the tiger can be generalized to most large carnivores. Mountain lions have been documented to use parks within the city of Los Angeles at dusk (Riley et al 2014). In fact, the celebrity mountain lion P-22 is the chief suspect in the death of the koala housed in the city zoo last year (https://www.reviewjournal.com/news/nation-and-world/well-known-mountain-...). Leopards have been shown to eke out a modest living off stray dogs amidst the urban sprawl of Mumbai, India. Western Europe, the most industrialized place in the world today, harbors more wolves than the continental USA.

These examples are only a few from among myriad cases involving large carnivores living in very close proximity to humans. It should be unsurprising then to learn that almost 90 % of the ranges of large carnivores today lie outside the boundaries of protected areas. In most cases these species rely on patches of natural habitats during the day and expand their territories into human modified areas at night to exploit resources. These resources could include the trash that dots urban areas that attract bears and coyotes or the dense cover that sugarcane crop offers to tigresses with cubs. What then does this portend for the future of large carnivores on our increasingly crowded planet?

“The boundary between tame and wild exists only in the imperfections of the human mind!” Aldo Leopold


Where will large carnivores persist in the face of human population explosion and climate change? Addressing this question has been an area of active research in conservation biology (Minin et al 2016). Possible answers to this question however have long been predicated by our prejudices of where these species can persist (Ghosal et al 2013). A dichotomous view of the world underpins the prevailing conservation paradigm. As per this view the world is comprised of wild and tame areas and large carnivores are creatures of the wild.  Vast and pristine protected areas have therefore been the preferred locations for the conservation of large carnivores. Consequently, large carnivores have remained outside the purview of modern debates surrounding biodiversity conservation on human modified lands. For example, the conversations about how agricultural lands should be managed in the future for biodiversity conservation (land sharing vs land sparing) (Phalan et al 2011) have excluded large carnivores. In addition, the myopic conservation focus on existing protected areas comes at the cost of neglecting individuals that range beyond their boundaries seasonally and/or sporadically.

It is therefore important to acknowledge that wide ranging species such as tigers and other large carnivores do not share our binary view of landscapes. To them, landscapes are a continuum of resources and threats that they often navigate expertly. It is therefore conceivable that given appropriate measures, human modified lands could help expand the area currently available to carnivore conservation world-wide. The pertinent question then is what measures need to be put in place to realize this vision?

“Tigers, except when wounded or when man-eaters, are on the whole very good-tempered...” Jim Corbett

In his book ‘The Descent of Man’, Charles Darwin suggested that our innate fear of darkness may be an adaptation to the risk of predation. Through much of our evolutionary history we have dealt with the very real risk of predation from lions, tigers, bears and wolves (Packer et al 2011). The vilification or deification of these species across human cultures is a response to the persistent threats they posed to human life and property. Engendering support for the conservation of large carnivores is thus most encumbered by the deep rooted and diverse prejudices that humans nurture towards them.  For example, this year alone, a man-eating tiger killed 17 people in my research site, yet community attitudes remain favorable towards tiger conservation. Can this favorable attitude be interpreted to mean that 17 human lives in a year is an acceptable price to pay for the conservation of an endangered species? In contrast, the issue of reintroduction of wolves in the western US remains highly contentious despite there being no known threat to human life on account of the species.

The most important measure, therefore, to ensure the conservation of large carnivores into the future is for conservationists to understand and address the actual and perceived risks that these species pose to the human communities with which they interact. In the case of tigers in my study area, the risks are largely the result of accidental or deliberate attacks on humans by tigers. Wolves and bears in the US and Europe may cause significant losses of livestock. While compensation schemes exist in all landscapes to mitigate losses, they are no panacea. A principal reason for this is that the valuation of the loss that someone experiences is often difficult, and where human lives are concerned, perhaps immoral. A more comprehensive strategy should involve devising measures to reduce the absolute risk that communities experience on account of these species. This may be achieved through a more thorough understanding of carnivore ecology in human modified landscapes and devising conflict prevention strategies. Such strategies could include devising better livestock herding practices that are based on an understanding of depredation behavior. In areas where attacks on humans are common putting in place safety measures and warning systems based on an understanding of carnivore habitat use are possible risk-reduction measures.

Whose conservation is it anyway?

The history of carnivore conservation is a checkered one. In the tropics, it is riddled with instances of eviction of communities from protected areas and the denial of community access to forest resources. Conservation of these species has typically been driven by the “existence value” placed on the species by people who are buffered from the potential risks these species may pose. If we are to embrace a landscape-scale conservation vision for carnivores it is important first to acknowledge that our attention cannot be narrowly focused on the species alone. Rather, this new vision of conservation should explicitly recognize the fact that it is local communities who shoulder the burden of our conservation ethos. Regardless of the attitudes that local communities may display towards carnivores, they should be made beneficiaries of the conservation program. This could take the form of a payment for ecological services style scheme or even placing a premium on products generated from carnivore friendly practices.

From the time of our inception as a species, we have shared the world with large carnivores. Yet it is only now that we are beginning to fully comprehend their behavioral complexity. Similarly, we are only just starting to recognize the complexity of human attitudes towards them. Hopefully, these nuanced insights into the full scope of human-carnivore interactions will help us understand how we might better coexist with these species in our rapidly changing world.


Di Minin, E., Slotow, R., Hunter, L.T., Pouzols, F.M., Toivonen, T., Verburg, P.H., Leader-Williams, N., Petracca, L. and Moilanen, A., 2016. Global priorities for national carnivore conservation under land use change. Scientific Reports, 6.
Ghosal, S., Athreya, V.R., Linnell, J.D. and Vedeld, P.O., 2013. An ontological crisis? A review of large felid conservation in India. Biodiversity and conservation, 22(11), pp.2665-2681.
Packer, C., Swanson, A., Ikanda, D. and Kushnir, H., 2011. Fear of darkness, the full moon and the nocturnal ecology of African lions. PloS one, 6(7), p.e22285.
Phalan, B., Onial, M., Balmford, A. and Green, R.E., 2011. Reconciling food production and biodiversity conservation: land sharing and land sparing compared. Science, 333(6047), pp.1289-1291.
Riley, S.P., Serieys, L.E., Pollinger, J.P., Sikich, J.A., Dalbeck, L., Wayne, R.K. and Ernest, H.B., 2014. Individual behaviors dominate the dynamics of an urban mountain lion population isolated by roads. Current Biology, 24(17), pp.1989-1994.

Farm Fresh Alexa: Implication of Amazon’s acquisition of Whole Foods for sustainable food system

HUMANnature - Tue, 10/24/2017 - 11:45am

Written by Libby Christensen, PhD. a 2017-2018 Sustainability Leadership Fellow and Post-Doctoral Fellow in the Department of Agricultural and Resource Economics

Last week I posed the question to my class, if you had $200 million, what would you do to fix the food system? Over the last two and half months, I have been meeting weekly with 40 undergraduate students in the Department of Food Science and Human Nutrition. During class, we discuss the strengths and weaknesses of the current food systems, and efforts around the country to improve or develop alternatives to that system. Each week, I encourage my student to consider the challenges to creating a sustainable food system by exploring a particular topic be it food waste, livestock production, food deserts, or the distribution system. One event that was recently in the news with important implications for the future of the U.S. food system is Amazon’s acquisition of Whole Foods.

At its core, the issue is around concentration in the food system. Amazon simplified many of our lives. Through their coordinated supply chains and easy online interfaces, they created a one-stop shop for all of our modern needs from entertainment to toilet paper. While their expansion into food has the potential to increase efficiencies and expanded access to a greater array of food products, the consolidation of market share by one entity has the potential to distort the market. As was noted in Spider Man, “With great power, comes great responsibility”.

Whole Foods started in 1980 as a small natural food store in Austin, Texas. Beginning in 1984, Whole Foods quickly expanded beyond the city of Austin. First opening stores in Houston and Dallas, and in 1989 opening their first California location. It then began aggressively expanding through the acquisition of smaller, geographically limited, natural food stores across the country (Howard, 2009). Whole Foods opened its 100th store in 1999, quickly becoming the nation’s most visible natural and organic food retailer.

As organic foods increased in popularity and represented one of the biggest growth categories for traditional food retailers, competition for market share increased. By 2015, traditional grocers and supercenter centers were responsible for 53% of organic food sales, while natural retailers, like Whole Foods, accounted for just over 37% (OTA, 2016). By the first quarter of 2017, Whole Foods reported its worst performance in a decade, and closed nine stores. As one analyst for Edward Jones explained, “Whole Foods created this space and had it all to themselves for years, but in the past five years a lot of people started piling in. And now there is a lot of competition” (quoted in Dewey, 2017).

In June of 2017, Amazon announced its plan to acquire Whole Foods. After one month of review by the U.S. Federal Trade Commission, Amazon closed on the acquisition on August 29, 2017 for $13.7 billion (Bhattarai, 2017). The acquisition catapults the e-commerce giant into hundreds of physical stores and fulfills a long-term goal of selling more groceries.

Despite its impressive growth, Whole Foods is still relatively small compared to other food retailers, accounting for 1.2% of the food retail market share (Cheddar Berk, 2017). Yet, it presents a unique opportunity for Amazon to finally successfully enter the world of food sales. Despite being the world’s largest online retail, with sales greater than the next ten online retailers combined, Amazon has continued to struggle with food sales. In 2007, Amazon tried to break into food sales with Fresh, and expanded its food offering with Prime Pantry and experimented with Go, a fully automated grocery store in Seattle, without much success. The acquisition of Whole Foods provides Amazon a proven venue for food sales.

Amazon’s purchase of Whole Foods sent shockwaves throughout the food retail sector. Stocks for other food retailers dropped dramatically. It has also left many of us in the field of food systems, considering the broader implications for the future of the U.S. food system.

The first visible impact of the acquisition for consumers was lower prices on key food staples across the store. The lower prices were concentrated at the front of the store on items like bananas, eggs, and avocados. Newspaper articles led with headlines like, “The real price of Whole Foods’ suddenly cheaper avocados” from Slate, “ Amazon’s play to rattle Whole Foods rivals: Cheaper kale and avocado” from the NY Times, and “Amazon will cut prices on avocados at Whole Foods” from The Verge. In an industrial sector with relatively inelastic pricing, the company made a concerted effort to effectively highlight the change in prices, showing prices before and after the acquisition. While this may have a short-term positive impact on the accessibility of healthy food options for consumers, some fear the initial lowering of prices is a ploy to attract new customers. Once the company secures the desired market share, Amazon will be able to make monopolistic decisions regarding what products are available and at what price. Quotes from two food system experts capture the potential opportunities and threats of the merger. Marion Nestle, professor of in NYU’s Nutrition and Food Studies program was quoted as saying, “This is monopoly capitalism in action” while Brian Frank, a food tech investor and advisor, posits that Amazon knowledge and expertise in the world of supply chain logistics “will democratize access and over time hopefully will create efficiencies that will reduce price” (both quoted in Giller, 2017).

For now it seems only time will tell how the acquisition of Whole Foods by Amazon will play out with regards to the sustainability of the U.S. food system. Much of the conversation surrounding the acquisition echoes the fears and hopes expressed during the expansion of Wal-Mart.



Bhattarai, A. (2017, August 23). FTC Clears Amazon.com Purchase of Whole Foods. Washington Post.

Cheddar Berk, C. (2017, June 16). Amazon and Whole Foods Control Only a Sliver of the Grocery Market – For Now. CNBC.

Dewey, C. (2017, February 9). Why Whole Foods is Now Struggling? Washington Post.

Giller, M. (2017, August 24). Whole Foods Prices Will Drop Significantly After Amazon Deal. Eater.

Heins, S. (2017, August 28). Whole Foods Trots Out Cheap Avocados and ‘Farm Fresh’ Alexa Devices on 1st Day of Amazon Takeover. Gothamist.

Howard, P. (2009). Organic Industry Structure. Media-N: Journal of the New Media Caucus, 5(3).

Organic trade Association. (2016). U.S. Organic Sales Post New Record of $43.3 Billion in 2015. Washington, D.C.

Artificial Intelligence and the Challenge of Sustainability

HUMANnature - Wed, 10/18/2017 - 4:03pm

Written by Faizal Rohmat, a 2017-2018 Sustainability Leadership Fellow and Ph. D. Candidate for the Department of Civil and Environmental Engineering

The challenge of sustainability

Today we are faced with the monumental challenge of sustainability. By the middle of this century, the United Nations predicts the earth will be inhabited by more than 10 billion people [1]. This high rate of population growth puts serious pressures on ecosystems, both wild and agricultural. One example of how our population strains resources is the increase, nearly 100%, in our grain demand [2]. Attaining sustainable outcomes is even more important because the world is being impacted by our population today. Unless something unimaginable happens, human population growth is inevitable. To accommodate such growth, humans must be able to manage their interaction with the ecosystems in sustainable ways. This means that current demand on resources must be met without compromising the supply of resources that will be needed for future generations to meet their needs, as sustainability is defined by WCED [3].

Pryshlakivsky and Searcy mentioned that numerous efforts to implement sustainability over the past two decades on a national, regional and organizational scale have been generally less than satisfactory [4]. Researchers refer to this failure of to implement sustainable development, or sustainability in general, as “complexity and uncertainty of natural and social phenomena” [5], “seemingly random interpretations and competing frameworks” of sustainability [6], and the “difficulties experienced in implementing any holistic approach” [7]. The challenge of sustainability is a wicked problem because it lacks clarity, incomplete, contradictory, and has system-of-system complexity [4]. We need to solve this sustainability problem in a way better than we have for the past two decades.

What is AI, its history, and where we are

Artificial intelligence (AI) could be the way to solve the wicked challenge of sustainability. AI is the intelligent behavior performed by the machine, as opposed to the behavior of natural intelligence performed by living things. The AI discipline first appeared in 1956 through the Dartmouth Summer Research Project on Artificial Intelligence [8]. In the next decade, research on the idea of AI blossomed, followed by various disappointments in the late 1970s, then reached its nadir point at the "AI winter" in the late 1980s [9]. Followed later in the 1980s - 1990s with research focusing on machine learning, i.e., ways to achieve artificial intelligence. Then in the early 21st century, with advances in computer software and hardware, promotes we saw the growth of AI research, development, and use in several disciplines. Today, AI has become a part of our daily lives, such as Apple's Siri, Amazon's Alexa, IBM's Watson, and even the driverless cars that will soon fill our streets [10].

The AI forms we have used in our daily life, according to Stephen Hawking, are still the primitive forms of AI. Nevertheless, it is enough to worry him about the dangers of intelligence, one of which includes the has the power to either destroy humanity [11]. Even back in March 2016, the world was shocked by the defeat of Lee Sedol, 18-times world champion Go chess game, by AI AlphaGo with a score of 4-1 [12]. Deep blue had beaten human chess grandmaster two decades ago, but the Go victory was special because Go chess is more analytically hard to crack for the computers and requires a more human-like way of thinking [13]. This breakthrough in the ability of a machine to compete against and beat humans in a game that challenges human analytical ability brings anxiety regarding evil AI robots like those in the Terminator films.

On the other hand, the emergence of AI also presents us optimism. We have a long history of success being innovative. Fire, domestication, steam machines, electricity, cars, smartphones are just a few examples where we have used technology to benefit our species. We had fears of strange and powerful things until we eventually managed to tame them and utilize them to achieve our objectives. Now, we are going to do the same and use AI to solve the wicked challenge of sustainability.

AI, machine learning, and how we can utilize them

The first cause of dissatisfaction with sustainability efforts is the complex nature of sustainability issues and our lack of understanding of how ecosystems work. The ecosystem is very complex; everything interacts with everything. We do not know exactly what the consequences of what we do. But, as Pedro Dominggos says in his book "The Master Algorithm", with more sensors and more data we have now through the big data blast combined with better machine learning, we are able to create better models so we can understand better about how the whole ecosystem works [14]. Dominggos even calls "the automation of discovery" as one of the definitions of machine learning. Machine learning helps us automate the discovery by learning from the existing knowledge, fill in the gaps, and systematically reduce uncertainties [14]. This is basically traveling down the road of discovery by cars instead of walking. Machine learning, as a subset of AI, can amplify what we already know and accelerate the pace of discovery to make us better understand how the ecosystem works.

The next point about the challenge of sustainability is the difficulty of implementing a holistic approach to addressing the challenges of sustainability. The approach that has been done to address sustainability challenges is through computer modeling to gain understanding and simulate scenarios of the specific components of the ecosystem. Currently, we already have computer models of specific components of the ecosystem, such as the model of ocean currents, atmospheric models, or models of animal diseases. However, we still lack a great way to combine these specific components into a holistic model. AI, especially through machine learning approach, with the characteristics of input-output mapping, adaptivity, very-large-scale-integration implementation, and neurobiological analogy [15], can help us combine individual models into a more holistic ecosystem model. An example is what Triana did in Lower Arkansas River Basin where he simulated the effects of agricultural practice scenarios to the sustainability of the irrigation valley by utilizing machine learning techniques for coupling groundwater and stream water models [16]. His research has proven to be way faster than the classical approach of groundwater-stream water model coupling. This example of coupling two individual models can be scaled to any numbers of individual models. With a more holistic ecosystem model, we can better understand ecosystems as a whole and see what happens to the ecosystem if we do different things. We can model scenarios that are of great benefit to us while minimizing the side effects on ecosystems without doing them in a real situation. With the application of AI, we can see further down the road and gain public support for proposing the sustainability solution.

In conclusion, we need to address this sustainability challenge in a better way than we have done so far and AI has great potential to help us answer those challenges. AI can amplify the knowledge we already have about the ecosystem, accelerate the pace of discovery, incorporate individual models into holistic, and help us simulate what-if scenarios so that we can make better decisions to answer the challenge of sustainability.

[1] https://esa.un.org/unpd/wpp/

[2] Alexandratos, N., 1999. World food and agriculture: Outlook for the medium and longer term. Proceedings of the National Academy of Sciences, 96(11), p. 5908–5914.

[3] WCED (1987) Our common future. Oxford University Press, Oxford.

[4] Jonathan Pryshlakivsky and Cory Searcy. 2013. Sustainable Development as a Wicked Problem.

[5] Midgley G, Reynolds M (2004) Systems/operational research and sustainable development:

towards a new agenda. Sustain Dev 12(1):56–64.

[6] Frame B, Brown J (2008) Developing post-normal technologies for sustainability. Ecol Econ


[7] Espinosa A, Harnden R, Walker J (2008) A complexity approach to sustainability—Stafford Beer

revisited. Eur J Oper Res 187:636–651

[8] https://www.dartmouth.edu/~ai50/homepage.html

[9] http://www.ainewsletter.com/newsletters/aix_0501.htm

[10] https://www.theguardian.com/technology/2016/aug/22/google-x-self-driving...

[11] http://www.bbc.com/news/technology-37713629

[12] https://www.theguardian.com/technology/2016/mar/15/googles-alphago-seals...

[13] https://research.googleblog.com/2016/01/alphago-mastering-ancient-game-o...

[14] Domingos, Pedro. The master algorithm: How the quest for the ultimate learning machine will remake our world. Basic Books, 2015.

[15] Haykin, Simon S. Adaptive filter theory. Pearson Education India, 2008.

[16] Triana, E., Labadie, J. W., Gates, T. K. & Anderson, C. W., 2010. Neural network approach to stream-aquifer modeling for improved river basin management. Journal of Hydrology, 391(3-4), pp. 235-247.


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