June 29, 2022— When Susan Tessier and her husband, Tim, went out for the day, they had a lake on their Native allotment. When they came back, It was gone. 

“My husband Tim and I left home in the morning and when we came back around 8:00 in the evening the whole lake had drained,” she writes in a post on the Local Environmental Observation Network site—a community science website where observers can report unusual changes in their local environment. “There was a hole that had blown out and it had drained into the ocean… It looked like it was blown up with dynamite.”

Water is the ecosystem engineer in the Arctic. The lowland tundra landscape is a network of lakes and streams, mosaicked across an expanse of frozen ground riddled with wedges of ice. The freezing, thawing, moving, eroding dynamics of these features shape the larger landscape, and determine the habitats of fish, birds, plants, mammals—and, of course people—living in the Arctic. 

Abrupt lake drainage, like Tessier described, is just one way that changes in water and ice can influence the landscape, but a recent review paper conducted by University of Florida Postdoctoral Associate, Dr. Elizabeth Webb, and Woodwell Climate Associate Scientist, Dr. Anna Liljedahl, indicates events like this may become more common as the climate warms— overtaking lake expansion and slowly drying out the Arctic tundra.

Evidence of lake drainage across the literature

This new paper comes on the heels of a 2022 study that Drs. Webb and Liljedahl also authored, which came to the same conclusion: despite the processes of lake expansion and drainage continuing simultaneously across the Arctic, net lake area is trending downward. The Arctic is getting dryer.

The review complements the strengths of the previous study, compensating for some of the limitations of using geographically coarse remote sensing data. Synthesizing data from 139 sites across the Arctic, pulled from 57 different studies, Drs. Webb and Liljedahl were able to corroborate their own past findings. 

“Lake size can vary from one season to the next in response to factors like precipitation or evaporation, so if you’re only looking at a limited set of remote sensing images, that can influence a trend analysis,” explains Dr. Webb. “It’s actually really exciting from a scientific rigor perspective to have two completely different remote sensing methods showing the same result.”

The review also adds weight to the idea that permafrost thaw is the primary driver in the loss of Arctic lakes. A large portion of Arctic soil is ice-rich, perennially frozen ground called permafrost, and as the climate heats up, it has begun to thaw and destabilize. That thawing can both create new ponds, and help drain them. The review indicates that decreases in size and number of Arctic lakes are more prevalent than expected, dominating the dynamic in some areas.

This contradicts another leading theory that changes in precipitation and evaporation rates— called the “water balance hypothesis” — are driving changes in lake area. Prior to Drs. Webb and Liljedahl’s investigations, the prevailing thought was that lake creation would outpace drainage rates, for at least the next several decades. 

Climate Change is Opening Drainage Channels in the Permafrost

It works like this: most Arctic lakes form when wedges of ice in permafrost melt, leaving behind a depression that fills with water. The water absorbs and holds more heat, slowly thawing and eroding surrounding permafrost, growing from puddle to pond to lake over the years.

Drainage can happen in one of two ways. The first is vertically, which occurs when the permafrost beneath the lake thaws down to the unfrozen ground beneath, allowing the water to seep out the bottom. This can take hundreds or thousands of years, depending on how deep the permafrost is.

The second way is horizontally, through what Dr. Liljedahl calls “capillaries”. Ice wedges are common across the Arctic, connected by an underground network of ice that pushes the soil above them upwards as they grow, creating ridges that impede water flow. But when the tops of these wedges melt, the ridged ground above them subsides, forming narrow channels between lakes and ponds. When an expanding lake meets one of these capillary channels, the lake can drain in a matter of hours, as if the plug has been pulled on a bathtub drain.

“The formation of lateral drainage channels can interrupt this lake expansion process at any time, and I think that’s what’s making it override expansion and cause the net drying effect,” Dr. Liljedahl says. “The lake that took millenia to grow can be gone in a couple of hours.

Fewer Arctic Lakes Leave Communities in the Lurch

So what does an Arctic with fewer lakes mean? In terms of carbon, the picture isn’t clear. Since lake expansion— a common source of methane emissions— and lake drainage are happening concurrently, the net effect is not easy to discern. 

“With lake drainage, it’s much less clear what the carbon consequences are. The current thinking is that lake expansion releases orders of magnitude more carbon than lake drainage, but because it’s complicated, we’re not quite sure,” says Dr. Webb.  “It’s definitely an open research question.”

Dr. Liljedahl notes that there is also documentation of permafrost recovering and re-growing in drained lake beds. “Over decades, they could develop new ice-wedges and vegetation on the surface. Lake beds could experience net carbon accumulation for at least a couple of decades after drainage,” Dr. Liljedahl says.

However, the ecological consequences of fewer Arctic lakes are more certain. Fish and other aquatic species will have the size of their habitat reduced and their freedom of migration restricted, as lakes drain and connecting streams dry up. Species that feed on fish or rely on wetland vegetation, like muskrats, will also be impacted.

Small lakes are an important source of freshwater for Arctic communities. Tessier wrote in her post about the lake drainage she witnessed, “We are sad to lose the lake because in winter, after it froze up, we used to go cut ice chunks for drinking water. It has really clear water. If we get enough snow we can use snow water instead, but it is not as good.”

As more lakes drain, clean freshwater could become harder to access. Combined with the destabilization of the ground itself as permafrost thaws, Arctic communities are facing massive changes.

Dr. Liljedahl hopes that refining our understanding of water dynamics in the Arctic will aid adaptation measures. She has been awarded a three year NSF grant to continue studying the ice wedge capillary network and its role in the Arctic hydrological system. She’ll use remote sensing to quantify the distribution of the ice-wedges contributing to increased drainage. She also plans to pull data from field measurements to figure out how permanent the capillaries are, since vegetation feedback loops could help permafrost recover and return the surface to its original elevation. 

“We have more to do before we can feel like the models are representing a realistic scenario. We need to better understand what is happening at the sub-meter scale with water, because the presence or absence of surface water will have a major impact on how the landscape evolves,” Dr. Liljedahl says.

Global Hotspots and Hot Moments of Nitrous Oxide Emissions

Lead PI: Dr. Jacqueline Hung

Co-PIs: Dr. Marcia Macedo, Kathleen Savage, Dr. Yushu Xia, Dr. Chris Neill

Nitrous oxide (N2O) is a prevalent, powerful—and understudied—greenhouse gas. Soils are the largest contributors of N2O emissions, but understanding of N2O fluxes is limited by lack of real-time monitoring technology. Given our broad geographic coverage and long history of innovation in measuring greenhouse gases, Woodwell Climate is well-positioned to address this gap. This award will support the purchase of cutting-edge field equipment for instantaneous N2O measurements, as well as the development of a laboratory system for measuring multiple greenhouse gases in soil experiments. Together, these will enable advances in understanding how changing soil conditions around the globe—from permafrost thaw to wetland restoration, rangeland management to tropical deforestation—affect the balance of nitrous oxide.

Can forest harvesting contribute to natural climate solutions (NCS) while maintaining economic viability?

Lead PI: Kathleen Savage

Co-PIs: Dr. Wayne Walker, Dr. Rich Birdsey, Zoe Dietrich, Emily Sturdivant

Trees accumulate carbon as they grow, making them critical climate assets. However, many forests are also commercial sources of timber and wood fiber. Forest harvesting is generally assumed to result in a net release of carbon, even after accounting for the carbon stored in wood products. As the search for practical climate solutions intensifies, a central question is whether this either-or thinking could be reframed as yes-and. In other words, whether commercial forests could be managed to meet multiple goals—providing wood and paper products, creating economic returns from natural resources, and sequestering carbon? The proposed work builds on our longstanding research at the Howland Research Forest, addressing whether shelterwood harvesting can be both an economically viable harvest practice and a natural climate solution.

Shallow or Deep: Can cover crops make soil carbon stick?

Lead PI: Dr. Taniya RoyChowdhury

Co-PIs: Dr. Jonathan Sanderman

Cover crops have the potential to enhance carbon uptake and stability in agricultural soils and, under the Inflation Reduction Act, the USDA is poised to invest billions of dollars in adoption of cover crops as a climate-smart practice. However, current understanding of the effectiveness of cover cropping to deliver climate benefits is lacking a key consideration—microbial processes. Soil microbial communities are key regulators of soil carbon dynamics, and may determine whether a given land management practice results in net loss or gain of carbon. This work will characterize microbial processes and their role in soil carbon stabilization in surface and deep soils in dynamic, mixed-species cover-cropping systems. The result will be enhanced understanding of the outcomes of cover-cropping practices, with potential policy relevance.

Mapping carbon stocks across native Cerrado and Amazon ecosystems with a known history of fire disturbance

Lead PI: Dr. Manoela Machado

Co-PIs: Dr. Marcia Macedo and Dr. Wayne Walker

The Amazon and Cerrado biomes hold vast carbon stores that are threatened by fires associated with both land clearing and a warmer, drier climate. However, the long-term responses of fire-impacted areas within these ecosystems could be dramatically different. While Amazon forests have not evolved with fire as a pressure, transitional forests and the  Cerrado are adapted for—and dependent on—regular fire for sustaining their structure and function. Understanding the effects of fire disturbance on carbon dynamics and the potential pathways of recovery in these ecosystems is critical. By mapping carbon stocks in fire-disturbed ecosystems and creating larger-scale scenarios, this work will provide a rich picture of what future carbon storage could look like under a range of possible fire disturbance/recovery dynamics.

Salt marshes across Buzzards Bay, in Southern Massachusetts, are experiencing significant stress from climate-change driven sea level rise, but also a range of other factors including tidal restrictions and nitrogen pollution. A recent report, “Buzzards Bay Salt Marshes: Vulnerability and Adaptation Potential,” released today by the Buzzards Bay Coalition, Buzzards Bay National Estuary Program, Woodwell Climate Research Center, and the U.S. Geological Survey assessed the loss and degradation of twelve salt marsh sites in  Westport, Dartmouth, Fairhaven, Mattapoisett, Marion, Wareham, Bourne and Falmouth. Using regular field monitoring alongside remote sensing data, the report reveals the widespread loss of salt marshes – in some places measuring up to 20-percent over an 18-year period. 

Buzzards Bay Coalition and Buzzards Bay National Estuary Program began field monitoring salt marsh vegetation and elevation four years ago. 

“We knew that salt marshes face a number of stressors, and we’d heard from our members that marshes in their neighborhoods were changing, but there was no consistent monitoring to track the health or stability of these critical ecosystems around Buzzards Bay,” explains lead author Dr. Rachel Jakuba, Buzzards Bay Coalition’s vice president for bay science. 

Salt marshes are important ecosystems that filter nutrients, store carbon, provide critical habitat for fish and birds, and protect coastal properties from storm surge. Salt marshes – existing at the interface of the land and sea – are adapted to a fluctuating environment with plants capable of tolerating regular inundation with salt water; however, salt marshes’ natural ability to adapt has limits, which this report documents.

“Looking at remote imagery of salt marshes all around Buzzards Bay, we documented how the marshes changed over a couple of decades. Marshes with low elevation appear most vulnerable to sea level rise and showed the greatest loss,” said co-author Dr. Joe Costa, executive director of the Buzzards Bay National Estuary Program. 

Co-author Neil Ganju of the U.S. Geological Survey added, “We’ve applied one of the tools used in this report up and down the East Coast. Marshes in the region are facing the same issues as in Buzzards Bay, and researchers are working hard to better understand marsh loss and ways to mitigate it.”

The news is not all bad though, as these iconic features of the Buzzards Bay coast are resilient and have the potential to migrate landward. 

“While the headline of salt marsh loss is sobering, these are remarkable ecosystems that, when given the room to adapt, can continue to flourish. This makes the protection of adjacent lands all the more important,” said co-author Linda Deegan of the Woodwell Climate Research Center.

Scientists conducted the analysis to better understand and document salt marsh change, and the Buzzards Bay Coalition produced this report with the hope that it will be used by municipalities faced with zoning and permitting decisions near salt marshes; by natural resource agencies capable of undertaking direct marsh restoration strategies such as runneling, thin-layer deposition, ditch management and others; and by private landowners, who might consider preserving the uplands that they own adjacent to salt marshes to allow marshes to migrate — unimpeded by seawalls, roads and buildings — in the future. 

“While much of this loss is attributable to climate change-driven sea level rise, some is due to legacy effects from human-made alterations like the creation of drainage ditches and marshes being altered for development and agriculture. We’re hoping that this research will be useful to planners, policymakers, and resource managers trying to mitigate the future impacts of both of those drivers,” said co-author Dr. Alice Besterman, assistant professor at Towson University.

Salt marshes across Buzzards Bay, in Southern Massachusetts, are experiencing significant stress from climate-change driven sea level rise, but also a range of other factors including tidal restrictions and nitrogen pollution. A recent report, “Buzzards Bay Salt Marshes: Vulnerability and Adaptation Potential,” released today by the Buzzards Bay Coalition, Buzzards Bay National Estuary Program, Woodwell Climate Research Center, and the U.S. Geological Survey assessed the loss and degradation of twelve salt marsh sites in  Westport, Dartmouth, Fairhaven, Mattapoisett, Marion, Wareham, Bourne and Falmouth. Using regular field monitoring alongside remote sensing data, the report reveals the widespread loss of salt marshes – in some places measuring up to 20-percent over an 18-year period. 

Buzzards Bay Coalition and Buzzards Bay National Estuary Program began field monitoring salt marsh vegetation and elevation four years ago. 

“We knew that salt marshes face a number of stressors, and we’d heard from our members that marshes in their neighborhoods were changing, but there was no consistent monitoring to track the health or stability of these critical ecosystems around Buzzards Bay,” explains lead author Dr. Rachel Jakuba, Buzzards Bay Coalition’s vice president for bay science. 

Salt marshes are important ecosystems that filter nutrients, store carbon, provide critical habitat for fish and birds, and protect coastal properties from storm surge. Salt marshes – existing at the interface of the land and sea – are adapted to a fluctuating environment with plants capable of tolerating regular inundation with salt water; however, salt marshes’ natural ability to adapt has limits, which this report documents.

“Looking at remote imagery of salt marshes all around Buzzards Bay, we documented how the marshes changed over a couple of decades. Marshes with low elevation appear most vulnerable to sea level rise and showed the greatest loss,” said co-author Dr. Joe Costa, executive director of the Buzzards Bay National Estuary Program. 

Co-author Neil Ganju of the U.S. Geological Survey added, “We’ve applied one of the tools used in this report up and down the East Coast. Marshes in the region are facing the same issues as in Buzzards Bay, and researchers are working hard to better understand marsh loss and ways to mitigate it.”

The news is not all bad though, as these iconic features of the Buzzards Bay coast are resilient and have the potential to migrate landward. 

“While the headline of salt marsh loss is sobering, these are remarkable ecosystems that, when given the room to adapt, can continue to flourish. This makes the protection of adjacent lands all the more important,” said co-author Linda Deegan of the Woodwell Climate Research Center.

Scientists conducted the analysis to better understand and document salt marsh change, and the Buzzards Bay Coalition produced this report with the hope that it will be used by municipalities faced with zoning and permitting decisions near salt marshes; by natural resource agencies capable of undertaking direct marsh restoration strategies such as runneling, thin-layer deposition, ditch management and others; and by private landowners, who might consider preserving the uplands that they own adjacent to salt marshes to allow marshes to migrate — unimpeded by seawalls, roads and buildings — in the future. 

“While much of this loss is attributable to climate change-driven sea level rise, some is due to legacy effects from human-made alterations like the creation of drainage ditches and marshes being altered for development and agriculture. We’re hoping that this research will be useful to planners, policymakers, and resource managers trying to mitigate the future impacts of both of those drivers,” said co-author Dr. Alice Besterman, assistant professor at Towson University.

Ecological research seeks to describe the interactions between an environment and the species living there. But there’s one important species most ecological work overlooks—us.

Human society, our histories, our economies, our politics, has played just as much hand in shaping the ecology as the migration of animals or the shifting of continents has. The darker sides of human history—war, colonialism, racism—have had especially long-lasting effects. Yet ecological research seldom attempts to grapple with these forces. Ignoring the human element within the history of a landscape has led to research and conservation efforts that are at best, clumsy, and at worse, extractive and exploitative. 

A recent paper, spearheaded by Yale Ph.D. student Gabriel Gadsden and Woodwell Climate postdoctoral researcher Dr. Nigel Golden, under the advisement of Yale University Professor, Dr. Nyeema Harris, has laid out a more interdisciplinary approach to conservation ecology, one that reckons with the negative histories affecting research sites and uses that knowledge to reduce bias within the scientific process. Failing to do so, the paper argues, perpetuates a societal “landscape of fear” — one that restricts the potential benefits of science for both wildlife and human communities.

Fear moves like a predator

In ecology, the term “landscape of fear” is used to describe animal behaviors as a product of perceived risk or fear, specifically of predation. For example, if you are an elephant, Dr. Golden suggests, one of the largest animals moving through the physical landscape, you have few predators; your risk of being hunted is low. The amount of time you can spend searching for food isn’t limited by fear.  But if you are one of the Arctic ground squirrels that Dr. Golden conducted his graduate research on, everything from grizzly bears to golden eagles to foxes and weasels, is hunting you. The elephant’s behavior is constrained by access to food and water and other resources, but the ground squirrel’s behaviors are likely more motivated by fear. Animals perceive threats within a landscape and react accordingly.

But, as Gadsden points out, “Fear is an emotion that humans deal with, too.”

Fear moves like a predator on human landscapes, creating perceptions of places and people that may be incomplete or flat out inaccurate. When science is constrained by these perceptions, everything from the methods used, to the research questions being asked, is tainted with bias. 

“If you fear a landscape, then you probably aren’t going to go there to do your research,” Gadsden explains. “If you have this dominant idea about people that maybe isn’t true, you’re not going to seek collaborations with them. Or maybe you will do research in that area, but it won’t be community-led and community-oriented. All of the unspoken restrictions that fear induces has implications on research outside of the significance of a result.” 

Like a predator, these fears often target the most vulnerable groups. In urban environments, unequal distribution of greenspace has resulted in less wealthy, often minority, neighborhoods suffering much higher risks of extreme heat and consequent health impacts. This disparity has its origins in racist housing and development policies like redlining—which limited financial services available to people deemed “hazardous to investment,” and reduced financial growth in their neighborhoods. 

At a larger scale, these biases can be seen in the types of environments that are prioritized for conservation. There is a false notion that “pristine” wilderness holds more value than areas deemed degraded or developed, an idea that ignores the fact that many “pristine” wilderness spaces were shaped for centuries by Indigenous communities.

Do your research before you do your research

Acknowledging history, Gadsden and Dr. Golden say, is a critical first step in conducting science and conservation that doesn’t play into these unequal and unjust perceptions— causing more harm, even when the intention is to help.

In the case of the first U.S. National Parks, intended to protect the country’s natural landscapes from development, the removal of Indigenous peoples has left an indelible mark on the history and ecology of the region. Not understanding that Native communities had been maintaining healthy and productive forests using controlled fire, U.S. Forest Service policies harshly suppressed fires for over a century which altered the ecological composition of the forest and allowed dry fuel to build up. This, coupled with a climate growing hotter and drier,  created the conditions for the intense and out-of-control wildfires seen today.

Examples like this are common in the field of conservation when researchers enter a new landscape without knowledge of the site’s histories. 

“We know that our science is not just informed by the landscape or the species,” says Dr. Golden. “It’s also informed by the social and political context around it.”

So Gadsden and Dr. Golden recommend scientists begin their research by asking the right questions. “Okay, so this is your study site?” says Gadsden. “How did your study site come to be?”

Recognition of these histories could be as simple as a paragraph embedded in an article, or a land acknowledgement published alongside the research, but the paper outlines additional steps for researchers to take. Including local communities at the outset of a project, especially when developing conservation plans that will impact them, can further strip back biases and help scientists better understand local perspectives on the natural environment.

“One generally would not venture into the jungle without first building a relationship with a local guide,” the authors write in the paper, pointing out that it should be equally unadvisable to venture into a community without building connections with people who can guide you through it. 

Building better science together

Their final recommendation involves collaboration across disciplines. The paper suggests that scientific research could benefit from “co-creating knowledge” with groups focused on sociological or environmental justice research to grapple with the ways societal and political forces have shaped ecology.

Dr. Golden has been applying these concepts to Woodwell Climate’s Polaris Project, which he coordinates. The project gives young scientists hands-on experience working in an Arctic environment.

“But it’s unethical for us to bring folks into Arctic science without having a clear understanding of the history of the Arctic and Arctic peoples, and how we’ve gotten to the problems that we are trying to solve today,” Dr. Golden explains. So the program is working on better understanding the history of their field site in Alaska. Polaris has partnered with the grassroots community leadership group Native Movement to conduct anti-colonial training for their participants. 

“Knowing the history and context of the communities living in Alaska is one of the guidelines that we can use for co-creating knowledge with those communities,” says Dr. Golden.

These recommendations, Dr. Golden hopes, will provide a path forward for scientists looking to reduce bias in their research, and bring forward the voices of groups historically marginalized by biased science.

“If we focus on the most marginalized, we’re more likely to produce outcomes that are equitable for everyone,” Dr. Golden says.

Switching light bulbs, recycling and composting, biking to school—to high school seniors Alice Fan, Amelia Kane, and Simone Colburn, these sorts of sustainability solutions being taught in their classes just didn’t feel like enough. 

“We were seeing a gap in climate education,” says Fan. “We would learn about the greenhouse gas effect, and about the polar bears, but the curriculum wouldn’t really touch on the human aspects of climate change, like environmental justice, redlining, and all the systemic issues that bring a different lens to climate change.”

Fan, Colburn, Kane, and some of their fellow students had come to understand the true scope of the issue through their individual interests and participation in activist and environmental groups outside of school. But the more involved they became, the wider the gap grew between them and their classmates. So they decided to take on the role of educators themselves, founding the Spring Forward Climate Education organization.

Spring Forward’s mission is to bring those larger conversations about climate justice into elementary and middle school classrooms, after-school programs, and summer camps. The organization’s high school members have developed lesson plans and activities that they lead for their younger peers. Mina Subramanian, Spring Forward’s Partnerships Coordinator, says climate education taught by students can be more impactful than receiving information from adults.

“I joined a climate organization before Spring Forward, but it was mostly adults. I felt like in that space, I didn’t have the voice that I wanted to,” Subramanian says. “But at Spring Forward, being youth led, it is such a different environment. We’re all on the same playing field and we all empower each other.”

Spring Forward has also begun branching out from classroom education, to develop additional materials that inform on broader climate topics. Collaborating with Woodwell, the team has created a policy brief around the issue of balancing solar panel installation with other land use considerations.

Solar panels require large clear tracts of land with good sun exposure. Some existing municipal development plans indicate their installation on land currently covered with forests or other vegetation. Forests are some of the best natural carbon sinks and sacrificing them in a rush to install renewable infrastructure is counterproductive. The Spring Forward team wanted to make the policy more accessible to the general public. 

“We need both solar and forests working together—not in competition—if we are going to be successful in addressing the climate crisis,” says Woodwell Carbon Program Director, Wayne Walker, who worked with the Spring Forward team on the brief. “Educating on these complex topics is so important, and the collaboration with Spring Forward offered me the unique opportunity not only to share some of my knowledge with the students, but also to play a small part in helping the students educate others.”

As the group continues to grow and evolve with new members and partnerships, they hope to temper the sting of a sometimes scary topic by showing both kids and adults that they have a voice they can use to make a difference. Talking about the problem helps everyone develop a path forward. 

“In our lessons we try to give information even if it’s scary, but then say ‘okay, well what can you do about it?’” says Colburn. “And one of our big beliefs is that if kids are getting weighed down by information, knowing that they can have power and that they can be influential is really helpful.”

Drought in the Western U.S. has plunged the largest reservoir in the country into alarming shortage conditions that have rippling impacts for the region. Lake Mead, formed by the construction of the Hoover Dam on the Colorado River, delivers water and hydroelectric power to 25 million residents in the Southwest. But its viability has been pushed to the brink by intensifying drought, exacerbated by climate change, triggering emergency measures to conserve water in the basin.

The region has been in a “megadrought” since 2000, but recently, Lake Mead’s water levels have been breaking ever lower lows, unearthing old shipwrecks and other long-forgotten debris and leaving a “bathtub ring” around the reservoir’s edges. The drought signals a larger trend of dwindling snowfall and longer summers brought on by the growing climate crisis.

New water scarcity measures enacted

Water usage on the Colorado River operates on a tier system. When water levels in a reservoir drop below a certain point, usage by neighboring states is restricted. Lake Mead hit Tier 1 in August 2021 after the elevation of the reservoir dipped below 1,075 feet, leading to a reduction in water supplies that largely impacted agricultural users across counties.

This was the first time a shortage condition has been implemented on Lake Mead. The Tier 2 decision was announced in August of 2022—stating that the water level would fall below 1,050 by the end of the year, triggering a more intense shortage.

This emergency declaration for Lake Mead is part of a plan to increase the water levels in Lake Powell— an upstream reservoir and the second largest in the United States behind Mead. Dealing with shortages in the Colorado River Basin has required officials to weigh the needs of one region over another. The Bureau of Reclamation has indicated that at present, keeping water levels up in Lake Powell supersedes the requirements of Lake Mead. The generators at Powell have a total capacity of 1,320 megawatts and the reservoir is considered a ‘bank account’ for the region to draw on in times of drought—which are anticipated to worsen with climate change.

According to the US Drought Monitor, extreme droughts were rare in the historical climate—a 5.5% likelihood. In 2022 however, nearly all of the watersheds in the Colorado River experienced extreme drought. In a world warmed by 2 degrees C, the likelihood of 12 or more months of extreme drought in the Colorado River Basin becomes as high as 40%.

Meeting water needs in dry times

But Lake Mead also serves a massive population in the lower basin, and filling demand for water even during shortages means some major cities have to turn to reservoirs on other river systems. Arizona, suffering some of the steepest cuts in their allotment of Colorado River water (21%) , will draw from the Salt and Verde rivers. Other strategies include pumping groundwater and implementing more aggressive conservation and re-use strategies, which have so-far helped to spare Las Vegas from the worst effects of the shortage.

The Southern Nevada Water Authority also began using its low lake level intake in 2022, which allows the state to draw water even when the elevation of the lake falls below “dead pool” status— the point at which downstream water releases are no longer possible. But this is only a temporary solution, as the water in the reservoir keeps falling.

The next significant threshold for Lake Mead would be a drop to Tier 3 (1,025 feet) which some experts say could come as soon as 2024. At 950 feet, the reservoir would be considered an “inactive pool”, meaning the dam’s generators can no longer run. Energy shortages could kick off a vicious cycle, requiring backfilling with fossil fuels that would exacerbate the climate crisis and warming-driven drought conditions.

Reversing the drought in the Colorado River Basin will ultimately depend on snowfall in the Rocky Mountains, which will ultimately depend on getting the climate crisis under control. Experts estimate there would have to be several consecutive heavy snow years in the mountains to make back the current deficits further downriver. 2023 is currently experiencing above average snowpack, but if temperatures keep rising, that will be a less likely annual occurrence. Water rights and resource usage will have to adapt rapidly to support residents as reservoir levels continue to drop, but pulling out of emergency scarcity measures for good will require curbing the greater impacts of global climate change.

What’s New?

Recent research has quantified the cumulative impact of dams on Brazil’s native savanna ecosystem, the Cerrado. The study created an index of the direct and indirect impacts of constructing hydroelectric facilities on both the rivers being dammed and the surrounding ecosystem.

While often offered as a cleaner alternative to fossil fuels, dams can have severe environmental impacts ranging from deforestation to obstruction of fish migrations, water pollution, and even direct greenhouse gas emissions resulting from inundation of the surrounding area. This study assessed these effects cumulatively, weighting them more heavily if multiple dams were present in a single watershed.

“For freshwater systems, there’s not the equivalent of a deforestation rate. We don’t have an easy metric of ecosystem damage. So this study was one way of building a method for assessing the unintended consequences of installing a dam in a Cerrado watershed,” says Woodwell Water program director Dr. Marcia Macedo, who collaborated on the paper.

The study puts forward a new Dam Saturation Index (DSI) for the region to approximate the environmental impacts of existing dams. High-saturation watersheds were concentrated in the central and western portions of the biome, and most planned dams are located in sensitive areas of native vegetation with little protection.

Understanding hydropower in Brazil

Hydropower is big in Brazil—66% of the country gets some or all of their energy from it. Harnessing the power of a river is often the easiest means of electricity production in rural and remote areas. However, large hydroelectric plants are more often used as a means of infrastructural support for extractive industries like mining, rather than to expand access to electricity for rural citizens. Conflicts have already arisen between communities and hydroelectric plants.

Conflict over water usage in the Cerrado is expected to increase as the region continues to get hotter and dryer due to human-caused climate change. Land use change in the biome has accelerated the impacts of climate change, removing the cooling and moisture-retaining effects of natural vegetation.

“There are a lot of dams already, and many more planned, and it’s only going to get more contentious as climate change continues,” Dr. Macedo says. “In the northern and eastern part of the Cerrado, it’s already quite dry. We’re already seeing conflict over water and these reservoirs could just make that worse as upstream locations are able to withhold water from those downstream.”

What this means for the Cerrado

The Cerrado has historically not garnered as much attention, or as many demands for its protection, as the neighboring Amazon rainforest. Less than 10% of the Cerrado is considered protected, and many of those protections are biased toward terrestrial habitats and species. Lack of research into the full impact of hydropower on the watersheds of the Cerrado has left the region vulnerable to unchecked development. Some dams have even been built in areas otherwise strictly protected. Dr. Macedo hopes this study will encourage a different attitude towards freshwater resources.

“There is a question of how we can innovate thinking about protecting freshwater systems, especially under climate change. They’re so important, and there are so many resources—fisheries and clean water and more—that come from these systems,” Dr. Macedo says.

This study focused on large hydroelectric dams, but Dr. Macedo notes that there are many more small dams, built to serve individual farms, that also impact the flow of headwater streams. Ongoing research is focused on understanding the cumulative impacts of dams of all sizes on tropical watersheds.

This study focused on large hydroelectric dams, but Dr. Macedo notes that there are many more small dams, built to serve individual farms, that also impact the flow of headwater streams. Ongoing research is focused on understanding the cumulative impacts of dams of all sizes on tropical watersheds.

A new study published in the peer-reviewed journal Forests and Global Change presents the nation’s first assessment of carbon stored in larger trees and mature forests on 11 national forests from the West Coast states to the Appalachian Mountains. This study is a companion to prior work to define, inventory and assess the nation’s older forests published in a special feature on “natural forests for a safe climate” in the same journal. Both studies are in response to President Biden’s Executive Order to inventory mature and old-growth forests for conservation purposes and the global concern about the unprecedented decline of older trees.

Scientists have long demonstrated the importance of larger trees and older forests, but when a tree is considered large or a forest mature has not been clearly defined and is relative to many factors. This study develops an approach to resolve this issue by connecting forest stand age and tree size using information in existing databases.  This paper also defines maturity by reference to age of peak carbon capture for forest types in different ecosystems. But the approach is readily applicable across forest types and can be used with other definitions of stand maturity.

Key findings include:

Researchers used thousands of forest plots obtained from the U.S. Forest Service “Forest Inventory and Analysis” (FIA) dataset to determine the amount of carbon absorbed from the atmosphere that accumulates and is stored in individual trees as they mature. As trees age, they absorb and store more carbon than smaller trees, making them uniquely important as nature-based climate solutions. Additionally, as the entire forest matures, it collectively accumulates massive amounts of carbon over centuries in vegetation and soils.  The study identified the forest age at which carbon accumulation is greatest, and used that as the threshold for defining a “mature” forest.  Scientists also determined the median diameter of trees at this threshold age and how much of the forest carbon of the larger trees in mature forests is unprotected from logging. The amount of carbon in unprotected larger trees in mature stands of the 11 forests studied, representing only 6% of federal forest land, is equivalent to one-quarter of annual emissions of carbon dioxide from fossil fuels in the U.S.  This is consistent with prior work.

According to lead researcher, Dr. Richard Birdsey of Woodwell Climate Research Center, “our study determined when an individual tree in a forest can be considered mature and when the forest itself is at an optimal rate of carbon capture and storage for conservation purposes. It is directly responsive to the president’s executive order.”

The Biden administration has set bold emissions reduction targets of 50-52% of 2005 levels and recently announced a “roadmap for nature-based solutions” as part of this effort. However, the roadmap neglects to connect the importance of protecting older forests to the climate targets. Federal agencies are proceeding with an inventory of mature and old-growth forests in response to the executive order, but policies regarding their management have not yet been established.  By protecting older forests and trees on federal lands from avoidable logging, the Biden administration can help close the gap on its emissions reduction goals.  The methodology in this paper provides a readily implementable path for critical policy solutions.

According to Dr. Dominick DellaSala, Chief Scientist at Wild Heritage, “there seems to be a big disconnect between what the White House is wanting and how federal agencies are responding to the president’s forest and climate directives. While the Forest Service recently withdrew a controversial timber sale in older forests on the Willamette National Forest in Oregon (“Flat Country Project”) because it was inconsistent with the president’s directives, dozens of timber sales in older forests remain on the chopping block.”

Dr. Carolyn Ramírez, Staff Scientist with the Forests Project at the Natural Resources Defense Council, pointed to the findings as supporting the push by over 100 conservation groups – the Climate Forests Campaign – for a national rulemaking to protect mature forests and big trees from logging for their superior climate and biodiversity benefits: “This work reinforces how essential mature forests on federal lands are to securing our climate future.  It’s now up to the agencies to protect these carbon storing champions from the chainsaw with formal safeguards.  Our approach shows that logging protections grounded in a straightforward, age-based cutoff—such as 80 years, as many are calling for—would protect significant amounts of carbon, accommodate forest growth differences, and be readily usable in the field.”