water Archives - Woodwell Climate

It didn’t matter that she didn’t speak any English at the time, or that the American researchers who had chartered her father’s boat that summer didn’t speak any Russian, 14 year-old Anya Suslova was a quick learner. She watched them dip sample bottles into the Lena River, filter the water, and mark information down on the side of the bottle. By the end of the two week research expedition, Suslova had mastered the protocol and was helping Dr. Max Holmes and his fellow scientists collect water samples.

When the scientists returned to the United States, they left behind some equipment, in case Suslova and her father were interested in sampling throughout the winter. After a year without contact with Suslova, the researchers were delighted to return to the Lena the following summer to find months of samples and a neatly organized logbook she made.

Twenty years later, Suslova is a Research Assistant at Woodwell Climate Research Center who continues to bring her expertise and unique perspective to the Arctic Great Rivers Observatory (ArcticGRO). Since 2003, participants of ArcticGRO—scientists and Arctic community members alike—have been sampling water from the six largest rivers in the Arctic: the Ob’, Yenisey, Lena, and Kolyma in Siberia, and the Yukon and Mackenzie in North America. It’s a rare example of a long-term research project, designed to span decades, deepening our understanding of change across the years.

We need to establish baselines

The Arctic is warming, on average, at least two times faster than the rest of the planet. We need to know the implications of this, but it can be difficult to study ecosystem change across such a vast area. Rivers can offer insights. The chemistry of a river connects environmental processes across its watershed, and the dissolved and particulate materials that are carried to the ocean can influence marine chemistry and biology. Measuring the concentrations of these materials, and how they are transported by rivers, provides vital information about changes in the linkages between terrestrial and aquatic ecosystems.

“Global climate change is rapidly and disproportionately affecting northern high latitude environments,” says Dr. Scott Zolkos, a Research Scientist at Woodwell Climate and one of ArcticGRO’s lead scientists. “Monitoring Arctic river chemistry is critical for detecting trends and understanding the effects of environmental change on northern ecosystems.”

In order to uncover those trends and effects, need to establish baselines on the key chemical constituents within rivers — organic matter, inorganic nutrients like nitrogen, sediments— to compare against future measurements. The more data gathered, the easier it is to sift out annual variability from longer term trends.

So, using Arctic rivers as sentinels of ecosystem health and environmental change was the idea behind the project’s creation, but it was the international collaboration that started with Suslova that gave ArcticGRO its longevity. The project leaders realized that enlisting the help of trained local residents could allow for sample collection in places, and during times of the year, that the researchers themselves couldn’t access. It also helped build enthusiasm for the project among Arctic communities.

“I believe that ArcticGRO has been able to go for so long because it is built on trust and a shared goal between scientists and local people who collect water samples,” says Suslova. “Amazingly the team of ArcticGRO hasn’t changed much over the last two decades, many of the original members are still involved. It feels like a family.”

Now, 20 years after its inception, the ArcticGRO team has published a paper in Nature Geoscience on long-term trends in pan-Arctic river chemistry. The team found strong signals of environmental change for some chemical constituents, but not in others. Alkalinity, which reflects rock weathering, increased in all rivers, while nitrate, an important nutrient for terrestrial and aquatic organisms, decreased. The authors hope the data and insights from this work will be invaluable to scientists refining models of the Arctic system.

“There’s nothing quite like ArcticGRO,” says Dr. Zolkos. “It’s unique in that it measures a comprehensive suite of chemical parameters across the Arctic’s largest rivers, uses consistent sampling and analytical methods across the rivers, and sampling occurs at the same times and locations. The consistency of ArcticGRO is increasingly valuable, because it is building a dataset which allows scientists around the world to detect, monitor, and understand northern environmental change in ways that no other scientific program does.”

We never would have known

A few thousand miles south of the Arctic circle, on the marshy coastline of Massachusetts, another long-term ecological research project has entered its third decade as well. The brainchild of Senior Scientist Dr. Linda Deegan, the TIDE project is unique even among long-term studies. Rather than simply monitoring the nutrient flows in the salt marshes of Plum Island Estuary, the TIDE project has been altering nutrients in carefully controlled amounts to understand the long term impacts of human development in coastal ecosystems.

TIDE focuses on nitrogen, an element of most fertilizers and a common pollutant from developed areas in the uplands. Previous studies of nitrogen impacts indicated coastal marsh plants could absorb a lot of nitrogen with no ill effects. But that dynamic was only examined on short time scales, and in small plots of marsh. Whether there were changes that might require many years or many acres to be detected, was unknown.

Thus TIDE was designed to increase nitrogen concentrations in the water to mimic coastal eutrophication across three marshes in the Plum Island estuary and document which effects might cascade through the system. The initial grant was for five years, but Dr. Deegan and her collaborators wanted to keep the project running for at least a decade, if not more, expecting the changes might be slow to reveal themselves.

After years of observations, Dr. Deegan says she remembers the exact moment they discovered a significant change.

“Several of the senior scientists—myself included—came back at the end of a long field day each of them saying, ‘I don’t remember it being this hard to walk through the nutrient enriched marsh when we started this project. Am I just getting older or has something changed?’ And then one of the new students said, ‘I thought that marsh was always like that—well, it’s not like that in the other sites where we haven’t added nitrogen.’”

So they followed the hunch, made some new measurements, and found the structure of the marsh had changed significantly with the added nitrogen. The plants, suddenly awash in a necessary component for growth, no longer needed to dedicate their energy to making roots to seek out nutrients; their root systems were shallower and less dense, thus less capable of holding the marsh together. At the same time, nitrogen-consuming microbes were breaking down organic matter in search of carbon to fuel the chemical processes that allow them to take up nitrogen. This combination made the marsh creek edges more susceptible to erosion by tides and storms.

It took more years than most experiments are run for, but increased susceptibility to erosion steadily altered the shape of stream channels. The ground along the edges of the streams, previously held in place by a deep network of roots, now collapsed underfoot. Chunks of marsh fell off the edges as the roots no longer held the marsh together. As the years went on, fish and other organisms that travel along stream floors to seek out food began to suffer from difficult terrain, resulting in slower growth and fewer fish.

These findings, published in Nature, upended the way people thought about the effects of eutrophication on marshes. “And we never would have known any of that,” says Dr. Deegan. “If we hadn’t done the project at an ecosystem scale and over such a long time.”

A pipe you can turn off

Over the decades, the TIDE project not only faced the challenges of running a consistent project for so long, but also of justifying making intentional changes to an otherwise healthy ecosystem. The question lingered: If the goal is to protect ecosystems from human disruption, what do we gain from knowingly tinkering with them?

Humans have already accidentally conducted thousands of ecological change experiments across the globe. Casually inflicted pollution, deforestation, or extinction with no control group, no careful observations, no time limits or safeguards—by scientific standards these are reckless and poorly designed experiments.

In Dr. Deegan’s mind, this makes controlled studies like TIDE even more significant.

“We need to know the true impact of the changes that we are already imposing on the environment. And once we do, we need to be able to halt those changes that threaten the integrity of an ecosystem.” Says Dr. Deegan. “This is a pipe I can easily turn off. Not like when you build a housing development and then you’re stuck with all those houses and their impacts forever.”

Climate change is perhaps the most all-encompassing of these involuntary experiments. As ArcticGRO’s and TIDEs results indicate, ecosystem responses to human disturbance, whether it is climate warming or nutrient over enrichment, are complex. Understanding and adapting to these responses will depend on continued monitoring, observation and experimentation.

A testament to the people

In the world of research, rife with limited grants and time-bound fellowships, ArcticGRO and TIDE have been uniquely successful. Research Associate, Hillary Sullivan, who has been part of the TIDE project since 2012, attributes this to the dedication of the researchers, who showed up year after year to get the research done even when funding wasn’t certain or while enduring a global pandemic.

“These large scale projects are a testament to the people that are involved in the effort, and the work that goes in behind the scenes to keep it running,” says Sullivan.

Both ArcticGRO and TIDE plan to continue. ArcticGRO is seeking additional funding to analyze new chemical constituents and continue providing invaluable data for scientists and educators to understand how rivers are responding to a warming climate. “ArcticGRO has improved our understanding of the Arctic, and our work is just getting started,” says Dr. Zolkos. “Continuing will be essential for generating new insights on climate change, northern ecosystems, and societal implications.”

TIDE has now shifted to a new phase of study — observing the legacy of the added nitrogen on marsh recovery in the face of climate change induced sea level rise. Nitrogen additions were halted 6 years ago and researchers hope to gain insights into marsh restoration and ways to improve their resilience to sea level rise.

Thinking in the long-term is not something humans have historically excelled at, Dr. Deegan admits. But the more we try to expand our curiosity past immediate cause and effect, the better we get at understanding nature. If you want to understand an ecosystem, you have to think like an ecosystem—which means longer time scales and larger areas that encompass every aspect of the system.

“Nature tends to take the long view and people tend to take the short,” says Dr. Deegan. “So if you can stick with it for the long view, I think you see things in a very different way.”

Climate change is having profound effects on the chemical composition of large Arctic rivers, signaling changes both on land and in the coastal ocean, according to new international research examining chemical signatures in rivers across Canada, Alaska and Russia.

The study, the result of a two-decade effort by the Arctic Great Rivers Observatory, analyzed nearly twenty years of water chemistry and discharge data collected from six rivers that comprise 60 percent of the Arctic Ocean watershed.

The researchers tracked river water ions, key nutrients, and dissolved organic carbon, among other indicators. They found that chemical concentrations changed substantially over the past two decades, but trends across chemical groups were different, with some increasing, some decreasing, and others showing little change.

The international scientific collaboration tracked river water ions, key nutrients and dissolved organic carbon among other metrics. Chemical concentrations changed substantially over the past two decades, but trends across chemical groups were different with some increasing, some decreasing, and some showing little change.

“The only way that this divergence in trends is possible is if multiple factors of change are being brought to bear on the Arctic system at the same time,” says Woodwell Research Assistant, Anya Suslova and co-author on the paper. “We know that permafrost is thawing, vegetation is changing and moving northward, and processing of nutrients and organic matter may be happening more quickly. Global climate change appears to be causing many systems that are critical for ecosystem function to change at the same time—and that change is showing up in the chemical composition of river water.”

Key nutrients observed in river water are declining, according to the study. This trend suggests warming temperatures are increasing biological uptake of nutrients on land or in aquatic ecosystems, leading to an overall decrease despite factors like wildfire and permafrost thaw releasing more nutrients into the waterways.

ArcticGRO represents a partnership between researchers at Woodwell Climate Research Center, University of Alberta, the Marine Biological Laboratory, Florida State University, and the University of New Hampshire, as well as scientific and community collaborators in Siberia and the North American Arctic.

“The success of this study is largely due to its collaborative nature,” says Dr. Max Holmes, Woodwell Climate President and CEO, and founder of the ArcticGRO project. “Without the dedication of scientists and community members across the Arctic, we never would have been able to generate the comprehensive dataset that allowed us to uncover these insights.”

Because trends in river water chemistry are not always acting in the same direction, Dr. Holmes and Suslova say the study will help give scientists a blueprint for thinking about how Arctic change will play out.

In a world plagued by rapid change and challenges, I think many of us are asking the question: “How can I help?” As individuals, it can be hard to find a way to give back and help steward the natural resources we rely on. But, for those who love fly fishing—anglers—Science on the Fly offers a path to do just that.

Science on the Fly engages the enthusiastic and passionate fly-fishing community, in the US and abroad, as community scientists. Members of the fly-fishing community have close relationships with their local rivers—from having a favorite fishing hole, to knowing the seasonally anticipated flows of the river and when certain bugs are hatching. They also are more aware than most of the impacts of climate change on local fisheries. In states like Colorado or Montana, anglers have given up the opportunity of even casting a fly rod at some points in the summer season. Why? The trout are too stressed and lethargic due to the droughts and rising water temperatures.

Crowdsourcing climate data

Our fly-fishing community scientists are excellent resources for data collection and observation of climate trends to create a clearer picture of how rivers are changing over time. With their help, we can increase the number of rivers subject to long-term studies of water quality and watershed health. Since Science on the Fly was founded in 2019, we have collected data on nutrients and organic compounds from over 350 river sites across the United States each month.

The science collection process is straight-forward and easy. Sample locations are chosen for their accessibility and interest to fly-fishing volunteers, who are responsible for collecting a small bottle of sterile river water from each location once a month, as well as data on air and water temperature. They then freeze the bottles and bulk ship them back to Woodwell Climate Research Center one or two times a year.

At Woodwell Climate’s Environmental Chemistry Lab, we analyze the concentrations of nutrients such as nitrate, phosphate, silica, ammonium, dissolved organic carbon, and total dissolved nitrogen. All data is shared publicly, and after we have a year’s worth of data, we write a report of the state of the river for those sampling locations.

A rapidly expanding network

This project got to where it is extremely quickly. A year after the program was founded, we had grown from two community scientists to 140 enthusiastic river activists. Over the course of four years, more than 7,000 bottles have been placed into the hands of our empowered community scientists.

It is easy to see how we got here so fast; when we offer a tool-kit that is free to the passionate angler and can help them give back to their watershed, they want to get involved. While it isn’t necessarily cheap for us, at a cost equaling $100 a bottle, it is an extremely effective way to add novel data to the climate science dataset on many watersheds—information we wouldn’t be able to gather otherwise.

We’re now exploring how best to integrate Science on the Fly’s water quality sampling and community scientist model with Woodwell Climate’s important research in the Alaskan Yukon-Kuskokwim Delta region. Located at the lowest section of the permafrost belt, this region is experiencing rapid thaw as the climate warms. We ask: Could water quality collection be done in a way that tells the story of the rivers over time? Could anglers floating down these remote rivers provide samples in a timely manner? The answers, we’ve found, are yes, but it has taken some practice to get there, and the region presented unique challenges that we didn’t encounter in other regions.

Our core team at Science on the Fly now rafts, researches, and fishes vulnerable and wild rivers in this region—including the Arolik, Kanektok, Kisaralik, Kwethluk, and the Goodnews—each summer season. Each morning of the trip, the teams gear up and take a variety of samples and water quality measurements—including the collection of our 60 mL sterile river water samples. We also install or retrieve water temperature monitoring sensors in the watershed, so we can see river temperatures from the entire year. Some samples collected during the trips are used directly for the Science on the Fly program, while others help collect data for different research projects associated with Woodwell Climate or other organizations.

Building partnerships to sustain science

These research trips are only answering some of our questions, however. We still want to see these rivers’ nutrient concentrations throughout the summer season—not just when we’re floating (which is normally 10 or fewer days per river). Like most science, it’s not cheap. It’s also not easy to logistically coordinate a river research trip—all the gear, travel, food, science supplies, safety equipment, and qualified team members to float—from afar.

PapaBear Adventures in Bethel, Alaska is our answer to the other half of the questions. PapaBear is an operation that helps the adventurous outdoors person get to the headwaters of remote rivers, and gives them the tools they need to float the rivers on their own. They have been instrumental in meeting the transportation needs of other Woodwell Climate projects like the Polaris Program, and now they are helping Science on the Fly get anglers out to the rivers throughout the summer season.

Beyond working with PapaBear on transportation, Science on the Fly now stations a team member—me or Joe Mangiafico, for now—at PapaBear for the summer months. This team member preps the research team’s trips, making sure they are properly prepared to go down the rivers with all materials needed. But their main goal is to encourage other PapaBear clients and their groups to be involved in the sampling. Pre-made kits are handed out to groups floating these rivers. After the groups get off the rivers, our team member retrieves the filled sample kits and freezes them for shipping back to Woodwell Climate.

The data that has returned from these endeavors is already exciting.

In summer 2021, our Science on the Fly research team sampled 2 rivers, the Kwethluk and Kisaralik, and by a lucky ask to some passing groups of anglers, the Kanektok and Goodnews Rivers were sampled as well. There were a total of 45 samples collected that summer. The following summer, the combination of Science On The Fly research teams and new efforts to increase engagement with volunteer community science groups, allowed us to increase collection to 248 sample bottles. We were able to successfully increase data collection on the other rivers of the Yukon-Kuskokwim delta, and added the Arolik to our list. We hope to accomplish even more in years to come.

Four years of Science on the Fly has shown that community scientists and community science programs can be a powerful way to collect data, conduct research, and educate the public through our reports. Now that we’ve built a solid project structure, with data coming in consistently, we are beginning to switch gears and make an impact with report writing and affecting policy—all while continuing to add to the growing body of water and climate science. We’ll be using community-collected data to create tangible reports for anglers to better understand their watersheds. We will then use these reports to help make an impact on policies, with the goal of creating or maintaining healthy watersheds, especially in the face of climate change. We look forward to continuing to give back to our community scientists and to our rivers.

To learn more about Science on the Fly, visit our website.

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.

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.

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

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.

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.

As the planet warms, drought is an increasing threat in many regions. Research led by Woodwell Research Assistant Isabelle Runde, modeled the frequency of drought across the globe, analyzing drought changes in forest, food, and energy systems as temperatures surpass 2, 3, and 4 degrees Celsius.
Models show that unlike in a stable climate, unreliable water resources and increasing temperatures make drought more likely in many places. For every increase of 0.5 degrees C, an additional 619 million people could become exposed to extreme drought 1 in every 4 years. This is in addition to the 1.7 billion people (nearly a quarter of today’s global population) who are already exposed to these conditions in a world that has warmed by a little more than 1 degree C.

2 Degrees of Warming Risks Damaging our Best Forest Carbon Sinks

Tropical forests are one of the planet’s key natural climate solutions— able to prevent 1 degree of warming through both carbon sequestration and regional cooling effects. Deforestation, fragmentation and degradation from things like fire, and disease threaten to turn these forests from a vital sink to a source of emissions.

In recent years, the Amazon has been a net carbon source due to increased extreme drought and deforestation, leaving the Congo rainforest as the world’s last remaining stable tropical forest carbon sink.

As warming surpasses 2 degrees, the annual likelihood of drought in the Congo rainforest begins increasing faster than in the Amazon. Drought can make a forest more susceptible to further degradation, such as fire or disease, and reduces carbon sink capacity by stressing or killing trees and placing the ecosystem under stress.

Productivity is Threatened in the Breadbaskets of Mediterranean, Mexico, China

Global crop production is highly concentrated in key breadbasket regions— nearly 72% of the world’s maize, wheat, rice, and soy are produced in just 5 countries. Extreme drought can reduce the productivity levels of these staple crops, among others, potentially triggering widespread food insecurity, hunger and economic disruption.

By 2 degrees of warming, the probability of drought in the breadbasket regions of both China and the United States will be greater than 50% — meaning an extreme drought roughly every other year.

Disruption will be much higher in countries where jobs in agriculture comprise a large segment of the economy. In Mexico, one of the world’s top 10 producers of maize, 12% of the workforce is in agriculture and at 1 degree, the country already has among the greatest areas of cropland exposed to drought. 90% probabilities—indicating near-annual drought—begin to emerge in some parts of the country at 2 degrees of warming.This kind of recurrent extreme drought will stress water resources for agriculture.

The Mediterranean also is a drought hotspot. Drought probability in Mediterranean croplands will increase rapidly between 2 and 3 degrees of warming, rising from just 10% to over 50% of cropland affected by drought in 3 out of 4 years.

Drying Rivers Will Plunge Hydro-dependent Countries into Energy-Shortages

Hydroelectricity supplies a sixth of global energy demand, and is a low-cost, low-emission alternative to fossil fuels. The overwhelming majority of new hydropower plants since 1990 have been constructed in fast-growing, developing nations.

High dependence on hydropower makes countries like Brazil and China vulnerable to energy disruption during periods of drought. Brazil draws nearly two thirds of its energy from hydroelectric resources. During a three year drought between 2012 and 2015 in Brazil, hydroelectric generation declined by 20% each year. If warming exceeds 3 degrees C, more than half of Brazil’s hydroelectric capacity will experience a likelihood of annual drought greater than 50%.

Extreme drought can also be counterproductive to reducing carbon emissions. During years of drought, expensive fossil fuel based energy is often brought in to fill demands. In addition, droughts often coincide with extreme heat events, when electricity demand peaks to run air conditioners. Beyond 3 degrees of warming, more than a third of the planet’s hydroelectric capacity will likely be exposed to extreme drought every other year.

Projections of a Dryer World

Current international climate goals aim to limit warming to between 1.5 and 2 degrees C, but without urgent intervention, we are on track to push past that limit to at least 2.5 degrees C. Projections past 2 degrees of warming show a future where extreme drought is common, exposing already-vulnerable people, places, and economies to greater water shortages, while making it even harder to curb emissions. In order to guard water resources and the systems that depend on them, emissions need to be cut rapidly. And places already feeling the impacts of warming will need to brace to adapt to a hotter, dryer version of the world.