What are ice wedges, and why are they important to climate change?
“I think ice wedges are what make permafrost interesting,” says Dr. Anna Liljedahl.
Liljedahl works on Woodwell Climate’s Arctic team as an Associate Scientist. She aims to understand how climate change is affecting water storage and movement. Much of her recent work focuses on ice wedges and how they are reacting to warming Arctic summers. But just what are ice wedges anyway?
Ice wedges are one of the three main features of the Arctic’s land surface. Permafrost, ground that remains below 0˚C for at least two consecutive summers, lies under a thinner layer of thawing and refreezing soil, called the active layer. When permafrost cracks during cold winter days, snowmelt and runoff water seep into the empty space. These eventually freeze and create a wedge-shaped spear of ice that extends vertically down into the permafrost.
Ice wedges actively re-shape the tundra. When they freeze, they grow and expand outward, pushing against the bordering permafrost and active layer. With nowhere else to go, permafrost and soil push upwards, and ridges form on the surface of the tundra. The ridges interlock and form distinct shapes, referred to as ice-wedge polygons.
The ridged borders of ice-wedge polygons form directly above expanding ice wedges below the surface, and are therefore more elevated. The lower internal portion of the polygon allows pools of water from runoff and snowmelt to form atop the active layer. These polygons are visible all the way from space.
Thanks to satellite imagery, scientists like Liljedahl are able to monitor ice-wedge polygons remotely. Satellite images date back to the mid-20th century and can be used to observe changes in the landscape overtime.
During unusually warm summers, the tops of ice wedges can melt, which removes underlying support of the ground surface, causing slumps along the borders of ice-wedge polygons. These leveling borders form channels that siphon the water from pools in the centers of neighboring polygons. The resulting runoff streams can drain small pools and even larger lakes that took thousands of years to form.
With the progression of climate change, these drainage systems have become more common. Liljedahl refers to them in the title of her manuscript, just published in the July issue of Nature Water, “The Capillaries of the Arctic Tundra.”
The increase in creation of new “capillaries” in the Arctic is impacting not only the topographical landscape of the region, but also the livelihoods of all beings that find their home there.
At first, the melt of these ice wedges can spark an uptick in the variation of vegetation due to moisture along the sides of the channel. This, however, is temporary. When the ice wedges stabilize again in the winter, this variation decreases once more.
Aquatic mosses— one of the most productive vegetal forms in the Arctic, equivalent in productivity to Arctic shrubs— inhabit pools formed alongside the edges of ice-wedge polygons. They lose their homes when bodies of water drain away. Major vegetation changes can alter carbon storage, availability, and emissions across the tundra.
Humans are also impacted. Homes become too dangerous to live in as the ground supporting vital infrastructure collapses. Roads connecting communities to important resources are destroyed by subsiding ground.
Despite their widespread impact, ice wedges are often overlooked in Arctic climate models. Historically, their inclusion “costs too much computer time,” Liljedahl says, to factor in. Many climate models take a holistic approach to the Arctic landscape, as opposed to focusing on smaller details.
To remedy this, Liljedahl suggests utilization of developing technology such as Artificial Intelligence (AI). Classifying the Arctic landscape by type, for example, into high-center polygons, low-center polygons, and capillary networks, would factor ice wedge change into climate models. As AI advances and becomes a more common research tool, it could help decrease the human computing time that Liljedahl identifies as a barrier.
Arctic research is likely to change drastically in the coming years. With new technologies, and as we learn more about the Arctic landscape, research models will likely become more inclusive of the varied features within it, and much more accurate.
“There are exciting years ahead,” Liljedahl says, “I think we’re going to see some cool stuff coming out [of tundra research] in the next five to ten years.”
A new study, just published in the journal Nature Communications Earth & Environment, finds that severe droughts in the Amazon basin over the last two decades have led to longer periods of low water levels and triggered profound impacts on the local population.
The severe droughts in 2005, 2010, and 2015-2016, in particular, not only drastically reduced water levels in a substantial part of the world’s largest river system, but also resulted in low water level periods exceeding 100 days, a month longer than expected.
These droughts have major impacts on rural, remote Amazonian communities who heavily rely on inland water transport to access goods and services, reach urban centers, and maintain their livelihoods. The study concludes that during severe droughts, when such water transport is not available, nearly 50% of non-Indigenous localities and 54% of Indigenous villages in the Brazilian part of the Amazon basin are prone to isolation. These droughts also expose Amazonian communities to scarcity of goods, restricted access to healthcare and education, limited access to fishing and hunting sites, and other major impacts.
“This is the new reality of the Amazon,” said Dr. Letícia Santos de Lima, researcher at the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) and lead author of the study. “Scientists have been warning for years that the Amazon basin is facing a substantial increase in the frequency and intensity of extreme events due to climate change, on top of severe changes in its hydrological system due to deforestation and forest degradation. These past droughts as well as the most recent one, 2023-2024, are showing that the impacts on the ecosystems extend severely to the Amazon population.”
“The Amazon faces increasingly severe droughts due to global warming, with very real consequences for the communities that live there,” added Dr. Marcia Macedo, Woodwell Climate Research Center scientist and study co-author. “To better prepare for these extreme climate events, we need climate solutions that prioritize water resources alongside efforts to curb carbon emissions. This will be key for sustaining resilient ecosystems and communities in the Amazon and around the world.”
The paper states that “actions to cope with recent droughts in the Amazon have been reactive rather than proactive and grounded in preparedness and adaptation principles,” and calls for Amazon countries to “develop long-term strategies for mitigation, adaptation, and disaster response.” The authors also stress that any solutions to isolation must not also worsen the problem. For example, roads would not be an effective solution as they are a well-known driver of deforestation, which leads to changes in rainfall, contributes to a higher volume of sediments in rivers, and would impair navigability even further.
Using an interdisciplinary approach, researchers combined spatial analysis, methods from hydrology, and news media content analysis to deliver the first spatiotemporal assessment of cross-sectoral impacts of droughts in the Amazon basin.
The MacGyver session at the annual American Geophysical Union (AGU) conference is full to the brim with scientists showing off blinking circuit boards and 3D-printed mechanisms. Research Assistant, Zoë Dietrich, stands in front of her poster and a plexiglass cube sprouting wires. As she speaks, a whizzing sound emanates from the box as it lifts itself up on one side, holding itself open long enough to flush the interior with air from the room. A laptop screen reads out numbers from the sensors in the box, detailing changes in the concentrations of carbon dioxide and methane within.
Dietrich constructed this device herself. It’s a low-cost, autonomous, solar-powered chamber designed to float on water and measure the flow of carbon into and out of the water. Dietrich has spent the past 1.5 years testing and troubleshooting various prototypes, and has already begun deploying models at research sites in Brazil and Alaska. Now she’s sharing her work with the broader scientific community in hopes of encouraging others to build their own versions.
“One of the goals of the chamber project is to make the construction very accessible so that scientists like me, without formal engineering training or background, can build the chambers pretty easily,” says Dietrich.
This was good news for Grand Valley University masters student, Jillian Greene, and her professor Dr. Sean Woznicki, who encountered Dietrich and her chambers at AGU. Though neither of them had experience with mechanical or electrical engineering, they knew immediately a device like Dietrich’s could be invaluable to their research.
Greene’s project involves sampling carbon emissions at drowned river mouth estuaries connected to Lake Michigan. She and Woznicki will then correlate that data with other ecological characteristics gleaned from satellite imagery. There are over one hundred of these freshwater estuary-like features around the region, and Greene and Woznicki are hoping to paint a complete picture of their cumulative role in carbon cycling.
“Originally, I was going to manually sample and quantify with a gas chromatograph,” Greene says. That’s a time-consuming process that limits the amount of data one team can collect. With the chambers, however, Greene can collect emissions data every 30 seconds—greatly expanding the amount of data she’ll be able to incorporate into her models.
“This is going to make our model a lot more robust and hopefully applicable to other drowned river mouth estuaries in the region,” says Greene.
Greene and her research team have already created and deployed 6 chambers. Since AGU, she has been in contact with Dietrich, troubleshooting issues as they arise and learning an entirely new set of skills as she goes.
“[the team] has learned how to solder, how to interpret the circuit diagrams, problem solve, and adjust for our kind of unique systems that we’re looking at,” says Woznicki. “It’s really been exciting to use Zoë’s design as a learning experience for masters and undergrad students.”
Dietrich has had other groups at Colgate University and the University of California, Berkeley reach out to her as well, and she is planning to publish a paper this fall that will include detailed instructions for anyone else to construct their own chambers. She’s already shared preliminary drafts of the step-by-step instructions, including photos, diagrams, and tips, as well as programming and data-processing code and a specific materials list with the other research groups. In turn, they have provided her with helpful revisions and ideas for new modifications. Dietrich is excited about the prospect of the designs being implemented by more people. More chambers means more data, which benefits the entire scientific community.
“Our sampling of carbon right now is limited by expensive instruments and where people can go and who has access to these resources,” says Dietrich. “But the goal of this project is to be low cost and more accessible to a broader set of researchers. The chambers are autonomous, and so are accessible to places and times that aren’t otherwise being sampled right now. And taking that a step further, we need to make them accessible to be built by anyone.”
“Why not float the aquatic greenhouse gas chamber on a surfboard?” Tropics Program Director Dr. Mike Coe suggested in one of our team meetings, and I could feel the gears in my brain begin turning. I started a sketch… If mounted on a surfboard, we would need a method to open the chamber, flushing it with outside air. Back in my office, I asked Google “what turns electrical energy into mechanical energy?” Google was quick to respond, “Motor.” Right, thank you, Google. Next, I typed, “motor that pushes something up.” Google replied, “linear actuator.” Three clicks later and I had ordered my first linear actuator for 35 bucks.
Three days later, that linear actuator sat expectantly on my desk. One red wire and one black wire, “12V DC” printed on its side. I turned back to Google, “How to wire a linear actuator?” Opening the first hit, I skimmed through the photos and diagrams. None of them striking my fancy, I moved on to the second hit: Step-by-step instructions, clear photos, even open-source code to program my Arduino microcontroller board – nice! Within an hour, my linear actuator was extending and retracting on command, ready to be mounted in an autonomous greenhouse gas chamber.
Adding the actuator to my sketch, I popped into Senior Research Scientist Kathleen Savage’s office to hear her thoughts. Savage always has new ideas brewing, and she suggested adding a feature that would allow the chamber to function on water and on land. The chambers are the product of a Fund for Climate Solutions (FCS) grant led by Savage to quantify carbon dioxide and methane emissions from small water bodies like lakes, ponds, and reservoirs. Because there are no low-cost and auto-sampling tools available on the market, we have been developing a new instrument to measure these emissions.
DIY science
“Chamber” is a fancy word for the upside-down buckets we use to measure how fast greenhouse gasses are released from different surfaces. By resting a bucket upside-down on a patch of soil or grass or water and measuring how fast gas concentrations increase or decrease inside the bucket, we can calculate a “flux” of gas over a set area and time. Common methods of measuring fluxes require manually collecting gas samples from a chamber to be processed in a lab, or connecting the chamber to a high precision analyzer that can cost around $40,000. These methods are costly in salary time and equipment, limiting where, when, and how often people can sample—usually daytime and in accessible areas and times of the year. We need new low-cost and autonomous systems that can measure around the clock to improve carbon emissions estimates. The recent commercialization of cheaper sensors and control systems to operate them, like the Arduino microcontroller, now make these developments possible.
I’m building a new floating chamber that measures aquatic fluxes autonomously using a $15 methane sensor and a $78 carbon dioxide sensor, improving previous designs published by Dr. David Bastviken’s group at Linköping University in Sweden. Powered by a solar panel and battery, the sensors measure gas concentrations, temperature, and humidity inside the chamber every 30 seconds. The data is stored on an SD card and transmitted within 50 meters via radio. The radio transmission allows us to check that the chamber is functioning properly from the shore and to see chamber measurements in real time. When gas concentrations have increased enough to discern a flux, the linear actuator extends to open the chamber, flushing the interior with outside air before retracting to close the chamber again for another flux measurement. Calibrating the chamber with a high precision analyzer in the field shows the low-cost sensors perform well, with an accuracy of approximately 1 ppm for methane and 3 ppm for carbon dioxide.
Field deployment
I first tested chamber prototypes last July on agricultural reservoirs at the Tanguro Field Station in Brazil. At the end of our field campaign, I left one chamber deployed to see how long the electronics would last and which components might eventually fail. After helping me deploy and calibrate the chamber, field technician Raimundo “Santarém” Quintino monitored it, checking its “vital signs” via radio every few weeks. In January, he noticed the linear actuator had stopped pushing the chamber open.
During a follow-up field campaign in March, I brought a couple of extra linear actuators and five more chambers to deploy on additional reservoirs at Tanguro. Tanguro staff and I worked together to modify chamber components that didn’t function well in the first deployment. These modifications included swapping the materials of the floating foam bases and improving the mounting mechanisms of the linear actuator and chamber hinge. Our adjustments were informed by recommendations from a Laboratory Operations Manager at the University of Maine in Orono (Christopher London), whom I met while doing fieldwork at the nearby Howland Research Forest. Woods Hole locals, such as John Driscoll and Fred Palmer of the Woodwell Climate Facilities department, kite foiler and carpenter Tad Ryan, and employees at Eastman’s Hardware, have also offered transformative recommendations on building materials and techniques to stabilize the floating chambers.
Working hands-on with the floating chambers on the reservoirs, Santarém, Dr. Leonardo Maracahipes-Santos, Tanguro’s Scientific Projects Coordinator, and Sebastião “Seu Bate” Nascimento of Tanguro Field Station have made invaluable improvements to the chamber design and deployments. A few of their contributions include advice on safe deployment locations, monitoring and collecting data from the chambers over time, and constructing aluminum and galvanized steel components for the floating bases. They also designed a new mount for the most recent chamber addition—a bubble trap that uses an inexpensive pressure sensor to autonomously measure the volume of gas released as bubbles.
Freshwater ecosystems worldwide emit nearly half as much carbon dioxide and methane as fossil fuel combustion. On the Amazon-Cerrado frontier, where Tanguro is located, there are hundreds of thousands of small agricultural reservoirs, which are important, yet overlooked, greenhouse gas sources. These artificial ponds—installed to provide drinking water for cattle, facilitate road crossings, or supply energy at the farm scale—can persist for decades, creating low-oxygen conditions that drive methane production. Monthly sampling of six reservoirs over a year by Water Program Director Dr. Marcia Macedo revealed high methane and carbon dioxide emissions, varying with season and reservoir size. But these measurements did not capture the significant variability that can occur on daily, monthly, and annual time scales, including transient “hot spots” and “hot moments” of high greenhouse gas emissions.
This lack of frequent measurements hinders climate scientists’ ability to integrate emissions at the reservoir scale in order to estimate cumulative greenhouse gas emissions at the landscape scale. The autonomous floating chambers will address that gap, enabling comprehensive carbon monitoring and modeling of the reservoirs.
From the tropics to the Arctic
Additionally, these chambers are versatile tools that can be used across different environments. Funded by a subsequent FCS grant, six new floating chambers will accompany me to the Yukon-Kuskokwim Delta, Alaska, this summer to measure greenhouse gas emissions from Arctic ponds. The chambers will supply the frequent data necessary to constrain the LAKE model utilized by Arctic Program scientists Dr. Elchin Jafarov and Andrew Mullen. The model predicts variations in carbon emissions from ponds, providing insight into processes regulating methane and carbon dioxide. By applying the LAKE model to both Arctic ponds and Amazon reservoirs, we can gain a deeper understanding of their impacts on regional greenhouse gas budgets.
“Deploying floating chambers will streamline the process of gathering aquatic data and enhance the temporal resolution of the data, which is vital for modeling and currently absent in existing datasets,” notes Jafarov.
Problem-solving and collaboration
While calibrating the low-cost sensors in our boat one March afternoon, Santarém and I noticed the linear actuator on another nearby chamber wasn’t retracting and extending as it should. Expecting another replacement was in store, we tuned into the radio and popped open the electronics case to check for “symptoms.” Blinking lights and radio silence revealed an entirely new and perplexing issue causing the malfunction.
Building this system from the ground up over the last year, the one constant has been mind-bending electronics puzzles that keep me up at night. As a biogeochemist by training, these problems usually require some tinkering, a dictionary, a lot of Googling, and sometimes bugging electrical engineers down the street at the Woods Hole Oceanographic Institution (Lane Abrams) and Spark Climate Solutions (Bashir Ziady), whose advice and contributions have substantially improved the chambers’ electrical designs. Each problem can usually be traced to a perfectly logical, satisfying solution, leaving me feeling wiser and excited to tackle the next one. I’ve tracked this new problem down to something potentially involving a “memory-leaking variable declaration” in my new bubble trap programming code. I might’ve fixed it with a “watchdog timer.” Both are new words for me, too. If the watchdog timer doesn’t pan out, Santarém and I will try another fix.
Designing, building, and testing these chambers has been an iterative and constantly evolving process. What works well? What doesn’t? How can we do this more simply? Using less energy? For a lower cost? How can we improve the design so that other researchers can easily build these floating chambers as well? Soon we plan to publish open-source instructions detailing how to build and troubleshoot the floating chambers—I have already sent preliminary instructions to three interested research groups. I’m lucky to collaborate with many talented people from Woods Hole to Maine and Brazil, many of whom are as new to chambers and fluxes as I am to engineering. Nevertheless, these floating chambers incorporate a brilliant flourish from each of them.
Andrea “Andie” Norton is an ecologist studying the world’s changing rivers. She examines patterns in temperature and nutrients to assess the response of watersheds to climate change, and to build a record of how river environments are changing that could help flag current threats, predict future changes and develop strategies for successful management.
Read more on Science on the Fly
1. Collaborating with Communities
This year, Woodwell Climate’s Just Access Initiative went global. Just Access works in close partnership with communities to provide tailored, actionable climate risk reports for Rio Branco, Brazil; Addis Ababa, Ethiopia; Summit County, Utah; and Lawrence, MA. At COP28, Just Access released their latest report in collaboration with the Ministry of Environment and Sustainable Development of the DRC, which focused on climate risks and potential solutions in the country and identified carbon markets as a potential funding mechanism for adaptation efforts.
Just Access collaborates with local officials and advocates to ensure the final reports cover information critical to their community’s planning. So far, 14 reports have been completed and more are on the way.
Read the report.
2. Tongass National Forest Protection
In January of 2023, the Biden Administration restored protections against logging and road-building for more than 9 million acres of the Tongass National Forest, the world’s largest intact temperate rainforest.
This came after Woodwell Climate’s Dr. Wayne Walker and Geospatial Analyst Seth Gorelik, along with long-time collaborator Dr. Dominick DellaSalla of Wild Heritage, delivered a research report to the Biden administration showing massive carbon stores in Tongass National Forest and highlighting the importance of roadless areas.
3. Citizen Science with Science on the Fly
In 2023, Science on the Fly’s (SOTF) focused their activities on stewarding their community of scientists. Together they collected more than 3,000 water samples from hundreds of locations around the globe. SOTF leverages the passion and dedication of the global fly fishing community to gather data on the health of rivers across the world. With this data, SOTF can improve our understanding of how watersheds and river systems change over time due to climate change and local effects.
Read about the project’s activities this year.
4. Training the Next Generation of Researchers
We sent 10 Polaris Project students into the field this summer. The Polaris Project engages the brightest young minds from a diversity of backgrounds to tackle global climate research in one of Earth’s most vulnerable environments: the Arctic.
Students conducted their own research projects over two weeks at a field research station near Bethel, Alaska. Afterwards, they returned to the Center to analyze samples, and presented their findings at the American Geophysical Union meeting in December.
Woodwell Climate also hosted several interns through the Partnership Education Program. These undergraduate students participated in research and communications activities across the center.
Read PEP intern, Jonathan Kopeliovich’s story about research in Howland Forest.
5. Convening Critical Conversations
Woodwell Climate has been conducting tropical forest research in Brazil for nearly two decades alongside partner organization IPAM Amazônia. This year, Water Program Director, Dr. Marcia Macedo and collaborators, including Dr. Ane Alencar of IPAM, convened a multi-day workshop in Brazil that produced a policy brief on forest degradation. They then organized experts to submit public comments on Brazil’s updated policy for controlling Amazon deforestation, which for the first time also addresses forest degradation.
Read the policy brief here.
Across the globe, Permafrost Pathways partner, Alaska Institute for Justice (AIJ), hosted a “Rights, Resilience, and Community-Led Adaptation” workshop on Dena’ina homelands in Anchorage, Alaska. The two-day workshop created space for Tribes to share their expertise with each other and connect face-to-face with federal and state government representatives to access resources and technical assistance.
Read more about the workshop.
6. Representing Our Expertise
Our experts showed up as thought leaders this year at several high profile events. As just a few examples, Woodwell Climate’s Arctic Program Director Dr. Sue Natali and Senior Science Policy Advisor Peter Frumhoff both spoke on panels alongside other leading voices in climate at SxSW in Austin, TX. Senior Geospatial Analyst, Greg Fiske attended the Esri User Conference, where his topographic map of Alaska garnered two awards. And Assistant Scientist, Dr. Ludmilla Rattis gave a talk at TED Countdown about her research on the role of Tapirs in rainforest restoration. (Recording coming in early 2024)
7. Making Headlines
Woodwell Climate team members showed up in over 5,000 media stories this year. Our scientific leadership provided quotes for a broad range of high profile climate stories in New York Times, Reuters, Boston Globe, CNN and Grist, just to name a few. Senior Scientist Dr. Jen Francis was quoted over 4.2K times, appearing in major news outlets like the Washington Post and AP News to provide accessible context about the links between climate change and extreme weather events.
8. Rebuilding an Arctic Research Station
Last fall, Scotty Creek Research Station in Canada—one of the only Indigenous-led climate research stations in the world—was almost entirely consumed by a late-season wildfire. Woodwell Climate’s Permafrost Pathways project is providing rebuilding support to the Łı́ı́dlı̨ı̨ Kų́ę́ First Nation. Project scientists Dr. Kyle Arndt and Marco Montemayor visited the site for two weeks this spring to restore an essential carbon monitoring tower.
Read the story of Scotty Creek.
9. Advancing the Scientific Literature
Our researchers published 80 peer-reviewed scientific publications this year. From the Arctic to the Tropics, from soil concentrations to river concentrations, Woodwell Climate had a part in discovery.
Recent trends in the chemistry of major northern rivers signal widespread Arctic change
Grain-cropping suitability for evaluating the agricultural land use change in Brazil
Explore all our publications.
10. Leading on the World Stage
Woodwell Climate’s President & CEO Dr. Max Holmes brought Woodwell Climate to the main stage of CERAWeek, Green Accelerator Davos, GenZero Climate Summit in Singapore, Climate Week NYC, and Mountainfilm Festival. He discussed cutting-edge climate science alongside notable figures like Bill McKibben and former Colombian President Iván Duque Márquez.Read about Dr. Holmes’ time at Davos.
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.