Researchers find decaying biomass in Arctic rivers fuels more carbon export than previously thought / 02
Increasing soy and maize production grows into low-suitability land / 03
Fire suppression deployed in Yukon Flats National Wildlife Refuge to protect carbon / 05
In the news: highlights / 07
Bill Wellock Research Media and Content Specialist, Florida State University
Carbon cycling is an essential part of life on the planet. Plants and animals use the element for cellular growth, it can be stored in rocks and minerals or in the ocean, and of course, it can move into the atmosphere, where it contributes to a warming planet.
A new study led by Dr. Megan Behnke, a former Florida State University doctoral student and Woodwell Polaris Project participant who is now a researcher at the University of Alaska, found that plants and small organisms in Arctic rivers could be responsible for more than half the particulate organic matter (a carbon-rich nutrient) flowing to the Arctic Ocean. That’s a significantly greater proportion than previously estimated, and it has implications for how much carbon is sequestered in the ocean versus how much moves into the atmosphere.
Scientists have long measured the organic matter in rivers to understand how carbon cycles through watersheds. But this research, published in Proceedings of the National Academy of Sciences, shows that organisms in the Arctic’s major rivers are a crucial contributor to carbon export, accounting for 40 to 60 percent of the particulate organic matter—tiny bits of decaying organisms—flowing into the ocean.
“When people thought about these major Arctic rivers and many other rivers globally, they tended to think of them as sewers of the land, exporting the waste materials from primary production and decomposition on land,” said Dr. Rob Spencer, a professor in the Department of Earth, Ocean and Atmospheric Science at FSU, and collaborator on the paper. “This study highlights that there’s a lot of life in these rivers themselves and that a lot of the organic material that is exported is coming from production in the rivers.”
Scientists study carbon exported via waterways to better understand how the element cycles through the environment. As organic material on land decomposes, it can move into rivers, which in turn drain into the ocean. Some of that carbon supports marine life, and some sinks to the bottom of the ocean, where it is buried in sediments.
The study was supported by the Arctic Great Rivers Observatory, and it examines six major rivers flowing into the Arctic Ocean:
The Yukon and Mackenzie in North America, and the Ob’, Yenisey, Lena, and Kolyma in Russia. Using data collected over almost a decade, they built models that used the stable and radioactive isotope signatures of carbon and the carbon-tonitrogen ratios of the particulate organic matter to determine the contribution of possible sources to each river’s chemistry.
Not all particulate organic matter is created equal, the researchers found. Carbon from soils that gets washed downstream is more likely to be buried in the ocean than the carbon produced within a river. That carbon is more likely to stay floating in the ocean, be eaten by organisms there and eventually breathed out as carbon dioxide.
“It’s like the difference between a french fry and a stem of broccoli,” said Dr. Behnke. “That broccoli is going to stay in storage in your freezer, but the french fry is much more likely to get eaten.”
That means a small increase in a river’s biomass could be equivalent to a larger increase in organic material coming from the land. If the carbon in that organic matter moves to the atmosphere, it would affect the rate of carbon cycling and associated climate change in the Arctic.
“I always get excited as a scientist or a researcher when we find new things, and this study found something new in the way that these big Arctic rivers work and how they export carbon to the ocean,” Dr. Spencer said. “We have to understand the modern carbon cycle if we’re really going to begin to understand and predict how it’s going to change. This is really relevant for the Arctic at the rate that it’s warming and due to the vast carbon stores that it holds.
The study was an international endeavor—a feature that, Dr. Behnke notes, is critical to Arctic work, especially as climate change advances.
“That pan-Arctic view of science is more important than ever,” Dr. Behnke said. “The changes that are occurring are far bigger than one institution in one country, and we need these longstanding collaborations. That’s critically important to continue.”
This
A recent paper, led by Woodwell Climate postdoctoral researcher Dr. José Safanelli, revealed that Brazil’s farms have been steadily moving out of the most suitable regions for agriculture—opening up a significant portion of the world’s agricultural production to vulnerability from the changing climate.
The study, published in Applied Geography, used an index to assess “Grain-cropping suitability” for two key staple crops—soy and maize. Suitability was determined by climatic factors (temperature and precipitation), as well as soil quality and terrain. The result was a continuous map detailing the areas of the country with the best biophysical conditions for growing crops.
Overlaying land use change data from the past two decades with this new map revealed a historical trend of agricultural lands expanding towards areas with poorer soil quality and lower suitability for grain-cropping, primarily in the north central and northeastern portion of the country.
Farmers in Brazil have been moving north to this “agricultural frontier” since the 1980s—drawn primarily by economic opportunity, as well as the higher quality
climate and terrain conditions along the southern edge of the Amazon.
Despite the favorable climate, the soil is inferior. Farmers are seeking cheap land, which often comes in the form of degraded pasture, originally created by clearing forest. Rainforest soils are not naturally nutrient rich and, without any additional inputs, the soil quality becomes depleted after just a few years. Many farmers know this fact, but come anyway. Dr. Safanelli has even seen this trend unfold within his own family.
“I was born in the south of Brazil, a region that has good soil conditions. Recently, two of my uncles who are farmers emigrated to Mato Grosso. There, the climate is wetter and more stable, but the soils are poor—depleted of nutrients.”
Additional research by Woodwell Climate Assistant Scientist Dr. Ludmila Rattis suggests that climatic advantage may be short-lived. Her work indicates that the climate in these areas is changing— becoming drier and hotter as global temperatures rise—and deforestation for agricultural expansion just makes the problem worse.
“We showed in our paper that these places have good climate and terrain suitability for now,” says Dr. Safanelli. “But they are restricted in soil quality.
In Mato Grosso—the largest agricultural production state in Brazil—for example, the climate has been more stable and favorable than in other parts. The problem is that, according to projected climate scenarios, climate change may push these areas out of a good suitability space.”
Brazil is currently the world’s top producer of soy, and in the top three for maize. But this expansion into lower-suitability regions has introduced greater vulnerability into the agricultural system. Farmers already must provide greater investment in fertilizing the soil to make it productive, which cuts into their margins for profit. Add to that the fact that poor-quality soils, typically low in organic matter, can make crops less resilient to extreme heat and drought.
“Crop evapotranspiration—a process that directly governs crop growth and yield—depends on soil for absorbing rainfall and storing water. These marginal soils can make farmers more susceptible to climate change’s expected drier and warmer conditions, as they have limited capacity for storing water,” says Dr. Safanelli.
Reducing these vulnerabilities, Dr. Safanelli says, will require an integrated
study maps the most suitable lands for grain-cropping in Brazil. Agriculture is expanding beyond them.
Sarah Ruiz Science Writer
approach—improving land management practices and increasing crop yields on existing land to reduce the pressure to expand. “Reducing the vulnerability of croplands may be possible by adopting
management practices that increase the resilience of the farming system, such as fully incorporating the principles of conservation agriculture, integrated production through agroforestry, crop-
forest-livestock systems, or irrigation to control dryness. And perhaps allocating some of these marginal lands for land restoration, concentrating our resources in more highly suitable croplands.”
For migrating farmers, terrain has been the most important factor in cropland expansion…
…followed by climate, and then soil quality.
Farmland expansion has typically neglected soil suitability in favor of better climate and terrain conditions.
This has introduced risk into the system, making food security more fragile.
above: maps by Christina Shintani
Fighting fire in remote boreal forests could be a cost effective way of combating climate change
Sarah Ruiz Science WriterLocated in Eastern Alaska, the Yukon Flats National Wildlife Refuge is larger than many U.S. states. It’s a roadless landscape of rocky mountain outcroppings, flat meadows, treeless tundra, and dense spruce forests, bisected by the Yukon River and dotted with thousands of lakes and wetlands. Several Alaska Native communities call the refuge home and subsist off of its natural resources. This diverse, expansive wilderness is well adapted to fire, and it’s not uncommon to see pink fireweed blooms or young grass and seedlings sprouting from burn scars.
But the relationship between fire and land here—as in many places—has been changing as the climate warms.
Yukon Flats sits atop ancient, ice-rich ground, called Yedoma permafrost, formed during the last ice age. Thawing Yedoma is a significant source of carbon dioxide and methane emissions to the atmosphere. Fire, made more intense and frequent by climate change, threatens to accelerate that thaw. In an effort to
preserve carbon stores, the U.S. Fish and Wildlife Service recently dedicated 1.6 million acres of the Yukon Flats refuge to piloting a new firefighting regime, one designed to protect carbon, in addition to human lives and property.
This decision was, in part, influenced by research led by Dr. Carly Phillips, during her time as a research scientist at the Union of Concerned Scientists, alongside Woodwell Climate Senior Science Policy Advisor, Dr. Peter Frumhoff, and Associate Scientist, Dr. Brendan Rogers. In a 2022 paper in Science Advances, the group quantified the threat boreal forest fires pose to climate goals. Wildfires in boreal North America alone could, by mid-century, use up 3% of remaining global carbon dioxide emissions associated with keeping temperatures below the Paris Agreement’s 1.5°C limit. This is a conservative estimate—the authors suggest the true numbers could
be even larger as the accelerating effect of fires on permafrost thaw, and the release of other greenhouse gasses, were not included in the analysis.
The study also examined the costeffectiveness of combatting those fires as a potential climate solution. Molly Elder, an economics and public policy Ph.D. candidate at Tufts, performed an analysis of data from across Alaska’s fire management zones and found that actively suppressing boreal fires could cost less than 13 dollars per ton of carbon dioxide emissions avoided—putting it on par with other carbon mitigation solutions like onshore wind or utilityscale solar.
“The work we did in this project proved and quantified what the management community already knew, which is that management is effective at reducing burned area when fires are actively suppressed,” says Elder.
Combating boreal fires could provide much needed mitigation, and at a
low cost, but there are some logistical obstacles between the hypothetical model and actual implementation. Typically, in Alaska, boreal forest fires are left to burn unless they present a risk to human life or property. This is partly because these forests are fire-adapted, but also partly due to the sheer vastness of boreal wilderness. With limited resources, it is not always practical or possible to track down and put out a fire, especially in a place without roads like Yukon Flats. Firefighters are already stretched thin with lengthening and increasingly highintensity fire seasons.
The research group worked with the fire management community in Alaska, facilitated by the Alaska Fire Science Consortium, to better understand the needs of firefighters and demonstrate the co-benefits of fire suppression in addition to preserving carbon.
“Many of the fire managers expressed how stretched their resources already were and resistance to the idea that yet another mandate would be added to their plate,” says Dr. Phillips. “However, after discussing the implications of our research, and the ambition that additional funding would come with any mandate, we got more buy-in.”
The other concern managers raised was whether fire suppression would ultimately be successful in achieving their goals. Historically, fire suppression efforts in the US have been counterproductive to protecting forests.
In the late 1800s, lack of understanding of the ways Indigenous communities in Western states have used fire to maintain healthy forests resulted in decades of near-total suppression of fire in the region. In many western US forests, (adapted to what Dr. Rogers calls “high-frequency, low-intensity” fire) suppression allowed highly flammable, dry vegetation—which would normally be periodically burned away—to build
up. When fires did spark, they were then capable of growing to a size and intensity that could damage, rather than activate, the forest.
But in boreal Alaska and Canada, it’s just the opposite. The spruce-dominated forests are adapted to high-intensity fires that only return every hundred or so years. As climate change speeds up the return of fires with hotter and drier conditions, boreal forests have begun to suffer major losses.
“The frequency of boreal fires, ultimately, is increasing. In many places we’re seeing more reburning and larger burned areas,” says Dr. Rogers. “Climate change and human actions are shifting that fire regime out of its historical range into this new realm. So the whole idea of fire suppression in the boreal is to keep fires closer to historical levels, to which the systems and fauna are adapted. Suppression can help delay permafrost degradation, limiting carbon emissions and buying us time to reach our climate targets.”
Past missteps with fire suppression have made fire managers cautious, though.
Lisa Saperstein, Regional Fire Ecologist with U.S. Fish and Wildlife, notes that, with limited resources, priorities in intense fire seasons will have to shift to protecting human settlements over carbon and permafrost. But, given the cobenefits of keeping fire activity to historic levels—and the urgency of reigning in emissions in any way we can—managers in Yukon Flats were willing to try.
“This type of shift in values is always difficult, especially when the outcome is uncertain. Support from leaders of fire management organizations, in addition to land managers, has been a key factor in this effort moving forward,” says Saperstein.
This change in tactics won’t mean that every fire that ignites will be put out— both impractical and unhelpful from an ecological perspective—but it will mean more aggressively targeting fires when they arise. Since the 1980s, when fire was detected in Yukon Flats, it would be monitored by the Alaska Fire Service, but
above: Aerial view of recent burn scar. / photo by Torre Jorgensonnot suppressed, except when presenting a threat to human communities.
“This pilot project is a new twist to a longstanding partnership between the U.S. Fish and Wildlife Service and Alaska Fire Service. For select areas of the Refuge, now if a fire start is detected, we ask the Alaska Fire Service to only send a crew if they are confident in 100% containment within three days,” says Yukon Flats Refuge Manager, Jimmy Fox.
The suppression teams will target fires that they judge as “quick fixes,” curbing the potential for them to grow into large, stand-replacing sized blazes. If a fire becomes too big to fight quickly, the teams revert to the old tactic of simply monitoring.
“If a crew is deployed, we ask that they cease suppression and return to base after three days, regardless of containment status,” says Fox. “This request is grounded in concern for the Alaska Fire Service having resources available if communities become threatened from other fires.”
Fox says refuge management and Alaska Fire Service members will stay flexible
as the pilot project unfolds so they can respond to changing conditions.
“In conservation, we tend to focus on the technical aspects of a challenge and avoid the difficulties that come with asking ourselves to adapt,” says Fox. “This pilot project is both adaptive and technical. It has required me to stay curious and listen. It has required me to learn new information, and share it in a way that is comprehensible. It’s required being comfortable with uncertainty, and yet standing in purpose. It has been a learning journey so far, and will continue to be.”
On the research side, the team at Woodwell Climate hopes this new strategy will present an opportunity to study the practical implementation of fire suppression as a climate solution.
“This is the proof of concept,” says Dr. Frumhoff. “This is the opportunity to really see in a rigorous way whether we can apply this solution at a meaningful scale and gain meaningful carbon benefits with relatively modest cost. And it’s directly traceable to the conversations that the research team had with fire managers.”
Dr. Foster Brown was interviewed by TV Globo’s G1 about the causes of flooding in Acre, Brazil (Portuguese).
Alaska Public Media profiled Dr. Anna Liljedahl and her work with Permafrost Discovery Gateway to enable easier access and quicker sharing of Arctic research.
Dr. Zach Zobel was interviewed by ABC News to provide the climate context on the Colorado River’s low water levels.
Good Morning America noted that activewear company Girlfriend Collective would donate a portion of proceeds to Woodwell Climate in recognition of Earth Day.
Mother Jones published an article that highlighted Woodwell Climate’s risk assessment for Chelsea, MA, quoting Dominick Dusseau.
The Brown Daily Herald remembered a 1989 lecture by Dr. George Woodwell in a history of climate activism on Brown’s campus.
The 1.6 million acres slated for fire suppression are small compared to the 8.6 million that comprise the entire refuge, or the 5.6 billion acres of permafrost in the northern hemisphere, but it’s a very important start. Research and analysis of the effectiveness of this solution could aid its expansion to other regions of the Arctic.
“It’s a big moment, because, while it’s obviously a relatively small area compared to all of Alaska, 1.6 million acres is still a lot of land,” says Dr. Rogers. “We’re hoping that it’s a jumping off point and can translate to other refuges and other agencies with the addition of proper funding and staffing.”
And each summer, the case for protecting permafrost and boreal carbon, while working to dramatically reduce emissions from fossil fuels, continues to grow.
“Every year that goes by, as fires intensify and climate change gets worse, this message might resonate just a little more, ” says Dr. Rogers. “Because it’s a problem that’s not going away if we do nothing about it. And we can do something about it.”
Dr. Marcia Macedo was quoted in Mongabay to provide context on a recent study that showed how forests on Indigenous lands in the Brazilian Amazon absorb dangerous forest fire pollutants, preventing respiratory and cardiovascular infections.
Axios linked to Woodwell Climate’s 2022 agriculture and food security story in an article covering how a growing water-food deficit is leading to conflict in Central America.
A NASA article describing how climate change can affect transportation included a map by Greg Fiske, showing unique ship visits to Arctic waters from 2009-2016.
S&P Global published a blog article on the “soil carbon controversy” that mentioned a study on soil carbon quantification protocols by Woodwell Climate and EDF.
An article from
Planeta Campo quoted Dr. Ludmila Rattis on why intensive planting in Brazil can be better for soil management, and also quoted a CONSERV participant (Portuguese).cover: New plant growth in an area recovering from fire in the Yukon Flats National Wildlife Refuge. / photo by Dale Woitas
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