Despite facing regional threats like deforestation and wildfires, the world’s forests continue to be a powerful weapon in the fight against climate change. A new study reveals these vital ecosystems have consistently absorbed carbon dioxide for the past three decades, even as disruptions chip away at their capacity. The study, based on long-term ground measurements combined with remote sensing data, found that forests take up an average of 3.5 ± 0.4 billion metric tons of carbon per year, which is nearly half of the carbon dioxide emissions from burning fossil fuels between 1990 and 2019. 

The study titled “The enduring world forest carbon sink,” published in the June issue of the journal Nature, highlights the critical role of forests in mitigating climate change. The study further shows that deforestation and disturbances like wildfires are threatening this vital carbon sink. 

The research is co-led by U.S. Department of Agriculture (USDA) Forest Service Northern Research Station Senior Research Scientist Yude Pan and Woodwell Climate Senior Scientist Richard Birdsey, and includes 15 additional co-authors from 11 countries. 

Some of the key findings include:

“Our research team analyzed data from millions of forest plots around the globe,” Pan explained. “What sets this study apart is its foundation in extensive ground measurements – essentially, a tree-by-tree assessment of size, species, and biomass. While the study also incorporates remote sensing data, a common tool in national forest inventories and landsurveys, our unique strength lies in the detailed on-the-ground data collection.”

“The persistence of the global forest carbon sink was a surprise given global increases in wildfire, drought, logging, and other stressors,” according to Birdsey. “But it turns out that increasing emissions in some regions were balanced by increasing accumulation in other regions, mainly re-growing tropical forests and reforestation of temperate forests. These findings support the potential for improving protection and management of forests as effective natural climate solutions.”

The study describes how certain land management policies and practices can help preserve this global carbon sink. According to co-author Professor Oliver Phillips from the University of Leeds, who coordinates the pan-tropical ForestPlots.net coalition of scientists supporting key networks such as AfriTRON and RAINFOR, “the extraordinary persistence of the carbon sink shows that forests have mostly coped with climate change, so far. Deforestation, fire, and logging are damaging forests everywhere, but drought less so. Helping Earth’s forests resist climate change will mean keeping them as intact, healthy and vibrant ecosystems.”

Findings support a focus on curtailing deforestation across all forest biomes, for example, promoting forest restoration on lands that may be unsuitable for agriculture, and improving timber harvesting practices to minimize emissions from logging and related activities. The research also highlights the limitations in data collection, particularly in tropical regions. The study calls for increased research and establishment of more ground sampling plots in these areas to reduce uncertainties in carbon estimates and improve understanding of the global carbon budget.

When it comes to reversing climate change, trees are a big deal. Globally, forests absorb nearly 16 billion metric tonnes of carbon dioxide per year, and currently hold 861 gigatonnes of carbon in their branches, leaves, roots, and soils. This makes them a valuable global carbon sink, and makes preserving and maintaining healthy forests a vital strategy in combating climate change.

But not every forest absorbs and stores carbon in the same way, and the threats facing each are complex. A nuanced understanding of how carbon moves through forest ecosystems helps us build better strategies to protect them. Here’s how the world’s different forests help keep the world cool, and how we can help keep them standing.

Tropical forest carbon

Tropical rainforests are models of forest productivity. Trees use carbon in the process of photosynthesis, integrating it into their trunks, branches, leaves, and roots. When part or all of a tree dies and falls to the ground, it is consumed by microorganisms and carbon is released in the process of decay. In the heat and humidity of the tropics, vegetation grows so rapidly that decaying organic matter is almost immediately re-incorporated into new growth. Nearly all the carbon stored in tropical forests exists within the plants growing aboveground. 

Studies estimate that tropical forests alone are responsible for holding back more than 1 degree C of atmospheric warming. 75% of that is due simply to the amount of carbon they store. The other 25% comes from the cooling effects of shading, pumping water into the atmosphere and creating clouds, and disrupting airflow.  

In many tropical forest regions, there is a tension between forests and agricultural expansion. In the Amazon rainforest, land grabbing for commodity uses like cattle ranching or soy farming has advanced deforestation. Increasing protected forest areas and strengthening the rights of Indigenous communities to manage their own territories has proven effective at reducing deforestation and its associated emissions in Brazil. “Undesignated lands” have the highest levels of land grabbing and deforestation.

Fire has also become a growing threat to the Amazon in recent years, used as a tool to clear land by people illegally deforesting. When rainforests have been fragmented and degraded, their edges become drier and more susceptible to out-of-control burning, which weakens the forest even further. Enforcing and strengthening existing anti-deforestation laws are crucial to reduce carbon losses.

In Africa’s Congo rainforest, clearing is usually for small subsistence farms which, in aggregate, have a large effect on forest loss and degradation. Mobilizing finance to scale up agricultural intensification efforts and rural enterprise within communities, while implementing protection measures, can help decrease the rate of forest destruction. Forests and other intact natural landscapes such as wetlands and peatlands could be the focus of climate finance mechanisms that encourage sustainable landscape management initiatives. 

Temperate forest carbon

Much of the forest carbon in the temperate zone is stored in the trees as well— particularly in areas where high rainfall supports the growth of dense forests that are resilient against disturbances like drought or disease. The temperate rainforests of the Northwestern United States, Chile, Australia, and New Zealand contain some of the largest and oldest trees in the world. 

Two thirds of the total carbon sink in temperate forests can be attributed to the annual increase in “live biomass”, or the yearly growth of living trees within the forest. This makes the protection of mature and old-growth temperate forests paramount, since older forests add more carbon per year than younger ones and have much larger carbon stocks. Timber harvesting represents one of the most significant risks to the carbon stocks in temperate forests, particularly in the United States where 76% of mature and old growth forests go unprotected from logging. Fire and insects are also significant threats to temperate forests particularly in areas of low rainfall or periodic drought.  

Maintaining the temperate forest sink means reducing the area of logging, by both removing the incentive to manage public forests for economic uses and by providing private forest owners with incentives to protect their land. Low-impact harvesting practices and better recycling of wood products can also help bring down carbon losses from temperate forests. In areas threatened by increasingly severe wildfires, reducing fuel loads especially near settlements can help protect lives and property. 

Boreal forest carbon

In boreal forests, the real wealth of carbon is below the ground. In colder climates, the processes of decay that result in emissions tend to lag behind the process of photosynthesis which locks away carbon in organic matter. Over millennia, that imbalance has slowly built up a massive carbon pool in boreal soils. Decay is even further slowed in areas of permafrost, where the ground stays frozen nearly year round. It estimated that 80 to 90% of all carbon in boreal forests is stored belowground. The aboveground forest helps to protect belowground carbon from warming, thaw, decay, and erosion.

Wildfire— although a natural element in boreal forests— represents one of the greatest threats to boreal forest carbon. With increased temperatures, rising more than twice as fast in boreal forests compared to lower latitudes, and more frequent and long-lasting droughts, boreal forests are now experiencing more frequent and intense wildfires. The hotter and more often a stand of boreal forest catches fire, the deeper into the soil carbon pool the fire will burn, sending centuries-old carbon up in smoke in an instant. Logging of high-carbon primary forests is also a big issue in the boreal.

The number one protection for boreal forest carbon is reducing fossil fuel emissions. Only reversing climate change will bring boreal fires back to the historical levels these forests evolved with. In the meantime, active fire management in boreal forests offers a cost effective strategy to reduce emissions— studies found it could cost less than 13 dollars per ton of carbon dioxide emissions avoided. Strategies for fire management included both putting out fires that threaten large emissions, and controlled and cultural burning outside of the fire season to reduce the flammability of the landscape.

Scientists from Woodwell Climate Research Center are among the 195 leading experts in forest ecosystems, climate change, and the carbon cycle who have come together to urge the Biden Administration to immediately declare a moratorium on all logging in mature and old-growth forests on federal lands. The signers include seven members of the National Academies of Sciences and some of the most notable names in climate science.

The letter comes amid growing concerns within the scientific community around the U.S. Forest Service and Bureau of Land Management’s response to an executive order, issued by the Biden Administration on Earth Day 2022, to establish guidelines and best practices to safeguard mature and old-growth forests on federal lands. The letter was initiated by Dr. Beverly Law, Professor Emeritus at Oregon State University, and Dr. Bill Moomaw, Professor Emeritus at Tufts University and Distinguished Visiting Scientist at Woodwell Climate. Last week, Woodwell Climate Senior Scientist and signatory Dr. Rich Birdsey delivered the letter’s message to the Mature and Old Growth Science Summit, hosted by the Forest Stewards Guild, the U.S. Forest Service, and the Society of American Foresters.

“Old-growth forests are made up of our oldest, and typically largest, trees that store massive amounts of carbon,” said Dr. Rich Birdsey. “We need to protect old growth, as well as younger mature forests that can attain old-growth characteristics with time.”

“The carbon storage function these forests play is essential to our efforts to reduce carbon emissions and mitigate the impacts of the rapidly changing climate, yet millions of acres of mature and old-growth forests stand on federal lands that are vulnerable to logging,” said Dr. Beverly Law. “To align with the United States’s commitments to ending global forest deforestation and degradation, we must urgently halt any additional logging of these critical natural resources.”

The scientists point to recent efforts by the agencies to increase timber sales and logging of these forests rather than increasing their protection as directly contrary to these objectives, and call on President Biden to issue a new executive order prohibiting activities that further forest degradation in the short-term, while the Administration works, in partnership with policy and climate leaders, to develop and implement effective, long-term management policies. Reducing timber harvesting of carbon-dense forests can have an immediate effect of lowering emissions and is the most significant action that the U.S. can take to immediately limit greenhouse gasses.

“With their 2022 executive order to protect mature and old-growth forests, the Biden Administration laid the groundwork for the U.S. to emerge as a global leader in conserving these forests and making good on international climate commitments,” said Dr. William Moomaw. “Halting logging in the interim is necessary to protect these resources now, while also working with the agencies to develop strong, long-term policies consistent with the Administration’s commitments to addressing climate change and safeguarding forests as a natural climate solution.”

The full letter can be found here.

Research Assistant Colleen Smith crouches low to the ground over a tray of crumbled soil. Using a boxy grey device that looks like a heavy-duty flashlight, she presses the flat glass end against the soil and fires a beam of infrared energy that bounces off the soil and back into the device’s sensor. 

In moments, a readout pops up on a tablet screen, showing a spectrum of reflected light. With some analysis, Smith will have data on the chemical makeup of this patch of ground. With enough data points, she could estimate the soil properties of an entire field, pasture, ranch or farm, and how it might be changing over time. 

Soil spectroscopy is a newer but fast-growing technique employed by scientists studying soil composition. At Woodwell Climate Research Center, a group led by Carbon Program Director Dr. Jonathan Sanderman has been spearheading its use to help improve the availability and affordability of reliable soil quality information, which is essential if we want to get serious about soil carbon sequestration as a natural climate solution.

Why soil spectroscopy?

“The heart of the technology is essentially getting the fingerprint of the soil, which tells us something about the overall chemical makeup of that sample,” says Dr. Sanderman.

The principles of soil spectroscopy are based in nuclear physics. Elements in the soil react in unique ways to the energy from the electromagnetic spectrum, reflecting some wavelengths and absorbing others. The reflected wavelengths give scientists clues to which minerals and elements are present and in what quantities.

That information can then be related to certain soil properties, like whether it’s suitable for certain crops, or whether it’s effectively sequestering carbon. The former is valuable information for producers like ranchers or farmers who need to make land management decisions. The latter is what climate researchers are most interested in. Soil spectroscopy represents an opportunity to marry the interests of both.

In a single scan, soil spectroscopy can estimate carbon, nitrogen, phosphorus, moisture, pH levels, and more. Traditional methods rely on multi-step chemical analyses to get you the same information— a time consuming and expensive process that could involve grinding, drying, weighing, mixing with reagents, and other steps to extract information on just one or two indicators of soil quality. 

“With soil spectroscopy, you can get a pretty large suite of properties from one sixty second scan. A lab needs easily $2 million worth of instruments to be able to make all the same measurements using traditional methods,” says Dr. Sanderman. The most precise soil spectrometers can cost $100,000, but lower resolution and portable ones are substantially cheaper. “The speed and cost of spectroscopy are unmatched.”

Soil Spectroscopy for Global Good

These benefits make soil spectroscopy a method with big potential, but according to Dr. Sanderman there is still work to be done in refining the methodology to get universally accurate data. Alongside collaborators from the University of Florida and OpenGeoHub, he started the Soil Spectroscopy for the Global Good project (SS4GG) to jumpstart that work.

The project focused on two main efforts. The first was an extensive inter-laboratory comparison to understand how much the accuracy of scans varies between different instruments. Twenty laboratories across the globe participated, scanning identical samples which were then compared to the output from a lab widely regarded as the gold-standard in accuracy. The results were published in Geoderma late last year.

“We demonstrated that there is lab-to-lab variability, but also that there are procedures we can use to correct for differences between laboratories and get better integration of data,” says Postdoctoral Researcher, Dr. José Safanelli, who coordinated the study.

The second goal was to pool data from different labs into one accessible and open-source resource that also provides tools to analyze the data. The Open Soil Spectral Library (OSSL) now hosts over 100,000 soil spectra from across the globe that scientists can incorporate into their research and offers an engine for analysis. The idea is that with more people using and contributing soil spectral data, the faster the technology and the information gained from it will advance. 

“We hope that the OSSL will be a driver of the soil spectroscopy community, advancing the pace of scientific discovery, and promoting innovation,” says Dr. Safanelli.

Building a community of soil scientists

Throughout the project, SS4GG efforts remained dedicated to transparency. 

“We were always available to answer questions. We shared best practices and gave advice on which instruments are better, which manufacturers are the best in the market, and which procedures to use to collect spectra,” says Dr. Safanelli. 

According to Dr. Sanderman, that openness fostered trust and collaboration— in both contributing data to the OSSL and participating in the inter-laboratory study— strengthening the community of scientists using soil spectroscopy.

“As we built momentum, more groups began to contribute,” says Dr. Sanderman. “It’s been great to see people realizing the value of collaborative, open science. People are now taking advantage of the foundation we’ve built.”

The soil spectroscopy community convened this past year for several webinars and presentations, including the Agronomy, Crop, and Soil Science Society meeting, where Drs. Sanderman and Safanelli hosted a training workshop and symposium on spectroscopy, as well as a two-day immersive workshop on the future of the field. 

“We all benefit when this technology is more widely used,” says Smith.

Soil carbon as a climate solution

Speeding up the pace of soil science is key for developing climate solutions. Agricultural soils represent a large potential carbon sink; changes in farming and ranching practices can encourage sequestration of carbon in the soils. Soil carbon markets, and other payment for ecosystem services schemes could incentivise producers to make sustainable management decisions and soil spectroscopy could be a useful tool to track their contributions.

“The ultimate goal is to better monitor soils across landscapes to make food production more sustainable,” says Dr. Safanelli.

The handheld device that Smith was using is a test case for the speed and convenience of soil spectroscopy for analyzing soil carbon. If testing the quality of your soils can be as simple as a 60 second measurement with a low-cost piece of portable equipment, and the scan can get you additional information about soil fertility, then why not participate? 

“We are trying to verify that we actually are sequestering carbon, and that requires lots and lots of measurements. So this is where we start moving into field-based spectroscopy,” says Dr. Sanderman. “If we can eliminate bringing the sample back to the lab altogether, we’re cutting our costs by another order of magnitude and could potentially scan several hundred points in a field in a day.”

Smith theorizes that cost could be further diffused through farming cooperatives or extension offices offering soil testing using inexpensive spectrometers. “Soil spectroscopy could be an easier way to get answers to big questions,” says Smith. “And that’s exciting.”

With the OSSL now up and running, the team is now focusing efforts on maintaining the growing network of interested soil researchers, pursuing new opportunities for collaboration as they arise.

“The network is getting stronger,” says Dr. Safanelli. “More people are coming and reaching out to us. That’s our biggest contribution: creating a network and sharing information across the community.”

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.

Assessing carbon stocks and accumulation potential of mature forests and larger trees in U.S. federal lands

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

Observational and model evidence together support wide-spread exposure to noncompensable heat under continued global warming

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.

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 in 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-to-nitrogen 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.”

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

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

Key findings include:

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

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

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

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

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

Millions of acres of rangelands managed by the U. S. Bureau of Land Management are not meeting land health standards, according to a recent report  from watchdog organization Public Employees for Environmental Responsibility. Range degradation is also happening on U.S. Forest Service and privately held lands. Healthy rangelands are vital to the economic and public health of the communities that depend on them, which includes ranchers, Indigenous nations, and recreationists. Failing rangelands undermine these groups, lead to loss of habitat, and result in landscape degradation, and they also minimize our ability to mitigate climate change through carbon sequestration. Taking policy action to  ensure the longevity of rangelands has the potential to increase climate mitigation potential and improve the health of U.S. ecosystems.

What is healthy rangeland?

Covering more than 31 percent of the U.S., rangelands are any wilderness or rural open space grazed by domestic or wild herbivores, including grassland, shrubland, and pasture. Rangelands provide a wide array of ecosystem services, including food for livestock, habitat for wild species, and climate regulation through the uptake of carbon dioxide (CO2) by growing plants and the transfer of this sequestered carbon into the soil (as soil organic carbon). Globally, rangelands store 20 percent of the world’s soil organic carbon and U.S. rangelands may have the capacity to offset 2.5 – 3 percent of U.S. CO2 emissions from fossil fuels, but only if the rangelands are considered in “full health”.

Improving monitoring to foster healthy rangelands

The capacity for  rangelands to sequester carbon is increasingly threatened by drought and overgrazing and there is an urgent need for improved land use planning to tackle these issues. However, the lack of an integrated monitoring system makes it difficult to know what changes to land management are needed on the individual ranch scale.  

An important first step, then, to fostering healthy rangelands is establishing an open-access region-wide range monitoring platform that ranchers can use to verify and track changes in rangeland ecosystem condition and carbon storage across entire land units. Large-scale monitoring for these indicators will make it clearer where land is being effectively managed, and where it is not. 

Dr. Jennifer Watts focuses on how climate change and human disturbance are affecting vegetation, soils, and the carbon cycle. She and her colleagues are currently working to develop a monitoring platform to provide stakeholders access to land health information. 

“Having free, easy access to long-term information about lands will empower us to become fully aware of how our land use is impacting  the health and future of rangeland ecosystems,” Dr. Watts explains. “This gives us the ability to invest in alternative management approaches that provide a more sustainable future for our lands while protecting our communities and ecosystems  in the face of climate change.” 

Building a system of rewards and incentives

Reward systems can then be established across different scales to incentivize land use that improves ecosystem services. Monitoring platforms can be used in conjunction with clear land management directives to ensure rangelands are managed in a way conducive to ecosystem health.

Overgrazing is one of the biggest drivers of rangeland carbon loss and land degradation. It not only undermines the carbon storage potential of rangelands but also compromises other ecosystem services and limits future grazing capacity for livestock and wildlife. Consequently, it is in the best interest of everyone–ranchers, conservationists, Indigenous groups, and recreationists–to ensure that grazing on rangelands is managed in a way that increases vegetation cover, diversity, and rooting depth, while minimizing bare ground. Grazing practices can be addressed through process-oriented approaches.

Practicing management intensive grazing could help limit overgrazing. This adaptive technique involves concentrating grazing animals in one place for a very short period of time and then moving them to a different location. This ensures that the ecosystem has a chance to recover and regrow following a concentrated period of grazing. Ranchers will need technical assistance to develop grazing and management plans. Given that this is a practice under the Environmental Qualities Incentive Program (EQIP) it is likely to receive a boost in funding from the 2022 Inflation Reduction Act. Building more programs, at the federal, state, and county level, that reward ranchers for shifting grazing techniques to those that support the sustainability of ecosystem services and provide equipment needed to support fencing and water distribution could be a way to incentivize more effective land management. 

Manipulating grazing fees to more accurately represent the costs associated with maintaining the integrity of rangelands is another option for fostering healthier rangelands given the current low fees and stagnant pricing of grazing fees. Furthermore, revenue generated from increasing grazing fees on public lands could be used to support a monitoring system for all U.S. rangelands. 

Most stakeholders agree that better rangeland monitoring, soil health, and payment for land improvements are important, but a big question is how to actually pay for these services across multiple levels of governance. Exploring how to leverage different options for funding, then, will be the necessary next step in supporting thriving rangeland ecosystems and reaping the potential climate benefits.