I’m a field research scientist. What does this mean? I enjoy being outside, in forests and wetlands, studying the environment up close and personal. One of my favorite places to work and explore over the course of my career has been Howland Research Forest in central Maine. 

Dominated by red spruce, eastern hemlock, and red maple, this mature northern forest feels old. There is a 400 year old yellow birch that was already a mature tree during the American revolution. The ground is soft— spongy with a lot of “holes” where past trees have fallen and roots decomposed. My feet often plunge into these holes, which can sometimes be filled with water.

The Howland Forest Research station was established in 1986 by the University of Maine in partnership with a packaging and paper company, International Paper. My first trip to Howland Forest was in 1998 and at the time the research center was just a collection of trailers housing equipment. I had never seen so much mouse poop in a building. 

Howland was one of the first sites ever dedicated to measuring the net exchange of carbon between a forest and the atmosphere. Its support comes from the Ameriflux Network, a grass roots, science driven network of research stations spread across North and South America that monitors the flow of carbon and water across ecosystems. In these early years, Howland forest also served as a training site for testing out NASA’s remote sensing capabilities. At one time, Howland Research Forest was the most photographed site on earth from space. Soon the well used trailers were replaced with multiple buildings to accommodate the ever expanding research. The mice were evicted. 

Howland forest was selectively harvested over 100 years ago, evidenced by cut stumps, but the forest has remained intact, growing under natural conditions since then. Most trees range between 100-120 years old. In 2007, International Paper was scheduled to harvest these mature trees. Recognising the value of maintaining a continuous long-term record of observations, scientists from Woodwell Climate Research Center, The University of Maine (UMaine Orono), and the U.S. Forest Service (USFS) partnered with the Northeast Wilderness Trust (NEWT) to purchase the forest. The Howland Research forest, now owned by NEWT, was protected in a forever wild state. This science and conservation partnership saved an invaluable mature natural forest and research site. As scientists continued to collect data over the next decades, we would learn just how important this partnership was to our understanding of mature forests.

Long-term measurements of carbon exchange between the forest and the atmosphere are being taken from the top of a tower, as part of the Department of Energy (DOE) supported Ameriflux Network, and paired with measurements on the ground. It’s the measurements on the ground where I come in. Myself and collaborators at UMaine Orono, USFS and a host of other scientists and students over the decades have measured carbon exchange from soils, tracked changes in temperature and moisture, and taken tree inventories. 

Mature forests contain large stores of carbon in their tree stems, foliage, roots, and within the soils, accumulated over decades of growth and decomposition. Allowing mature forests to continue to grow, untouched, is beneficial to maintaining carbon stores along with the natural biodiversity and water cycling, often collectively called “ecosystem services”.  

Over the last 25 years, Howland Research Forest has seen the warmest, driest, and wettest years. Observations show an increasing trend in the net uptake of atmospheric carbon (as carbon dioxide) into this mature forest, meaning that Howland forest is continuing to take up and store more carbon each passing year.

If the forest had been harvested in 2007, observations spanning that shorter time frame would have indicated a decreasing trend in net net carbon uptake, meaning that Howland Forest was taking up less carbon each passing year.  

Although Howland Forest continues to take up carbon, the overall number of live trees has been declining (17% decline since 2001 in live trees, particularly red spruce and northern white cedar) and  the number of dead trees has nearly doubled since 2001. Theoretically, fewer live trees would indicate less carbon uptake, but that is not happening. The mature, large diameter trees continue to grow; although there may be fewer in number, they continue to take up significant amounts of carbon.

Tree species can differ in how they respond to environmental changes as well as how carbon is allocated within the tree and across a mature forest ecosystem. Teasing out these complex, multi-scaled, multispecies responses requires long term studies. However,  given the challenges to acquiring and sustaining funding for long-term studies, it’s unusual to have this type of paired dataset like we have at the Howland Research forest. This would not have been possible without the forward-looking vision of scientists and NEWT, and the consistent support from the Ameriflux Network.   

Thanks to its preserved, forever-wild status, a new generation of scientists has the opportunity to continue this work, building on our understanding of the mechanisms driving climate resilience in this mature northern forest.  

The partnership between science and conservation is a victory for both. Results from the Howland Research Forest demonstrate the need to continue supporting long-term studies to fully understand how natural, mature forests respond to a changing climate. Conservation organizations and land trusts are preserving and restoring critical habitats across the U.S. and the globe. This is an opportunity to build alliances between science and conservation, to inform how natural ecosystems function and the impact of restoration efforts on the ecosystem services that we all benefit from, while preserving natural spaces for future generations. 

The last decade has shattered global temperature records, with all 10 of the planet’s warmest years occurring since 2015. Under the Paris Climate Agreement, countries across the world are working to limit global warming to 1.5 degrees Celsius by decreasing their heat-trapping greenhouse gas emissions. But researchers say more action is needed to protect us from the worst impacts of climate change. 

“We’re beyond the point where emission cuts alone are going to keep us within a safe climate range. We need to remove carbon from the atmosphere,” Dr. Jonathan Sanderman, carbon program director and senior scientist at Woodwell Climate Research Center, says. “And there’s really two ways of doing that: tech-based solutions, like direct air capture or other engineering-based solutions, or we could try to reverse the last several 100 years of degrading nature and pull more carbon back into the biosphere.”

While both solutions are likely needed, Sanderman and others at Woodwell Climate are focused on using the power of natural environments, such as forests, wetlands, agricultural land, and rangelands, to reduce carbon in the atmosphere. These methods, called nature-based climate solutions, help combat climate change in three major ways: decreasing greenhouse gas emissions from deforestation, capturing and storing carbon from the atmosphere, and building ecosystems more resilient to climate hazards such as flooding and wildfires, according to the International Union for Conservation of Nature (IUCN). 

Natural climate solutions could contribute more than 30% of the cost-effective climate solutions needed globally in the next few decades. They could also save countries hardest hit by climate change $393 billion in 2050 and reduce climate hazards by 26%. 

Storing carbon on land

Sanderman researches one of Earth’s largest carbon pools: the soil. Plants release carbon they’ve absorbed from the atmosphere back into the ground when they die, which stores a total of about 2,500 gigatons of carbon globally. 

“Soils hold four times as much as trees do — about three times as much as the atmosphere,” Sanderman says.

Good land management can stabilize the amount of carbon in soil, but soils across the world have degraded substantially due to cultivation and overgrazing around the turn of the century. 

Storing carbon in the ground not only reduces the level of this greenhouse gas in the atmosphere, but carbon is the backbone of soil organic matter, which is a key regulator of soil health and crop yield consistency. It helps reduce erosion, keep soil structure in place and retain water. Carbon is often used as an indication of soil quality, with healthy soils usually containing about 2% organic carbon. Yet, precisely determining how much carbon is stored in soils worldwide — and which land management techniques lead to the most efficient carbon storage — is tricky. 

Rangelands as a nature-based climate solution

Sanderman is working with Dr. Jennifer Watts, the Arctic program director and an associate scientist at Woodwell Climate, to understand how much carbon dioxide U.S. rangelands are helping capture. These lands have big potential for sinking carbon: Rangelands make up about 31% of land area across the U.S. and about 54% across the world. Using both field data and satellite data, Sanderman and Watts are creating models of overall rangeland health in the U.S. Using this information, they can then quantify how much carbon is gained or lost over time under different scenarios.

“We are hoping, with our integrated system, to be able to provide the ability to scan all landscapes to determine their carbon status, and then go back in time and look at the trajectories of change,” Watts explains. “And provide that information directly to the land managers so they can make really informed decisions on where they should invest conservation work. At the same time, it’s great for us, because as an output, we get to quantify how much carbon is being gained versus lost in certain places and what the climate benefits are.”

Capturing Methane

While carbon dioxide is one of the most abundant and long-lasting greenhouse gases, methane is far more efficient at trapping heat in the atmosphere. Per molecule, it’s about 80 times more harmful in the atmosphere than carbon dioxide, though it lasts an average of only a decade in the air, whereas carbon dioxide can persist for centuries. Nevertheless, reducing methane emissions by 45% by 2030 could help us reach our goal of limiting global warming to 1.5°C, per the United Nations. 

Cutting anthropogenic methane emissions should be prioritized, but using nature-based solutions to increase uptake can also help bring down methane concentrations in the atmosphere. Although forests and soils play a smaller role in methane cycling, “When you start thinking about how much they can do over large areas, the numbers really get big,” Watts says. “And then it makes a huge difference.”

In northern forests across the U.S., Woodwell Climate researchers have set up methane monitoring systems, including specialized towers that measure the exchange of greenhouse gases, energy, and water between the ecosystem and the atmosphere. The team also analyzes soil samples from the forest to see exactly where methane-consuming and methane-producing microbes are thriving. 

The team has discovered a unique feature of the Howland Research Forest in Maine: It is an overall methane sink — though exactly why remains unknown. But by understanding more about how and under which conditions these methane-consuming microbes live, forest managers can change their strategies to harness the creatures’ natural power to reduce the effects of climate change. 

To combat the climate crisis, we must do “a lot of things simultaneously,” Watts says, including using good land management practices to capture and store greenhouse gases.

“Working with nature has a lot of advantages, because you’re optimizing the health of ecosystems, at the same time providing ecosystem services, not just for climate but also for local communities,” Watts says. “If we identify how to do this effectively, we’re really unleashing the power of something that’s already there, and then trying to work with it instead of against it.”

Associate Scientist, Dr. Brendan Rogers has walked in many forests, but primary forests, he says, “just feel different.” 

Rogers’ work often takes him to the cool, dark understories of black spruce and pine boreal forests, where he’s learned the subtle markers of a truly old, healthy, stable forest ecosystem.

“Generally cooler, often wetter, the trees are bigger but sparser and more likely to be conifers than shrubs or deciduous broadleaf trees,” says Rogers. “The ground is squishy to walk on, from the build-up of peat-like soils, mosses, and lichens.”

Primary forests are also a critical piece in the climate puzzle. They represent centuries of sequestered carbon, and every year they remain standing these forests continue to pull carbon from the atmosphere and lock it away in their trees and soils. They are also the subject of intense debates in forest management circles because, according to Rogers, despite knowing intuitively when you are standing in a primary forest, quantitatively identifying one is a tricky task. 

That fact hasn’t deterred Rogers and his collaborator Dr. Brendan Mackey at Griffith University, from their work to identify and map metrics indicative of primary forests. In a joint project launched in 2018, Rogers and Mackey created an index of one such metric— forest stability. 

Measuring forest stability

Forest stability is a measure of a forest’s resistance to disturbances, both manmade and natural. A stable forest has a high level of ecosystem integrity—a holistic term referring to the combination of ecosystem structure, function, species composition, and adaptive capacity. Stability reflects the ability of a forest to maintain all of those elements in the face of disturbance.

To quantify stability, Rogers and Mackey isolated two metrics that correlate heavily with integrity in forests— “greenness” and water stress. Greenness, also known as the fraction of photosynthetically active radiation (fPAR), indicates the amount of thriving, photosynthesizing plants. Water stress is an index of anomalies in vegetation moisture, indicating an area is dryer than usual. Both of these metrics can be remotely derived from satellites and, when combined with additional data, form an index of overall stability level. 

This index was first tested by a postdoctoral scientist at Woodwell Climate, Dr. Tatiana Shestakova, who pulled data from NASA’s MODIS satellite sensor to map stability in sample regions in the Kayapo Indigenous Territory in the Brazilian Amazon and southern Taiga region of Siberia. After testing the model, Rogers, Mackey, and Shestakova expanded it to map stability across the entirety of Ontario, Quebec, boreal Siberia, and the Amazon rainforest. 

The studies used a method called a time series analysis, which compares satellite data stretching back to 2002 to determine whether a forest had experienced a large-scale disturbance, reducing vegetation greenness and increasing water stress and thus lowering overall stability. These insights were only possible due to the long, consistent dataset produced by MODIS.

“It can be a little bit dicey to assess stability on shorter time scales,” says Rogers. “Because when you work with remote sensing data, forests can fluctuate year to year and sometimes you can’t completely eliminate things like cloud contamination or other errors from the data, so a longer time series helps smooth the data and lets you see the true patterns.”

Prioritizing protection for primary forests

These maps of stability have a crucial role to play in informing forest management policy.

“We’re trying to analyze and spatially map the ecological condition of forests,” says Mackey. “Because this information is needed to help guide where investments for forest protection and restoration go and how they should be prioritized.”

For a long time, Mackey says, management conversations did not distinguish between types of forests, lumping monoculture tree plantations into the same category as ancient natural forests, despite the vast differences in their carbon storage, biodiversity, ecosystem benefits, and overall resistance against disturbances. 

“We weren’t seeing the forest for the wood,” Mackey jokes.

Quantifying a characteristic like stability makes it easier for managers to see the difference between the two, identify the forests best able to provide myriad ecological benefits, and ideally, prioritize those for protection.

Mackey uses the example of woodland caribou in Canada, which are considered a threatened species. These animals require large areas of intact primary forest to support successful populations. Overlaying forest stability on top of caribou habitat maps can help decisionmakers narrow in on the largest, highest-stability tracts of forest as top priority for conservation.

According to Rogers, a future goal would be to eventually link maps of forest stability with carbon estimates in order to create forest protection plans with climate mitigation in mind. Research in primary forests has shown they continue to sequester carbon year over year, even though tree growth has tapered off. With primary forests in many places under intense political and economic pressures, it will become even more important to demonstrate the many co-benefits of protecting the earth’s stable forests.

“There’s no forest anywhere that isn’t threatened,” says Mackey. “Development, infrastructure, roading, damming, logging, clearing for agriculture. It’s happening everywhere.” 

Stable forests are resilient forests

Tracking stability of forests also allows us to approach a much harder-to-define characteristic of primary forests—resilience.  

Stability and resilience go hand in hand, though they are not the same thing. While resilience speaks to an ecosystem’s adaptive capacity or its ability to recover to its original state after some disturbance, stability is a measure of resistance, which is why it correlates so highly to primary forests that haven’t experienced any recent large-scale disturbance.

“If the stability index is showing recovery, then there’s obviously some resilience happening, but beyond that, primary forests tend to be more resistant to certain disturbances,” says Mackey. “Sometimes resistance is better even than being resilient. You’re not destroyed in the first place.”

Highly stable forests do tend to have better adaptive capacities as well, which is why they are so critical to protect.

“By and large,” says Rogers, “forests are resilient.” The stable ones can handle disruptions, and if you leave them to recover they will do just that, as he and Mackey have seen in the data.

But resilience is not infinite. If you hit too hard too fast—overlapping disturbances on an already unstable forest—you can overwhelm its resilience. Fires, larger and more frequent as a result of climate change, have already begun to override boreal forests’ adaptation. And there are more changes coming as the planet continues heating up. 

For now, at least, Rogers says, “resilience is still largely what we see out there.”

Despite thorough preparations, flying the drone is still nervewracking.

Dr. Manoela Machado, a Research Scientist at Woodwell Climate, has double- and triple- checked her calculated flight path over a study plot in the Cerrado, Brazil’s natural savanna. The drone can essentially fly itself, and she’ll be monitoring its speed, altitude, and battery life from her handheld controller on the ground, but many things could still go wrong. High winds, an unforeseen obstruction, loss of connectivity— all could jeopardize the mission, potentially dropping the expensive equipment 40 meters into the woodland canopy below.

Aboard Machado’s drone sits a powerful piece of technology – a LiDAR sensor. Developed originally for use in meteorology, this remote sensing technique now has widespread applications across scientific fields, from archaeology, to urban planning, to climate science. At Woodwell Climate, Machado and others employ LiDAR to create detailed three dimensional models of landscapes, which provide valuable insight into the structure of ecosystems and the amount of carbon stored in them— all with just a few (million) pulses of light.

What is LiDAR?

LiDAR stands for Light Detection and Ranging. Put simply, it is a sensor that uses laser light to measure distance. 

Similar to other technologies like sonar and radar, which use sound and radio waves, respectively, LiDAR is an example of an “active” sensor. “Passive” sensors like cameras collect ambient light, while LiDAR actively pings the environment with beams of laser light and records the time those beams take to bounce back. The longer the return time, the further away an object is. That distance measurement is then used to calculate the precise location in three-dimensional space for each reflection.

This process is repeated millions of times during a single scan, resulting in a dense cloud of point locations. With some advanced computing, the data can be assembled into a 3D picture of the landscape.

“It’s effectively three dimensional pointillism,” says Woodwell Climate Chief Scientific Officer, Dr. Wayne Walker, who has been using LiDAR in his studies for 25 years. 

Far more detailed than an oil painting however, a LiDAR model can reconstruct nearly every leaf, twig, and anthill on a landscape.

“Once you construct that cloud of millions of points, you get to walk inside the forest again,” says Machado. “When you finish processing the data and see the cloud you go, ‘I remember that tree! I remember standing there!’ It’s mesmerizing.”

For a project like Machado’s, scanning a few dozen hectares, the sensor is usually placed on a drone. Larger study areas require sensors mounted on low-flying airplanes or even satellites, but for small ground-based applications there are sensors one can carry, mount on a tripod, or attach to a backpack. Some newer phone models even have LIDAR apps built in. Regardless of how LIDAR is deployed, it remains a straightforward method of data collection. Just point the sensor at what you want to scan and within minutes, you’ve captured the data for a detailed three-dimensional model of your area of interest.

Estimating the weight of a forest

What Machado and Walker are often after from a LiDAR scan is a measurement of biomass, or the total weight of the organic matter present in an ecosystem. Plants store carbon in the form of organic matter, so biomass measurements are an easy way to estimate an area’s carbon storage. 

However, measuring a forest’s biomass directly would require cutting down all the trees, drying them out, and weighing what’s left — impractical and needlessly destructive— so scientists use proxy measurements. Walker likens the process to trying to estimate the weight of a human without access to a scale. 

“What are the measurements you might use if you couldn’t actually physically measure weight? You might record height, waist size, inseam, and if you obtain enough of these measurements you can start to build a model that relates them to weight,” says Walker. “That’s what we’re trying to do when we estimate the biomass of an entire forest.”

Raw LiDAR data is only a measurement of distance, but by classifying each point based on its location relative to the cloud, researchers are able to extract the proxy measurements needed to model biomass across the ecosystem. Before LiDAR, these proxy measurements— things like trunk diameter, height, and tree species— had to be recorded entirely by hand, which limits data collection based on human time and resources. The time-saving addition of LiDAR has vastly expanded the possible scale of study plots. While field measurements are still essential to calibrate models, LiDAR is one of the only technologies that can give scientists enough detail and scope to assess carbon stocks over entire ecosystems.

“There is no other kind of sensor that even comes close to LiDAR,” says Walker.

The power and potential of LiDAR

At Woodwell Climate, researchers have employed the power of LiDAR to map biomass and carbon from Brazilian forests, to the Arctic tundra. Outside of the Center, the technology has found applications in archaeological surveys, lane detection for self-driving cars, and topographical mapping down to a resolution of half a meter.

But the detail that makes LiDAR so powerful can also make the data a challenge to work with. A single scan produces millions of data points. According to Geospatial Analyst and Research Associate, Emily Sturdivant, who analyzed LiDAR data for Woodwell’s Climate Smart Martha’s Vineyard project, that wealth of data often overwhelms our ability to extract the full potential of information available in one point cloud.

“LiDAR creates so much data that when you look at it, it’s hard not to be blown away imagining all the different things you could do with it. But then reality kicks in,” says Sturdivant. “It’s challenging to take full advantage of all those points with our current processing power. It’s a matter of the analysis technology catching up with the data.”

Processing LiDAR data requires large amounts of computing time and storage space, especially when performing more complex analyses like segmenting the data on the scale of individual trees. As machine learning and cloud computing technologies advance however, this becomes less of an obstacle, and the potential insights from LiDAR datasets will advance along with them.

LiDAR can be an expensive endeavor, too. Drones with the right equipment can cost tens of thousands of dollars, as can hiring a plane and pilot and paying for jet fuel, so data sharing has been important in making the method more cost effective. U.S. government agencies like NASA and the USGS have facilitated the collection of LiDAR data through satellites and plane flights, making the data available for public use. Woodwell Climate research has benefitted from these public datasets, using them to inform landscape studies and carbon flux models. 

According to Sturdivant, the reliable production of public data has been greatly beneficial to advancing LiDAR-based studies, though it now faces risks from federal cuts to science agency funding.

“One of the greatest advantages of having publicly supported data is the consistency, but that’s exactly what’s now at risk,” says Sturdivant. “Public accessibility has been so important in allowing new scientists to learn and experiment and then help everyone else learn.”

Each new LiDAR scan represents a trove of information that could be used to better understand our changing planet, making it critical to continue supporting and collecting LiDAR data. Its intensely visual and highly detailed nature has made it one of the most powerful tools we have for understanding something as complex as a forest. 

“And on top of that,” says Machado “It’s just visually beautiful.”

In the Amazon Rainforest, there is no such thing as a natural fire. Yet every year we see headlines of rainforest vegetation aflame, smoke drifting across populated areas, and stored carbon spilling into the atmosphere. So how does a rainforest—one of the wettest ecosystems on Earth—catch fire?

Climate impacts on Amazon fire

Whether directly or indirectly, human activities are the root cause of fire in the Amazon.
In order for a fire to start anywhere, you need three things— favorable climatic conditions, a fuel source, and an ignition source. In the Amazon, each side of this “triangle of fire” has been exacerbated by warming temperatures and deforestation, creating flammable conditions that can allow fires to spread out of control deep into the forest once they are ignited.

Climate conditions

High temperature and dryness combine to create the right conditions for fires to spread through the Amazon. As global temperatures have risen, the Amazon region has become hotter and drier, more vulnerable to prolonged droughts and extreme climatic events. Most recently, a climate-driven drought spanning 2023 and 2024 has deeply impacted water levels in the forest— to the point of isolating riverside communities.

Wildfire danger days, or days considered hot and dry enough to increase the likelihood of fire, have become a much more common occurrence deeper in the Amazon, where previously it was just too wet to burn.

Fuel

Felled trees and dry vegetation form the fuel for more fires in the Amazon. How do the trees fall? Some are killed in extreme drought and previous fire, but many are intentionally cut, pushed over by bulldozers for conversion of forest to pasture land. Large-scale deforestation has been advancing into the Amazon for decades, fragmenting thick blocks of forest and replacing them with ranch or farm land. Scientists and activists have been pushing for an urgent stop in deforestation to achieve, among other benefits, a drop in fire numbers. However, despite slowly declining deforestation rates, fires are still increasing, pointing to another important piece of the puzzle – degradation.

When a forest is fragmented by deforestation, it degrades the vegetation that remains standing. Forests along the edges of clearings dry out and weaken, making them more susceptible to future burning. And burning weakens nearby forests yet again, creating more available fuel, setting off a chain of degradation.

Ignition

Ignition in the Amazon is almost entirely human caused— whether accidentally or intentionally. Ranch and farm operations both legally and illegally clearing Amazon rainforest use fire to burn away cut vegetation or prepare existing pasture land for other uses. With climate change creating hotter and drier conditions, and lengthening the dangerous dry season, any ignition becomes potentially risky, whether or not its use is legalized. Especially where forest edges have already been weakened.

However, a study led by Woodwell Climate Postdoctoral Researcher and fire ecologist Dr. Manoela Machado, found that long-term solutions to the Amazon’s fire crisis will require distinguishing between the complex uses of fire. One-size-fits-all fire bans, usually employed as emergency measures and not always strictly enforced, may reduce fire in the short term, but don’t adequately address the underlying reasons people have decided to burn the land.

Ending deforestation and supporting firefighters

Fire in the Amazon follows deforestation and degradation, namely from logging, fires, droughts and fragmentation. Climate change and human encroachment have worked in concert to foster a devastating annual burning regime in the Amazon rainforest that threatens one of the Earth’s most valuable mechanisms for keeping the planet cool.

Eliminating fire from the Amazon will require the elimination of deforestation and degradation sources, as well as the enforcement of strategic fire bans and support of firefighting brigades. Machado, has led several successful workshops with Indigenous fire brigades in Brazil, bringing together groups from across the country to learn about Geographic Information Systems (GIS) technology they can use to monitor and manage their own forests.

According to Machado, a big part of fire prevention happens in the off-season. Support for activities like community outreach, building fire breaks in collaboration with farmers, and technical assistance to replace legal use of fire, can all help reduce the prevalence of catastrophic fires when the dry-season comes around.

The Amazon is a massive place, and firefighting can be a dangerous job. Especially on the frontiers of deforestation, where land grabbing and illegal deforestation are common and fire fighters are often threatened to stay out of an area. Ultimately, government support, bolstered enforcement of deforestation laws, and viable alternative livelihoods have a major role to play in bringing down fires, alongside continued global efforts to curb climate change.

In recent public comment, scientists at Woodwell Climate Research Center warn against the use of the Inflation Reduction Act’s (IRA) clean electricity tax credits to support biomass as an effective clean energy solution. Scientists cited its higher carbon footprint per unit energy compared to burning fossil fuels, and highlighted that claims to offset these emissions by planting trees are misleading, as new trees take decades to centuries to recapture lost carbon. The comment, submitted in response to the Internal Revenue Service (IRS) and U.S. Department of Treasury’s proposed guidance on the Clean Electricity Production Credit and Clean Electricity Investment Credit, advocates for more rigorous guardrails from the agencies regarding the use of wood for bioenergy, greater regulatory clarity, and more accurate accounting of emissions from wood-burned fuel.

The Clean Electricity Production and Investment Credits were designed to provide incentives “to any clean energy facility that achieves net zero greenhouse gas emissions.” The proposed guidance, released in June, is intended to clarify and add certainty around how to measure and define “net zero,” and how clean energy production facilities can qualify for these incentives.

In their comment, however, scientists emphasize more work must be done to achieve this goal: “The content of the proposed guidance is ambiguous or even conflicting about some parts of the rule regarding sources of forest bioenergy,” they write. “Parts of the guidance should be made much clearer and more definitive to ensure that there are no unintended consequences. Guardrails could be put in place to avoid the many ways that increasing use of wood for bioenergy would increase emissions rather than having the desired effect of decreasing emissions. It is also important to consider the many values of forests beyond climate mitigation, such as timber, biodiversity, water, and recreation.”

Scientists also note the proposed guidance does not properly account for the net emissions associated with forest bioenergy – all of which contribute to its high carbon footprint and add to concerns from experts that biomass can actually worsen the climate crisis – including those from harvesting intact forests, logging debris, transporting woody biomass, and converting biomass to fuel, as well as from feedstock, fertilizers, and forest management practices like thinning, where live trees are removed to reduce wildfire risk or promote forest growth, and more. 

Because many of these emissions are left out, the proposed guidance overestimates the potential of forest bioenergy to achieve the IRA’s intended goal of lowering emissions, and further fuels incorrect assumptions that biomass energy is an effective, carbon-neutral alternative to fossil fuels.

Throughout the comment, scientists offer recommendations to help decision makers more accurately incorporate and represent these emissions in policy. For example: 1) account for both direct and indirect emissions; 2) avoid the fallacy of assuming carbon neutrality; and 3) take a case-by-case approach to calculate the counterfactual emissions, or what the emissions would have been had the wood or biomass not been used for bioenergy; among others.

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.

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.