What is the Science?

To stop climate change, we must drastically reduce fossil fuel emissions and remove greenhouse gases (GHG) already in the atmosphere. Natural Climate Solutions offer a way to make forests, wetlands, grasslands, farms and ranches part of the solution to climate change. Globally, these conservation, improved land management, and restoration practices could deliver up to a third of the carbon reduction necessary by 2030 to keep global warming in check.

While Natural Climate Solutions alone cannot solve climate change, there is no way to limit global warming to 1.5ºC without integrating these solutions alongside efforts to reduce emissions from the energy, transportation, and industrial sectors. Thankfully, conserving, restoring, and rethinking the way we manage our natural and working lands have multiple payoffs not only for climate, but also for people and our economy, for air and water quality, and for fish and wildlife.

To estimate the climate change mitigation potential of forest, grassland, agricultural, and blue carbon Natural Climate Solutions pathways, U.S. Nature4Climate worked with scientists from both coalition and external organizations in 2023 to incorporate the most up-to-date scientific literature. The results of this effort can be found below: 

Forests & Trees

The 823 million acres of forest lands in the United States are managed by public agencies, Native American Tribes, forestry companies, families, and municipalities. These lands can play a crucial role in our efforts to mitigate climate change by capturing and storing carbon in trees, roots, and soils.

There are many approaches for leveraging this natural climate benefit. Preventing the conversion of forests to agriculture or development keeps more carbon on the landscape and protects the ability of forests to continue capturing carbon. Agroforestry practices, post-fire reforestation, tree planting in urban areas, and forest regrowth in the historically forested lands outside our cities can sequester more carbon as well.

Climate-smart management techniques can keep forests growing faster, healthier, and longer. Not only do these practices help address climate change, but they can also prevent soil erosion and improve water quality, enhance habitat for fish and wildlife habitat, and make our communities healthier and safer.

Climate-Smart Management of Existing Forests

A variety of climate-smart (also known as climate-informed) management practices can increase carbon sequestration and storage in forests, aiming to balance forests’ ability to adapt to and mitigate climate change while still providing essential co-benefits like clean water, wood products, and wildlife habitat. These climate-smart practices include optimizing forest stocking at ecologically-appropriate levels, restocking degraded forests, restoring the diversity of species in the forest, extending timber rotations, controlling browsing and grazing by animals, actively managing forest pest and drought impacts, reducing the risk of catastrophic wildfire, and controlling competition from invasive plants.

There are multiple methodologies available for calculating the climate change mitigation impact of these practices. A review of existing literature provides estimates on some practices. One study (Domke et al, 2020) focused specifically on using existing seedling production to increase stocking density in forests in the United States, which would sequester an additional 48 million metric tons of carbon and cover 4 million acres each year. Another study (Robertson et al, 2022) focused on extending timber rotations on half of harvested natural forests in the United States, finding that this would sequester an additional 12 million metric tons of CO2e a year. Combined, these two practices would yield 60 million metric tons of additional CO2e sequestered per year.

  • Forest Restocking: 48 million metric tons of CO2e/year from fully stocking understocked forestland (Domke et al, 2020)
  • Forest Restocking Acreage: 4 million acres each year 
  • Extended Timber Rotations: 12 million metric tons of CO2e/year from extending timber rotations (Robertson et al, 2022)
  • Extended Timber Rotation Acreage: 76.6 million acres

Beyond restocking and extended rotations, there are other climate-smart forest management practices that could be applied across the hundreds of millions of acres of managed forestland nationwide to provide additional climate mitigation. For example, reducing harvest intensity in selectively logged forest can help to boost stand level carbon values (Family Forest Carbon).  

Finally, modeling conducted by American Forests in Pennsylvania and Maryland breaks down the climate change mitigation impact of eliminating diameter limit cuts on private lands, controlling deer browse, restocking understocked stands, and extending timber rotations, finding that implementation of these four practices across 19 million acres of forests in those two states would sequester an additional 1.2 million metric tons CO2e a year, including both biomass and soil carbon dynamics. American Forests is conducting similar research in other states, and is working toward providing national estimates.

GHG estimate (Maryland & Pennsylvania only): 1.2 million tons CO2e per year

  • 309,037 metric tons CO2e/year from eliminating diameter limit cuts (high grades) on private lands
  • 307,055 metric tons CO2e/year from controlling deer browse
  • 308,620 metric tons CO2e/year from restocking understocked stands
  • 314,989 metric tons CO2e/year from extending rotations

Acreage: 19 million acres of forested land (Pennsylvania and Maryland only)

Increasing Urban Tree Cover

Increasing urban tree cover by planting trees in urban open spaces provides another mechanism for sequestering carbon. 

According to the Reforestation Hub, reforesting developed open spaces in suburban and surrounding areas can sequester up to 101.6 million metric tons of carbon a year over 26 million acres, an area about the size of Kentucky. While people may not want trees in all those places, increasing tree cover in at least part of the available space can help capture carbon, cool our cities, and create habitat for biodiversity.  

There are also opportunities to plant additional trees along streets in highly-developed urban areas. Analysis from American Forests suggests that planting 522 million additional trees in urban areas – allowing every American city to achieve Tree Equity – could sequester and store 8.7-13.7 million metric tons of CO2e/year, including avoided energy emissions from reduced heating and cooling needs.  Furthermore, a new, high resolution study suggests that there is room to plant 1.2 billion trees in metro areas (McDonald et al, pre-print). These trees could capture 23.7 million metric tons of carbon and avoid a further 2.1 million metric tons from heating and cooling that would no longer be needed due to trees’ ability to insulate buildings from low and high temperatures. 

In addition to planting new trees in urban areas, it is also critical to keep existing tree cover healthy and well maintained so that the trees already in our cities sequester their full potential of carbon.  

Reforesting Open Spaces in Suburban-Exurban Areas:

  • GHG Estimate: 101.6 million metric tons of CO2e per year 
  • Acreage: 26 million acres (full implementation)

Urban Trees

  • GHG Estimate: 8.7 – 25.8 million metric tons of CO2e per year
  • Number of Trees: 522 million-1.2 billion

Emerging Pathway: Wildfire Resilience Treatments – Prescribed Burning & Thinning

Practices that help prevent the occurrence of catastrophic wildfire on forested land, such as thinning and prescribed fire, can help prevent the massive release of CO2 that occurs in these fires, providing an important long-term climate mitigation benefit.

Prescribed Fire: Prescribed fire treatments entail restoring frequent, low-severity understory fires in fire-adapted forest ecosystems to reduce the potential for high-severity wildfires which release significantly more carbon than prescribed fires and decrease net sequestration resulting from increased tree mortality. 

Thinning: Thinning refers to the practice of removing smaller trees and other vegetation in overgrown forests to reduce the severity of wildfires and reduce tree death – and avoiding the higher carbon emissions that would have resulted from a severe fire.

Thinning and application of prescribed fire  can be implemented either alone or together, depending on the ecological and logistical requirements and constraints of the landscape. Note that both practices result in a short-term carbon loss, as living trees are removed from the forest landscape. However, by reducing fire risk and severity, and avoiding the significant carbon emissions associated with catastrophic wildfires, there is a long-term carbon benefit. 

Research suggests that these treatments could result in net carbon benefits ranging from 4.8-18 million metric tons of CO2e per year (Fargione/2018, American Forests IRA Analysis/2022); however, given the unpredictable nature of fire behavior and minimal data on the success of wildfire resilience treatments, these estimates comes with a high degree of uncertainty. More research is needed on these topics to refine estimates of carbon benefits from wildfire resilience treatments.

Emerging Pathway: Wood Products

Long-lived wood products represent a significant pool of long-term carbon storage. When wood is harvested, a portion of the carbon in that wood remains stored there as long as the wood is still intact. This storage can last for many decades when harvested wood is utilized in buildings and other long-lived structures. The U.S. Environmental Protection Agency estimates that in 2021, nearly 103 million metric tons of CO2e was transferred to and stored in harvested wood products in the United States – equivalent to 13% of the annual  U.S. forest carbon sink. 

The Inflation Reduction Act and Infrastructure Investment & Jobs Act included $560 million for wood innovation – such as incorporating low-value wood materials produced by wildfire management efforts into greener building materials,increasing wood use in multi-story and commercial buildings, and developing new nanocellulose technologies.  A recent American Forests analysis suggests that innovations unlocked by these investments alone could sequester an average of 1.7 million metric tons CO2e per year in wood products. 

Recent reports on the impact of climate-smart forestry in Pennsylvania and Maryland suggest that substituting sustainably harvested wood products for emissions-intensive building materials could avoid net emissions of 15 and 2.5 million metric tons CO2e Pennsylvania and Maryland, respectively, over 10 years. More research is necessary to understand the potential trade-offs between management practices that are designed to increase forest ecosystem carbon stocks and provide ecosystem service benefits versus policies and practices that would increase demand for harvested wood product volumes. In addition, further work must be done to ensure sustainable harvesting practices and create markets for sustainably harvested wood building materials.

Agriculture & Grasslands

In the United States, about 16% of the country’s land area, or 396 million acres, is cultivated to produce crops. Intensive cultivation practices have impacted a large proportion of the original soil carbon in croplands. By changing management of croplands, we can store more carbon in the soil, prevent soil erosion, improve water quality and, in many places, increase the productivity of the land. Increasing productivity, in turn, can ease pressures to convert natural forests and grasslands to food production in the U.S. and abroad. There is also the possibility of adding more trees in agricultural lands. Agroforestry includes four practices that store carbon: alley cropping, silvopasture, windbreaks, and riparian buffers. 

Many of these practices, like cover crops, have already been adopted by numerous farmers, though overall adoption rates are still low. At the same time, research is underway to determine the carbon mitigation potential of other agricultural practices, like composting, crop rotations and planting deep rooted crops, and to determine the scalability of innovative practices like biochar and alley cropping. By advancing research and applying a variety of innovative and proven management practices that reduce agricultural emissions and/or enhance carbon sinks, America’s farms can be an important part of the solution to climate change.

Taking action to preserve and improve the management of America’s pasture and rangelands can also help mitigate climate change. In the U.S., pasturelands and rangelands cover about 401 million acres – more than twice the size of Texas. Pasture and rangelands store high levels of carbon in their soils. A significant fraction of that carbon has been lost through conversion to cropland and overgrazing. Taking additional steps to protect and improve grazing practices on pastures and rangelands would provide significant carbon benefits, while also protecting habitat for wildlife and safeguarding our water.

Potential Pathway: No-Till/Reduced Till Farming

Some research indicates that implementing no-till or reduced-till farming practices on farmland, which entails limiting disturbance of soil to manage plant residue on the soil surface year round, could be a potential natural climate solution. There is consensus that no-till and reduced till farming has many benefits, including preventing soil erosion and improved overall soil health, and the U.S. Department of Agriculture’s COMET Planner tool suggests a significant climate change mitigation benefit from implementing no-till. 

However, some recent studies have made the case that the potential climate change mitigation potential of no-till has been overstated for several reasons. No-till has been found in many cases to redistribute the carbon in the soil profile, resulting in higher SOC concentrations in the topsoil and lower SOC concentrations in the subsoil (i.e. below the tillage depth), with little to no change in total SOC stocks in the full profile (shallow sampling schemes, which are common, miss the redistribution and overestimates SOC gains). Further, no-till has the potential to increase nitrous oxide emissions, which can counteract gains in SOC when considering net GHG emissions. And because no-till is often practiced together with other climate-smart practices, it can be difficult to segregate out the climate benefits that can be directly attributed directly to no-till on working farms. As a result of these uncertainties, more research is necessary to better understand under what conditions no-till and reduced-till lead to lower net GHG emissions. Finally, 60-70% of U.S. farmland is already under no-till or reduced-till management, so there is limited potential to implement this practice at a larger scale.

This topic was discussed in 2022 by an expert panel convened by U.S. Nature4Climate – a summary of that discussion can be found here.

In addition, here is a recent study on no-till that provides more context.

Blue Carbon

Protecting and restoring coastal ecosystems, such as mangroves, tidal marshes and seagrass beds, that capture and store “blue carbon,” can sequester significantly more carbon per acre than terrestrial forests, and if left undisturbed, can store this carbon for a millenia. Most of the carbon is stored in underlying sediments, and these carbon stocks can be thousands of years old.  Beyond carbon sequestration, protecting and restoring coastal wetlands provides significant benefits to society: protecting coastal communities, supporting recreational and commercial fisheries, enhancing tourism, and improving water quality that can be worth many thousands of dollars per acre per year. For example, scientists estimate that US coastal wetlands provide $23.2 billion in storm protection services each year. In addition to coastal blue carbon efforts, research is underway on oceanic blue carbon strategies for addressing climate change, including kelp farming and  protection of certain fish populations.

Coastal Wetland Protection and Restoration: Avoided Tidal Wetland Loss

Avoided Tidal Wetland Loss: 

In addition to restoring tidal wetlands, ensuring that existing tidal wetlands remain intact is also important. A recent brief by the Pew Charitable Trusts notes that, according to the Environmental Protection Agency’s 2021 greenhouse gas inventory, coastal wetlands in the lower 48 states sequestered 4.8 million metric tons of CO2 equivalent—and held a total of about 2.9 billion metric tons in their soils—as of 2019. A “no net loss” policy for wetlands in the United States, first established by President George H.W.  Bush in response to significant rates of wetland loss, confers some degree of protection, though destructive impacts may still be permitted if “compensatory mitigation” (e.g., creation of a new wetland) takes place. Compensatory measures like wetland creation are often not tracked to see if they are successful, and also does not account for loss of ecosystem functions like carbon sequestration and storage. As a result, despite the no net loss policy, the U.S. is still losing its coastal wetlands due to continued development, as well as from sea level rise and subsidence, which together “drown” coastal wetlands. 

Management options to help prevent tidal wetland loss include closing permitting loopholes, shifting from a net loss to net ecological gain policy, and building resilience in existing tidal wetlands from sea level rise, such as adding sediment or creating space for wetlands to migrate inland and away from rising seas. There is a need to assess the carbon impact of measures that protect existing tidal wetlands from loss.

Emerging Pathway: Seaweed/Kelp

A 2022 report issued by the Environmental Defense Fund explores the role that kelp and other seaweeds can play as a Natural Climate Solution, summarizing the existing literature on carbon sequestration by seaweed, and evaluating the potential for  interventions to increase carbon sequestration, such as conserving and restoring existing kelp forests, increasing productivity of seaweed farms, and expanding seaweed farming to offshore waters while creating conditions to incentivize increased carbon sequestration. The report reveals that, while the processes that influence carbon sequestration by seaweed are understood, there are significant gaps in existing data, as well as the need for new policy and accounting frameworks to govern these activities, which often cross jurisdictional boundaries. 

As noted above, carbon sequestration provided by kelp and other forms of  seaweed can occur through efforts to protect and restore wild seaweed, as well as efforts to cultivate seaweed through farming activities – which could be undertaken for the purposes of creating food and energy products, or for the carbon benefit alone. Moreover, it is important not to replace existing natural seaweed stands with cultivated seaweed. Potential avoided emissions from protecting kelp forests has been estimated at 42.9 million metric tons of CO2e a year globally (calculated from several studies 1,2,3,4).

Cultivated macroalgae (kelp farming) also has the potential to increase carbon mitigation – with an estimated increase in carbon burial of 1.4 tons of CO2e per hectare per year. However, the climate benefits of farming kelp to make products for human use would have a variable climate benefit depending on the product and its lifespan. Using kelp for food or short-lived products such as nutraceuticals offers lower climate benefits than long-lasting seaweed products because that carbon is released or transferred up the food chain (Scown 2022). Climate benefits from short-lived products stem from reduced production of their fossil fuel-intensive counterparts (DeAngelo et al. 2023).


The Science: Peatlands are known by many names (e.g., mire, marsh, swamp, fen, bog, pocosin), but can simply be defined as a class of wetlands with a naturally accumulated layer of peat. Peat is formed when organic matter accumulates faster than it decomposes due to the lack of oxygen in waterlogged conditions. Even though peatlands cover only 3% of Earth’s surface, they store more than twice as much carbon as the world’s forests. Protecting existing peatlands can help keep carbon sequestered in these ecosystems, and restoring degraded peatlands can help increase carbon sequestration and reduce emissions, while also reducing wildfire risk.