Landscapes as Carbon Sinks: How Do We De-risk Conservation Investments?
In our efforts at the Mighty Arrow Family Foundation to do the most with the resources and time we have, we are constantly researching and asking, ”What can we champion that will make the most impact? When it comes to addressing climate change and biodiversity loss, carbon sequestration is paramount—but it’s a complex issue, one we thoughtfully consider in our investment and conservation approaches. We’ve been diving into the science of ecosystems and carbon storage, and will share some of what we’ve learned about protecting landscapes as carbon sinks, and how it applies to our evolving climate strategies and philanthropic work.
What exactly is a carbon sink?
A carbon sink absorbs more carbon from the atmosphere than it releases. For example, a forest ecosystem absorbs carbon dioxide from the atmosphere, and through photosynthesis converts it to biomass, where it’s stored. What we are curious to know is which ecosystems store the most carbon—and what management and stewardship actions are needed to continue sequestration and to avoid becoming a carbon source.
All ecosystems play a role in mitigating climate change by storing carbon and reducing greenhouse gas concentrations in the atmosphere, but each one is unique in its sequestration capacities. Landscapes vary in vegetation type, soil composition, climate conditions, and disturbance history. This all affects their carbon-sequestration values.
How do landscapes differ in their carbon sequestering?
In North America, the northern boreal forest has the highest carbon sequestration potential, storing 208 billion tons of carbon, or 11% of the world's total. Its dense coniferous forests store a significant amount of carbon in tree biomass, soil organic matter (SOM) and carbon associated with soil minerals, and peatlands. The cold climate and slow decomposition rates contribute to the ecosystem’s long-term carbon storage.
In more moderate climates, temperate forests also sequester a substantial amount of carbon, storing it in their biomass and soil. But their carbon sequestration potential is lower than boreal forests due to faster decomposition rates and higher human disturbance.
Wetlands, including marshes, peatlands, and vernal pools, are also highly effective carbon sinks. These landscapes accumulate carbon in the form of organic matter in waterlogged soils and can sequester carbon for long periods due to anaerobic conditions that slow down decomposition. Peatlands alone only cover about 3% of the world’s land surface, but store at least twice as much carbon as all of Earth’s standing forests.
Another important carbon-sequestering landscape in North America is intact grasslands. The majority of carbon in grasslands is stored in belowground biomass, including roots and soil organic matter. These areas are often disturbed, though, by woody vegetation encroachment, conversion, tilling, and poorly managed grazing.
The Arctic tundra, on the other hand, is unique in that it has relatively low carbon sequestration potential compared to other ecosystems—due to the cold climate and short growing season—but the tundra stores significant amounts of carbon in frozen organic matter (permafrost) beneath the surface.
Finally, subalpine and mountain forest ecosystems also sequester high rates of carbon. Their high-density mix of coniferous trees and forest wetlands have such a high organic content that the National Conference of State Legislators say the nation’s forests offset nearly 16 percent of domestic carbon dioxide emissions. They store 866 million metric tons of carbon dioxide per year.
But what about climate resiliency?
While each ecosystem is important, looking at how human disturbances and climate change is impacting them can help us make smart choices in prioritizing which ones to conserve and protect. “In a vulnerable, warming, drought-likely future, we could lose some of the most productive carbon sinks on the planet,” writes Benjamin Houlton, director of the John Muir Institute of the Environment at UC Davis. Houlton urges us to consider this in our conservation strategies going forward.
For example, in a stable climate, trees store more carbon than grasslands. But we’re not in a stable climate anymore. More recently, grasslands have been shown to be more resilient to rising temperatures, moderate drought and fire. They’ve also been better than forests at preserving sequestered soil carbon and preventing it from re-entering the atmosphere. But that’s referring to intact ecosystems, as conversion from natural grassland to cropland or pasture significantly reduces the belowground biomass. Also, extreme drought is having a surprising impact on grasslands in places like Colorado—and in contrast to the impact of fire on forests, the exclusion of fire can lead to encroachment of woody shrubs in grasslands, potentially reducing soil carbon pools.
What does this mean for us?
In Houlton’s words, “We really need to start thinking about the vulnerability of ecosystem carbon and use this information to de-risk our carbon investment and conservation strategies in the 21st century.” These strategies include tactics relative to conservation agriculture, 30x30, policy development, forest health, climate justice, water security, and emissions reductions. Looking at what we’ve learned, here are some high-level recommendations.
More investment should be made to keep grasslands intact and support sustainable, grass-based agriculture. Grasslands are critically imperiled ecosystems in the world, with only a few large, intact tracts remaining. More than 70% of America’s prairies have been destroyed. This is a major contributor to the precipitous decline of grassland biodiversity and the loss of vast amounts of sequestered carbon. The UN recognizes this issue, declaring 2026 the International Year of Rangelands and Pastoralists.
Restoring grasslands has the global potential to sequester approximately 3 Gt of carbon per year—equivalent to reducing atmospheric carbon dioxide by 50 ppm over 50 years. To get there, support for multi-national and inter-tribal collaborative communication, policy advocacy, research agendas and best practices is needed. We’re excited to continue supporting Mighty Partners working in this area, such as the Soil Carbon Solutions Center at Colorado State University, the Central Grasslands Roadmap Initiative and Green Foothills Foundation.
Our partners at SPUN (the Society for the Protection of Underground Networks) out sampling fungal networks in the grasslands of Portugal, documenting fungal biodiversity's connection to carbon sequestration potential.
Focus on protecting old growth forests and forested wetlands. The best way to sequester carbon in forests is by leaving healthy trees standing and protecting them from natural disturbances such as fire or insects. The next best strategy is sustainable logging, if the harvested wood replaces alternatives, such as cement or steel. Initiatives like the Colorado Mass Timber Coalition are exploring that strategy.
Of mature and old growth forests, 76% go unprotected from logging and are often sacrificed to create more young forests to feed demand for timber products. This could release large amounts of carbon, and a new forest would take decades to sequester as much carbon as currently stored in the old-growth forest. Additionally, forested wetlands cover about 86 million acres in the US and peatlands 42 million acres. It’s crucial to map, measure and conserve the forest wetlands we still have.
Support local and state-based efforts to protect wetlands and freshwater ecosystems. More than 10% of all species, including 50% of all endangered ones, rely on wetlands. And when wetlands are destroyed, their carbon is often released into the atmosphere, further worsening the climate crisis. Drivers that tend to disturb wetlands in the West are drought and livestock grazing. Climate change and increased aridity in the West could dry up half the region’s remaining wetlands by 2050, and following the Sackett vs EPA ruling, wetland losses to development and other land uses also occur more quickly, leading to vast carbon emissions, water quality impairment, and biodiversity loss.
Our partners at Coalition for the Poudre River Watershed, TRCP, Audubon Rockies, and more out studying beaver impacts in the forested headwaters of the Poudre River watershed.
We need strong advocacy and science-based evidence to secure policies or rulemakings that protect waters no longer under federal jurisdiction. Colorado recently created its own permitting authority to replace federal oversight lost under the Sackett ruling, and other state-based efforts, such as those in New Mexico, Illinois, Arizona, and California, are aiming to establish and fund similar state programs. In each, we must consider the role of community-based science and community organizations that conduct ongoing monitoring of pollution, and of polluters, such that water quality can be protected for all.
We also need a unified, focused campaign that includes philanthropy, conservation and environmental justice groups, Tribal communities, and other allies across the US to reimagine and reinstate federal clean water policy that restores protections for all US waters and addresses issues unanticipated by the original 1972 Clean Water Act, including climate change, non-point source pollution, Tribal sovereignty, and equity and justice for historically excluded communities.
These recommendations are just a start, more needs to be done to understand the complexities of our landscapes as carbon sinks, and how we can best prioritize their protections, and support good stewardship. For now, we hope this summary of what we’re learning about carbon and ecosystem storage sparks some thought and strategic excitement for important work ahead.
