What are Nature Based Climate Solutions?
Natural ecosystems could be our most effective tool for pulling carbon from the atmosphere
Researchers collect soil samples at Howland Forest in Maine.
photo by Jonathan Kopeliovich
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%.
Canopy of Amazonian rainforest tree.
photo by Mitch Korolev
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.
Cattle overgrazing can deplete carbon on grasslands. Proper management can reverse that process.
photo by Sarah Ruiz
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.”
A carbon flux monitoring chamber deployed in Howland Forest, Maine to measure methane.
photo by Johnathan Kopeliovich
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.
A wetland soil sample from Howland Forest, Maine.
photo by Johnathan Kopeliovich
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.”
