Farmer in tractor pulling an air seeder planting cover crops in a farm field on a blue sky day with white puffy clouds.
Cover Crops: Wisconsin farmer using an air seeder donated by The Nature Conservancy to plant cover crops. © Outagamie County

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New U.S. Study Reveals Nature Can Help Reduce Global Warming

Cover crops already capturing carbon and returning it to the soil in Wisconsin

MADISON, WI: Restoring the United States’ lands and coastal wetlands could play a much bigger role in reducing global warming than previously thought, according to the most comprehensive national assessment to date of how greenhouse gas emissions can be reduced and stored in forests, grasslands and wetlands.

The peer-reviewed study in Science Advances from The Nature Conservancy and 21 institutional partners, including University of Wisconsin-Madison, found that nature’s contribution could equal 21% of the nation’s current net annual emissions by adjusting 21 natural management practices to increase carbon storage and avoid greenhouse emissions.

The study further identified the important role that existing croplands can play in Wisconsin and other states to capture carbon from the atmosphere and return it the soil, improving soil health in the process. Maximizing the use of cover crops alone in Wisconsin could remove as much as 2.57 million tons of CO2 annually, equivalent to removing the carbon pollution from more than 550,000 cars per year. Other natural solutions including more efficient use of manure and other fertilizers could remove even more tons of CO2 from the atmosphere.

“Wisconsin farmers are already capitalizing on the many benefits that planting cover crops provide from building soil health to improving water quality,” said Steve Richter, Director of Conservation Programs for The Nature Conservancy in Wisconsin. “Capturing carbon and returning it to the soil during times of the year when fields would normally be bare is another, very exciting benefit.” 

The Nature Conservancy is supporting the efforts of five farmer-led groups in Sheboygan, Door, Dane, Lafayette and St. Croix counties to improve soil health and water quality. This includes putting conservation practices such as cover crops and reduced tillage on their croplands and improving nutrient and manure management. Currently, the farmers in these groups have put practices on more than 80,000 acres of land, including 50,000 acres in cover crops.

“Our goal in the next five years is to help farmers in other Wisconsin counties form collaborative groups and put conservation practices on another 300,000 acres,” Richter adds.

“The Nature Conservancy is just one of many organizations supporting farmers who are taking the lead on conservation in their farm operations,” said Paige Frautschy, Agriculture Strategies Manager for The Nature Conservancy in Wisconsin. “The Natural Resources Conservation Service (NRCS), UW Extension and the National Corn Growers Association, through their Soil Health Partnership Initiative, are some of the many organizations involved in this effort.”

In October the Intergovernmental Panel on Climate Change special report called for global action immediately to limit warming to 1.5˚Centigrade (approximately 3˚ Fahrenheit) to avoid the most damaging climate change impacts.  This new study highlights how, and which, natural solutions in the United States offer the most promise to help limit temperatures below that 3˚ Fahrenheit goal.

Joe Fargione, Director of Science for The Nature Conservancy, was the study’s lead author: 
One of America’s greatest assets is its land. Through changes in management, along with protecting and restoring natural lands, we demonstrated we could reduce carbon pollution and filter water, enhance fish and wildlife habitat, and have better soil health to grow our food -- all at the same time.  Nature offers us a simple, cost-effective way to help fight global warming. In combination with transitioning to zero carbon energy production, natural climate solutions can help protect our climate for future generations.” 

In the U.S., of the 21 natural solutions analyzed, increased reforestation (the planting of trees) emerged as the largest means to achieve greater carbon storage, equivalent to eliminating the emissions of 65 million passenger cars. Almost a million acres of forest are being converted to non-forest habitat a year, largely due to suburban and exurban expansion, which could be addressed through better land use planning. The study also finds that urban reforestation can add important carbon storage benefits.

Grasslands are underappreciated for their carbon storage opportunity. Grassland in the U.S. is being lost at a rate of over one million acres per year. When grassland is converted to cropland, about 28% of the carbon in the top meter of soil is released to the atmosphere. This trend could be reversed by re-enrolling 13 million acres of marginal cropland in conservation programs and restoring them to provide habitat and storage of carbon in the soil. 

The new study is the first to analyze the climate-related benefits of grasslands thanks, in part, to the efforts of UW-Madison co-authors, Associate Researcher and UW-Madison Nelson Institute for Environmental Studies alum Dr. Tyler Lark and Geography graduate student, Seth Spawn. Lark and Spawn – both researchers in the Nelson Institute’s Center for Sustainability and the Global Environment (SAGE)– led the analyses of grassland conservation and restoration and its potential to reduce global warming.

Not only do natural climate solutions have strong benefits for personal enjoyment, healthier water, air, wildlife, and soil, many are quite affordable. As states and the federal government evaluate rules and markets for greenhouse gas emissions, these low-cost reductions from natural solutions offer the United States a powerful tool to address a warming planet.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world's toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 72 countries, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit www.nature.org or follow @nature_press on Twitter.