Soil carbon

Forests are an essential part of Earth’s operating system. They reduce the buildup of heat-trapping carbon dioxide in the atmosphere from fossil fuel combustion, deforestation and land degradation by 30% each year. This slows global temperature increases and the resulting changes to the climate. In the U.S., forests take up 12% of the nation’s greenhouse gas emissions annually and store the carbon long term in trees and soils. Mature and old-growth forests, with larger trees than younger forests, play an outsized role in accumulating carbon and keeping it out of the atmosphere. These forests are especially resistant to wildfires and other natural disturbances as the climate warms. Most forests in the continental U.S. have been harvested multiple times. Today, just 3.9% of timberlands across the U.S., in public and private hands, are over 100 years old, and most of these areas hold relatively little carbon compared with their potential. The Biden administration is m...

Earth’s boreal forests circle our planet’s far northern reaches, just south of the Arctic’s treeless tundra. If the planet wears an Arctic ice cap, then the boreal forests are a loose-knit headband wrapped around its ears, covering large portions of Alaska, Canada, Scandinavia and Siberia. The boreal region’s soils have long buffered the planet against warming by storing huge quantities of carbon and keeping it out of the atmosphere. Its remoteness has historically protected its forests and wetlands from extensive human impact. These two traits rank boreal forests among the most important ecosystems on Earth. In addition, numerous species of mammals, fish, plants, insects and birds make these forests home. For over two centuries, scientists have recognized that climate plays a key role in determining the geographic zones of plant communities. Because boreal forests and soils face subzero winters and short summers, these forests and the animals that li...

For the 20th time since 1933, Congress is writing a multiyear farm bill that will shape what kind of food U.S. farmers grow, how they raise it and how it gets to consumers. These measures are large, complex and expensive: The next farm bill is projected to cost taxpayers US$1.5 trillion over 10 years. Modern farm bills address many things besides food, from rural broadband access to biofuels and even help for small towns to buy police cars. These measures bring out a dizzying range of interest groups with diverse agendas. Umbrella organizations like the American Farm Bureau Federation and the National Farmers Union typically focus on farm subsidies and crop insurance. The National Sustainable Agriculture Coalition advocates for small farmers and ranchers. Industry-specific groups, such as cattlemen, fruit and vegetable growers and organic producers, all have their own interests. Environmental and conservation groups seek to influence policies that affect land use and sustaina...

Forests are critically important for slowing climate change. They remove huge quantities of carbon dioxide from the atmosphere – 30% of all fossil fuel emissions annually – and store carbon in trees and soils. Old and mature forests are especially important: They handle droughts, storms and wildfires better than young trees, and they store more carbon. In a 2022 executive order, President Joe Biden called for conserving mature and old-growth forests on federal lands. Recently Biden protected nearly half of the Tongass National Forest in Alaska from road-building and logging. The Biden administration is compiling an inventory of mature and old-growth forests on public lands that will support further conservation actions. But at the same time, federal agencies are initiating and implementing numerous logging projects in mature and old forests without accounting for how these projects will affect climate change or forest species. As scientists who have spent decades...