Forests are an essential part of the Earth’s operating system. They reduce the build-up of heat-trapping carbon dioxide in the atmosphere due to fossil fuel combustion, deforestation and land degradation by 30% per year. This slows global temperature rise and resulting changes in climate. In the US, forests account for 12% of the country’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 particularly resistant to wildfires and other natural disturbances as the climate warms.
Most forests in the continental US have been logged multiple times. Today, only 3.9% of U.S. forest areas, in public and private hands, are more than 100 years old, and most of these areas contain relatively little carbon compared to their potential.
The Biden Administration is improving protections for old-growth and mature forests on federal lands, which we see as a welcome step. But this will mean regulatory changes that will likely take several years. In the meantime, existing forest management plans that allow the felling of these important old, large trees remain in force.
As scientists who have spent decades studying forest ecosystems and the effects of climate change, we believe it is essential to start protecting the carbon stores in these forests. In our opinion, there is sufficient scientific evidence to justify an immediate moratorium on logging of mature and old-growth forests on federal lands.
Federal action to protect mature and old-growth forests
A week after his 2021 inauguration, President Joe Biden issued an executive order setting a goal of conserving at least 30% of America’s land and water by 2030 to confront what the order called “a profound climate crisis” . In 2022, Biden recognized the climate importance of mature and old-growth forests for a healthy climate and called for their conservation on federal lands.
Most recently, in December 2023, the US Forest Service announced it was evaluating the effects of changing management plans for 128 US national forests to better protect mature and old-growth stands – the first time an administration has taken this type of action has undertaken.
These actions are intended to make existing primary forests more resilient; maintain the ecological benefits they provide, such as habitats for endangered species; establishing new areas where old growth conditions can develop; and monitor forest conditions over time. The amended National Forest Management Plans would also ban the felling of old trees for mainly economic purposes – i.e. producing timber. Tree felling would be allowed for other reasons, such as thinning to reduce fire severity in hot, dry areas where fires are more common.
Remarkably, the Forest Service’s initial analysis barely takes logging into account, even though research shows that logging causes greater carbon losses than forest fires and pests.
In an analysis across eleven western US states, researchers calculated total above-ground carbon loss from logging, beetle infestations and fire between 2003 and 2012 and found that logging accounted for half of this. In California, Oregon and Washington, crop-related CO2 emissions averaged five times those from wildfires between 2001 and 2016.
A 2016 study found that total CO2 emissions from logging nationwide between 2006 and 2010 were comparable to emissions from all U.S. coal-fired power plants, or to direct emissions from the entire construction sector.