Nature plays big role in shaping regional carbon storage

U.S. forests have stored more carbon in the past two decades than at any time in the last century, an increase attributable to a mix of natural factors and human activity, finds a new study.

To unravel the cause behind this spike, researchers used nationwide forest data to examine how six environmental factors may have contributed to the increase in carbon sequestered by forests. They found that natural forces such as increasing temperatures, shifting precipitation, and carbon fertilization are among the largest contributors to carbon gains, but human drivers, like letting forests get older and planting trees, are also becoming bigger factors.

Since most decarbonization efforts focus on curbing active emissions, this new analysis aims to help researchers better separate what portion of carbon held by forests is related to human action and which portion isn’t, said Brent Sohngen, co-author of the study and a professor of environmental and resource economics at The Ohio State University.

“Identifying and separating these influences hasn’t really been done before,” said Sohngen. “But with this data, the U.S. can be much more explicit about its carbon accounting, and that ability will provide a lot more information and long-term benefits for people who manage their forests and try to create carbon sinks.”

The study was published recently (Jan. 20, 2026) in the Proceedings of the National Academy of Sciences.