New research from the U.S. Department of Agriculture shows that trees are losing their ability to absorb carbon, which could worsen global warming in the future.
The report predicts that over time, forests will not be able to hold onto as much carbon and that absorption ability will continue to plateau. By 2070, the report states that forests in the Mountain West will be “the most sensitive” to climate changes and contribute to the climate problem by being a “net carbon source.”
But that doesn’t mean trees will change their properties and suddenly release carbon, said Bill Keeton, a professor of forest ecology and forestry at the University of Vermont.
“Forests are not going to be a carbon emitter,” he said. “It's just that the rate at which they're sequestering more carbon is going to decline.”
This is due to the fact that forests are aging and taking in carbon at a slower rate. Some people think the solution is to cut down forests and add younger trees, but Keeton said that’s not the takeaway —and aging forests aren’t necessarily a bad thing.
“These forests are now storing a lot of carbon, [so] we need to think of them as this carbon reservoir, this is now money in the bank … ” he said. “Now we need to try to hang on to as much of that carbon that's now in the bank as possible.”
So while age impacts how much new carbon a tree can take in, he said, age also impacts how much carbon it has stored over time.
Many other factors are destroying those old trees and causing this change. More people want to live out in nature, for example, so forests are torn down for development. The report predicts this trend will continue – and intensify.
Keeton was happy the report drew attention to development.
“That's a really important issue and clearly a top threat to the integrity of forests nationwide," he said. "It's sometimes forgotten about, but it's especially important in the Eastern U.S. and also in some parts of the West.”
Meanwhile, data from the National Interagency Fire Center shows that in 2022, more than 65,000 fires burned more than 7.5 million acres in the United States. And the World Resources Institute found that forest fires are burning twice as many trees as they did 20 years ago.
“The sort of artificial condition of high carbon storage is likely to reverse with more and more big mega-fires so that the emissions will flux the carbon back to the atmosphere,” Keeton said.
These factors can impact how forests offset the United States’ carbon emissions. Currently, forests absorb more than 10 percent of the country’s emissions, according to the report. That’s 150 million metric tons a year – equal to the emissions from 40 coal power plants. But if trees continue aging and decreasing, that 10 percent could become much smaller.
He recommended that forests in the West be protected from fire to save that stored carbon – whether they are put in a reserve or undergo some fire-based restoration.
“Thinning and prescribed burning will remove some carbon from these forests,” he said. However, allowing huge wildfires would be worse.
He cautioned against halting all timber industry work and encouraged the creation of more large and durable wood products to help store the carbon for many years.
“There's absolutely no reason why we can't protect some forests and also manage other forests sustainably,” he said. “These approaches go hand in hand...it’s like a portfolio of carbon approaches, like we’re not putting all our eggs in one basket.”
Regardless of the solution, Keeton said people need to be strategic in protecting and restoring forests, so they can continue to be a climate solution for the future.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
