Some Trees Could Help Fight Climate Change

Just as athletes stressed by exercise breathe more efficiently over time, trees stressed by a slowly warming climate can alter how much carbon dioxide (CO2) they release into the atmosphere, a new study suggests. And they may be doing it in a way that could slow climate change: Compared with trees suddenly exposed to hot temperatures, these acclimated trees release far less CO2 at night. This hints that future CO2 emissions from Northern Hemisphere forests won’t be as large as scientists thought, even though they would still be on the rise.

“We’ve known that trees respond to changing temperatures over the course of a day and over the course of the seasons, but we didn’t know how well they acclimated over longer periods of time,” says Kevin Griffin, a forest ecologist at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “This really needs to be included in climate models.” Yet some researchers say the new findings won’t significantly alter these models.

When they breathe, trees and other plants take in CO2 during the daytime, combining the planet-warming gas with water and sunlight to make sugars and build tissues. Then at night, the reverse occurs. Plants burn some of the sugars for energy and release CO2 into the atmosphere via respiration. Previous studies have shown that the rate of respiration is strongly linked to temperature: The higher the ambient temperature, the more quickly a leaf’s sugars are burned and the more CO2 returns to the atmosphere during nighttime hours.

Priya Saihgal