Carbon Off-sets or Snow: New England Forests May Need Clearings

Sometimes it's not about seeing the forest for the trees. At times, it's about seeing the snow-covered clearing, not the forest, say Dartmouth researchers in a recent study.

While it's generally assumed that forests should be used to store carbon as a way to slow climate change, this Dartmouth-led study finds that the occasional snow-covered ground acting as a mirror can be useful, if you want to use some forestlands to cool the climate.

The findings, as reported in the journal Ecological Applications, don't support deforestation. They suggest that carbon offset policies ignore that forests also include surface reflectivity, or albedo-especially in high-altitude areas with slow-growing trees and frequent rainfall.

"We aren't suggesting that removing carbon from the atmosphere isn't a crucial step in mitigating climate change, but it's very important that we enact policies that solve the problems they are designed to address," says lead author David Lutz, a research associate at Dartmouth, in a release. "In this case, there's evidence that carbon-centric offset policies miss some important complexities of how these natural systems operate."

This question is being addressed because New England's forests are increasingly being used to generate carbon-offset credits for climate frameworks. This involves long-term conservation of mature forests and/or reductions in the frequency and intensity of timber harvests. "Our goal was to see if this carbon-only approach was appropriate, and we found that in some cases it likely was not," Lutz says in a statement. "Our findings suggest that these types of policies should definitely include additional considerations, such as albedo, in order to understand the full climatic influence."

In the study, researchers used a computer model to examine nearly 500 forests across New Hampshire, calculating the influence of carbon storage and surface reflectivity on the time to harvest timber.

"Our results shouldn't be interpreted as promoting rapid deforestation of high altitude forest stands, for instance in the White Mountains," Lutz says in a statement. "There are many benefits to having old growth forests, including aesthetics, habitat for birds and mammals, recreation, preventing erosion and maintaining water quality. Were we to add these components, our model may tell another story. We are actively working on adding in these pieces, but, as you can imagine, it is a complex process to model and place an economic value on each one, so we are working on them one at a time."

All of this might depend on how much longer New England forests have snow, as co-author Elizabeth Burakowski, a postdoctoral researcher at the National Center for Atmospheric Research, notes in the release. "Scientists have estimated that snow cover could decline up to 50 percent by 2100 in New England. Though deforestation may provide cooling effects today, we cannot assume that will hold for the future. Forest management strategies will have to adapt to a warming climate, and our future studies will address this."

Other researchers were from the National Center for Atmospheric Research, the University of New Hampshire, Dartmouth's Thayer School of Engineering and Stanford University.