In the news:
Could cutting down some trees help cool the planet?
Two Dartmouth College researchers are suggesting that in some circumstances, the cooling value of an open, snowy field may be greater than the climate benefits that a stand of trees can provide.
The Washington Post
It’s an article of faith that preserving trees is critical to cooling our warming planet. Deforestation is a major contributor of carbon dioxide to the atmosphere, responsible for 17 percent of the heat-trapping greenhouse gases that are warming the planet, according to the Environmental Protection Agency (EPA).
Governments and environmental groups worldwide have worked hard to reduce that total and provide incentives to plant more trees.
But two Dartmouth College researchers are suggesting that in some limited circumstances, the cooling value of an open, snowy field may be greater than the climate benefits that a stand of trees can provide — and that it is possible to calculate where that might be the case.
“In some cases, the cooling influence of albedo can equal and surpass the climatic benefits of carbon sequestration from forest growth,” postdoctoral fellow David Lutz and professor of environmental studies Richard Howarth wrote in their paper. Funded by the National Science Foundation, it was presented at the fall meeting of the American Geophysical Union last week.
Albedo is the reflectivity of the earth’s surface, the amount of solar energy it sends back into space. White surfaces, such as snow, send back more of this shortwave radiation than dark surfaces, such as green, leafy forests.
What that means is that when managers are trying to determine when to harvest trees, they might want to account for the benefits of the open field they will leave behind. Where snow remains on the ground for a long time and trees grow slowly, limiting the amount of carbon dioxide they can take in, it might make sense to take down trees sooner rather than later and leave fields unplanted longer.
“In spruce-fir stands, very short rotation periods of just 25 years become economically optimal when albedo is considered,” Lutz and Howarth wrote. They noted there is a body of research that shows that cutting down northern forests can produce “net climatic benefits.”
“This is an important publication,” said Jonathan Thompson, an ecologist at the Harvard Forest at Harvard University, who was not associated with the research.