Author: Lindsey Hadlock-Cornell | Published: September 6, 2017
Deforestation and use of forest lands for agriculture or pasture, particularly in tropical regions, contribute more to climate change than previously thought, research finds.
The study also shows just how significantly that impact has been underestimated. Even if all fossil fuel emissions are eliminated, if current tropical deforestation rates hold steady through 2100, there will still be a 1.5 degree increase in global warming.
“A lot of the emphasis of climate policy is on converting to sustainable energy from fossil fuels,” says Natalie M. Mahowald, the paper’s lead author and faculty director of environment for the Atkinson Center for a Sustainable Future at Cornell University.
“It’s an incredibly important step to take, but, ironically, particulates released from the burning of fossil fuels—which are severely detrimental to human health—have a cooling effect on the climate. Removing those particulates actually makes it harder to reach the lower temperatures laid out in the Paris agreement,” she explains.
She says that in addition to phasing out fossil fuels, scientific and policymaking communities must pay attention to changes in land use to stem global warming, as deforestation effects are “not negligible.”
While the carbon dioxide collected by trees and plants is released during the cutting and burning of deforestation, other greenhouse gases—specifically nitrous oxide and methane—are released after natural lands have been converted to agricultural and other human usage. The gases compound the effect of the carbon dioxide’s ability to trap the sun’s energy within the atmosphere, contributing to radiative forcing—energy absorbed by the Earth versus energy radiated off—and a warmer climate.
As a result, while only 20 percent of the rise in carbon dioxide caused by human activity originates from land use and land-cover change, that warming proportion from land use (compared with other human activities) increases to 40 percent once co-emissions like nitrous oxide and methane are factored in.