Tree loss may have led to less CO2 emission than thought

Since 1900 deforestation has led to about 92 billion tons of carbon emissions into the atmosphere, says a team of experts at Ohio State University and Yale University.

That may sound like a lot, but consider this: many experts assume it has been five times as much.

“Our estimate is about a fifth of what was found in previous work showing that deforestation has contributed 484 billion tons of carbon — a third of all manmade emissions — since 1900,” explains Brent Sohngen, a professor of environmental and resource economics at Ohio State University who is an author of a new study published in the Journal of Forest Economics.

Previous estimates, Sohngen argues, overlooked the fact that newly planted trees and effective forest management techniques have lessened overall emissions. Those estimates, which treated forest loss in isolation, attributed 27% of manmade net carbon emissions to deforestation. The new study’s authors argue that the real figure is around 7%.

“There was a significant shift toward treating forests as a renewable, rather than nonrenewable, resource in the last century, and we estimate that those reforestation and forest management efforts have led to a far smaller carbon burden on the environment,” Sohngen says. “Manmade land use and land use change has had a relatively small effect on carbon emissions compared to the almost 1,300 billion tons of industrial carbon emissions during the same time period.”

“Previous estimates overestimated net emissions because they did not take account of the planting and management of global forests over the last 70 years that was undertaken to build a renewable timber forest,” adds the study’s co-author Robert Mendelsohn of Yale University.

“This forest renewal was a market response to the expectation that old-growth timber was going to run out by the 1990s,” Mendelsohn says. “Companies started planting and managing forests in the 1950s to fill this gap, and the timber industry quietly switched from being a nonrenewable mining industry to a renewable forest-crop industry.”

That said, the authors of the new study agree that forests play a key role in mitigating the effects of climate change. That is why responsible forest management should include protecting old-growth forests, planting new trees and engaging in techniques that boost tree growth.

“Forestry and land use are blamed for being an enormous source of climate change, but they’re not an enormous source,” Sohngen stresses. “The energy sector is an enormous source, and that’s where we should focus our attention — that and looking for ways to maximize our forests’ role in protecting the environment.”

Needless to say, the role of forests extend far beyond mitigating the effects of climate change. The health of forests is vital both for conserving biodiversity and ensuring human wellbeing.