According to a new study published in Science, the massive restoration of forested land at a global scale could help capture atmospheric carbon and mitigate global warming.
If we start a global forest restoration with planting right species of trees in the right soil types today, in the next 40 to 100 years, this effort could create an additional 0.9 billion hectares of continuous forest, scientists suggest. “This would represent a greater than 25% increase in the forested area, including more than 500 billion trees and more than 200 gigatonnes of additional carbon at maturity.”
This additional forest of 0.9 billion hectares would translate to roughly 500 billion-1.5 trillion trees, adding to the 3 trillion trees already on Earth. When matured, these new trees could capture about 200 gigatonnes of carbon.
Today, forests cover 31 percent of the world’s land surface, just over 4 billion hectares. (One hectare = 2.47 acres.) This is down from the pre-industrial area of 5.9 billion hectares.
According to data from the U.N. Food and Agriculture Organization, deforestation was at its highest rate in the 1990s, when each year the world lost on average 16 million hectares of forest—roughly the size of the state of Michigan. At the same time, forest area expanded in some places, either through planting or natural processes, bringing the global net loss of forest to 8.3 million hectares per year.
In the first decade of this century, the rate of deforestation was slightly lower, but still, a disturbingly high 13 million hectares were destroyed annually. As forest expansion remained stable, the global net forest loss between 2000 and 2010 was 5.2 million hectares per year. (Source)
According to the study, storing 200 gigatonnes of carbon by planting at least 1 trillion trees has the potential to cut the atmospheric carbon pool by about 25%. This number accounts about two-thirds of all the carbon dioxide (CO2) humans have generated since the industrial revolution.
In short, as Steven Pinker has pointed out, “To prevent possibly catastrophic climate change we can’t just bring C02 emissions to zero – we have to go negative, sucking the CO2 that’s already there. The best tech is a billion years old: trees. Massive Reforestation could Slow Global Warming.”
“Massive Forest Restoration Could Greatly Slow Global Warming” on the Scientific American website
Study: The global tree restoration potential (Science)
Forest Cover on the Earth Policy Institute website