Climate of Our Future

Climate Crisis Coalition

Missing Carbon Mystery: Case Solved?
By Jane Burgermeister, Nature Magazine, August, 2007 Issue
“[Scientists have long been vexed by] the ‘missing carbon sink’, a billion tonnes of human-generated carbon assumed to be absorbed by northern forests, but unaccounted for in field studies. Scientists now say they have located the missing carbon in tropical forests that are removing much higher quantities of carbon dioxide from the atmosphere than realized… Of the 8 billion tonnes of carbon that human activity produces each year — 6.4 from fossil-fuel emissions, and 1.6 from deforestation, mainly in the tropics — on average, 3.2 billion tonnes remain in the atmosphere, 2.2 billion tonnes are stored in the oceans and 2.6 billion tonnes are sucked up by land-based carbon sinks, mainly forests. Carbon-uptake models predict that as much as 2.4 billion tonnes of this carbon ends up in northern mid- to high-latitude forests. But scientists searching for it on the ground — measuring trees and carbon exchanges between the vegetation and the atmosphere — have only been able to account for about 0.7 billion tonnes there… Researchers led by Britton Stephens from the National Center for Atmospheric Research in Boulder, Colorado in the USA have now found an answer to this mystery. In a paper published in Science, they show that tropical forests are absorbing about one billion tonnes more carbon than previously thought and that northern mid-latitude forests are absorbing 0.9 billion tonnes, or 38%, less than assumed up until now… The latest IPCC report on mitigating climate change found that during 2004, the contribution of deforestation — primarily in the tropics — and the decay of biomass to global warming was 17.3% of total global greenhouse-gas emissions. ‘Cutting down tropical forests not only increases carbon emissions but it also removes a strong sink and its potential for offsetting future emissions,’ says Stephens.”