Between 1990 and 2007 global forests absorbed nearly one-sixth of all carbon released by fossil fuel emissions, reports a new study published in Science. The results suggest forests play an even bigger role in fighting climate change than previously believed.
The research, conducted by an international team using field data and statistical models across 95 percent of global forests, estimates that forests absorbed a net of 1.1 billion tons of carbon per year from 1990-2007. Forests’ total carbon uptake of 2.4 billion tons per year was offset by deforestation, which released an average of 2.9 billion tons of carbon, but augmented by forest regrowth, which sucked up 1.6 billion tons. Global emissions from fossil fuels averaged 6.9 billion tons per year between 1990-2007, reaching 8.5 billion tons in 2007, according to the Carbon Dioxide Information Analysis Center.
The proportion of emissions absorbed by forests is declining due to rising fossil fuel emissions.
The authors say the findings lend support to the Reducing Emissions from Deforestation and Degradation (REDD) program, which aims to create a financial mechanism to compensate developing countries for preserving and sustainably managing their forests. Yet the research also indicates the importance of forests in boreal regions, which store large amounts of carbon, especially in their soils.
“Our estimates suggest that currently the global established forests, which are outside the areas of tropical land-use change, alone can account for the terrestrial C sink,” the authors, led by Yude Pan of the U.S. Forest Service, write. “A large amount of atmospheric carbon dioxide has been sequestrated by the natural system of forested lands (~4.0 billion tons of carbon per year), but the benefit is significantly offset by the carbon losses from tropical deforestation (~2.9 billion tons of carbon per year). This result highlights the potential for Reducing Emissions from Deforestation and Degradation (REDD) to lessen the risk of climate change.”
Forest in Oregon. Photo by Rhett A. Butler (2011).
The authors suggest that a relative abundance of young forests should continue to offset carbon emissions in the future, although they warn that climate change could threaten the effectiveness of forests — especially in boreal and tropical regions — as carbon sinks.
“Because of the large carbon stocks in both boreal forest soils and tropical forest biomass, warming in the boreal zone and deforestation and occasional extreme drought, co-incident with fires in the tropics represent the greatest risks to the continued large carbon sink in the world’s forests,” they conclude.
CITATION: Yude Pan et al. A Large and Persistent Carbon Sink in the World’s Forests, 1990-2007. Science. Volume 333. 15 July 2011.
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