Two prominent groups of researchers have reached a consensus estimate for emissions from tropical deforestation between 2000 and 2005.
The groups, led by Winrock International and Woods Hole Research Center, conclude that carbon dioxide emissions from tropical deforestation during the period averaged three billion (800 million tons of carbon) tons per year, with an error range of 1.1 billion tons. The consensus is important because two groups earlier this year published academic papers that initially seemed to offer starkly different estimates on emissions. However once timeframes, differences in methodologies, and disparities in data sets were considered, the results were “remarkably consistent,” according to a joint statement issued by the groups.
“Both initial studies offer insights into different ways to measure tropical deforestation. But the fact that we were able to reconcile these different studies across very different sets of data and methodologies, should provide remarkable reassurance to policymakers that they can act with science on their side,” said the Woods Hole Research Center’s Alessandro Baccini, lead author of the Nature Climate Change study published in January.
“With this new scientific consensus and reconciliation between our two independent studies, policymakers now have an unbiased, historic benchmark against which emission reduction targets for tropical deforestation can be set and progress can be measured,” added Nancy Harris, lead author of the Science paper, which was published in June.
One of the major differences in the estimates stemmed from emissions from forest degradation and peatlands. Baccini’s study factored these emissions into their results, where as the group led by Harris did not. The researchers have not yet reached consensus on these emissions, which can be substantial. Both groups estimated gross, rather than net, emissions.
The findings suggest that tropical deforestation represented about 10 percent of global greenhouse gas emissions from human activities from 2000-2005. The results are important because policymakers are negotiating a mechanism that would pay tropical countries on a performance basis to reduce emissions from deforestation and degradation. To ensure that the mechanism — called REDD+ — actually cuts greenhouse has emissions, it is critical to establish credible baselines on emissions from deforestation.
CITATION: Harris et al. Progress Toward a Consensus on Carbon Emissions from Tropical Deforestation. November 2012
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