A recent study by the Helmholtz Centre for Environmental Research (UFZ) finds that carbon dioxide emissions in Brazilian rainforests are a fifth higher than previous estimates indicated, as a result of deforestation and fragmentation. As the UFZ notes in a press release, previous estimates were inaccurate because it was difficult to calculate the carbon loss at forest edges.
Using satellite imagery, scientists from the UFZ analyzed the distribution of the tropical rainforest in the Amazon region and in coastal forests. High-resolution scans indicate that the coastal tropical forests take up merely 11 percent of their original, pre-deforestation surface area, and the 157,000 square kilometers of coastal tropical forest are split up into more than 245,000 fragments. According to the report, “90 percent of the forest remains are smaller than 100 hectares.” In the Brazilian Amazon rainforests, 3.1 million square kilometers are split up into more than 300,000 segments.
These fragmented “peripheral” segmented areas are difficult to measure and, due to their larger-than-average proportion of forest edges, they lose a larger amount of carbon than contiguous sections of rainforest. These peripheral segments comprise 46 percent of the Atlantic Coastal rainforests in Brazil, leading to more than 68 million tons of carbon lost in a ten year period that was previously unaccounted for. These peripheral regions only comprise approximately seven percent of Brazil’s sections of the Amazon rainforest, but this is still enough to result in 600 million tons of carbon loss that could not previously be measured.
As Dr. Andreas Huth of the UFZ notes, carbon loss at the fringes “is a forgotten process in the global carbon circulation of the vegetation.” According to the UFZ, ten percent of tropical forests worldwide are found at the edges of forests, and these areas are not factored into most calculations of carbon loss, including those calculations used by the Intergovernmental Panel on Climate Change (IPCC).