AGU: Geophysical Research Letters

 

Editors' Highlight

Large methane emissions from the eastern Amazon basin

Recent satellite and laboratory observations have suggested that the Amazon rain forest emits large amounts of methane, a potent greenhouse gas. However, direct measurements of methane in the air high above the Amazon basin were lacking. Using a light aircraft, Miller et al. (2007) collected air samples for 4 years along vertical profiles spanning 4 km above two sites in the central and eastern Amazon. They then compared these profiles with data collected at islands in the Atlantic Ocean, which represent background air entering the Amazon basin. Through this comparison, the authors found large enhancements of methane over the eastern Amazon, averaging about 34 parts per billion each year. For comparison, the entire north-south, pole-to-pole difference in methane concentrations is about 150 parts per billion. Previous estimates of methane emissions from sources like wetlands, fires, and aerobic processes in plants are not large enough to explain the observed concentrations above the Amazon, but among these, wetlands may release the bulk of this added methane.

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