The RAINFOR consortium had a paper in Nature last week, describing the declining in the Amazon biomass carbon sink. This result is based on decades of monitoring of forest sample plots across Amazonia (particularly since the 1990s), and provides the only medium-term ground observational evidence for a carbon sink in tropical forests. Our previous work has shown the evidence for a carbon sink in Amazonian biomass (Phillips et al 1998, Science), and evidence that it briefly shut off after the 2005 drought (Phillips et al 2009, Science). The new study shows evidence of a gradual multi-decadal decline, apparently because growth stimulation has flattened out, but tree mortality rates are increasing gradually over time. The gradual nature of the increase in mortality suggests it is not driven by specific drought events, but reflects a general shortening of tree life times. On this trend the Amazon biomass carbon sink can be expected to disappear in about a decade.
The paper can be accessed here...
Brienen R.J.W. et al. (2015) Long-term decline of the Amazon carbon sink, Nature 519, 344–348. doi:10.1038/nature14283
Yadvinder Malhi is an ecosytem ecologist and Professor of Ecosystem Science at Oxford University