During the period 2006-2010, we found a mean net terrestrial carbon uptake in Asia of -1.56 Pg C yr-1, consisting of -2.02 Pg C yr-1 uptake by the terrestrial biosphere and +0.47 Pg C yr-1 release by biomass burning. This terrestrial uptake partly compensates the CO2 emissions from fossil fuel burning and cement manufacturing of +4.15 Pg C yr-1. An uncertainty for the Asian terrestrial CO2 uptake derived from a set of sensitivity experiments has been conducted and the estimated sink ranges from -1.07 to -1.80 Pg C yr-1, while the formal Gaussian uncertainty estimates are -1.56 ± 1.18 Pg C yr-1 retrieved from the posterior covariance. The estimated Asian net terrestrial CO2 sink is further partitioned into 65% of the carbon sinks in Boreal Eurasia (-1.02 Pg C yr-1) and 44% in Temperate Eurasia (-0.68 Pg C yr-1), whereas 9% release of CO2 from the tropical Asia (+0.14 Pg C yr-1).
The annual mean spatial distribution of net terrestrial carbon uptake over Asia is shown in Figure 3. Note that the estimated fluxes include terrestrial fluxes and biomass burning sources but exclude fossil fuel emissions. Most Asian regions were natural carbon sinks over the studied period, with strongest carbon uptake in the middle and high latitudes of the Northern Hemispheric part of Asia, while the low-latitude region releases CO2 to the atmosphere. This flux distribution pattern is quite consistent with previous findings that northern temperate and high latitude ecosystems were large sinks and tropical land was carbon sources.