Regional trends in terrestrial carbon exchange and their seasonal signatures
Tellus: Series B, Chemical and Physical Meteorology
A B S T R A C T The trends of terrestrial carbon exchange and their mechanistic drivers are key components in understanding how carbon reservoirs will respond to climate change. Here we show trends in seasonal non-fossil land-atmosphere carbon exchange from 1980 to 2008 using atmospheric CO 2 inversion results. Four indices were analysed: growing-season net flux (GSNF), dormant-season net flux (DSNF), amplitude and annual net carbon flux (NCF). We find that the global land carbon sink is
... rbon sink is intensifying at −0.057 ± 0.01 PgC yr −2 , resulting in −1.65 ± 0.29 PgC of additional uptake over the period examined. This increased total land uptake is driven by a decline in the DSNF (−0.04 ± 0.01 PgC yr −2 ) and intensification of the GSNF (−0.02 ± 0.008 PgC yr −2 ). Regional analysis shows the dominant role of the southern half of the African continent; intensification of the GSNF (−0.02 ± 0.005 PgC yr −2 ) and a decline in the DSNF (−0.013 ± 0.004 PgC yr −2 ) imply that Africa has shifted from a net carbon source in the 1980s to near-neutral emissions. By contrast, a weakening of the GSNF is found in temperate North America (0.015 ± 0.007 PgC yr −2 ) and tropical America (0.01 ± 0.005 PgC yr −2 ).