Abstract
The terrestrial carbon (C) sink has been large in recent
decades, but its size and location remain uncertain. Using
forest inventory data and long-term ecosystem C studies,
we estimated a total forest sink of 2.4 ± 0.4 Pg C yr–1
globally for 1990-2007. We also estimated a source of 1.3 ±
0.7 Pg C yr–1 from tropical land-use change, consisting of
a gross tropical deforestation emission of 2.9 ± 0.5 Pg C
yr–1 partially compensated by a C sink in tropical forest
regrowth of 1.6 ± 0.5 Pg C yr–1. Together, the fluxes
comprise a net global forest sink of 1.1 ± 0.8 Pg C yr–1,
with tropical estimates having the largest uncertainties.
This forest sink is equivalent in magnitude to the
terrestrial sink deduced from fossil fuel emissions and
constraints of ocean and atmospheric sinks.