Global patterns and drivers of tropical aboveground carbon changes

Abstract

Tropical terrestrial ecosystems play an important role in modulating the global carbon balance. However, the complex dynamics and factors controlling tropical aboveground live biomass carbon (AGC) are not fully understood. Here, using remotely sensed observations, we find a moderate net AGC sink of 0.21 ± 0.06 PgC yr−1 throughout the global tropics from 2010 to 2020. This arises from a gross loss of −1.79 PgC yr−1 offset by a marked gain of 2.01 ± 0.06 PgC yr−1. Fire emissions in non-forested African shrubland/savanna biomes, coupled with post-fire carbon recovery, substantially dominated the interannual variability of tropical AGC. Fire radiative power was identified as the primary determinant of the spatial variability in AGC gains, with soil moisture also playing a crucial role in shaping trends. We highlight the dominant roles of anthropogenic and hydroclimatic determinants in orchestrating tropical land carbon dynamics and advocate for land management to conserve indispensable ecosystem services worldwide. Tropical aboveground biomass carbon is a crucial, yet complex, component of the terrestrial C budget. Here remote observations demonstrate that fire emissions and post-fire recovery in non-forested African biomes dominate the interannual variability of aboveground biomass carbon, which acts as a moderate net C sink.