Fire decline in dry tropical ecosystems enhances decadal land carbon sink

The terrestrial carbon sink has significantly increased in the past decades, but the21 underlying mechanisms are still unclear. The current synthesis of process-based estimates of land22 and ocean sinks requires an additional sink of 0.6 PgC yr-1 in the last decade to explain the observed23 airborne fraction. A concurrent global fire decline was observed in association with tropical24 agriculture expansion and landscape fragmentation. Here we show that a decline of 0.2±0.1 PgC25 yr-1 in fire emissions during 2008-2014 relative to 2001-2007 also induced an additional carbon26 sink enhancement of 0.4±0.2 PgC yr-1 attributable to carbon cycle feedbacks, amounting to a27 combined sink increase comparable to the 0.6 PgC yr-1 budget imbalance. Our results suggest that28 the indirect effects of fire, in addition to the direct emissions, is an overlooked mechanism for29 explaining decadal-scale changes in the land carbon sink and highlight the importance of fire30 management in climate mitigation.