Fire decline in dry tropical ecosystems enhances decadal land carbon sink

Yi Yin,A Anthony Bloom,Christian Frankenberg,Sassan Saatchi,John Worden,Junjie Liu,David Schimel,Yan Yang,Helen Worden,Mathew Williams,Kevin Bowman,Zhe Jiang

doi:10.1038/s41467-020-15852-2

Abstract

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

Highlights

The terrestrial carbon sink has significantly increased in the past decades, but the underlying mechanisms are still unclear
Instead of treating the land sink as a residual term between the anthropogenic emissions and the atmospheric and ocean uptakes as historically being done, the most recent report provides explicit land sink estimates using an ensemble of land models that account for climate warming, CO2 fertilization, and land use change impacts, which result in a budget imbalance that requires an additional sink of ~0.6 PgC per year to explain the observed airborne fraction during the last decade[13]
Our results suggest a decline of 0.2 ± 0.1 PgC per year in fire emissions between the two period 2008–2014 and 2001–2007, which induced an additional carbon sink enhancement of 0.4 ± 0.2 PgC per year attributable to carbon cycle feedbacks, amounting to a combined sink increase comparable to the 0.6 PgC per year budget imbalance

Summary

Introduction

The terrestrial carbon sink has significantly increased in the past decades, but the underlying mechanisms are still unclear. Instead of treating the land sink as a residual term between the anthropogenic emissions and the atmospheric and ocean uptakes as historically being done, the most recent report provides explicit land sink estimates using an ensemble of land models that account for climate warming, CO2 fertilization, and land use change impacts, which result in a budget imbalance that requires an additional sink of ~0.6 PgC per year to explain the observed airborne fraction during the last decade[13].

Results

Conclusion