Future carbon emissions from global mangrove forest loss.

Maria F Adame,Rod M Connolly,Jordan Holdorf,David Lagomasino,Christopher J Brown,Dale Bryan‐Brown,Sigit D Sasmito,Michael Sievers,Liza A Goldberg,Daniel A Friess,Mischa P Turschwell,Catherine E Lovelock,J Boone Kauffman,Temilola Fatoyinbo,Jonathan Sanderman,Christina Buelow

doi:10.1111/gcb.15571

Abstract

Mangroves have among the highest carbon densities of any tropical forest. These ‘blue carbon’ ecosystems can store large amounts of carbon for long periods, and their protection reduces greenhouse gas emissions and supports climate change mitigation. Incorporating mangroves into Nationally Determined Contributions to the Paris Agreement and their valuation on carbon markets requires predicting how the management of different land‐uses can prevent future greenhouse gas emissions and increase CO2 sequestration. We integrated comprehensive global datasets for carbon stocks, mangrove distribution, deforestation rates, and land‐use change drivers into a predictive model of mangrove carbon emissions. We project emissions and foregone soil carbon sequestration potential under ‘business as usual’ rates of mangrove loss. Emissions from mangrove loss could reach 2391 Tg CO2 eq by the end of the century, or 3392 Tg CO2 eq when considering foregone soil carbon sequestration. The highest emissions were predicted in southeast and south Asia (West Coral Triangle, Sunda Shelf, and the Bay of Bengal) due to conversion to aquaculture or agriculture, followed by the Caribbean (Tropical Northwest Atlantic) due to clearing and erosion, and the Andaman coast (West Myanmar) and north Brazil due to erosion. Together, these six regions accounted for 90% of the total potential CO2 eq future emissions. Mangrove loss has been slowing, and global emissions could be more than halved if reduced loss rates remain in the future. Notably, the location of global emission hotspots was consistent with every dataset used to calculate deforestation rates or with alternative assumptions about carbon storage and emissions. Our results indicate the regions in need of policy actions to address emissions arising from mangrove loss and the drivers that could be managed to prevent them.

Highlights

The capacity of mangroves to store carbon and mitigate greenhouse gas emissions became prominent a decade ago (Donato et al, 2011)
Predictions may vary due to possible changes in future deforestation rates, we provide the business as usual (BAU) scenario to assess current management practices
Erosion can cause large emissions in one location, but these can be partly compensated by mangrove accretion in other location (Lagomasino et al, 2019)

Summary

Introduction

The capacity of mangroves to store carbon and mitigate greenhouse gas emissions became prominent a decade ago (Donato et al, 2011). Hundreds of site-scale studies have been conducted to understand the distribution and accumulation of mangrove soil carbon and aboveground biomass (Kauffman et al, 2020) These site- scale measurements have supported globally comprehensive spatial models of carbon storage (e.g. Rovai et al, 2018; Sanderman et al, 2018; Simard et al, 2019). Global efforts to accurately map and monitor mangrove cover and health have provided unprecedented knowledge on the risks that mangrove forests face (Bunting et al, 2018; Goldberg et al, 2020; Hamilton & Casey, 2016) These studies have enabled global-scale estimation of mangrove carbon storage and its historical loss across different nations (Murdiyarso et al, 2015; Serrano et al, 2019) and globally (Atwood et al, 2017)

Results

Discussion

Conclusion