Subsea Permafrost Carbon Stocks and Climate Change Sensitivity Estimated by Expert Assessment
Abstract
The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter and methane (CH4), representing a potential ecosystem feedback to climate change not included in international climate agreements. We combined estimates from 25 permafrost researchers, to approximate that the subsea permafrost domain contains ~550 gigatons carbon (GtC; 170-740, 90% confidence interval) in organic matter and 45 GtC (10-110) in CH4. Current fluxes of CH4 and CO2 to the water column were estimated at 18 (2-34) and 38 (13-110) megatons C yr-1, respectively. Under Representative Concentration Pathway RCP8.5, the subsea permafrost domain could release 50 Gt CO2-equivalent by 2100 (14-140) and 240 Gt CO2-equivalent by 2300 (42-730), with ~40% less emissions increase under RCP2.6. The range of uncertainty demonstrates a serious knowledge gap but provides initial estimates of the magnitude and timing of the subsea permafrost climate feedback. Together, these results suggest that this climate feedback is less sensitive to anthropogenic warming than the terrestrial permafrost climate feedback, but potentially similar in magnitude.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB027...08S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0702 Permafrost;
- CRYOSPHERE