Abstract
A huge amount of carbon (C) is stored in permafrost regions. Climate warming and permafrost degradation induce gradual and abrupt carbon emissions into both the atmosphere and hydrosphere. In this paper, we review and synthesize recent advances in studies on carbon stocks in permafrost regions, biodegradability of permafrost organic carbon (POC), carbon emissions, and modeling/projecting permafrost carbon feedback to climate warming. The results showed that: (1) A large amount of organic carbon (1460–1600 PgC) is stored in permafrost regions, while there are large uncertainties in the estimation of carbon pools in subsea permafrost and in clathrates in terrestrial permafrost regions and offshore clathrate reservoirs; (2) many studies indicate that carbon pools in Circum-Arctic regions are on the rise despite the increasing release of POC under a warming climate, because of enhancing carbon uptake of boreal and arctic ecosystems; however, some ecosystem model studies indicate otherwise, that the permafrost carbon pool tends to decline as a result of conversion of permafrost regions from atmospheric sink to source under a warming climate; (3) multiple environmental factors affect the decomposability of POC, including ground hydrothermal regimes, carbon/nitrogen (C/N) ratio, organic carbon contents, and microbial communities, among others; and (4) however, results from modeling and projecting studies on the feedbacks of POC to climate warming indicate no conclusive or substantial acceleration of climate warming from POC emission and permafrost degradation over the 21st century. These projections may potentially underestimate the POC feedbacks to climate warming if abrupt POC emissions are not taken into account. We advise that studies on permafrost carbon feedbacks to climate warming should also focus more on the carbon feedbacks from the rapid permafrost degradation, such as thermokarst processes, gas hydrate destabilization, and wildfire-induced permafrost degradation. More attention should be paid to carbon emissions from aquatic systems because of their roles in channeling POC release and their significant methane release potentials.
Highlights
In this paper, we review and synthesize recent studies on and research advances in C stock and its stability in permafrost regions, biodegradability of organic C in permafrost regions, C emission impacted by permafrost degradation, and model projecting/modeling of permafrost C feedback to climate warming
This study can help provide a baseline understanding on Permafrost organic carbon (POC) stock and its positive feedbacks to climate warming and close the research gaps on permafrost C dynamics
Stocks of soil organic carbon (SOC) in permafrost regions have been intensively studied in recent years (e.g., [1,25,26,27,28,29,30,31,32,33,34,35])
Summary
Carbon fluxes in Arctic permafrost regions are estimated as a CO2 sink at rates of 0.3–0.6 Pg C·yr−1 and a CH4 source at rates of 23–75 Tg C·yr−1 and they are projected to be both CO2 and strengthened CH4 sources by 2100 [9] Another portion of POC will be delivered into the aquatic ecosystems in forms of particulate organic C (PTOC) and dissolved organic C (DOC) (e.g., [10,11,12]). In this paper, we review and synthesize recent studies on and research advances in C stock and its stability in permafrost regions, biodegradability of organic C in permafrost regions, C emission impacted by permafrost degradation, and model projecting/modeling of permafrost C feedback to climate warming. This study can help provide a baseline understanding on POC stock and its positive feedbacks to climate warming and close the research gaps on permafrost C dynamics
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.