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| Titel |
Estimating the near-surface permafrost-carbon feedback on global warming |
| VerfasserIn |
T. Schneider von Deimling, M. Meinshausen, A. Levermann, V. Huber, K. Frieler, D. M. Lawrence, V. Brovkin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 2 ; Nr. 9, no. 2 (2012-02-03), S.649-665 |
| Datensatznummer |
250006758
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| Publikation (Nr.) |
 copernicus.org/bg-9-649-2012.pdf |
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| Zusammenfassung |
| Thawing of permafrost and the associated release of carbon constitutes a
positive feedback in the climate system, elevating the effect of
anthropogenic GHG emissions on global-mean temperatures. Multiple factors
have hindered the quantification of this feedback, which was not included in
climate carbon-cycle models which participated in recent model
intercomparisons (such as the Coupled Carbon Cycle Climate Model
Intercomparison Project – C4MIP) . There are considerable uncertainties
in the rate and extent of permafrost thaw, the hydrological and vegetation
response to permafrost thaw, the decomposition timescales of freshly thawed
organic material, the proportion of soil carbon that might be emitted as
carbon dioxide via aerobic decomposition or as methane via anaerobic
decomposition, and in the magnitude of the high latitude amplification of
global warming that will drive permafrost degradation. Additionally, there
are extensive and poorly characterized regional heterogeneities in soil
properties, carbon content, and hydrology. Here, we couple a new permafrost
module to a reduced complexity carbon-cycle climate model, which allows us
to perform a large ensemble of simulations. The ensemble is designed to span
the uncertainties listed above and thereby the results provide an estimate
of the potential strength of the feedback from newly thawed permafrost
carbon. For the high CO2 concentration scenario (RCP8.5), 33–114 GtC
(giga tons of Carbon) are released by 2100 (68 % uncertainty range). This
leads to an additional warming of 0.04–0.23 °C. Though projected
21st century permafrost carbon emissions are relatively modest, ongoing
permafrost thaw and slow but steady soil carbon decomposition means that, by
2300, about half of the potentially vulnerable permafrost carbon stock in
the upper 3 m of soil layer (600–1000 GtC) could be released as CO2,
with an extra 1–4 % being released as methane. Our results also suggest
that mitigation action in line with the lower scenario RCP3-PD could contain
Arctic temperature increase sufficiently that thawing of the permafrost area
is limited to 9–23 % and the permafrost-carbon induced temperature
increase does not exceed 0.04–0.16 °C by 2300. |
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