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| Titel |
Biogeophysical feedbacks enhance the Arctic terrestrial carbon sink in regional Earth system dynamics |
| VerfasserIn |
W. Zhang, C. Jansson, P. A. Miller, B. Smith, P. Samuelsson |
| 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 ; 11, no. 19 ; Nr. 11, no. 19 (2014-10-08), S.5503-5519 |
| Datensatznummer |
250117631
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| Publikation (Nr.) |
 copernicus.org/bg-11-5503-2014.pdf |
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| Zusammenfassung |
| Continued warming of the Arctic will likely accelerate terrestrial carbon
(C) cycling by increasing both uptake and release of C. Yet, there are still
large uncertainties in modelling Arctic terrestrial ecosystems as a source
or sink of C. Most modelling studies assessing or projecting the future fate
of C exchange with the atmosphere are based on either stand-alone
process-based models or coupled climate–C cycle general circulation models,
and often disregard biogeophysical feedbacks of land-surface changes to the
atmosphere. To understand how biogeophysical feedbacks might impact on both
climate and the C budget in Arctic terrestrial ecosystems, we apply the
regional Earth system model RCA-GUESS over the CORDEX-Arctic domain. The
model is forced with lateral boundary conditions from an EC-Earth CMIP5
climate projection under the representative concentration pathway (RCP) 8.5 scenario. We perform two simulations,
with or without interactive vegetation dynamics respectively, to assess the
impacts of biogeophysical feedbacks. Both simulations indicate that Arctic
terrestrial ecosystems will continue to sequester C with an increased uptake
rate until the 2060–2070s, after which the C budget will return to a weak C
sink as increased soil respiration and biomass burning outpaces increased
net primary productivity. The additional C sinks arising from biogeophysical
feedbacks are approximately 8.5 Gt C, accounting for 22% of the total C
sinks, of which 83.5% are located in areas of extant Arctic tundra. Two
opposing feedback mechanisms, mediated by albedo and evapotranspiration
changes respectively, contribute to this response. The albedo feedback
dominates in the winter and spring seasons, amplifying the near-surface
warming by up to 1.35 °C in spring, while the evapotranspiration
feedback dominates in the summer months, and leads to a cooling of up to
0.81 °C. Such feedbacks stimulate vegetation growth due to an
earlier onset of the growing season, leading to compositional changes in
woody plants and vegetation redistribution. |
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