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| Titel |
Asymmetry and uncertainties in biogeophysical climate–vegetation feedback over a range of CO2 forcings |
| VerfasserIn |
M. Willeit, A. Ganopolski, G. Feulner |
| 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. 1 ; Nr. 11, no. 1 (2014-01-03), S.17-32 |
| Datensatznummer |
250117102
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| Publikation (Nr.) |
 copernicus.org/bg-11-17-2014.pdf |
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| Zusammenfassung |
| Climate–vegetation feedback has the potential to significantly contribute to climate change, but
little is known about its range of uncertainties. Here, using an Earth system model of
intermediate complexity we address possible uncertainties in the strength of the biogeophysical
climate–vegetation feedback using a single-model multi-physics ensemble.
Equilibrium experiments with halving (140 ppm) and doubling (560 ppm)
of CO2 give a contribution of the vegetation–climate feedback to global
temperature change in the range −0.3 to −0.1 °C and −0.1 to
0.2 °C, respectively. There is an asymmetry between warming and
cooling, with a larger, positive vegetation–climate feedback in the lower
CO2 climate. Hotspots of climate–vegetation feedback are the boreal
zone, the Amazon rainforest and the Sahara. Albedo parameterization is the
dominant source of uncertainty in the subtropics and at high northern
latitudes, while uncertainties in evapotranspiration are more relevant in the
tropics. We analyse the separate impact of changes in stomatal conductance,
leaf area index and vegetation dynamics on climate and we find that different
processes are dominant in lower and higher CO2 worlds. The reduction in
stomatal conductance gives the main contribution to temperature increase for
a doubling of CO2, while dynamic vegetation is the dominant process in
the CO2 halving experiments. Globally the climate–vegetation feedback is
rather small compared to the sum of the fast climate feedbacks. However, it
is comparable to the amplitude of the fast feedbacks at high northern
latitudes where it can contribute considerably to polar amplification. The
uncertainties in the climate–vegetation feedback are comparable to the
multi-model spread of the fast climate feedbacks. |
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