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| Titel |
Effects of CO2, continental distribution, topography and vegetation changes on the climate at the Middle Miocene: a model study |
| VerfasserIn |
A.-J. Henrot, L. François, Eric Favre, M. Butzin, M. Ouberdous, G. Munhoven |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 6, no. 5 ; Nr. 6, no. 5 (2010-10-21), S.675-694 |
| Datensatznummer |
250003761
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| Publikation (Nr.) |
 copernicus.org/cp-6-675-2010.pdf |
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| Zusammenfassung |
The Middle Miocene was one of the last warm periods of the Neogene,
culminating with the Middle Miocene Climatic Optimum (MMCO, approximatively
17–15 Ma). Several proxy-based reconstructions support warmer and more
humid climate during the MMCO. The mechanisms responsible for the warmer
climate at the MMCO and particularly the role of the atmospheric carbon
dioxide are still highly debated. Here we carried out a series of sensitivity
experiments with the model of intermediate complexity Planet Simulator,
investigating the contributions of the absence of ice on the continents, the
opening of the Central American and Eastern Tethys Seaways, the lowering of
the topography on land, the effect of various atmospheric CO2
concentrations and the vegetation feedback.
Our results show that a higher than present-day CO2 concentration is
necessary to generate a warmer climate at all latitudes at the Middle
Miocene, in agreement with the terrestrial proxy reconstructions which
suggest high atmospheric CO2 concentrations at the MMCO. Nevertheless, the
changes in sea-surface conditions, the lowering of the topography on land and
the vegetation feedback also produce significant local warming that may,
locally, even be stronger than the CO2 induced temperature increases. The
lowering of the topography leads to a more zonal atmospheric circulation and
allows the westerly flow to continue over the lowered Plateaus at
mid-latitudes. The reduced height of the Tibetan Plateau notably prevents the
development of a monsoon-like circulation, whereas the reduction of
elevations of the North American and European reliefs strongly increases
precipitation from northwestern to eastern Europe.
The changes in vegetation cover contribute to maintain and even to intensify
the warm and humid conditions produced by the other factors, suggesting that
the vegetation-climate interactions could help to improve the model-data
comparison. |
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