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| Titel |
Assessing the impact of late Pleistocene megafaunal extinctions on global vegetation and climate |
| VerfasserIn |
M.-O. Brault, L. A. Mysak, H. D. Matthews, C. T. Simmons |
| 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 ; 9, no. 4 ; Nr. 9, no. 4 (2013-08-02), S.1761-1771 |
| Datensatznummer |
250085197
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| Publikation (Nr.) |
 copernicus.org/cp-9-1761-2013.pdf |
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| Zusammenfassung |
| The end of the Pleistocene was a turning point for the Earth system as
climate gradually emerged from millennia of severe glaciation in the
Northern Hemisphere. The deglacial climate change coincided with an
unprecedented decline in many species of Pleistocene megafauna, including
the near-total eradication of the woolly mammoth. Due to an herbivorous diet
that presumably involved large-scale tree grazing, the mammoth extinction
has been associated with the rapid expansion of dwarf deciduous trees in
Siberia and Beringia, thus potentially contributing to the changing climate
of the period. In this study, we use the University of Victoria Earth System
Climate Model (UVic ESCM) to simulate the possible effects of these
extinctions on climate during the latest deglacial period. We have explored
various hypothetical scenarios of forest expansion in the northern high
latitudes, quantifying the biogeophysical effects in terms of changes in
surface albedo and air temperature. These scenarios include a Maximum Impact
Scenario (MIS) which simulates the greatest possible post-extinction
reforestation in the model, and sensitivity tests which investigate the
timing of extinction, the fraction of trees grazed by mammoths, and the
southern extent of mammoth habitats. We also show the results of a
simulation with free atmospheric CO2-carbon cycle interactions. For the
MIS, we obtained a surface albedo increase and global warming of 0.006 and
0.175 °C, respectively. Less extreme scenarios produced smaller
global mean temperature changes, though local warming in some locations
exceeded 0.3 °C even in the more realistic extinction scenarios.
In the free CO2 simulation, the biogeophysical-induced warming was
amplified by a biogeochemical effect, whereby the replacement of
high-latitude tundra with shrub forest led to a release of soil carbon to
the atmosphere and a small atmospheric CO2 increase. Overall, our
results suggest the potential for a small, though non-trivial, effect of
megafaunal extinctions on Pleistocene climate. |
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