Assessing the impact of late Pleistocene megafaunal extinctions on global vegetation and climate
Abstract
The end of the Pleistocene marked a turning point for the Earth system, as climate gradually emerged from millennia of severe glaciation in the Northern Hemisphere. It is widely known that the deglacial climate change then was accompanied by an unprecedented decline in many species of large terrestrial mammals, featuring among others the near-total eradication of the woolly mammoth. Due to a herbivorous diet that involved the grazing of a large number of trees, their extinction is thought to have contributed to the rapid and well-documented expansion of dwarf deciduous trees in Siberia and Beringia, which in turn would have resulted in a significant reduction in surface albedo, leading to an increase in global temperature. In this study, we use the UVic Earth System Climate Model (an EMIC) to simulate various scenarios of the megafaunal extinctions, ranging from the catastrophic to more realistic cases, in order to quantify their potential impact on the climate system, and investigate the associated biogeophysical feedbacks between the growing vegetation and rising temperatures. The more realistic experiments include sensitivity tests based on the timing of extinction, tree clearance ration, and size of habitat, as well as a gradual extinction and a simulation involving free (non-prescribed) atmospheric CO2. Overall, most of the paleoclimate simulations and the sensitivity tests yield results that correspond well with our intuition. For the maximum impact scenario, we obtain a surface albedo increase of 0.006, which translates into a global warming of 0.175°C; these numbers are comparable in magnitude to those in similar studies.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMPP31B2034B
- Keywords:
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- 4908 PALEOCEANOGRAPHY / Albedo;
- 4928 PALEOCEANOGRAPHY / Global climate models