Biophysical feedbacks between the Pleistocene megafauna extinction and climate: The first human-induced global warming?

A large increase in Betula during a narrow 1000 year window, similar to 13,800 years before present (YBP) in Alaska and Yukon corresponded in time with the extinction of mammoths and the arrival of humans. Pollen data indicate the increase in Betula during this time was widespread across Siberia and Beringia. We hypothesize that Betula increased due to a combination of a warming climate and reduced herbivory following the extinction of the Pleistocene mega herbivores. The rapid increase in Betula modified land surface albedo which climate-model simulations indicate would cause an average net warming of similar to 0.021 degrees C per percent increase in high latitude (53-73 degrees N) Betula cover. We hypothesize that the extinction of mammoths increased Betula cover, which would have warmed Siberia and Beringia by on average 0.2 degrees C, but regionally by up to 1 degrees C. If humans were partially responsible for the extinction of the mammoths, then human influences on global climate predate the origin of agriculture. Citation: Doughty, C. E., A. Wolf, and C. B. Field (2010), Biophysical feedbacks between the Pleistocene megafauna extinction and climate: The first human-induced global warming?, Geophys. Res. Lett., 37, L15703, doi:10.1029/2010GL043985.