GFI/BCCR Seminar: Northern Hemisphere Control over Antarctic Glaciation in the Warm Pliocene Epoch
Timothy Herbert (Brown University)
Northern Hemisphere Control over Antarctic Glaciation in the Warm Pliocene Epoch
The earth’s climate system has gone through major changes over time that serve as natural experiments to test our understanding of linkages and feedbacks that may come into play if the Earth continues to warm, as expected from greenhouse gas forcing. Our project investigates patterns of climate change between the northern and southern hemispheres during the mid-Pliocene epoch (~3-4 Myr ago) when the overall climate state was warmer than today. Critically, evidence suggests that the amount of ice on Antarctica was similar to today, but that there was little or no permanent ice on land in the northern hemisphere. Most climate scientists have therefore supposed that climate change would focus on the region around the Antarctic. I will present an interpretation based on new data that, contrary to this view, change initiated in the northern hemisphere propagated all the way southward, and actually determined the timing and amount of temperature change globally. The most likely mechanism would link changes in the high latitude North Atlantic to atmospheric CO2 levels, thereby determining ice volume in the southern hemisphere.