A BI-HEMISPHERIC PERSPECTIVE ON THE LAST GLACIAL TERMINATION FROM THE SOUTHERN ALPS OF NEW ZEALAND, THE HAIZI SHAN OF SOUTHEASTERN TIBET, AND ALTAI MOUNTAINS OF WESTERN MONGOLIA

The last glacial termination (~18,000 – 11,000 yrs ago) represents the last great global warming and the last time CO₂ rose by a substantial amount before the industrial period. Understanding the processes that drove this glacial to interglacial transition will help refine the global climate system sensitivity to CO₂ and will place ongoing global warming into a paleoclimatic context. Here, we test possible drivers of the last glacial termination by comparing chronologies of mountain glacier recession in the middle latitudes of both polar hemispheres. Glacier fluctuations afford insight into past climate conditions, because extra-polar mountain glaciers are highly sensitive to atmospheric temperature. We present ¹⁰Be surface-exposure chronologies and glacial geomorphologic maps of mountain glacier recession since the Last Glacial Maximum in the Southern Alps of New Zealand (44°S, 170°E), the Haizi Shan of southeastern Tibet (30°N, 100°E), and the Altai Mountains of western Mongolia (49°N, 88°E). On the basis of these chronologies, we evaluate the relative roles of rising atmospheric CO₂, local insolation forcing, and ocean-atmosphere reorganizations in driving the warming that ended the last ice age.