NEAR-SYNCHRONOUS GLOBAL GLACIER RETREAT DURING THE LAST DEGLACIATION ASSOCIATED WITH INCREASING ATMOSPHERIC CO2

The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties in the timing of retreat. We use recent improvements in cosmogenic nuclide production-rate calibrations to recalculate the ages of 164 globally-distributed moraines and show that global glacier retreat was nearly synchronous during the last deglaciation and largely coincident with the rise in CO₂. This revised history, in conjunction with transient climate model simulations, suggests that greenhouse gases were the primary driver of global glacier retreat, while other factors modulated glacier responses regionally.