THE INFLUENCE OF ICE MARGINAL SETTING ON EARLY HOLOCENE RETREAT RATES IN WEST GREENLAND

Ice sheets are changing rapidly but given the historic record alone, we have a difficult time assessing the climatic impact on ice sheet change as it is filtered through complex set of processes known as ‘ice dynamics.’ Ice margin reconstructions that span millennia allow us to evaluate dynamic controls on ice sheet change. We present two ¹⁰Be chronologies of early Holocene ice sheet retreat from West Greenland in two distinctly different ice marginal settings - a marine–based glacier setting and a land-based glacier setting. These chronologies track the retreat of the Greenland Ice Sheet along two transects in the Disko Bugt region between 12-8 ka. We use this natural laboratory to evaluate the behavior of the ice sheet margin during a period of warming climate by comparing the timing and rate of retreat between the two transects. Our results indicate similar rates of retreat of ~40-50 m a^-1 from both transects during the early Holocene. In addition, seven previously published deglacial chronologies from West Greenland yield retreat rates between 10 to 65 m a^-1, revealing similar early Holocene retreat rates throughout West Greenland despite the high diversity in ice marginal settings. Furthermore, the retreat rates demonstrate that terrestrial sectors of ice sheets can retreat at rates comparable to their marine counterparts, a phenomenon not prevalent in the shorter observational record. This may indicate that stable land-based sectors of the Greenland Ice Sheet will potentially experience rapid recession in the future.