Present and past climate control on fjord glaciations in Greenland: Implications for IRD-deposition in the sea

Calving of icebergs is the dominant ablation mechanism for large outlet gla ciers from the Greenland ice sheet except in northernmost Greenland where b ottom melting from floating glaciers dominates. This difference is controll ed by present climate conditions. Glacial geological evidence indicates tha t the transition between the associated types of fjord-glaciations moved no rth-south in response to past climate change. In cold periods, local melt-o ut of debris from the bottom of an increasing number of floating glaciers r educes the potential for iceberg transport of IRD. Thus, the marine IRD sig nal of Greenland origin is not a simple cold climate signal. Our findings a re discussed in the context of the ongoing debate about the kind of ice tra nsporting IRD - icebergs or sea ice.