Melt-Water-Pulse (MWP) events and abrupt climate change of the last deglaciation

The last deglaciation is characterized by massive ice sheet melting, which results in an average sea-level rise of ～120 140 m. At least three major Melt-Water-Pulse (MWP) events (19ka-MWP, MWP-1A and MWP-1B) are recognizable for the last deglaciation, of which MWP-1A event lasting from ～14.2 to ～13.7 ka B.P. is of the most significance. However, the accurate timing and source of MWP-1A event remain debatable and controversial. It has long been postulated that meltwater of the last deglaciation pouring into the North Atlantic resulted in a slowdown or even a shutdown of the thermohaline circulation (THC) which subsequently affected the global climate change. Accordingly, the focus of this debate consists in establishing a reasonable relationship between MWP events and abrupt climate change. Here we summarize a variety of geological and model results for the last deglaciation, reaching a conclusion that the major MWP events did not correspond with the rigorous stadials, nor always happened within climate reversal intervals. MWP events of the last deglaciation had very weak influences on the intensity of the THC and were not able to trigger a collapse of the global climate. We need to reevaluate the influences of the temporal meltwater variability on the global climate system.