The Younger Dryas cooling at ~13 ka, after 2 kyr of postglacial warming, is a century-old climate problem. The Younger Dryas is thought to have resulted from a slow-down of
the Atlantic meridional overturning circulation in response to a sudden flood of
Laurentide Ice Sheet meltwater that reached the Nordic Seas. Although there is no
oxygen isotope evidence in planktonic foraminifera from the open western North Atlantic
for a local source of meltwater from the Gulf of St. Lawrence where it was predicted, we
report here that the eastern Beaufort Sea contains the long-sought signal of 18O-depleted
water. Beginning at ~12.94 ± 0.15 ka, oxygen isotopes in planktonic foraminifera from
two sediment cores as well as sediment and seismic data indicate a flood of melt water,
ice and sediment to the Arctic via Mackenzie River that lasted about 700 years. The
minimum in oxygen isotope ratios lasted ~130 years. The floodwater would have
travelled north along the Canadian Archipelago, and through Fram Strait to the Nordic
Seas where freshening and freezing near sites of deepwater formation would have
suppressed convection, and caused the Younger Dryas cooling by reducing the
meridional overturning
