The
Younger Dryas was probably caused
by a massive flooding of the
North Atlantic by freshwater outflow
from the melting ice sheets.
Studies
with numerical models of the
climate system indicate that a large
meltwater pulse could cause a
shutdown of the thermohaline circulation
and cooling of the magnitude
observed.
As we
have noted in earlier lectures,
the thermohaline circulation
transports warm water from
the tropics to the northern North
Atlantic, maintaining warm temperatures
in this region.
North
Atlantic thermohaline circulation
Current
evidence indicates the Younger
Dryas was probably confined
to the North Atlantic, consistent
with the thermohaline shutdown
mechanism.