Sunday, December 20, 2009

Natural

clipped from www.john-daly.com
As we can see from recent history, both the
extent and thickness of Arctic sea ice is certainly subject to variation. But
it would be a mistake to assume that a brief period during which the Arctic is
in a thinning cycle is anything more than that - a cycle. We know from past
history that it has been subject to earlier retreats as suggested by the opening quote
from 1817.
The limits on the thickness of Arctic ice
are determined by how low the air temperature can get, and on how warm and
fast-moving the
subsurface water is. Air temperatures measured in the Arctic region show no
recent warming, thus discounting the possibility that recent thinning of ice could be
caused by atmospheric warming above the ice. Rather, the  thinning of ice
in the 1990s is clearly associated with a warming of the sub-surface ocean, as
shown by the SCICEX data, caused in whole or in part by the strong NAO
increasing the flow rate of Atlantic water into the Arctic Ocean.