Polar climate changes

E. Linacre

10/'98


Several climatic trends have been observed at the two poles during the 20th century (Table 1). Most changes have been concentrated during the last few decades. The evolution of most variables is consistent with global warming, although so far the magnitude of the change is less than what most GCM simulations had predicted. It is possible that the cooling effect of manmade aerosols is larger at higher latitudes, as is the warming effect of enhanced greenhouse gas concentrations.

Table 1: Changes of various climate parameters during the 20th century in the polar regions (1).

parameter

Arctic

Antarctic

surface temperature

mostly warmer

warmer, especially over Peninsula

lower tropospheric temperature

warmer

unknown

stratospheric temperature

colder (in summer only)

colder

precipitation

wetter (at least at land stations)

uncertain

ocean temps

warmer

slightly warmer

snow cover

less

-

extent of sea ice

slightly less

no trend since '78, a probable decline '50-'78

sea ice thickness

thinner in some parts

unknown

ablation of ice sheet

glaciers retreating in South Greenland

less, in Queen Maud Land

ice shelf extent

reduced, in Canada

small ice shelves by Peninsula have shrunk

extent and depth of permafrost

less in Alaska, Canada, Siberia

N/A

 

Reference

(1) Walsh, J.E., H.L. Tanaka & G. Weller 1996. Wadati conference on Global Change and the Polar Climate, 7 - 10 November 1995, Tsukuba, Japan. Bull. Amer. Meteor. Soc. 77, 1268-73.