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 |
|
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.