Enhanced Warming at High Latitudes

Eugene S. Takle
© 2001

All global climate models agree that future warming of the planet will be enhanced at high latitudes, particularly in the northern hemisphere, although they do not agree on how much such regional warming will exceed the global mean. The Intergovernmental Panel on Climate Change (IPCC), in its conclusions assembled from all available evidence, reports that the earth warmed by 0.6 ± 0.2 ^oC during the 20^th century (Houghton et al., 2001). Vaughan et al (2001) report that the warming in Antarctica for the period 1959-96 was twice the global average: 1.2 ^oC per century. Various stations around Antarctica demonstrate varying degrees of warming, with the longest record showing warming in excess of the continental trend. Some stations report warming at 10 times the global average.

The warming is affecting ecosystems by expanding the range of flowering plants, shrinking seasonal snow cover and causing glaciers to retreat. Nesting grounds used by Adelie penguins continuously for 644 years are being abandoned and taken over by penguins requiring more open water. Vaughan et al (2001) report that there is a 99% likelihood the 20^th century trend is exceptional compared to the last 500 years and unmatched in the last 1900 years.

Three possible mechanisms are candidates to explain this warming, according to Vaughan et al (2001):

1. changing oceanographic circulation may have brought relatively warm circumpolar deep water onto the continental shelf.
2. large scale atmospheric circulation changes
3. global warming amplified by sea-ice atmospheric feedback.

References

Houghton, J. T., et al. Eds., 2001: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Re;ort of the Intergovernmental Panel on Climate Change. Cambridge University Press.

Vaughan, D. G., G. J. Marshall, W. M. Connolley, J. C. King, and R. Mulvaney, 2001: Devil in the detail. Science, 293, 1777-1779.