Excerpt from a good article on the global warming debate with facts to back it up. The full article can be found at
http://www.reason.com/news/show/34939.html
To show how hard answering that question can be, let's take a little closer look at the two reports mentioned above. The Arctic Council report is based on the observations and deliberations of 300 scientists from eight countries and six groups of indigenous people over the past four years. They find that the Arctic region is warming at twice the rate of the rest of the world. They further find that the sea ice that covers the Arctic Ocean is thinning, and could almost disappear in the summer months by 2100.
But University of Alabama at Huntsville climatologist
John Christy, a climate expert on whom I have relied for years, makes some interesting observations about the Arctic Council's report. "If you look at the long term records, the Arctic has been as warm or warmer than it is today," says Christy. He cites temperature data from the Hadley Centre in the UK showing that from 70 degrees north latitude to the pole, the warmest years on record in the Arctic were 1937 and 1938. This area is just slightly above the
Arctic Circle.
Furthermore, those same records show that the Arctic warmed twice as fast between 1917 and 1937 as it has in the past 20 years. After 1940, the Arctic saw a big cool-down and climatologists noted sea ice expanding in the northern Atlantic. Christy argues that what he calls the Great Climate Shift occurred in the late 1970s and caused another sudden warming in the Arctic. Since the late 1970s there has not been much additional warming in the region at all. In fact, on page 23, the Arctic Council
Assessment offers very similar data for Arctic temperature trends from 60 degrees north latitude?the area that includes most of Alaska and essentially all of Greenland, most of Norway and Sweden, and the bulk of Russia.
Interestingly, the recent increase in temperatures in Alaska and Siberia seem to have coincided almost simultaneously with a shift in the Pacific Decadal Oscillation (PDO) in the late 1970s. Could this be part of Christy's Great Climate Shift? Swings in the PDO occur on 30 to 40 year time frames, and the most recent one brought warmer currents flowing north to the coast of Alaska. The
Assessment does note that "several important natural modes of variability that especially affect the Arctic have been identified, including the
Arctic Oscillation, the
Pacific Decadal Oscillation, and the
North Atlantic Oscillation. Each of these can affect the regional patterns of such features as the intensity and tracks of storm systems, the direction of prevailing winds, the amount of snow, and the extent of sea ice."