Heating of earth8217;s surface accelerating 8212; Study

The differences are between land-based weather stations, that have shown a rise in temperatures, and satellite measurements that show little change in atmospheric temperature over last 20 years.

quot;The difference between surface and upper-air trends in no way invalidates the conclusion that the earth8217;s temperature is rising,quot; said John M Wallace, one of the authors of the report and a professor at the University of Washington in Seattle.

The study8217;s authors suggest that certain human and natural activities may actually have cooled the upper atmosphere, even as the general effect of all these activities has been to heat up the earth8217;s surface.

However, sceptics are not convinced and Arthur Robinson, president of the Oregon Institute of Science and Medicine, called the report a quot;political documentquot; and evidence that quot;the National Academy Board has pretty much been taken over by the envirosquot; enviornmentalists.

Robinson contended that the extent of global warming is part of a natural trend that need not cause any worries.

quot;One must not loose track of the fact that the earth8217;s temperature has been warming now for the past 300 years, not just 50 years. And there was no coal or gas 300 years ago,quot; he said.