Erik, "BTW: A little perspective on warming during middle ages. This is evidence that the warming is greater today. Note the mention of Glaciers that survived "thousands of years"." That is Mann's data and there is a lot of evidence it is incorrect (over 100 peer reviewed articles) and that there was more warming during the Medieval Warm Period and hence less ice in the arctic. See http://www.springerlink.com/content/g15qv13t1v12np00/ First when you say polar you mean north polar since the ice in Antarctica has actually increased. See http://icecap.us/index.php/go/joes-blog/proof_we_are_causing_polar_warming_m elts_away_in_the_cold_light_of_reality/ and http://www.co2science.org//articles/V5/N40/C3.php Don -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of erikhansen@TheBlueZone.net Sent: Thursday, March 12, 2009 10:24 AM To: Utah-Astronomy@mailman.xmission.com Subject: [Utah-astronomy] 20th Century Temp Trends. Hi All, The below is the intro to an article about the history of temp changes. The graph Ron showed still showed that the ice sheets are at the 2nd smallest extent. IE: Only slightly greater than 2007. "Tracking the world's average temperature from the late 19th century, people in the 1930s realized there had been a pronounced warming trend. During the 1960s, weather experts found that over the past couple of decades the trend had shifted to cooling. With a new awareness that climate could change in serious ways, many scientists predicted a continued cooling, perhaps a phase of a long natural cycle or perhaps caused by human pollution of the atmosphere with smog and dust. Others insisted that the effects of such pollution were temporary, and humanity's emission of greenhouse gases would bring warming over the long run. This group's views became predominant in the late 1970s. As global warming resumed it became clear that the cooling spell (mainly a Northern Hemisphere effect) had indeed been a temporary distraction. When the rise continued into the 21st century with unprecedented scope, scientists recognized that it signaled a profound change in the climate system." http://www.aip.org/history/climate/20ctrend.htm BTW: A little perspective on warming during middle ages. This is evidence that the warming is greater today. Note the mention of Glaciers that survived "thousands of years". "Scientists were still less able to answer the question of whether climate change was gradually melting the rest of the world's glaciers and ice caps, or instead was adding snow to them. In "those huge areas where little or no information is available," an expert explained in 1993, "almost anything might be happening." But in 2005 a survey of mountain glaciers around the world found that most of those for which historical records existed had been shrinking since 1900. Some that had survived for many thousands of years were vanishing, a striking sign of unprecedented climate change.Experts could only speculate how far this might affect sea level, especially if it were counteracted by the increased snowfall that some models predicted global warming would bring in the remote dry highlands of Antarctica.(26*)" Erik _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com