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[Phys-l] global temperatures



I noticed nobody has answered Bob's question about global temps over the last ten years. I'm sure he knows, but I actually didn't. So I Googled 'Global Temperature by year'. I would suggest two quick looks....

www.boston.com/bostonglobe/editorial_opinion/oped/articles/2008/01/06/br_r_r_where_did_global_warming_go/

This one gives a typical newspaper (and GW skeptic) account, but

http://www.cru.uea.ac.uk/cru/info/warming/

is not from a skeptic and has an informative graph.

The bottom line is that the temp hasn't really changed in the past 10 years--it has been high, but that is the predominant trend that has been clear for some time now. If anything the trend looks to be turning some (but too little data to be sure). Now this flattening is during a time of a 4% CO-2 increase, but what is interesting to me is that the rate of increase from 1975 to 2000 is about the same as it was between 1915 and 1940, when the CO-2 concentrations weren't nearly what they were at the end of the 20th Century.

These are, IMO, the types of data that should trigger some caution, at least some healthy skepticism concerning the model predictions. Again, this is just SO complicated. Is the leveling because of increased aerosols and Global dimming -- or is the global air quality better than earlier which makes a ten year leveling more mysterious? What about the other natural drivers--the sun for example. What's it been doing during this ten year period--has it cooled off enough to compensate for the greenhouse increases or is it pumping in more energy such that we would have expected continuing record setting temps (1998 is still the hottest--according to the graph and the Boston Globe story). I would point to the last paragraph of the Globe story! ;-)

Rick

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Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN
rtarara@saintmarys.edu
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