Yes, it’s cold in places. No, that doesn’t disprove climate change.

2000-2009 mean global temperature, compared to the 1951-1980 mean. Image credit: NASA and Goddard Institute for Space Studies (click image to go there).

With all of the talk of ‘Snowmageddon’, keep the big climatological picture in mind.  Conservatives here in the US have been mocking the concept of climate change for as long as I can remember, but recent snowstorms have seemed to really spur them on (e.g. here).  Here’s some news released last month, from NASA and the Goddard Institute for Space Studies (GISS).  2000-2009 was the hottest decade on record.  2009 was the second hottest year on record.  The map above shows the overall temperature rise in 2000-2009 versus average temperatures from 1951-1980, a commonly used reference.  NASA uses three sources to assemble this sort of dataset:  worldwide weather stations, satellite observations (for sea surface temperature), and measurements from Antarctic research stations.

Earth surface temperatures since 1880, relative to the average global temperature from 1951-1980. Image credit: NASA and Goddard Institute for Space Studies (click image to go there).

Yes, global temperatures fluctuate on an interannual (year to year) basis due to things like El Nino and other mechanisms, but if larger scales of variation are used (i.e. decadal,etc.), the average temperature on earth is clearly rising.  The above graph shows the rise of global temperatures (except for a fleeting leveling out in the 1940s and 1970s) since 1880.  Most climate scientists agree that the rise of atmospheric carbon dioxide and other greenhouse gases are driving this warming.  Global climate is a hugely complicated system with other factors, aerosol levels, changes in tropical sea surface temperatures, variability in the sun’s irradiance, and over longer timescales, the orbital geometry of our planet and other events, affecting temperatures as well.  However, these other factors simply cannot account for this level of warming since 1880, according to NASA and GISS.  So politicians, please inform yourselves and make policy decisions based on science, not ideology.  I’m looking at you, US Senator and family who built an igloo and stuck signs on it to make fun of climate change (via the NY Times)…

Ref.

Voiland, A. (2010, January 21). 2009: Second Warmest Year on Record; End of Warmest Decade. NASA Goddard Institute for Space Studies. Accessed February 11, 2010.

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