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The Dodgy Statistical Basis for ‘Global Cooling’ Claims

February 6, 2010

Think about this series: 1, 2, 3, 10, 2, 4, 6, 7, 8, 9.

Is the series not increasing because the 4th element (10) is higher than the most recent ones? No, the ’10’  is an outlier, and the trend is clearly still increasing. Child’s play, right?

Apparently not if you’re an anti-science ideologue (see here, or here, for examples.)

The bogus claim that global temperature is not increasing ‘for the last ten years’ is based on the same dishonest logic. Ie. letting one unusually hot year (1998) serve as the basis for the claim. See for yourself from NASA’s temperature data:

(Following the common practice of the IPCC, the zero on this figure is the mean temperature from 1961-1990.)

This image shows the instrumental record of global average w:temperatures as compiled by the w:NASA's w:Goddard Institute for Space Studies. The data set used follows the methodology outlined by Hansen, J., et al. (2006) "Global temperature change". Proc. Natl. Acad. Sci. 103: 14288-14293.

 Incidentally, if you were to update this data series with the 2008-9 data points, you’d find that the upward trend is continuing after the short term ‘stabilisation’ of the previous few years. 2009 was the second hottest year since official records began in 1850, as noted in this excellent video by Peter Sinclair

One Comment
  1. Systematic analysis is what the sceptics hate. They find it easier to cherry pick the stories and the information to suit themselves.

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