WHEN IS A TREND NOT A TREND?
There has recently been discussion on the blogosphere as to whether or not global temperatures are continuing to rise, have levelled off, or are falling. For example the ‘Met Office in the Media’ site had a rebuttal of an article in the (United Kingdom) Daily Mail which, inter alia, claimed there had been no warming for 15 years. ( http://metofficenews.wordpress.com/2012/01/29/met-office-in-the-media-29-january-2012 /) In their rebuttal the Met Office pointed out that most of the highest temperatures on record have occurred in the last 15 years. They also present a chart of temperature in 10 years blocks which showed that the first decade of the 21stcentury was the warmest on record. In the IPCC Technical Assessment Report of 2007 many of the temperature graphs are smoothed using 13 point binomial moving average (for example figure 3.8). Elsewhere they talk of decadal smoothing. One of the contributors to the blog in support of the Met Office’s position refers to the ‘Skeptical Scien...