Big chill on global warming

The cold winter has given many climate sceptics the chance to air their views about "global cooling" – the idea that the world has not got any warmer since the warmest year of 1998. In fact, data collected by Nasa's Goddard Institute for Space Studies shows that 2009 tied as the second-warmest year in the 130 years of instrumental measurements. Indeed, the Nasa data shows that 2005, not 1998, was the warmest on record – the 1998 "record" comes from less compete data set of the Hadley Centre in Britain.
More interestingly, perhaps, is the fact that last year was the warmest ever for the southern hemisphere, which is especially significant given that most of globe south of the equator is covered by water, which warms more slowly and is subject to less variability than land temperatures.
It all goes to show that it is no good trying to look for long-term global trends by concentrating on short-term regional events, such as a colder-than-usual winter for north-western Europe. Apparently, the residents of Bethel in Alaska have experienced what is for them an unusual event – a brown Christmas – but that on its own does not prove global warming, no more so than a white Christmas in Britain proves global cooling.