Guardian: This year is set to be the coolest since 2000, according to a preliminary estimate of global average temperature that is due to be released next week by the Met Office. The global average for 2008 should come in close to 14.3C, which is 0.14C below the average temperature for 2001-07.
The relatively chilly temperatures compared with recent years are not evidence that global warming is slowing however, say climate scientists at the Met Office. "Absolutely not," said Dr Peter Stott, the manager of understanding and attributing climate change at the Met Office's Hadley Centre. "If we are going to understand climate change we need to look at long-term trends."
But not too long, of course, for then he'd have to account for numerous warming and cooling trends that were clearly not anthropogenic in origin. Starting with 1960 seems about right right for Dr. Scott--sufficiently long to permit scientists to dismiss inconvenient years like 2008, but not so long as to require them to account for and explain the unusually hot 1930's.
2008's cooling is all the more remarkable given that atmospheric levels of greenhouse gases reached record levels in 2008:
Officials from the UN World Meteorological Organization concluded in their latest report that the levels of methane, nitrous oxide (NO2) and carbon dioxide (CO2) in the atmosphere reached their largest ever recorded levels, though they increased steadily over 2007. Methane levels registered their largest increase over the last decade in a single year, which prompted scientists to say that this gas may soon become as dangerous as CO2 or NO2.
"The major greenhouse gases – CO2, methane and N2O – have all reached new highs in 2007. Two of them, CO2 and N20, are increasing steadily and there is no sign of leveling off of those two gases," said WMO expert, Geir Braathen, during a news conference, also adding that existing data were insufficient to predict if methane would level off or continue rising next year as well.