The Met Office have changed their decadal forecast for the next four years from a predicted 0.54 degree rise to a 0.43 degree rise, measured relative to the 1971-2000 average. This doesn’t sound all that exciting, even to real climate geeks like us, but then Lord Lawson’s climate denial outfit, the Global Warming Policy Foundation, got hold of the story and turned it into ‘Global Warming at a standstill’ in the Telegraph and similarly dramatic variations on the BBC’s Today programme and elsewhere.
Or, if you’re not interested in reading long explanations of data manipulation, here’s the gist:
Basically, you can’t see a long-term trend by looking at the short term. When you’re measuring changes over brief stretches of time, you can find periods where the Dow Jones seems to show the collapse of capitalism, the climate appears to be cooling, or QPR look likely to win the Premiership. But take a step back, and things look very different.
So no, sadly global warming has neither stopped nor paused, when you look at climatic trends rather than weather patterns.
But the ‘new’ version of this old chestnut did contain one interesting detail which foxed us for a while. The news coverage included a claim that 1998 was the ‘the warmest year in the Met Office Hadley Centre’s 160-year record’, when the Hadley Centre’s temperature record, HadCRUT4, shows 2010 as the hottest year, with 2005 in second place and 1998 third. This is in line with the two other global temperature datasets, GISS (produced by NASA) and NCDC (the US’s National Climatic Data Center), and, not altogether surprisingly, with the World Meteorological Organisation’s figures, which are produced from combining those three datasets.
That seemed like a rather simple thing to get wrong, and so we were just about to loudly decry the appallingly low standards of modern science journalism when we discovered the source of the error.
The 1998 claim was lifted from the Met Office’s webpage announcing their new decadal forecasts -
“The warmest year in the 160-year Met Office Hadley Centre global temperature record in 1998, with a temperature of 0.40°C above long-term average.” (all errors in the original)
The Met Office appear to have used HadCRUT3, an earlier, less comprehensive version of their dataset, which had 1998 as the warmest year (there’s only a few hundredths of a degree between the top three).
So the Met Office are now releasing figures that contradict the figures produced by the Met Office.
Hopefully the Hadley Centre scientists who collated HadCRUT4 will have a word with the Met Office PR department and get them to use the correct data. That way, there’d be a slightly improved chance of the media using the correct data too.