The Met Office has announced that 2014 may have been the hottest on record.
The Met Office's caution is interesting. Why the reluctance to say definitively?
The data show that 2014 was 0.56°C (give or take 0.1°C) above the average global temperature. That makes it the hottest year ever, tied with 2010. But the Met Office only said it's "one of" the warmest years – "We can say with confidence that 2014 is one of 10 warmest years in the series" going back to 1850, said Colin Morice, a climate monitoring scientist at the Met Office.
It's because the uncertainty range is greater than the difference between the hottest years.
But the odds are it really was the hottest year.
"It's fairly clear that 2014 was the hottest," said Mark Lynas, the author of Six Degrees: Our Future on a Hotter Planet, because all three datasets released in the last few weeks – NASA's, the NOAA's, and the Met Office's – agree. Often in the past there have been slight discrepancies.
Lynas thinks the Met Office's caution is in part due to "blowback" from climate sceptics: After the NOAA released its data, there was criticism that it hadn't taken this sort of uncertainty into account.