Proposition 02: The warmest ten years

I was reading the Evening Standard on my way home tonight, and saw the Rt Hon Ed Miliband MP’s op-ed – “Climate change sceptics are today’s flat-earth brigade”. In it he mentions a line I’ve heard numerous times before.

Proposition:

The 10 warmest years on record have all occurred since 1997

Methodology:

It seems to me that this statement is either true or false, and can be checked using temperature records from weather stations – the sort of data I’m collecting already. For any particular station, the statement is either true or false. For the planet as a whole, a clear majority of stations should ‘vote’ for the statement being true.

  • Collect daily station records from the NOAA here
  • Exclude stations which don’t include the years 1985 – 2008 (12 years either side of 1997 – it’s no use using the station if the test is necessarily true because it’s only post-1997 or necessarily false because there aren’t ten years after 1997 to be the warmest)
  • Exclude stations without records for at least 90% of days
  • Calculate the annual mean temperature for each station in each year
  • Sort station data by annual mean temperature to find the ten warmest years, see if they’re all after 1997 or not

I expect there’ll be some stations for which it’s true and some for which it’s false – there will always be random weather effects – but if recent years are the warmest this should be clear from the measurements. It would be strange to imagine a warm year which left most places colder!

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