Last month, we are told, the world enjoyed “its hottest March since records began in 1880”. This year, according to “US government scientists”, already bids to outrank 2014 as “the hottest ever”. The figures from the US National Oceanic and Atmospheric Administration (NOAA) were based, like all the other three official surface temperature records on which the world’s scientists and politicians rely, on data compiled from a network of weather stations by NOAA’s Global Historical Climate Network (GHCN).
But here there is a puzzle. These temperature records are not the only ones with official status. The other two, Remote Sensing Systems (RSS) and the University of Alabama (UAH), are based on a quite different method of measuring temperature data, by satellites. And these, as they have increasingly done in recent years, give a strikingly different picture. Neither shows last month as anything like the hottest March on record, any more than they showed 2014 as “the hottest year ever”.