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.