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”.
Back in January and February, two items in this column attracted more than 42,000 comments to the Telegraph website from all over the world. The provocative headings given to them were “Climategate the sequel: how we are still being tricked by flawed data on global warming” and “The fiddling with temperature data is the biggest scientific scandal”.
My cue for those pieces was the evidence multiplying from across the world that something very odd has been going on with those official surface temperature records, all of which ultimately rely on data compiled by NOAA’s GHCN. Careful analysts have come up with hundreds of examples of how the original data recorded by 3,000-odd weather stations has been “adjusted”, to exaggerate the degree to which the Earth has actually been warming. Figures from earlier decades have repeatedly been adjusted downwards and more recent data adjusted upwards, to show the Earth having warmed much more dramatically than the original data justified.
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