There are perfectly valid reasons for adjusting older temperature data (growing heat island effects around measuring stations, etc.), but there appear to be some anomalies in at least some of the corrections, probably due to a combination of human errors and perhaps bias. The total effect of the anomalies is not known, however.
The “vanishing” of polar ice (and the polar bears) has become a poster-child for warmists. Photo: ALAMY
10:15PM GMT 07 Feb 2015
When future generations look
back on the global-warming scare of the past 30 years, nothing will
shock them more than the extent to which the official temperature
records – on which the entire panic ultimately rested – were
systematically “adjusted” to show the Earth as having warmed much more
than the actual data justified.
Two weeks ago, under the headline “How we are being tricked by flawed data on global warming”, I wrote about Paul Homewood, who, on his Notalotofpeopleknowthat blog, had checked the published temperature graphs for three weather stations in Paraguay against the temperatures that had originally been recorded. In each instance, the actual trend of 60 years of data had been dramatically reversed, so that a cooling trend was changed to one that showed a marked warming.
This was only the latest of many examples of a practice long recognised by expert observers around the world – one that raises an ever larger question mark over the entire official surface-temperature record.
Homewood has now turned his attention to the weather stations across much of the Arctic, between Canada (51 degrees W) and the heart of Siberia (87 degrees E). Again, in nearly every case, the same one-way adjustments have been made, to show warming up to 1 degree C or more higher than was indicated by the data that was actually recorded. This has surprised no one more than Traust Jonsson, who was long in charge of climate research for the Iceland met office (and with whom Homewood has been in touch). Jonsson was amazed to see how the new version completely “disappears” Iceland’s “sea ice years” around 1970, when a period of extreme cooling almost devastated his country’s economy.
One of the first examples of these “adjustments” was exposed in 2007 by the statistician Steve McIntyre, when he discovered a paper published in 1987 by James Hansen, the scientist (later turned fanatical climate activist) who for many years ran Giss. Hansen’s original graph showed temperatures in the Arctic as having been much higher around 1940 than at any time since. But as Homewood reveals in his blog post, “Temperature adjustments transform Arctic history”, Giss has turned this upside down. Arctic temperatures from that time have been lowered so much that that they are now dwarfed by those of the past 20 years.
Homewood’s interest in the Arctic is partly because the “vanishing” of its polar ice (and the polar bears) has become such a poster-child for those trying to persuade us that we are threatened by runaway warming. But he chose that particular stretch of the Arctic because it is where ice is affected by warmer water brought in by cyclical shifts in a major Atlantic current – this last peaked at just the time 75 years ago when Arctic ice retreated even further than it has done recently. The ice-melt is not caused by rising global temperatures at all.
Of much more serious significance, however, is the way this wholesale manipulation of the official temperature record – for reasons GHCN and Giss have never plausibly explained – has become the real elephant in the room of the greatest and most costly scare the world has known. This really does begin to look like one of the greatest scientific scandals of all time (author's opinion).
