The senders and recipients of the leaked CRU emails constitute a cast list of the IPCC's scientific elite, including not just the "Hockey Team", such as Dr Mann himself, Dr Jones and his CRU colleague Keith Briffa, but Ben Santer, responsible for a highly controversial rewriting of key passages in the IPCC's 1995 report; Kevin Trenberth, who similarly controversially pushed the IPCC into scaremongering over hurricane activity; and Gavin Schmidt, right-hand man to Al Gore's ally Dr James Hansen, whose own GISS record of surface temperature data is second in importance only to that of the CRU itself.

There are three threads in particular in the leaked documents which have sent a shock wave through informed observers across the world. Perhaps the most obvious, as lucidly put together by Willis Eschenbach (see McIntyre's blog Climate Audit and Anthony Watt's blog Watts Up With That), is the highly disturbing series of emails which show how Dr Jones and his colleagues have for years been discussing the devious tactics whereby they could avoid releasing their data to outsiders under freedom of information laws.

They have come up with every possible excuse for concealing the background data on which their findings and temperature records were based.

This in itself has become a major scandal, not least Dr Jones's refusal to release the basic data from which the CRU derives its hugely influential temperature record, which culminated last summer in his startling claim that much of the data from all over the world had simply got "lost". Most incriminating of all are the emails in which scientists are advised to delete large chunks of data, which, when this is done after receipt of a freedom of information request, is a criminal offence.

But the question which inevitably arises from this systematic refusal to release their data is -- what is it that these scientists seem so anxious to hide? The second and most shocking revelation of the leaked documents is how they show the scientists trying to manipulate data through their tortuous computer programmes, always to point in only the one desired direction -- to lower past temperatures and to "adjust" recent temperatures upwards, in order to convey the impression of an accelerated warming. This comes up so often (not least in the documents relating to computer data in the Harry Read Me file) that it becomes the most disturbing single element of the entire story. This is what Mr McIntyre caught Dr Hansen doing with his GISS temperature record last year (after which Hansen was forced to revise his record), and two further shocking examples have now come to light from Australia and New Zealand.

In each of these countries it has been possible for local scientists to compare the official temperature record with the original data on which it was supposedly based. In each case it is clear that the same trick has been played -- to turn an essentially flat temperature chart into a graph which shows temperatures steadily rising. And in each case this manipulation was carried out under the influence of the CRU.

What is tragically evident from the Harry Read Me file is the picture it gives of the CRU scientists hopelessly at sea with the complex computer programmes they had devised to contort their data in the approved direction, more than once expressing their own desperation at how difficult it was to get the desired results.

The third shocking revelation of these documents is the ruthless way in which these academics have been determined to silence any expert questioning of the findings they have arrived at by such dubious methods -- not just by refusing to disclose their basic data but by discrediting and freezing out any scientific journal which dares to publish their critics' work. It seems they are prepared to stop at nothing to stifle scientific debate in this way, not least by ensuring that no dissenting research should find its way into the pages of IPCC reports.