His predictions have proved so wildly wrong – along with those of the Met Office's £33 million computer model which forecast that we should now be enjoying a "barbecue summer" and that 2009 would be one of "the five warmest years ever" – that the propaganda machine has had to work overtime to maintain what is threatening to become the most expensive fiction in history.
In the past few years, Dr Hansen's temperature record has become ever more eccentric, often wildly at odds with the other three officially recognised data sources, all of which showed a dramatic drop in temperatures in 2007 leading to markedly cooler summers and two of the coldest and snowiest winters the world has known for decades. All this has equally made nonsense of the predictions of the computer models that the UN's Intergovernmental Panel on Climate Change relies on, which are programmed to assume that temperatures should soar in line with rising levels of greenhouse gases.
Carbon dioxide levels continue to rise, but temperatures – apart from those revealed by Dr Hansen – have seriously parted company with them. This has not prevented the propaganda machine's media groupies continuing to peddle a daily stream of stories about how in all directions global warming is already affecting the world for the worse.
Soay sheep are shrinking in size (I am sure they've really noticed the global warming up on that bleak Scottish islet). The tiny Pacific nation of Tuvalu, we are yet again told, is pleading for international aid, as it sinks below the rising ocean – even though an expert study in 2001 showed that sea levels around Tuvalu have in fact been falling for 50 years. Even a report on the record number of Painted Lady butterflies in Britain this summer cannot resist ending with a ritual forecast that many butterfly species will soon disappear because of "climate change".
Meanwhile even America's foremost pro-warmist scientific blog, RealClimate – run by, among others, Dr Michael Mann of "hockey stick" fame – concedes that global temperatures are not only declining but are likely to continue to do so for at least another decade – after which, of course, they will leap up again higher than ever.
None of this is proving of much assistance to the politicians still desperately hoping to reach agreement on a new climate treaty in Copenhagen in December. With the still-developing countries, led by China, India, Russia and Brazil, all saying that they will only co-operate if rich governments such as the US and the EU compensate them to the tune of trillions of dollars a year, the chances of any meaningful successor to the Kyoto Protocol look like zero. (India's environment minister delights these days in saying that his country has no intention of sabotaging its fast-growing economy by agreeing to curb its CO2 emissions.)
But we are already committed, in any case, to paying out barely credible sums for our blind faith in global warming (quite apart from the £100 billion Gordon Brown wants us to spend on 10,000 more useless windmills, most of which he hasn't got a hope of seeing built).
A new study by an Australian analyst, Joanne Nova, based on official figures (available at the website of the Science and Public Policy Institute), shows that since 1991 US federal spending alone on climate change has been $79 billion. The cost of international carbon trading in 2008 was a staggering $126 billion, and is soon likely to run into trillions, making buying and selling the right to emit CO2 "the largest single commodity traded" in the world. Yet for all that money (along with countless billions more spent in Britain and elsewhere), "no one is able to point to a single piece of evidence that man-made carbon dioxide has a significant effect on global climate".
Are we all missing something – apart from all that money, of course?