Professor Sir David King, 77, was the architect of the policy to cut fuel duty for diesel cars as Tony Blair’s personal scientist

The scientist behind the dash for diesel is a committed climate change activist who once described global warming as a greater threat than terrorism.

Professor Sir David King, 77, was the architect of the policy to cut fuel duty for diesel cars as Tony Blair’s personal scientist.

Yesterday he admitted he got it wrong, having been driven by an obsession with carbon emissions. The former Government chief scientific adviser, knighted in 2003, has presided over many controversies.

In 2004 he wrote in the journal Science: ‘In my view, climate change is the most severe problem that we are facing today – more serious even than the threat of terrorism.’

He refused to back down when called in to Parliament and asked about his comments, which came just three years after the 9/11 attacks.

Sir David also persuaded Tony Blair to order a mass cull of livestock after being put in charge of handling the foot-and-mouth crisis.

In 2007, the South Africa-born academic divided opinion by recommending a badger cull to control the spread of TB. He has also been a long-term supporter of GM food.

His strong belief in man-made climate change has seen him publish a book, The Hot Topic, on how to tackle global warming, and he has been accused of being a politician in scientist’s clothing for his strong views.

Just over a decade ago the chemist warned that temperatures will rise to dangerous levels within decades, leaving large sections of Britain’s coastline under water, while 400 million people could go hungry.

He has also said that global warming is pushing thousands of animals and plants towards extinction.

Sir David has stuck to his guns on GM crops, which he claimed had cost Britain up to £4billion through the country’s failure to embrace them.

Under current Vehicle Excise Duty bands drivers of diesel vehicles generally pay less - because the cars emit less CO2 despite producing other dangerous fumes

Ministers have come under fire after spending years recommending that motorists should buy diesel cars

This graphic shows the amount diesel drivers will pay under the plans compared to car owners who drive petrol and electric vehicles

In 2003 he chaired the Government’s GM Science Review Panel, at the time of allegations that a leading member of the scientific establishment had warned senior academic Dr Andrew Stirling his career would be ruined unless he stopped questioning the safety of so-called Frankenstein food.

Sir David admitted he had made no effort to identify the culprit, despite the resignation of another expert, Professor Carlo Leifert, in protest at the influence of GM supporters on the panel.

Also in 2003, he backed research to create animal-human embryos, saying they could have ‘massive impacts’ on society, generating treatments for conditions from Alzheimer’s to heart disease.

He was appointed permanent Special Representative for Climate Change in September 2013 and left the post last month.