By Roger Harrabin
BBC Environment Correspondent
The Archbishop of Canterbury has called on the UK government to coerce people into cutting greenhouse gas emissions.
Dr Rowan Williams said drivers should be forced to stick to the 70mph speed limit on motorways to radically reduce their releases of carbon dioxide (CO2).
He said the public had a moral responsibility to change lifestyles.
The consequences if they did not, the Archbishop warned, would be the deaths of billions of people worldwide from the effects of extreme climate change.
He said US President George W Bush's stance of refusing to cut emissions because it might compromise American jobs was not compatible with a Christian point of view.
"I think if we look at the language of the Bible we very often come across situations where people are judged for not responding to warnings," he told BBC Radio 4's Today programme.
"I think what the Bible and the Christian tradition suggest is that those who have that challenge put before them, and not only that challenge but the evidence for it, and don't respond, bear a very heavy responsibility before God."
His comments come on the day of the UK government's long-awaited climate change review. This is supposed to demonstrate how the government will achieve its self-imposed 20% cut in CO2 levels by 2010.
But the most optimistic scenario in the document will achieve no more than 18%; the worst-case scenario is less than 15%. The Department for Trade and Industry (DTI) has been bidding for big business to be allowed to actually increase emissions.
In a foreword to the climate policy review document, the Prime Minister says the government is still aiming to cut levels by 20%. Ministers say more cuts can be obtained through the energy review, the housing review and through future budgets.
Dr Williams said the consequences of global warming could be catastrophic unless governments were prepared to take difficult decisions.
"I think this is something in the long run the government has to brazen out.
"Nobody likes talking about governmental coercion in this respect, whether it's speed limits or anything else. Nobody for that matter likes talking about enforceable international protocols.
"And yet unless there's a real change in attitude we have to contemplate those very unwelcome possibilities if we want the global economy not to collapse and millions, billions of people to die".
The UK is currently on track to meet its Kyoto commitment to reduce emissions of six different greenhouse gases by an average of 12.5% compared with 1990 levels over the years 2008 to 2012
The fall in emissions through the 1990s and early part of the 2000s was achieved at a time of strong growth in the UK economy
Carbon dioxide emissions have risen recently, largely due to increased burning of coal in power stations. This was prompted by a rise in the price of gas (gas is 'cleaner' than coal)
The Labour administration has stated in three election manifestos that it would like to see a 20% cut in CO2 emissions by 2010