Britain may have to double its investments in cutting carbon emissions to up to two per cent of GDP, Nicholas Stern has warned.
The author of the 2006 Stern review on the economics of climate change, who suggested then that one per cent of GDP would have to be invested to halt climate change at 2C by 2100, has now shifted his view.
He told the Today programme that "one to two per cent" was needed because scientific estimates had become "still more worrying".
"Ambitions for emissions reduction should be higher than those in the Stern review," Lord Stern said.
He warned that "the window for action is closing" after figures released yesterday showed record emissions.
Energy-related carbon dioxide emissions in 2010 hit 30.6 gigatonnes, a five per cent jump from the previous record year in 2008.
Around four-fifths of projected emissions from the power sector are already 'locked in', as they will come from power plants which are currently being built or are already in place.
"We're slipping behind in our intentions," Lord Stern added.
"The room for manoeuvre is narrow and the window of opportunity is closing. But if we act urgently, strongly now, what we can do is launch a new industrial revolution."
Last December in Cancun countries committed to reductions which would leave the world around ten per cent above the 2C path.
Forty per cent of global emissions but only 25% of emissions growth came from developed countries last year.
But on a per capita basis developed countries collectively emitted 10 tonnes, the International Energy Agency (IEA) said, compared with 5.8 tonnes for China and 1.5 tonnes for India.
IEA chief economist Fatih Birol said the latest estimates were a "wake-up call" for the world.
"The world has edged incredibly close to the level of emissions that should not be reached until 2020 if the 2ºC target is to be attained.
"Given the shrinking room for manoeuvre in 2020, unless bold and decisive decisions are made very soon, it will be extremely challenging to succeed in achieving this global goal agreed in Cancun."
Lord Stern said: "The risks are immense and we're in danger of sleepwalking. But if we act strongly, the opportunities are also immense."