The news came a day after Mr Brown made a pre-budget statement that embraced virtually none of the recommendations of the Stern report, and dashed hopes the Blair Government would move swiftly to a new environmental agenda.
Brown had been trying to sideline Stern by commissioning him to write the report, but this came back to bite him on the bum. There will be more in the future as the reality of global warming keeps bumping into the rhetoric of the denialist and skeptic.
Sir Nicholas issued a statement saying he had planned the move for some time and had hugely enjoyed working with Mr Brown. But relations between the two men are widely known to be tense, a Downing Street policy adviser said. It was understood that Mr Brown had initially asked Sir Nicholas to write his report in order to sideline him, and that it only achieved global prominence because of its timeliness.
The report says that fighting climate change will save, not cost, the global economy money, and has been hugely influential around the world. Many environment ministers quoted it in addresses to the global summit in Nairobi last month. The Guardian described Sir Nicholas, 60, as the first climate change rock star.
He will leave in March to take a chair at the London School of Economics. The Government lured him from the World Bank, where he was chief economist, in 2003.
The Stern report recommends using carbon and other green taxes as part of a comprehensive response to global warming. Its most significant finding is that the cost of effectively fighting climate change is just 1 percent of GDP. Just 1 percent.
Mr Brown's proposed new air tax on 75% of of flights increases amount to just 0.1 per cent of GDP. From £5 ($A12) to £10.
Global Warning Climate Change Global Economy The Stern Report UK Carbon Tax