A new report has painted one of the direst pictures of global warming yet seen. Prepared by Sir Nicholas Stern, the World Bank's former chief economist, the 700 page analysis projects that the economic losses from climate change could cost as much as $ 7 trillion, or 20% of the world's GDP.

"Whilst there is much more we need to understand - both in science and economics - we know enough now to be clear about the magnitude of the risks, the timescale for action and how to act effectively," Sir Nicholas said.

The report implicitly supports an analysis by PricewaterhouseCooper that places the cost of a 60% reduction in emission by 2050 as being one year's economic growth. Taken together, the two reports make an inarguable business case, if not human imperitive, for sustainable world climate policy.

Tony Blair has responded with strong words and promises of renewed leadership on the issue. His Environmental Secretary David Miliband has already pledged a new climate law, and today finance minister Gordon Brown announced a raft of new green initiatives including the hiring of Al Gore as an environmental advisor.

The British government's formal policy agenda for the coming year will be announced during the annual Queen's speech on November 15th.