But there are also powerful voices being raised amid the din of despair, saying that now is precisely the time to seize the initiative and launch the “global revolution” the IEA is calling for. And not just because it will stave off disasters two or three decades away, but also because it can provide the impetus to pull the global economy out of the slump it’s in now and put it on a more solid foundation than it’s had in at least a generation. British Prime Minister Gordon Brown and French President Nicolas Sarkozy have already taken up the cause. United Nations Secretary-General Ban Ki-moon last month called for a “Green New Deal” that would rebuild and reshape the economy of planet Earth in ways reminiscent of the programs that President Franklin Roosevelt used to revitalize the economy of the United States during the Great Depression. Indeed, even as the slowing economy and falling oil prices make it harder to justify huge new investments in a green economy, there’s a strong counterargument that now is precisely the time to make them.

The world, simply put, needs a new economic driver. Proponents of a Green New Deal argue that massive public investments can lay the groundwork for the private sector to develop whole new industries and create millions of jobs in the near term — and oh, by the way, save the planet in the medium term. “You are not just putting money into hot paper or into a financial-services sector that destroys itself,” says Oliver Schäfer, policy director of the European Renewable Energy Council. “You are investing in clean technology, which is real business.”