Some 3 million years ago, when the earth was a little more than 3°C warmer than preindustrial levels (about 2.2°C warmer than today), Antarctica had far less ice and sea levels were a stunning 25 meters higher than today. If we stay on our current emissions path, the planet will almost certainly be that warm by the century's end.

Protecting dozens of major coastal cities from future flooding will be challenging enough-rebuilding major coastal cities destroyed by super-hurricanes will be an almost impossible task.

The science is crystal clear: we humans are the primary cause of global warming, and we face a bleak future if we fail to act quickly.

If our government won't spend the money to protect New Orleans sufficiently today, what are the chances we will spend the money to protect dozens of coastal cities post-2050, once everyone knows that sea levels will keep rising and intense hurricanes will occur relentlessly?

If the politics of inaction and delay that have triumphed in this country continues for another decade, then Planetary Purgatory in the likely future facing our country before midcentury - probably in your own lifetime.

The entire western Siberian sub-Arctic region is melting, and it has all happened in the last three or four years.

The world beyond 450 ppm atmospheric concentrations of carbon dioxide, the world that crosses carbon cycle tipping points that quickly take us to 1000 ppm, is a world not merely of endless regional resource wars around the globe. It is a world with dozens of Darfurs. It is a world of a hundred Katrinas, of countless environmental refugees