To match the growing global demand for energy, "we'd need 10,000 of our current 1-gigawatt reactors, and that means we'd have to build one every other day somewhere in the world for the next 50 straight years. … It isn't going to happen," he said. Besides, there isn't enough uranium to run all those power plants, so they would have to run on plutonium, the stuff that nuclear bombs are made of.
We hear a lot about pumping carbon dioxide back into the ground, and "sequestering" it so we can continue to burn fossil fuels. We might be able to do that, but if just one-tenth of 1 percent leaks out of the reservoirs, that would wipe out all the progress on the drawing boards for reducing greenhouse gases.
"We know that CO2 migrates underground," Lewis said. "It bubbled up in Lake Nyos, Cameron, on Aug. 26, 1986, and killed some 1,700 people. So we're going to have to demonstrate within the next 10 years that it will leak less than 0.1 percent, globally averaged, for the next millennium in thousands of different aquifers around the world."
"It's cheap, it's abundant, and we've pretty much maxed it out."
OK, so we've got a problem. But what's the rush? Don't we have a few decades to work things out?
Lewis is part of a growing number of scientists who believe we've overlooked a few things when it comes to estimating just how quickly the globe's climate is likely to change.
He cites permafrost, the upper latitude soils that are supposed to remain permanently frozen, as one example.
"As the ice crystals in it melt, it reflects less light and turns darker, absorbing more light, and that melts more permafrost. Helium dating of trapped bubbles in the permafrost shows that we're melting permafrost now that hasn't been melted in 40,000 years. And there's enough CO2 and methane trapped in the permafrost to have the greenhouse gas levels not go up by a factor of two, but by a factor of 10."
So if we stay on the current course, the problem could be much worse than current projections.
My guess is nobody has ever accused Lewis of sounding like a preacher. But there is something messianic in his comments these days. He began his talk to the Caltech symposium with these words:
"Energy is the single most important technological challenge facing humanity today. Nothing else in science or technology comes close in comparison. … "
"With energy, we are in the middle of doing the biggest experiment that humans will have ever done. And there is no tomorrow, because in 20 years that experiment will be cast in stone. If we don't get this right, we can say as students of physics and chemistry that we know that the world will, on a time scale comparable to modern human history, never be the same."