Will Earth's Ocean Boil Away?
Yes—a billion years from now, as the sun gets brighter. But could we make it happen sooner through climate change?
The key to the argument is a well-documented positive feedback loop. As carbon dioxide warms the planet through the greenhouse effect, more water evaporates from the ocean—which amplifies the warming, because water vapor is a greenhouse gas too. That positive feedback is happening now. Hansen argues that fossil-fuel burning could cause the process to run out of control, vaporizing the entire ocean and sterilizing the planet.
Respected as Hansen is, the argument hasn't convinced climate scientists who specialize in the evolution of planetary atmospheres. During the Paleocene-Eocene Thermal Maximum (PETM), 56 million years ago, a huge natural spike in CO2 sent temperatures on Earth soaring—but life went on and the ocean remained intact.
"I think you can say we're still safe
