(See "Global Warming 'Marches On'; Past Decade Hottest Known.")

No matter what we do to fight global warming, at least 6 percent of lizard species will go extinct by then, due to the greenhouse gases already in the atmosphere, the study says.

"We've committed ourselves to 6 percent," said lead study author Barry Sinervo, a herpetologist at the University of California, Santa Cruz. "That's our fault, and there's nothing we can do."

And those percentages are conservative, Sinervo said. For example, the study doesn't account for threats such as competition between lizard species or the effects of global warming-caused water shortages.

(Also see "New Giant Lizard Discovery 'an Unprecedented Surprise.'")

The study team calculated extinction risks for more than a thousand lizard