Earth Will Survive Global Warming, But Will We?

The notion that human activity, or the activity of any organism, can affect Earth on a planetary scale is still a hard one for many people to swallow. And it is this kind of disbelief that fuels much of the public skepticism surrounding global warming.

A poll conducted last summer by the Pew Research Center found that only 41 percent of Americans believe the burning of fossil fuels causes global warming. But in a meeting this week in Paris, officials from 113 nations have agreed that a highly anticipated international report will state that global warming was "very likely'' caused by human activity.

The idea that biology can alter the planet in broad and dramatic ways is widely accepted among scientists, and they point to several precedents throughout the history of life.