What do you think of when you hear the words "global warming?" You might envision melting ice caps, drowning polar bears and shrinking coast lines. Or perhaps your mind turns to magazine covers, politicians and celebrity activists. Global warming has become a very divisive term, but is it real?
The short answer, according to environmental scientist David Keith, is yes.
"There is no disagreement among really anybody who is scientific in any way that the world is a lot warmer than it was 100 years ago," Keith says. "If there are interesting disagreements, the disagreements are about whether this is the warmest it's been since the ice ages 10,000 years ago."
A recipient of honors that include MIT's prize for excellence in experimental physics, Keith has spoken to governments, corporations and media outlets about climate change. As he points out, scientists use various methods to measure global warming; they produce varying answers.
"If all the scientists in the world believed there was only one answer, it would be right for all the rest of us to be skeptical," Keith said. "There's nothing in the world that one ever measures with perfect accuracy."