Brrr! What Global Warming?

What harm man can do, nature can undo -- at least for a while. While the alumni of the Rio environment conference undertake complex schemes to combat global warming, scientists are finding that Mother Nature is quietly applying her own highly efficient methods.

Since the Industrial Revolution, gases like carbon dioxide and methane have been wafting into the atmosphere, where they let the sun's rays in to warm the earth but keep excess heat from escaping back into space. Acting like the glass walls of a greenhouse, these gases have forced the planet's temperature up 0.8 degreesC (1.5 degreesF) over the...