Polar bear declared "threatened," but Secretary limits decision's impact.

A kilometers-long ice core from Antarctica has been recording climate information for the past 800,000 years and has revealed a three millennia–long period when carbon dioxide levels in the air were lower than any previously measured.

Monster data crunch strengthens case that climate is disrupted.

The Sahara, one of the hottest and driest regions on Earth, gradually became arid over a period of centuries, a finding that contradicts many previous studies.

In lab simulations of future ocean conditions, brittle stars grow extra-calcified but puny arms.

“New Orleans, at the end of the century, will be an island” — literally, predicts Bruce Babbitt. Whether or not you believe his assessment, he makes a good case for considering the implications of climate change when planning federal projects.

Fossil-fuel pollution has been offsetting global warming to the tune of about 30 percent per year. Cleaning up that pollution, a must, threatens to accelerate warming unless humanity changes its fuel-use strategy.