Like a prehistoric fly trapped in amber during dinosaurs' days, airborne relics of Earth's earlier climate can end up trapped in glacial ice for eons. How do climate scientists turn those tiny relics into a story about Earth's ancient climate?

In October 2003, a little-known think tank in the Department of Defense quietly released a report warning that climate change could happen so suddenly it could pose a major threat to our country's national security. Why was the Pentagon worried about abrupt climate change? Because new evidence from Greenland showed it had happened before. 

The current drought in the Southwest is not drier or longer-lasting than historic episodes documented in tree rings, but the current dry conditions stand out from the historical record by being hotter, according to Jonathan Overpeck, professor of geosciences at the University of Arizona.

Carbon dioxide is everywhere: in the air, rising from cracks in the ocean floor, and in your soda can. Now it's showing up in the news! Find out why carbon dioxide is such a hot topic, and why it's going to be around for a long, long time.

Richard Feely discusses new findings about how increased carbon dioxide in the atmosphere is making the oceans more acidic, and how that will affect ocean ecosystems and the marine animals that inhabit them.

This visualization shows in five steps how ice cores provide a measure of the temperature in the past.

This is a lab about evidence for past climate change as captured in ice sheets of Greenland and Antarctica. Students investigate climate changes going back thousands of years by graphing and analyzing ice core data from both Greenland and Antarctica. They use information about natural and human-caused changes in the atmosphere to formulate predictions about Earth's climate.

sea-surface height from satellite data

Forecasters are still calling for a 65% chance of El Nino conditions being met in the next few months. Isn't this late for the start of an ENSO event?