NCAR

A solar eclipse might darken the day for minutes, but 65 million years ago the sun may have disappeared for 18 months. New simulations show that atmospheric particles would have blocked sunlight, disrupting plants' photosynthesis and cascading into a mass extinction event.

Arctic temperatures in the 1990s reached their warmest level in 2,000 years, new research indicates. The study provides new evidence that the Arctic would be cooling if not for greenhouse gas emissions that are overpowering natural climate patterns.