Observing temperature patterns in the lower stratosphere gives scientists clues about our planet’s changing climate. Global average temperatures in the lower stratosphere for 2013 were slightly below the 1981–2010 average.  

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?

Among the questions triggered by the entrapment of a Russian ship near Antarctica on Christmas Eve were whether the ice conditions were out of the ordinary, and, if so, whether long-term climate change was playing a role.

In the Arctic, an ocean is surrounded by continents, while Antarctica is continent surrounded by oceans. These differences in the arrangement of land and water contribute to differences in each polar region’s climate, oceanic and atmospheric circulation patterns, and seasonal and long-term sea ice patterns.

The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on September 12, stretching 10.05 million square miles, the ninth largest on record. Above the...