Questions from visitors to the Earth Observatory and answers from scientists.

Alpine glaciers are a good indicator of climate change. If the climate is getting warmer or drier, they will shrink. If it is getting colder or wetter, they tend to grow.

12 months of high-resolution global true color satellite imagery.

In the summer of 2002, graduate student Derek Mueller made an unwelcome discovery: the biggest ice shelf in the Arctic was breaking apart

Newly available upward-looking sonar shows significant decreases in sea ice thickness in recent decades.

Russian scientists mapped Mount Kazbek in the Caucasus Mountains, site of a massive glacial collapse, and used satellite data to assess the possibility of additional dangers.