Mystery Craters

In recent years, mysterious craters have appeared in the Russian province of Siberia. Some are more than 1 kilometer (0.6 miles) wide and 85 meters (278 feet) deep. Scientists suspect the giant holes might be caused by thawing permafrost.

Permafrost is soil that stays frozen for years. Parts of Siberia have been frozen for 100,000 years, but climate change is thawing them out. Craters may form when large pockets of buried ice melt, causing soil above the ice to collapse. Another possibility is that methane gas frozen in the soil may explode as it thaws, says ecologist Ben Abbott of Brigham Young University. Methane is a powerful greenhouse gas. As it’s released from the soil into the atmosphere, it traps heat, causing more warming.