Area of glaciers
Median annual temperature
Mexico has about a dozen glaciers situated atop active volcanoes, such as the Popocatépetl and Iztaccihuatl. If they were to erupt, the melt could bring heavy debris flows or mudflows, posing a very serious hazard in populated areas. In 1964, the glacier on the north side of Popocatépetl was estimated to be 600 m long and cover 0.2 km². As of 2006, the Popocatépetl glacier, Glaciar Norte, was declared extinct due to thinning caused by increased volcanic activity, the Iztaccíhuatl glacier has been given only a few years left. The most critical effects of glacier extinction in Mexico are on the population who depend on the rivers and lakes for water supply.