Andrew C. Revkin

About the author: Andrew C. Revkin is a staff writer for the New York Times.

The recent melting of mountain glaciers indicates that contemporary global warming is largely the result of human activity. Although natural climatic changes are partly responsible for the rise in average temperatures over the past century, the current rate of glacial erosion suggests that higher levels of greenhouse gases— resulting from pollution—are contributing significantly to global warming. Glacial melting could lead to damaging flash floods in some locales. Other regions that depend on melting snow for hydroelectric power could run low on water after glaciers have disappeared, requiring more communities to use pollution-creating oil or coal for energy—which in turn would produce more greenhouse gases and more global warming.

The icecap atop Mount Kilimanjaro...