Part 2. Exploring Scientific Evidence and Evaluating Choices

What other evidence suggests global warming?

Mountain glaciers

There are other indicators suggesting that the earth is warming. Mountain glaciers can be used as indicators of long term average temperatures because they accumulate or lose ice only very slowly in response to long term temperature changes. Old paintings, sketches, and geological debris left by glaciers indicate of glacier sizes at various times in the past. A measure of long-term warming or cooling in the region of a mountain glacier is the location in the mountain valley of the terminus or lower end of the glacier. If the glacier extends far down the valley (advancing), the climate has been cooling; if the terminus is far up the mountain valley (retreating), the climate has been warming. The graph below shows that all eight glaciers reported show retreat in the past several years, and the rate of retreat (terminus moving up the valley) is increasing in later years.

Adapted from IPCC, 364pp (1990).

Click on the image below to continue exploring other evidence, or click on the back button to Part 2: Advanced Information on the Evidence of Global Warming