A collection of repeat photography of glaciers from the National Snow and Ice Data Center (NSIDC). The photos are taken years apart at or near the same location, and at the same time of year. These images illustrate how dramatically glacier positions can change even over a relatively short period in geological time: 60 to 100 years. Background essay and discussion questions are included.

Global Forest Watch is an interactive, online forest monitoring and alert system that provides users globally with the information they need to better manage and conserve forest landscapes.

This applet is an ocean acidification grapher that allows user to plot changes in atmospheric C02 against ocean pH, from 1988 to 2009, in the central North Pacific.