Some of the most beautiful natural features on Earth -- glaciers -- are changing right before our eyes. Many glaciers look remarkably different today than they did even 100 years ago. For those of you interested in monitoring these changes, wouldn’t it be nifty to have photographs of the same glacier, taken from the same vantage point and at the same time of year, but taken many years apart? Well, we’ve got a whole collection of them, featuring 45 sets of repeat photographs of glaciers taken from 1880 to 2009 in the USA, Peru, and Australia. This unique collection of photographs provides striking visual evidence of glacier changes over climatological time scales. To browse and download the photos, visit the NSIDC Glacier Photograph Collection. In the ordering interface, make sure that “Repeat glacier photography” is selected under the “Search Type” drop-down list. Additionally, if you’re looking for teaching materials that use these photographs, check out the classroom activity created by UCAR’s Spark.