An increase of one degree Fahrenheit in average global temperature sounds innocuous enough. Daily high and low temperatures can fluctuate far more than that on an average day. However, changes to global averages can alter conditions that most of us take for granted. This interactive activity adapted from materials from the Wright Center for Science Education at Tufts University describes how climatologists obtain and interpret evidence from the Greenland Ice Sheet in an effort to piece together a picture of Earth's distant climate history.