This video describes the role that dendrochronology plays in understanding climate change, especially changes to high elevation environments at an upper tree line. Dendrochronologists from the Big Sky Institute sample living and dead trees, describe how correlations between trees are made, and explain how tree cores record climate changes.

This short video, adapted from NOVA, explains how Earth's position relative to the Sun might be responsible for the dramatic shift in the climate of what is now the Saharan nation of Djibouti.