Yosemite’s glaciers have been the subject of study since John Muir first confirmed their presence in 1871. Since that time, many scientists have returned to the glaciers to document their condition and observe changes in the ice. This animation brings together more than 130 years of data to show the retreat of Yosemite's two remaining glaciers, the Lyell and Maclure, from 1883 to 2015. Note how the drought and warm temperatures of the past four years have greatly accelerated their retreat. This winter's near-average snowfall is a welcome change, but even a major snowfall year like 2011 (178% of average) does not add substantial mass to these glaciers—it only slows their retreat.
Check out the retreat of the Maclure and Lyell glaciers from 1883 to 2016 animation near the bottom of the page.