Sierra Glacier Update, 26" H x 30" Embroidery on silk & velvet

Glaciers provide the most visible evidence of climate change. In California, most glaciers are found in the Sierra Nevada above 10,000 feet in elevation, from Yosemite National Park in the north to Sequoia National Park in the south.

The surface area of seven Sierra Nevada glaciers has decreased dramatically since the beginning of the twentieth century. The graph shows the fraction of the area of these glaciers relative to the year 1903. These glaciers are among the largest at higher elevations for which data are available. Historical photographs and field measurements were used to estimate the surface area of each glacier.

Between the early 1900s and 2014, some of the largest Sierra Nevada glaciers lost an average of 70 percent of their surface area. The glacier retreat in the Sierra Nevada occurred during extended periods of above-average spring and summer temperatures.

The magnitude and rate of change in surface area are variable among the seven Sierra Nevada glaciers. These differences suggest that factors other than regional climate influenced these changes. For example, structural features such as cliffs can protect against loss by shading solar radiation, and avalanching from cliffs can enhance snow accumulation on a glacier.

The observations in the Sierra Nevada are consistent with the loss of glacier mass reported worldwide.