USGS Contributions to the Climate Change Science Program

Glaciers are particularly sensitive to changes in regional and global climate. Seasonal changes in sea ice and snow cover and decadal changes in glacier area can be monitored regionally and globally with image data from Earth-orbiting satellites. The U.S. Geological Survey has played a leading national and international role in using satellite image data to provide baseline data and other information about glaciers from a global perspective. NASA and USGS scientists are also carrying out experimental geodetic airborne, satellite laser altimetry, radar interferometric, and other remote-sensing surveys of glaciers. The 11-volume Satellite Image Atlas of the World (USGS Professional Paper 1386 A-K) is being compiled by more than 80 scientists representing 45 institutions and 25 nations, and includes a compilation of accurate maps (in both printed and digital formats) which show coastal changes in floating (ice fronts) and grounded (ice walls) glacier ice during the past 30 years. Seven volumes have been published to date: B, Antarctica; C, Greenland; E, Glaciers of Europe; G, Glaciers of the Middle East and Africa; H, Glaciers of Irian Jaya, Indonesia, and New Zealand; I, Glaciers of South America; and J, Glaciers of North America.

The world's glaciers react to and interact with changes in global and regional climates. Most mountain glaciers have been retreating since the latter part of the 19th century.

Grinnell Glacier in Glacier National Park, Montana; photograph by Carl H. Key, USGS, in 1981. The glacier has been retreating rapidly since the early 1900's. The arrows point to the former extent of the glacier in 1850, 1937, and 1968. Mountain glaciers are excellent monitors of climate change; the worldwide shrinkage of mountain glaciers is thought to be caused by a combination of a temperature increase from the Little Ice Age, which ended in the latter half of the 19th century, and increased greenhouse-gas emissions.

USGS scientists are closely monitoring glaciers in Alaska to document if climate change is impacting Alaska's temperate glaciers. The USGS assessment shows that throughout the state, more than 98% of valley glaciers that terminate at an elevation below 1,000 m are retreating, thinning, or stagnating. Since 1986, Hubbard Glacier, one of the few advancing glaciers, has twice temporarily blocked the entrance to Russell Fiord. Glaciers and ice sheets are sensitive indicators of changing climate. On a global basis, the USGS is combining field observations with satellite- and aerial-remote-sensing to compile a baseline inventory of the health of Earth's glaciers during the first decade of Landsat, 1972-1981. This compilation serves as a benchmark for documenting cryosphere change on a global scale. Additionally, the USGS has produced the longest glacier mass balance record in North America. This forty-year-long record has provided a unique record of glacier response to climate variations in the latter half of the 20th century. The South Cascade Glacier in Washington, one of the USGS monitoring sites, has dramatically retreated, losing 20 m of water equivalent averaged over the entire surface of the glacier since the mid 1970's.