Global Change

Paleontologists now have evidence that dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago) the continents we now know were arranged together as a single...
A glacier is a large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope under the influence of its own weight and gravity. Typically, glaciers exist and may even form in...
Not specifically. Our charge is to understand characteristics of the earth, especially the earth's surface, that affect our Nation's land, water, and biological resources. That includes quite a bit of environmental monitoring. Other agencies, especially...
Definitions of often used glaciology and glacial geology terms can be found at the USGS Glacier Photoglossary Web site.
While there is no global standard for what size a body of ice must be to be considered a glacier, USGS scientists in Glacier National Park use the commonly accepted guideline of 0.1 square kilometers (about 25 acres) as the minimum size of a glacier....
No, it does not. The term actually refers to changes in the position of the glacier’s terminus over a period of time. Like water, ice flows down its surface gradient and never goes back up valley. Retreat occurs when melting or calving removes ice more...
In addition to qualitative methods like Repeat Photography. USGS scientists in Glacier National Park collect quantitative measurements of glacier area and mass balance to track how some of the park’s glaciers are retreating (Glacier Monitoring Studies)....
The term “Benchmark Glaciers” refers to three North American glaciers that have been selected to be the subjects of a long-term glacier monitoring program which investigates climate, glacier geometry, glacier mass balance, glacier motion, and stream...
Repeat photographs provide a good way to see how Alaska's glaciers are changing. Muir and Riggs glaciers, 1950 and  Muir and Riggs glaciers, 2004.Learn more: Glaciers of  North America - Glaciers of Alaska
Glaciers act as reservoirs of water that persist through summer. Continual melt from glaciers contributes water to the ecosystem throughout dry months, creating perennial stream habitat and a water source for plants and animals. The cold runoff from...