Frequently Asked Questions

Climate and Land Use Change

USGS science helps communities understand the implications of change, anticipate the effects of change, and reduce the risks associated with a changing environment.

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lone road lined by palm trees on a small flat island, with water from the sea washing over the road
There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Learn more: USGS Water Science School: Glaciers and Icecaps National Snow and Ice Data Center: Facts about...
Erosion and climate change along Alaska's Arctic Coast
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 glaciers also affects downstream water temperatures. Many aquatic species in mountainous...
Repeat oblique photographs of Wolverine glacier in Alaska.
“Benchmark Glacier” refers to four North American glaciers that have been selected for long-term glacier monitoring that investigates climate, glacier geometry, glacier mass balance, glacier motion, and stream runoff. Benchmark glaciers monitored by the USGS are: Gulkana Glacier and Wolverine Glacier in Alaska South Cascade Glacier in Washington...
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
In addition to qualitative methods like Repeat Photography, USGS scientists collect quantitative measurements of glacier area and mass balance to track how some glaciers are retreating (Glacier Monitoring Studies). For example, ablation stakes show the seasonal gain and loss of snow, snow-pit analyses measure density of snow, and precision GPS...
Image: Getting the Shot, Grinnell Glacier, Glacier National Park.
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. Below this size, ice is generally stagnant and does not have enough mass to move.
Image: Surprise Glacier
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 areas where: mean annual temperatures are close to the freezing point winter precipitation...
El Nino map
The term El Niño (Spanish for 'the Christ Child') refers to a warming of the ocean surface (or above-average sea surface temperatures) in the central and eastern tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other...