What is a 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 produces significant accumulations of snow
- temperatures throughout the rest of the year do not result in the complete loss of the previous winter’s snow accumulation
Over multiple decades this continuing accumulation of snow results in the presence of a large enough mass of snow for the metamorphism from snow to glacier ice process to begin. Glaciers are classified by their size (i.e. ice sheet, ice cap, valley glacier, cirque glacier), location, and thermal regime (i.e., polar vs. temperate). Glaciers are sensitive indicators of changing climate.
Learn more: USGS Water Science School: Glaciers and Icecaps
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Sculpted by water, elevated by earthquakes—The coastal landscape of Glacier Bay National Park, Alaska
Within Glacier Bay National Park in southeastern Alaska, the Fairweather Fault represents the onshore boundary between two of Earth’s constantly moving tectonic plates: the North American Plate and the Yakutat microplate. Satellite measurements indicate that during the past few decades the Yakutat microplate has moved northwest at a rate of nearly...
Witter, Robert C.; LeWinter, Adam; Bender, Adrian M.; Glennie, Craig; Finnegan, David
The United States National Climate Assessment - Alaska Technical Regional Report
The Alaskan landscape is changing, both in terms of effects of human activities as a consequence of increased population, social and economic development and their effects on the local and broad landscape; and those effects that accompany naturally occurring hazards such as volcanic eruptions, earthquakes, and tsunamis. Some of the most prevalent...
Markon, Carl J.; Trainor, Sarah F.; Chapin, F. Stuart; Markon, Carl J.; Trainor, Sarah F.; Chapin, F. Stuart
Fifty-Year Record of Glacier Change Reveals Shifting Climate in the Pacific Northwest and Alaska, USA
Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change. The USGS Benchmark Glacier Program began in 1957 as a result of research efforts...
A Century of Retreat at Portage Glacier, South-Central Alaska
Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (...
Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.
Satellite Image Atlas of Glaciers of the World
In 1978, the USGS began the preparation of the 11-chapter USGS Professional Paper 1386, 'Satellite Image Atlas of Glaciers of the World'. Between 1979 and 1981, optimum satellite images were distributed to a team of 70 scientists, representing 25 nations and 45 institutions, who agreed to author sections of the Professional Paper concerning either...
Williams, Richard S.; Ferrigno, Jane G.
Hubbard Glacier, Alaska: growing and advancing in spite of global climate change and the 1986 and 2002 Russell Lake outburst floods
Hubbard Glacier, the largest calving glacier on the North American Continent (25 percent larger than Rhode Island), advanced across the entrance to 35-mile-long Russell Fiord during June 2002, temporarily turning it into a lake. Hubbard Glacier has been advancing for more than 100 years and has twice closed the entrance to Russell Fiord during the...
Trabant, Dennis C.; March, Rod S.; Thomas, Donald S.
Satellite image atlas of glaciers of the world -- North America
Williams, Richard S.; Ferrigno, Jane G.
Global ice-core research: Understanding and applying environmental records of the past
One way to study Earth’s past environmental conditions is to look at ice cores recovered from glaciers. Every year a layer of snow accumulates on glaciers, like a page in a history book, and eventually turns to ice. Like reading the pages of a history book, analyzing the layers in a glacial ice core for specific chemical and physical components is...
Cecil, L. DeWayne; Green, Jaromy R.; Naftz, David L.
A strategy for monitoring glaciers
Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff. Assessing and predicting the effect of glaciers on water resources require a monitoring program to provide basic data for this understanding. The monitoring program of the U.S. Geological Survey employs a nested approach whereby...
Fountain, Andrew G.; Krimmel, Robert M.; Trabant, Dennis C.
Columbia Glacier, Alaska; research on tidewater glaciers
Krimmel, Robert M.
Glaciers Rapidly Shrinking and Disappearing: 50 Years of Glacier Change in Montana
The warming climate has dramatically reduced the size of 39 glaciers in Montana since 1966, some by as much as 85 percent, according to data released by the U.S. Geological Survey and Portland State University.
EarthView–As Glaciers Worldwide Are Retreating, One Defies the Trend
In this Landsat EarthView, one glacier in Chile bucks the global trend:
Fifty Years of Glacier Change Research in Alaska
ANCHORAGE, Alaska — This year marks the 50th anniversary of one of the longest continuous glacier research efforts in North America.
From Icefield to Ocean - What Glacier Change Might Mean for the Future of Alaska
Frozen bodies of ice cover nearly 10 percent of the state of Alaska, but the influence of glaciers on the environment, tourism, fisheries, hydropower, and other important Alaska resources is rarely discussed.
Rare Insect Found Only in Glacier National Park Imperiled by Melting Glaciers
The persistence of an already rare aquatic insect, the western glacier stonefly, is being imperiled by the loss of glaciers and increased stream temperatures due to climate warming in mountain ecosystems, according to a new study released in Freshwater Science.
Washington’s Benchmark Glacier Still Shrinking
TACOMA, Wash. — Washington’s only “benchmark” glacier continues to lose mass as a result of changes in climate, according to a report by the U.S. Geological Survey.
Glaciers Retreating in Asia
Many of Asia’s glaciers are retreating as a result of climate change.
Footloose Glaciers Crack Up
Glaciers that lose their footing on the seafloor and begin floating behave very erratically, according to a new study published in the journal Geophysical Research Letters. Floating glaciers produce larger icebergs than their grounded cousins and do so at unpredictable intervals.
Salazar Releases Long-Term Report Detailing Glaciers Shrinking in Alaska and Washington
A report on long-term glacier measurements released today by Secretary of the Interior Ken Salazar shows that glaciers are dramatically changing in mass, length and thickness as a result of climate change.
Most Alaskan Glaciers Retreating, Thinning, and Stagnating, Says Major USGS Report
Most glaciers in every mountain range and island group in Alaska are experiencing significant retreat, thinning or stagnation, especially glaciers at lower elevations, according to a new book published by the U.S. Geological Survey. In places, these changes began as early as the middle of the 18th century.
Decline of World's Glaciers Expected to Have Global Impacts Over This Century
The great majority of the world’s glaciers appear to be declining at rates equal to or greater than long-established trends, according to early results from a joint NASA and United States Geological Survey (USGS) project designed to provide a global assessment of glaciers. At the same time, a small minority of glaciers are advancing.
Alaskan Glaciers Yield Massive Floods
Torrents of meltwater are unleashed suddenly from the margins of the great moving sheets of snow and ice, known as glaciers. In Alaska, these pulses of activity, called "outburst floods," are usually caused by the failure of ice dams that restrain the meltwater of glacial margin lakes.
Endpoint of Mendenhall Glacier, Juneau, United States.
Glaciers: "Rivers" of Frozen Water
Even though you've maybe never seen a glacier, they are a big item when we talk about the world's water supply. Almost 10 percent of the world's land mass is currently covered with glaciers, mostly in places like Greenland and Antarctica. Glaciers are important features in the hydrologic cycle and affect the volume
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Image of the Week - New Rift on Greenland's Petermann Glacier
A new rift is forming across the Petermann Glacier. If this rift connects to existing rifts, it could result in another large iceberg breaking free.
At the USGS EROS Center, we study land change, operate the Landsat satellites, and maintain the longest, continuously acquired collection of images of the Earth's land surface.
USGS EROS Center (
Image of the Week - Pine Island Glacier’s Newest Iceberg
These Landsat 8 images show the latest iceberg to break free in Antarctica's Pine Island. Warmer ocean waters are melting the ice from beneath, causing increasing instability.
At the USGS EROS Center, we study land change, operate the Landsat satellites, and maintain the longest, continuously acquired collection of images of the Earth's land surface.
USGS
USGS Public Lecture: Warm Ice—Dynamics of Rapidly Changing Glaciers
- Glacier Numerology – The how big, how long, how thick, how much, how often, of glacier science.
- Glacier Photography – While a picture may be worth a thousand words, a collection of images may tell a complete forensic story.
- Glacier Geophysics – How new technologies are being introduced to reexamine and refine decades old glacier analyses.
Monitoring glaciers in Glacier National Park.
Monitoring glaciers in Glacier National Park.
Petermann Glacier
Located on the northwestern coast of Greenland, Petermann Glacier covers 1,295 square kilometers (500 square miles). The glacier's floating tongue of ice extends from the lower right corner of the image toward the top center. At 15–20 kilometers (9–12 miles) wide and 70 kilometers (43 miles) long, it is the longest floating glacier in the Northern Hemisphere. Infrared
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Getting the Shot, Grinnell Glacier, Glacier National Park.
USGS scientist shoots a repeat photograph of Grinnell Glacier in Glacier National Park to illustrate glacial recession due to impacts of climate change.
*note – logo on scientists hat is logo from USGS Northern Rocky Mountain Science Center, not private.
USGS Public Lecture Series: Baked Alaska--What's Happening to the Glaciers in Alaska?
Glaciers are Earth's largest reservoir of freshwater. As they change, so does global sea level. Alaska has one of the largest accumulations of glaciers anywhere on Earth outside of the Polar regions. For most of the past half century, Alaska has experienced a significant increase in temperature that has profoundly impacted its glaciers. Join USGS scientist Dr. Bruce F.
Surprise Glacier
Surprise Glacier (in background), Harriman Fiord, western Prince William Sound.
Bear Glacier
Oblique aerial photograph that shows the terminus of Bear Glacier, Kenai Mountains, Kenai Fjords National Park, Alaska.