How long can we expect the present Interglacial period to last?

No one knows for sure. In the Devils Hole, Nevada, paleoclimate record, the last four interglacials lasted over ~20,000 years with the warmest portion being a relatively stable period of 10,000 to 15,000 years duration. This is consistent with what is seen in the Vostok ice core from Antarctica and several records of sea level high stands. These data suggest that an equally long duration should be inferred for the current interglacial period as well. Work in progress on Devils Hole data for the period 60,000 to 5,000 years ago indicates that current interglacial temperature conditions may have already persisted for 17,000 years. Other workers have suggested that the current interglacial might last tens of thousands of years.

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How many glaciers currently exist in Alaska?

Based on the most recent comprehensive survey in 2011, there were about 27,000 glaciers in Alaska. However, the number of glaciers is a misleading statistic. Scientists are more interested in total glacial land coverage as a measure. The number of glaciers is less important since large ones can split up into several as they retreat. The amount of...

How old is glacier ice?

The age of the oldest glacier ice in Antarctica may approach 1,000,000 years old The age of the oldest glacier ice in Greenland is more than 100,000 years old The age of the oldest Alaskan glacier ice ever recovered (from a basin between Mt. Bona and Mt. Churchill) is about 30,000 years old. Glacier flow moves newly formed ice through the entire...

Was all of Alaska covered by glaciers during the Pleistocene Ice Age?

No--most of interior Alaska, south of the Brooks Range and north of the Alaska Range, was a non-glaciated grassland refuge habitat for a number of plant and animal species during the maximum Pleistocene glaciation. This ice-free corridor also provided one route for humans to move into North America.

Are today's glaciers leftovers from the Pleistocene ice age?

Yes and no. It depends on which glaciers you are considering. Parts of the Antarctic Continent have had continuous glacier cover for perhaps as long as 20 million years. Other areas, such as valley glaciers of the Antarctic Peninsula and glaciers of the Transantarctic Mountains may date from the early Pleistocene. For Greenland, ice cores and...

Is glacier ice a type of rock?

Yes – glacier ice, like granite, is a type of rock. Glacier ice is actually a mono-mineralic rock (a rock made of only one mineral, like limestone which is composed of the mineral calcite). The mineral ice is the crystalline form of water (H 2 O). It forms through the metamorphism of tens of thousands of individual snowflakes into crystals of...

Why is glacier ice blue?

Because the red (long wavelengths) part of white light is absorbed by ice and the blue (short wavelengths) light is transmitted and scattered. The longer the path light travels in ice, the more blue it appears.

How much of the Earth's water is stored in glaciers?

About 2.1% of all of Earth's water is frozen in glaciers. 97.2% is in the oceans and inland seas 2.1% is in glaciers 0.6% is in groundwater and soil moisture less than 1% is in the atmosphere less than 1% is in lakes and rivers less than 1% is in all living plants and animals. About three-quarters of Earth's freshwater is stored in glaciers...

How does present glacier extent and sea level compare to the extent of glaciers and global sea level during the Last Glacial Maximum (LGM)?

The Last Glacial Maximum (LGM) occurred about 20,000 years ago, during the last phase of the Pleistocene epoch. At that time, global sea level was more than 400 feet lower than it is today, and glaciers covered approximately: 8% of Earth’s surface 25% of Earth’s land area 33% of Alaska Beginning about 15,000 years ago, continental glaciers...

How would sea level change if glaciers melted?

If all of the glacier ice on Earth were to melt, sea level would rise ~ 80 m (~ 265 ft), flooding every coastal city on the planet. If all of Earth’s temperate glaciers melted, sea level would rise ~ 0.3–0.6 m (~ 1-2 ft). If all of Greenland’s glaciers melted, sea level would rise ~ 6 m (~ 20 ft). If all of Antarctica’s glaciers melted, sea level...

Is there a size criterion for a glacier?

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.

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...
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Date published: May 10, 2017

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.

Date published: September 28, 2016

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.

Date published: March 18, 2015

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.

Date published: January 20, 2015

Melting Glaciers Increase the Flow of Carbon to Downstream Ecosystems

ANCHORAGE, Alaska Melting glaciers are not just impacting sea level, they are also affecting the flow of organic carbon to the world’s oceans, according to new research that provides the first ever global-scale estimates for the storage and release of organic carbon from glaciers.

Date published: August 25, 1995


Greenland’s inland glacier ice -- covering a combined area larger than Alaska and Oregon and the largest remnant of the last "Ice Age" in North America -- is described and illustrated in the latest chapter in the U.S. Geological Survey’s (USGS) "Satellite Image Atlas of Glaciers of the World."

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Glacier off Sargent Icefield
December 31, 2017

Glacier off Sargent Icefield

Landscape view of an un-named glacier off the Sargent Icefield, directly across from Wolverine Glacier, above the Nellie Juan River, in Alaska. Taken during a visit to a wolverine glacier field site as part of a study to examine how alpine areas are changing as temperatures rise in Alaska. 

July 27, 2017

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.
South Crillon Glacier
June 5, 2016

South Crillon Glacier

Periodic calving of ice from the snout of South Crillon Glacier.

This is a glacier animation for Glacier National Park.
April 5, 2016

Glacier Animation

The simulation below reflects the predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 "global warming" scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent (based on the

Monitoring glaciers in Glacier National Park.
April 5, 2016

Monitoring glaciers in Glacier National Park.

Monitoring glaciers in Glacier National Park.

August 6, 2009

The Cold Facts About Melting Glaciers

Most glaciers in Washington and Alaska are dramatically shrinking in response to a warming climate.

USGS scientist Edward Josberger discusses research from the past 50 years to measure changes in the mass (length and thickness) of three glaciers in Alaska and Washington. These are the longest such records in North America and among the longest in the world.

Image: Barry Glacier
August 20, 2008

Barry Glacier

Barry Glacier, Barry Arm, western Prince William Sound.

Tidewater glaciers of south-central Alaska
November 30, 2000

Tidewater glaciers of south-central Alaska

Present-day tidewater glaciers of south-central Alaska can be found in Prince William Sound and southern Kenai Peninsula. Icebergs form as portions of the glacier terminus collapses. Modern tidewater glaciers in Alaska are very small in comparison with massive glaciers that reached the sea during full glacial time. 

Image: Muir and Riggs Glaciers, Muir Inlet, Alaska - 1941
August 13, 1941

Muir and Riggs Glaciers, Muir Inlet, Alaska - 1941

This northeast-looking photograph, on the southeastern side of White Thunder Ridge ,shows the lower reaches of Muir Glacier, then a large tidewater calving valley glacier, and its tributary Riggs Glacier. The séracs in the lower right-hand corner of the photograph mark Muir Glacier’s terminus. The ice thickness is more than 700 meters. Muir Glacier had been retreating