This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
What is a Benchmark Glacier?
“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
- Sperry Glacier in Montana
Learn more:
Related Content
Does the USGS monitor global warming?
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 NOAA and NASA, are specifically funded to monitor global temperature and atmospheric phenomena such as ozone concentrations. The work through...
What is the difference between global warming and climate change?
Although people tend to use these terms interchangeably, global warming is just one aspect of climate change. “Global warming” refers to the rise in global temperatures due mainly to the increasing concentrations of greenhouse gases in the atmosphere. “Climate change” refers to the increasing changes in the measures of climate over a long period of time – including precipitation, temperature, and...
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 related data suggest that all of southern Greenland and...
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 area glaciers occupy in Alaska is trending downward...
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 length of a typical Alaskan valley glacier in 100...
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. Learn more: USGS Water Science School - Glaciers: Things to Know
Is glacier ice a type of rock?
Glacier ice, like limestone (for example), 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). Most glacier ice forms through the metamorphism of tens of thousands of individual snowflakes into crystals of glacier ice. Each snow flake is...
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. Therefore, glacier ice is the second largest reservoir...
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 retreated and sea level began to rise. Sea level reached...
How would sea level change if all glaciers melted?
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 Glaciers U.S. Global Change Research Program: Sea...
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. Learn more: Status of Glaciers in Glacier National Park
Sperry Glacier perimeter: 1966,1998, 2005, 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
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 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.
PubTalk 8/2011 — Through the Lens of Time
Repeat Photography in an Era of Global Change
by Robert Webb, Hydrologist
Repeat Photography in an Era of Global Change
by Robert Webb, Hydrologist
Repeat oblique photographs of Gulkana glaciers in Alaska.
Repeat oblique photographs of Gulkana glaciers in Alaska. 1967, Unknown USGS photographer. 2016, L. Sass, USGS.
Repeat oblique photographs of Gulkana glaciers in Alaska. 1967, Unknown USGS photographer. 2016, L. Sass, USGS.
Repeat oblique photographs of Wolverine glacier in Alaska.
Repeat oblique photographs of Wolverine glacier in Alaska. 1966 image by unknown USGS photographer; 2015 image by L. Sass, USGS.
Repeat oblique photographs of Wolverine glacier in Alaska. 1966 image by unknown USGS photographer; 2015 image by L. Sass, USGS.
1928 South Cascade Glacier
1928 black-and-white oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately southeast.
1928 black-and-white oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately southeast.
1958 South Cascade Glacier
1958 black-and-white vertical aerial photo of South Cascade Glacier, northwestern Washington State. Top of photo is south.
1958 black-and-white vertical aerial photo of South Cascade Glacier, northwestern Washington State. Top of photo is south.
2006 South Cascade Glacier
2006 oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately south-southeast.
2006 oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately south-southeast.
Related Content
- FAQ
Does the USGS monitor global warming?
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 NOAA and NASA, are specifically funded to monitor global temperature and atmospheric phenomena such as ozone concentrations. The work through...
What is the difference between global warming and climate change?
Although people tend to use these terms interchangeably, global warming is just one aspect of climate change. “Global warming” refers to the rise in global temperatures due mainly to the increasing concentrations of greenhouse gases in the atmosphere. “Climate change” refers to the increasing changes in the measures of climate over a long period of time – including precipitation, temperature, and...
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 related data suggest that all of southern Greenland and...
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 area glaciers occupy in Alaska is trending downward...
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 length of a typical Alaskan valley glacier in 100...
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. Learn more: USGS Water Science School - Glaciers: Things to Know
Is glacier ice a type of rock?
Glacier ice, like limestone (for example), 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). Most glacier ice forms through the metamorphism of tens of thousands of individual snowflakes into crystals of glacier ice. Each snow flake is...
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. Therefore, glacier ice is the second largest reservoir...
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 retreated and sea level began to rise. Sea level reached...
How would sea level change if all glaciers melted?
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 Glaciers U.S. Global Change Research Program: Sea...
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. Learn more: Status of Glaciers in Glacier National Park
- Multimedia
Sperry Glacier perimeter: 1966,1998, 2005, 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
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 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.
PubTalk 8/2011 — Through the Lens of TimeRepeat Photography in an Era of Global Change
by Robert Webb, Hydrologist
Repeat Photography in an Era of Global Change
by Robert Webb, Hydrologist
Repeat oblique photographs of Gulkana glaciers in Alaska.Repeat oblique photographs of Gulkana glaciers in Alaska. 1967, Unknown USGS photographer. 2016, L. Sass, USGS.
Repeat oblique photographs of Gulkana glaciers in Alaska. 1967, Unknown USGS photographer. 2016, L. Sass, USGS.
Repeat oblique photographs of Wolverine glacier in Alaska.Repeat oblique photographs of Wolverine glacier in Alaska. 1966 image by unknown USGS photographer; 2015 image by L. Sass, USGS.
Repeat oblique photographs of Wolverine glacier in Alaska. 1966 image by unknown USGS photographer; 2015 image by L. Sass, USGS.
1928 South Cascade Glacier1928 black-and-white oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately southeast.
1928 black-and-white oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately southeast.
1958 South Cascade Glacier1958 black-and-white vertical aerial photo of South Cascade Glacier, northwestern Washington State. Top of photo is south.
1958 black-and-white vertical aerial photo of South Cascade Glacier, northwestern Washington State. Top of photo is south.
2006 South Cascade Glacier2006 oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately south-southeast.
2006 oblique-angle aerial photo of South Cascade Glacier, northwestern Washington State, looking approximately south-southeast.
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