All About the Cryosphere
What is the Cryosphere?
Some places on Earth are so cold that water is a solid—ice or snow. Scientists call these frozen places of our planet the "cryosphere." The word "cryosphere" comes from the Greek word for cold, "kryos."
Why does the cryosphere matter?
The cold regions of our planet influence our entire world's climate. Plus, the cryosphere is central to the daily lives of the people, plants, and animals that have made it their home.
Where is the cryosphere?
When scientists talk about the cryosphere, they mean the places where water is in its solid form, where low temperatures freeze water and turn it into ice.
People most often think of the cryosphere as being at the top and bottom of our planet, in the polar regions. We call the area around the North Pole the Arctic and the area around the South Pole the Antarctic. But snow and ice are also found at many other locations on Earth.
The North Pole is covered by a cold ocean called the Arctic Ocean. In the Arctic Ocean, sea ice grows in the winter and shrinks in the summer.
Frozen ground and permafrost ring the Arctic Ocean. Glaciers, snow, and ice cover the nearby land, including a thick sheet of snow and ice covering Greenland.
Antarctica, at Earth's South Pole, is an icy continent. A huge ice sheet covers the land mass of Antarctica and, in some places, shelves of floating ice extend into the ocean. The outer sections of ice break off or "calve" from these shelves and form icebergs. The icebergs float in the oceans, melting and falling apart as they drift into warmer waters.
And in between
The cryosphere also exists in places far away from the cold poles, at high elevations. For example, the snow on Mount Kilimanjaro is in Africa. Frozen soil can be found high in the mountains of the United States, as well as in the northern reaches of Canada, China, and Russia.
The cryosphere expands during the cold winter months. Seasonal areas of the cryosphere include places where snow falls, and where soil, rivers, and lakes freeze.
What is in the cryosphere?
Snow, ice, or both are key ingredients in every aspect of the cryosphere, including sea ice, glaciers, ice shelves, icebergs, and frozen ground.
Snow is precipitation made up of ice crystals. When cold temperatures and high humidity levels combine in the atmosphere, snow crystals form. As long as air temperature remains below freezing, the crystals will fall to the Earth as snow. Snow:
- can be found all over the world, even near the equator at high elevations
- reflects sunlight and affects our planet's climate
- provides a habitat for some animals and plants
- supplies water for people, plants, and animals around the world
- is an important part of the world's climate
For more details on snow, see All About Snow.
Ice forms when temperatures drop below the freezing point and liquid water becomes a solid, creating a tightly bonded substance. Ice is a key ingredient in glaciers, sea ice, ice shelves, icebergs, and frozen ground. Naturally occurring ice:
- exists all over the world, but mostly forms in the high latitudes, at high elevations, or at night when temperatures cool
- in oceans, lakes, and rivers may not be as common if climate continues to change and temperatures warm
- provides water for people, animals, and plants
- on lakes and in oceans can get so thick that special ships called icebreakers have to create a path through the ice
- can tell scientists about the past climate of Earth through ice cores
Sea ice forms when water in the oceans is cooled to temperatures below freezing. Most sea ice forms in the Arctic and Antarctic Oceans. Sea ice:
- does not raise sea level when it melts, because it forms from ocean water
- is closely linked with our planet's climate, so scientists are concerned about its recent decline
- fills a central role in the lives and customs of native Arctic people
- provides a place for polar bears, seals, and other animals to live
- is one way that scientists study the effects of climate change
Glaciers are thick masses of ice on land. The ice has built up from many seasons of snowfall. Glaciers move downhill very slowly. Glaciers:
- cover 10 percent of the world's land
- are smaller, today, than they used to be because of climate change
- sometimes look pink because of the algae living in the top layers of the snow and ice
- store 75 percent of the world's fresh water and provide water for many people around the world
- change the land they flow through, carving landscapes with their weight
For details on glaciers, see All About Glaciers.
Ice shelves and icebergs
Ice shelves are platforms of ice that form where ice sheets and glaciers move out into the oceans. Ice shelves exist mostly in Antarctica and Greenland, as well as in the Arctic near Canada and Alaska. Icebergs are chunks of ice that break off glaciers and ice shelves and drift in the oceans. Ice shelves and icebergs:
- raise sea level only when they first leave land and push into the water, but not when they melt in the water
- break off and melt as temperatures rise; in 2002, Antarctica's huge Larsen B Ice Shelf shattered in only a few months, sending hundreds of icebergs into the ocean
- provide shelter for krill, small fish that penguins, seals, whales, and sea birds eat
- are one important area of study for a wide range of scientists who study biology, glaciers, climate, and other fields
- may hold clues to the future of ice sheets and glaciers in a world with warming temperatures
For more information on ice shelves and icebergs, see Quick Facts on Ice Shelves and Quick Facts on Icebergs. For advanced information, see The State of the Cryosphere: Ice Shelves. For information on the Larsen B breakup, see Larsen Ice Shelf Breakup Events.
Frozen ground is soil or rock in which part or all of the water has frozen. If the ground is frozen all year long, we call it "permafrost," or permanently frozen ground. Frozen ground:
- exists mostly in the Arctic and Antarctic, but frozen ground can also be found at high elevations
- has begun to melt as climate warms
- often has an "active layer" near the surface, where plants can live because the soil is thawed for at least part of the year
- creates problems for people who are building structures, roads, or dams because it can shift them when it melts
- stores greenhouse gases like carbon and methane; scientists are studying how these gases will affect climate as temperatures warm and permafrost thaws
Learn About NSIDC
Tour of the Cryosphere Movie
An animated flight through the frozen areas of the Earth, produced by NASA using NSIDC data. Updated in 2009.
Google Earth Outreach
Google Earth files highlighting environment, climate change, and science.
University of Colorado at Boulder: Learn More About Climate
NSIDC Scientists Ted Scambos, Mark Serreze, and Shari Gearheard discuss climate change in a video, "Colorado's Changing Climate."
"The Day After Tomorrow" Q&A Response
The official NASA response to the 2004 movie with appended information from NSIDC
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