What is the cryosphere?

The cryosphere consists of all the frozen water on Earth. It includes various forms of ice and frozen ground.

Components of the cryosphere

• Ice sheets - Vast domes of ice covering large land and sea areas.
• Ice caps - Smaller dome-shaped ice masses in polar or mountainous regions.
• Ice fields - Networks of interconnected glaciers in mountainous terrain.
• Valley glaciers - Ice flows that fill old river valleys.
• Cirque glaciers - Small glaciers in bowl-shaped mountain hollows.
• Permafrost - Ground that remains frozen for at least two consecutive years.

The cryosphere stores about 69% of the world's freshwater but covers only around 15% of Earth's surface.

The role of the cryosphere in global systems

The cryosphere interacts with other Earth systems, influencing water movement, climate patterns, and carbon levels.

Contribution to the hydrological cycle

The hydrological cycle involves the continuous movement of water on, above, and below Earth's surface.

The cryosphere affects the hydrological cycle by:

• Removing water from the atmosphere through snowfall, which accumulates as ice.
• Releasing water back into the cycle when ice and snow melt, feeding river systems and oceans.

This process regulates water availability in many regions.

Regulation of climate systems

The cryosphere helps control global temperatures through reflective properties and energy balance.

The albedo effect:

Albedo refers to the proportion of solar radiation reflected by a surface. Ice and snow have high albedo, reflecting much of the Sun's energy back into space. This keeps polar regions cold and indirectly moderates temperatures elsewhere.

• Ice surfaces reflect about 90% of solar radiation, with only 10% absorbed.
• In contrast, open water reflects just 6%, absorbing 94%, which leads to warming.

Carbon storage in permafrost

Permafrost stores large amounts of carbon. This reduces carbon dioxide levels in the atmosphere.

Types of ice masses

Ice masses are classified as unconstrained (not limited by terrain) or constrained (shaped by valleys or mountains).

Unconstrained ice masses

These cover land without being restricted by topography (the physical features of the landscape).

Ice sheets:

• Ice sheets are massive, dome-shaped bodies of ice, often several kilometres thick and covering more than 50,000 km².
• They flow outwards from their centres, largely unaffected by underlying topography.
• Only two exist today: the Antarctic Ice Sheet and the Greenland Ice Sheet.
• Extensions over the sea form ice shelves, which are floating platforms vulnerable to ablation (the loss of ice from an ice mass).

Ice caps:

• Ice caps are smaller than ice sheets, covering less than 50,000 km², and are dome-shaped.
• They form in polar regions or high mountains, with flow mostly independent of underlying topography.
• An example is the Vatnajökull ice cap in Iceland.

Constrained ice masses

These are shaped by surrounding terrain, such as valleys or hollows.

Ice fields:

• Ice fields consist of interconnected valley glaciers in mountainous areas where snow accumulates over time.
• Topography influences their flow, with mountain peaks often visible above the ice.
• An example is the Patagonia ice field in South America.

Valley glaciers:

• Valley glaciers occupy former river valleys, sometimes extending to the sea.
• They range from a few kilometres to over 100 km in length.
• An example is the Franz Josef Glacier in New Zealand, which is about 12 km long.

Cirque glaciers:

• Cirque glaciers develop in bowl-shaped depressions high in mountains.
• They are typically around 1 km² but vary with the hollow's size.
• They may connect to valley glaciers.
• An example is the Lower Curtis Glacier in the USA.

Ice cover in polar environments

Polar environments are extremely cold, supporting large ice sheets due to low temperatures and minimal precipitation. These regions are defined by latitude and temperature boundaries.

Characteristics of polar environments

• Arctic - Defined by the Arctic Circle (66.5° N) or the 10 °C July isotherm (areas north of this have average July temperatures below 10 °C).
• Antarctic - Includes areas south of 66.5° S or the 10 °C January isotherm (average January temperatures below 10 °C).
• These are cold deserts with temperatures often below -40 °C and little precipitation.
• Higher latitudes receive less direct solar radiation, spreading energy over larger areas and resulting in colder conditions.

About 90% of Earth's glacier ice is in Antarctica. During the Last Glacial Maximum, ice sheets covered much larger areas, especially in the northern hemisphere due to more landmass there.

Ice cover in temperate environments

In temperate regions, ice masses form at high altitudes where conditions mimic polar cold. These alpine environments host glaciers despite being outside polar zones.

Formation at high altitudes

• Air temperature drops by about 0.65 °C for every 100 metres of altitude gain.
• This allows snow to fall and persist, forming glaciers.
• Some ice melts to produce meltwater, which can drive glacial movement or cause retreat.

Examples of alpine environments

Major ranges include the Alps in Europe, the Himalayas in Asia, and the Andes in South America.

Relict glacial landscapes

Relict glacial landscapes preserve features from past ice ages, showing where glaciers once existed even if no ice remains today. These formed during the Pleistocene epoch. Glaciers eroded and shaped the terrain, leaving distinctive landforms.

Examples of relict landscapes

• In the UK, areas like the Lake District and Snowdonia show glacial features from Pleistocene ice cover, which extended over most of northern Europe but spared the southernmost UK.
• Similar landscapes exist across northern Europe, Canada, and Alaska, where ice sheets were extensive during glacial periods.