What is an Ice Cap ?

A dome shaped glacier with a generally outward and radial flow of ice is known as ice cap. The marginal regions of the ice cap may be drained by outlet glaciers which flow beyond the ice cap in U-shaped shallow valleys.

What is an Ice Sheet ?

It is a large dome-shaped glacier (over 50,000 sq km in area) with a generally outward and radial flow of ice . Ice sheets and ice caps are formed layer by layer from the snowfall of each year. With time the snow is compressed into ice.

On a continental scale such ice sheets can exceed a thickness of 4 km , as they do in Antarctica. Antarctica alone has 91% of all the glacial ice on the Earth.

Must read: CONSEQUENCES OF CLIMATE CHANGE – WORLD

What is the difference between ice cap and Ice Sheet ?

The difference between ice cap and ice sheet is normally taken to be one of scale with the former being less than 50,000 sq. km. in area, while the ice-sheet is more than 50,000 sq km.

What is Antarctic Ice Sheet ?

Antarctica is a continent covered by a single enormous ice sheet. The edges of the ice sheet that enter bays along the coast form excessive ice shelves, with sharp ice cliffs rising up to 30 m above the sea. Large tabular islands of ice are formed when sections of the shelves break off and move out to sea.

What is happening to the ice caps and ice sheets ?

The ice caps and ice sheets are melting and Antarctica’s ice sheets are breaking up. The icebergs
and ice-shelves after breaking move seaward.

In March 2000, the second largest iceberg ever recorded broke free from the Ross Ice Shelf (Antarctica around 150°W) and floated into the Ross Sea. The huge iceberg was 11,000 square kilometers in size, being about 300 kilometers in length and 37 kilometers in width.

CONSEQUENCES OF ICE CAP , SHEETS AND PERMAFROST MELTING

If the ice sheet of Antarctica melts the sea level will rise by about 70 meters. The socio-economic
consequences of ice-sheet melting may be catastrophic.

What this will do to the global socio-economic system one can only guess. Some of the important consequences of ice cap, ice sheet and permafrost melting have been briefly described in the following:

1. The Changes in Plant and Animal Life

The melting of ice caps and permafrost are affecting the biosphere and bringing changes in plants and animals.

For example, the population of penguins on Antarctica is decreasing which has dropped by about 40 per cent in the last quarter of the 20th century. The hypothesis is that the warmer temperatures make it harder for the penguins to find food and breed.

Moreover, phytoplankton and zooplanktons which are the basic component of food chain are decreasing. Coral reefs are dying at an unprecedented rate.

Vegetation, like lichen and mosses has started appearing on the steep slopes of mountains of Antarctica.

It has been observed that in Alaska, the melting of permanently frozen ground is changing the
migratory patterns of the caribou (reindeer). In the National Park (USA), there is an unusual growth of
spruce trees.

Moreover, millions of birds have migrated towards north from the western coast of USA because of warmer water.

Rates of natural migration and adaptation of species and plant communities, however, appear to be much slower than the rate at which climate is changing.

2. Spread of Tropical Diseases

Melting of cryosphere is the result of global warming. Extremes of heat and cold, and wet and dry
conditions have been frequent in recent years.

Down through the history such extreme events have often been followed by outbreaks of diseases. There is a possibility of increase in the cases of malaria by about 15 per cent.

Other diseases, such as dengue fever, yellow-fever, Ebola fever, and viral-encephalitis would also increase. In fact, malaria is spreading even in the temperate countries of Europe.

3. Reduction in Biodiversity

According to some of the ecologists and environmentalists about one third of all ecosystems would shift
to another type. The rapid change in ecosystems would greatly reduce biodiversity in many climatic
regions and biomes.

4. Shift in Climatic Zones

Mid-latitude climate zones could shift pole-ward by as much as 550 km causing conversion of forest
to grassland and scrubland. Some species of forest trees would not be able to migrate quickly enough
and would die out.

5. Desertification

As a result of climatic change and change in the precipitation patterns deserts would expand and the continental interiors in general, would become drier.

Must read: DESERTIFICATION – AN UNDERESTIMATED THREAT

6. Effect on Agriculture

The beneficial agricultural effects include milder winters in northern regions as well as increased
precipitation and faster crop growth in some areas.

The grain belts of North America and Russia would expand northward. It may affect the international trade of grains also.

7. Effect on Coastal Population

About 50 per cent of the total urban population of the world is living along the coastal areas. In case of
sea level rise, the low-lying coastal urban centres will be adversely affected.

Cities like Aden, Amsterdam, Athens, Baltimore, Bangkok, Boston, Buenos Aires, Belfast, Chennai, Colombo, Copenhagen, Dhaka, Dubai, Dublin, Galveston, Halifax, Ho Chi Minh City, Hong Kong, Houston, Jakarta, Kandla, Kochi, Kolkata, Lagos, Lisbon, London, Los Angeles, Male (Maldives), Manila, Mumbai, Muscat, Nagasaki, New Orleans, New York, Okha, Philadelphia, Rio de Janeiro, Rome, Rotterdam, San Francisco, Seoul, Shanghai, Singapore, Surabaya, Sydney, Tianjin, Tokyo, Vancouver, Washington D.C., Yangon etc. will submerge under water.

8. Change in Lakes Ecosystems

Changing temperatures will have a detrimental effect on living organisms in the lakes, especially those
which are in the higher latitudes.

The warmer water kills the planktons on which higher life forms are dependent. In fact, less plankton mean less fish.

9. Submergence of Sea Beaches

The submergence of sea beaches and sea-resorts will adversely affect the domestic and international
tourism.

10. Increase in the frequency of Tropical Cyclones

Because of sea level rise there will be more evaporation which shall induce more latent heat and water vapour in the troposphere (atmosphere). This process may lead to more stormy weather in the tropical latitudes.

Must read: Impact of climate change on tropical cyclones

11. Shift in Natural Vegetation Belts

Under the changed climatic conditions because of melting of ice caps, the rainfall pattern will change.
A change in precipitation patterns will transform the belts of natural vegetation which shall ultimately affect the soil-belts and the agricultural practices.

External link: https://www.worldwildlife.org/pages/why-are-glaciers-and-sea-ice-melting