Subantarctic

The sub-Antarctic zone is a special area in the Southern Hemisphere, just north of Antarctica. It lies between about 46° and 60° south of the Equator. This region includes many islands in the southern parts of the Atlantic, Indian, and Pacific oceans, especially those north of the Antarctic Convergence.

These islands are important because they have unique plants and animals that are not found anywhere else in the world. The cold and windy climate makes life there challenging, but some tough plants, birds, and insects have managed to survive.

Glaciers found on these subantarctic islands are called subantarctic glaciers. Glaciers on the actual continent of Antarctica are known as Antarctic glaciers. Both types of glaciers are important for understanding how Earth's climate has changed over time.

Geography

The subantarctic region is found in the Southern Hemisphere, just north of Antarctica. It lies roughly between 46° and 60° south of the Equator. This area includes many islands in the southern parts of the Atlantic, Indian, and Pacific oceans, especially those located north of a special ocean area called the Antarctic Convergence.

The subantarctic region has special ocean fronts and currents that shape its climate and wildlife. The Antarctic Circumpolar Current is the most important current in the Southern Ocean, flowing completely around the Earth. It connects the Atlantic, Indian, and Pacific Oceans and carries a huge amount of water. These ocean patterns help control the climate and support many kinds of sea life.

Some islands in this area, like the Crozet Islands and the Kerguelen Islands, are considered subantarctic. Others, such as the Falkland Islands, have different climates and landscapes but are still close to the Antarctic Convergence. The region's islands often have tundra landscapes, though some have trees or grasslands.

Climate

Impact of climate change on SAMW

The Subantarctic Mode Water and Antarctic Intermediate Water work together like a carbon sink, taking in atmospheric carbon dioxide and keeping it stored. If the temperature of Subantarctic Mode Water goes up because of climate change, it will be able to hold less carbon dioxide. Studies using computer models show that if the amount of carbon dioxide in the air grows to about 860 parts per million by 2100—which is about twice what it is today—the Subantarctic Mode Water will become less dense and salty. This change might mean that these waters take in and keep less carbon dioxide in the Southern Ocean.

Flora and fauna

Main pages: Category:Flora of subantarctic islands and Category:Fauna of subantarctic islands

The Antarctic realm and Antarctic Floristic Kingdom include most plants and animals found on subantarctic islands. Many plants and animals here are found only in this area.

Subantarctic island example

See also: Category:Flora of Heard Island and McDonald Islands and Category:Fauna of Heard Island and McDonald Islands

The land and plants and animals of Heard Island and McDonald Islands keep changing because of volcanic activity, strong winds and waves, and climate change. Since the mid-1980s, we have seen new lava flows on Heard Island. Satellite imagery shows that McDonald Island grew from about 1 to 2.5 square kilometers between 1994 and 2004 because of volcanic activity.

Because Earth is getting warmer, glaciers on these islands are melting back. This creates new places on land and in fresh water where plants and animals can live.

Heard Island has many colonies of penguins and petrels, and large groups of seals that live on land. Because there are so many sea birds and marine animals here, the area is very important for nature. The waters around the islands have many different sea creatures, including corals, sponges, barnacles and echinoderms. These waters also help young fish grow.

Retreat of subantarctic glaciers

See also: Retreat of glaciers since 1850 and Glacier mass balance

Glaciers around the world, especially in the Southern Hemisphere, are shrinking faster than ever. Scientists have studied many glaciers in places like South America, New Zealand, and Antarctica, and they all show signs of retreat.

Many glaciers near Antarctica are also shrinking. On islands like Kerguelen, Heard, South Georgia, and Bouvet, the amount of ice has been decreasing a lot.

Heard Island, a volcano covered in ice, shows clear signs of glacier retreat. Between 1947 and 2004, the ice on Brown Glacier shrank by about a third. The ice cliffs that once reached the ocean have disappeared, and glaciers have pulled back far inland. Scientists think this is because the world is getting warmer. Studies since 2000 show the ice is melting even faster now. The glaciers on Heard Island will likely keep shrinking as the climate continues to change.