Antarctica is Earth’s southernmost continent, containing the geographic South Pole. It is situated in the Antarctic region of the Southern Hemisphere almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres (5,400,000 square miles), it is the fifth-largest continent and nearly twice the size of Australia. About 98% of Antarctica is covered by ice, which averages 1.9 kilometres (1.2 mi) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.
Antarctica’s icy surface
Antarctica is the coldest, windiest and driest continent. The lowest temperature ever recorded on Earth (-89.2°C) was on 21 July 1983, at Vostok Station. Winds have been recorded at over 200 km/h (124 mph) on the inland ice sheet. There is very little precipitation over the central portion of the continent. Over 50 million years ago, Antarctica was quite different. Dinosaurs roamed the lush landscapes and swamps thrived. The continent began cooling about 40 million years ago before becoming the vast desert it is today. Antarctica is 98% covered by ice which averages 1.9 km (1.2 miles) in thickness. The ice covers land and open sea. In some coastal areas the ice sheet is as much as 4.8 km (3 miles) thick. The Antarctic ice sheet contains 90% of the world’s ice and 70% of its freshwater. If all the land ice covering Antarctica were to melt — around 600,000 cubic kilometers (144,000 cubic miles) of ice — the seas would rise by about 60 meters (197 feet). For perspective, 60 meters is about as tall as a 6-story building.
Lake Vostok
Lake Vostok is the largest of Antarctica’s almost 400 known subglacial lakes. Lake Vostok is located at the southern Pole of Cold, beneath Russia’s Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at 3,488 m (11,444 ft) above mean sea level. It is defined by ice core samples taken by the Russian Vostok station drilling down through the ice shield that covers it to a depth of 3,666 m (12,021 ft); analysis of trace gases in the ice samples suggests that the lake water is situated at around 500 m (1,600 ft) below the ice surface. Measuring 250 km (160 mi) long by 50 km (30 mi) wide, and covering an area of 12,500 km2 (4,830 sq mi) and an average depth of 432 m (1,417 ft), it has an estimated volume of 5,400 km3 (1,300 cu mi). The lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m (700 ft), compared to roughly 400 m (1,300 ft) deep in the northern basin and 800 m (2,600 ft) deep in the southern.
Due to the location of Lake Vostok, there is speculation that microbes exist in the lake isolated from the rest of the world for millions of years. Russian scientist Peter Kropotkin first proposed the idea of fresh water under Antarctic ice sheets at the end of the 19th century. He theorized that the tremendous pressure exerted on the ice’s underside by the overriding ice was melting the bottom ice, and the pressure at the base was compressing and warming the ice above the water, turning it into something like a gel. Kropotkin further hypothesized in 1899 that microbial life could exist in this under-ice environment. Several attempts were made in the 20th century to determine whether life exists in Lake Vostok. In 1974, British scientists did airborne ice-penetrating radar surveys and determined the existence of a giant freshwater lake, between the size of Lake Ontario and Lake Erie. In 1983, Soviet scientists fetched the first ever ice cores that touched the waters of the lake; at a depth of 3,538 m (11,608 ft) they extracted an ice core that contained frozen water samples less than a year old — the youngest water ever reached and sampled from the Antarctic ice sheet thus far. This indicated the location of the upper boundary of the lake no more than 100 m (330 ft) from the ice surface. In subsequent decades, U.S. and British expeditions also successfully drilled into the lake, extracting ice cores through the entire depth of the ice sheet.
Subglacial volcanoes
Scientists have discovered 91 volcanoes below Antarctica, adding to the 47 already known. This makes it the largest volcanic region on Earth. These 138 volcanoes exist in the anthropologically named ‘West Antarctic Rift System’ (WARS) between the Transantarctic Mountains and the West Antarctic ice sheet. The region was known to have volcanic activity, but the extent was not previously known. Some of the volcanoes stand at over 3,000 meters, but the vast majority are buried under large swathes of ice.
This region was recently identified as one of the densest accumulations of subglacial volcanoes anywhere on Earth. The tallest rises to around 3,850 metres (12,631 ft), while the lowest identified volcano is 160 metres (525 ft) tall. All are covered in ice, which can in some places be more than 4 kilometres (2.5 mi) thick. The newly outlined region is 4.8 times larger than east Africa’s volcanic ridge which contains Mount Kilimanjaro and Mount Kenya. This is the densest concentration anywhere in the world – about four times as many volcanoes as in east Africa. The tallest volcano stands at almost 4,000 meters (13,100 feet), but most are much smaller, standing around 500 to 1,000 meters (1,600 to 3,300 feet).
Subglacial lakes
Antarctica has over 400 subglacial lakes that scientists have detected beneath the ice. They range in size from 1 km to 25,000 km squared. These lakes were first discovered in 1970 when scientists noticed surface changes on some parts of the ice sheets, indicating water flowing beneath the ice. The lakes form as meltwater on the surface makes its way down through cracks and fissures in the ice until it pools together under the pressure of the ice sheet. The largest is Lake Vostok located near the Russian Vostok research station, which can hold approximately 5400 cubic km of water. Subglacial lakes provide important habitats for extremophile microbes, contain preserved historic climate records, and may lubricate the ice sheet’s flow towards the ocean.
Hidden lifeforms
The extreme conditions of subglacial lakes, such as intense pressure, low nutrient levels, oxygen scarcity, limited energy sources, lack of sunlight, and constant darkness, are thought to promote the evolution of unique types of extremophile microorganisms. Scientists are hopeful of finding new species that have adapted to live in these environments. Proving their existence and studying these organisms could provide insights into how life might exist on other icy worlds in our solar system, such as Jupiter’s moon Europa.
In the few subglacial lake water samples analyzed so far, researchers have found over 3000 species of microbes, most of which are previously unknown to science. Many have evolved the ability to derive energy from ammonium and methane by “breathing” iron, manganese and sulfur rather than oxygen. These lifeforms represent an almost completely unexplored branch of microbial diversity on Earth.
| Lake | Location | Size (km2) |
|---|---|---|
| Lake Vostok | East Antarctica | 12,500 |
| Lake CECs | West Antarctica | 1,800 |
| Lake Concordia | East Antarctica | 60 |
Climate records
The bottoms of subglacial lakes contain sediment deposits that were laid down continuously over time. By analyzing the sediments, paleoclimatologists can reconstruct past environmental conditions in Antarctica, including surface air temperature and precipitation levels going back about half a million years. This provides insights into the warmer climates and large-scale glacial retreats Antarctica experienced in the past.
One surprising finding is that during past super-interglacial periods when Antarctica had little or no ice cover, sea levels were up to 20 meters higher than today. This implies that if the continent’s ice sheets melted entirely in the future, we could see even more extreme sea level rise than currently predicted.
Mineral deposits
Antarctica has a variety mineral deposits under its ice, although full-scale mining has never been undertaken on the continent. Antarctica is speculated to hold large oil and gas deposits based on seismic surveys of the sea floor surrounding the continent. Coal seams have also been detected in multiple locations. In terms of metals, iron ore, chromium, copper, gold, nickel, platinum, and silver have been found in recoverable quantities. Uranium deposits and rare earth elements are also likely present.
Coal and oil
Geologists believe there are large oil and natural gas deposits under the seafloor just offshore of Antarctica. However, drilling has not been allowed under the Antarctic Treaty System which bans military activities, mineral exploration, and mining on the continent. On land, coal has been found in several locations in the Transantarctic Mountains and the Prince Charles Mountains. The coal occurs in seams up to 3 meters thick and the deposits may be extensive, but they remain unquantified. Again, no drilling or mining has taken place.
Metals and minerals
Iron ore deposits have been found in the Prince Charles Mountains and the Dobrowlsky Mountains. Based on magnetic and gravity surveys, potential iron ore reserves are estimated at over 2 billion tonnes. Other metals known to exist in recoverable quantities include copper, nickel, gold, silver, chromium, and platinum. Traces of uranium and rare earth elements have also been found but not quantified.
| Mineral | Location |
|---|---|
| Iron Ore | Prince Charles Mountains |
| Coal | Transantarctic Mountains |
| Oil & Gas | Continental shelf |
| Copper, Gold | Multiple regions |
Prehistoric life
Fossil evidence indicates that Antarctica once supported a diverse collection of Mesozoic flora and fauna around 250-65 million years ago when the continent was located farther north with a milder climate. Fossils of extinct land and marine animals have been found including mosasaurs, giant penguins, plesiosaurs, and dinosaur bones. Ancient fossil forests have also been discovered showing Antarctica was once heavily forested and home to a variety of plant and animal species.
Dinosaur remains
In 1991, a geology team in Antarctica’s Mt Kirkpatrick basin unearthed the foot bone of a meat-eating dinosaur dating back 230-240 million years. In 2003, part of a jaw bone likely belonging to a new plant-eating dinosaur species was found near Mt Strathcona. Other dinosaur remains have been recovered on James Ross Island, Vega Island, and Seymour Island. Finds include teeth and bones from sauropods, theropods, ornithopods, and ankylosaurians. More dinosaur bones likely await discovery under the ice.
Analysis of the bones found so far indicates Antarctica once supported a diversity of dinosaur species during the Early Cretaceous when it was connected to South America as part of the supercontinent Gondwana. Dinosaurs likely migrated between the once contiguous landmasses.
Plant fossils
Leaves, pollen, spores and fossilized wood are among the ancient plant remains that have been recovered from the Transantarctic Mountains and McMurdo Dry Valleys. They reveal that the continent was once covered in forests, swamps and grasslands supporting a diverse flora including ancestors of modern southern beeches, conifers, ginkoes, monocots and ferns. Fossilized leaves over a meter wide have been found, suggesting Antarctica was once home to towering broadleaf deciduous trees.
Marine reptiles
Many marine reptile remains have been found around Antarctica from the Mesozoic era, suggesting it had relatively warm shallow seas at the time. Finds include long-necked plesiosaurs, the shells of ammonites, and the well-preserved remains of giant mosasaurs up to 20 meters long. A specimen of an ichthyosaur from 220 million years ago is considered the most intact large marine reptile skeleton ever found. Plenty more remains likely lie buried waiting to be uncovered.
Potential undiscovered species
Given the extreme isolation of subglacial lakes in Antarctica, it’s possible that completely unique lifeforms have evolved in these hidden habitats, representing new branches on the tree of life that exist nowhere else on Earth. Even on the exposed surface, Antarctica’s harsh conditions drive adaptation into novel niches, as evidenced by extremophile microbes that metabolize minerals for energy and the discovery of new species thriving in Antarctic pools considered too cold for life.
Previous surveys have found Antarctica is home to many species found nowhere else, such as sea spiders, isopods, sponges, worms, and more. Ongoing research continues to uncover new species – in just a few cubic centimeters of lake sediment, one study reported finding over 10,000 species of microbes, 99% of which were previously unknown.
This suggests Antarctica likely contains an enormous undiscovered diversity of unique lifeforms still awaiting formal identification. As remote sensing technologies improve and new locations are explored, more pieces of Antarctica’s hidden biodiversity puzzle will be added.
New extremophile microbes
Experts estimate over 1 million undiscovered microbial species are likely holed away in isolated subglacial and coastal aquatic habitats across Antarctica. Subglacial lakes provide stable, low energy environments for novel microbes to evolve over millions of years. Recent sampling found DNA from over 3000 microbial species, forcing scientists to rethink the limits of possibility for life on Earth – and other icy worlds.
Lake Vostok life
With Lake Vostok completely sealed off from the atmosphere and any external influences for 15 million years, scientists are hopeful that unique organisms have evolved within the lake. Russian researchers who analyzed a sample of frozen lake water found DNA from an estimated 2500 unique species – most were less than 86% similar to known microbes and likely represent new branches on the evolutionary tree.
Cold-adapted vertebrates
Few vertebrate animals have been found to inhabit Antarctica, but evolutionary pressures may have driven unique adaptations in species like fish, allowing them to thrive in frigid waters chemically similar to their internal fluids. Undiscovered vertebrates adapted to the extreme cold may yet live in Antarctic lakes considered inhospitable to complex lifeforms.
Conclusion
Antarctica holds many secrets buried underneath its vast ice sheet. Subglacial lakes and geothermal hotspots provide oases for life, preserved historic climate records, and untapped mineral reserves. Exploring these hidden features without contaminating them poses an ongoing challenge. As remote sensing technologies improve, Antarctica’s concealed diversity and resources will gradually come into sharper focus – but much remains to be uncovered about the mysteries entombed under the ice.
