The climate of Antarctica is the coldest on Earth. The continent is very dry, making it a desert, with an average of 166 mm (6.5 in) of precipitation each year. Snow rarely melts on most parts of Antarctica and, when it is pressed together, forms glacier ice that makes up the ice sheet. Strong winds called katabatic winds prevent weather fronts from reaching far inland. Most of Antarctica has an ice-cap climate, classified as EF in the Köppen system, with very cold and dry weather.
Temperature
The highest temperature ever recorded in Antarctica was 19.8 °C (67.6 °F). This temperature was measured at Signy Research Station on Signy Island on January 30, 1982.
The highest temperature recorded on the Antarctic mainland was 18.3 °C (64.9 °F). This occurred at Esperanza Base in Argentina on February 6, 2020.
The lowest air temperature ever recorded in Antarctica was −89.2 °C (−128.6 °F). This temperature was measured at Vostok Station on July 21, 1983. This temperature is 10.7 °C (19.3 °F) colder than the temperature at which dry ice turns directly into gas at sea level pressure. The location where this temperature was recorded is at an elevation of 3,488 meters (11,444 feet).
Satellite data has found even colder ground temperatures. On August 10, 2010, a temperature of −93.2 °C (−135.8 °F) was observed on the cloud-free East Antarctic Plateau.
The lowest recorded temperature on Earth’s surface, at coordinates 81°48′S 63°30′E, was revised in 2018. New data showed temperatures ranging from −93.2 °C (−135.8 °F) to −98 °C (−144.4 °F). This area, located between Dome A and Dome F on the Antarctic Plateau, was measured on August 10, 2010. Scientists used satellite data, including measurements from Landsat 8, to calculate this temperature. The discovery was made in December 2013, and the temperature was confirmed in June 2018. This temperature is not the same as the −89.2 °C (−128.6 °F) reading because it is a skin temperature calculated from satellite data, not a temperature measured directly in the air 1.5 meters (5 feet) above the ground.
The average temperature in the interior of Antarctica is −43.5 °C (−46.3 °F). Coastal areas are warmer, with average temperatures around −10 °C (14.0 °F) in the warmest regions. Inland areas at high elevations, such as Vostok, have average temperatures of about −55 °C (−67.0 °F). At McMurdo Station, monthly average temperatures range from −26 °C (−14.8 °F) in August to −3 °C (26.6 °F) in January. The highest temperature ever recorded at the South Pole was −12.3 °C (9.9 °F) on December 25, 2011. Along the Antarctic Peninsula, temperatures as high as 18.3 °C (64.9 °F) have been recorded, though summer temperatures are usually below 0 °C (32 °F). Extremely low temperatures depend on latitude, elevation, and distance from the ocean. East Antarctica is colder than West Antarctica because of its higher elevation. The Antarctic Peninsula has the mildest climate. Higher temperatures occur in January along the coast, and average temperatures are slightly below freezing.
Precipitation
The average amount of precipitation across the entire Antarctic continent is about 166 millimeters (6.5 inches) each year, according to a study by Vaughan and others in the Journal of Climate in 1999. Precipitation levels vary greatly depending on location. For example, the Antarctic Peninsula receives between 380 to 640 millimeters (15 to 25 inches) of precipitation yearly, while the high interior areas receive as little as 50 millimeters (2.0 inches) annually, as reported by Bromwich in Reviews of Geophysics in 1988. Regions that get less than 250 millimeters (9.8 inches) of precipitation yearly are considered deserts. Most precipitation in Antarctica falls as snow. Rain is uncommon and typically occurs only during the summer months in coastal areas and nearby islands. It is important to note that the measured precipitation values represent the amount of water that would result if the snow melted, not the actual depth of the snow. The air in Antarctica is also very dry due to extremely low temperatures, which lead to very low absolute humidity. This dry air causes challenges for scientists and researchers, such as dry skin and cracked lips.
Weather condition classification
The weather in Antarctica can change a lot, and conditions often shift quickly and suddenly. Different types of weather are used to describe conditions in Antarctica. Rules for workers during these conditions depend on the station and the country.
Ice cover
Most of Antarctica is covered by ice that is about 1,500 meters (5,000 feet) thick on average. Antarctica holds 90% of the world's ice and more than 70% of its fresh water. If all the land ice in Antarctica melted—about 30 × 10^ km (7.2 × 10^ cubic miles) of ice—global sea levels would rise more than 60 meters (200 feet). Antarctica is extremely cold, and even with temperature increases of a few degrees, temperatures would still remain below the melting point of ice. Higher temperatures may lead to more snowfall, which adds more ice to Antarctica. This could reduce about one third of the sea level rise caused by warmer ocean water expanding. Between January 1992 and January 2003, East Antarctica gained about 1.8 centimeters (11/16 inch) of ice each year, while West Antarctica lost about 0.9 centimeters (3/8 inch) of ice each year. For more information about Antarctica's role in sea level changes, see "sea level rise." Because ice moves slowly, the ice within the ice sheet is younger than the sheet itself.
About 75% of Antarctica's coastline is covered by ice shelves. Most ice shelves are made of floating ice, while some parts consist of glaciers that slowly move from land into the sea. Ice shelves lose mass when glaciers break off (calving) or when warm ocean water melts ice from below.
Breaking up floating ice shelves does not directly raise global sea levels, but they help slow the movement of ice behind them. If ice shelves break up, the ice behind them may speed up, leading to more melting of Antarctica's ice and greater contributions to rising sea levels.
Known changes in ice along the Antarctic Peninsula include the George VI Ice Shelf, which may be unstable. This ice shelf has existed for about 8,000 years after melting 1,500 years earlier. Warm ocean currents may have caused the earlier melting. Ice sheets are losing mass, and this loss is happening faster over time.
Climate change
Antarctica, though far from other lands, has experienced rising temperatures and ice loss in recent decades due to greenhouse gas emissions. West Antarctica warmed by more than 0.1°C each decade from the 1950s to the 2000s. The Antarctic Peninsula, which is more accessible, has warmed by 3°C (5.4°F) since the mid-20th century. East Antarctica, which is colder and more stable, showed no warming until the 2000s. The Southern Ocean around Antarctica has absorbed more heat than any other ocean, with strong warming observed below 2,000 meters (6,600 feet). Near West Antarctica, the ocean has warmed by 1°C (1.8°F) since 1955.
The warming of the Southern Ocean has weakened or caused the collapse of ice shelves, which float near glaciers and help keep them stable. Many coastal glaciers have lost ice and moved backward, leading to overall ice loss in Antarctica, even though East Antarctica continues to gain ice inland. By 2100, ice loss from Antarctica is expected to raise global sea levels by about 11 cm (5 inches). If instability in West Antarctica’s ice sheets is triggered before 2100, it could add tens of centimeters to sea level rise. Higher warming would make this instability more likely and could double the sea level rise expected during the 21st century.