Antarctica, holding approximately 90 percent of the world’s ice, is a significant part of the global climate system. Its ice sheets and surrounding ocean are interconnected with Earth’s atmospheric patterns, making the region highly sensitive to changes in global temperature. Global warming is altering the continent through climatic shifts, impacts on ice and sea levels, consequences for its wildlife, and its role in planetary climate regulation.
Documented Climatic Shifts in Antarctica
Antarctica is not warming uniformly, with documented regional differences in temperature trends. The most pronounced atmospheric warming is on the Antarctic Peninsula, which has experienced an air temperature increase of 3°C, a rate five times the global average. In contrast, the vast East Antarctic region showed little to no warming until the 2000s, highlighting the geographic disparity of climate impacts.
These atmospheric changes are coupled with significant warming in the surrounding ocean, which has absorbed substantial excess heat. The upper ocean waters west of the Antarctic Peninsula have warmed by over 1°C since 1955. This warming is not limited to the surface, as it has also been observed at depths below 2,000 meters, affecting the entire water column.
The Antarctic Circumpolar Current, the planet’s largest ocean current, is warming more rapidly than the global ocean as a whole, affecting the stability of ice shelves. Changes in wind patterns have also been observed, which can alter ocean circulation and the distribution of sea ice.
Melting Ice and Rising Seas
Accelerated melting of Antarctica’s ice formations is a primary contributor to global sea level rise. An important distinction exists between the melting of land-based ice sheets, which adds new water to the ocean, and floating sea ice, which has a less direct impact. The main concern is the loss of mass from the continental ice sheets.
The West Antarctic Ice Sheet is particularly vulnerable because it is largely grounded below sea level. This makes it susceptible to incursions of warm ocean water that can melt the ice from beneath, leading to the thinning and collapse of ice shelves. These large floating platforms of ice buttress the flow of glaciers, and the collapse of the Larsen B ice shelf in 2002 is a prominent example of their rapid disintegration.
Concerns are centered on glaciers like the Thwaites Glacier, whose retreat could trigger a wider collapse of the West Antarctic Ice Sheet, which would result in a sea level rise of approximately 4.3 meters. While the larger East Antarctic Ice Sheet is more stable, it has begun to show signs of ice loss. Between 1992 and 2017, Antarctica shed an estimated 2,720 billion tons of ice, and its melt could contribute around 11 cm to sea level rise by 2100.
Impacts on Antarctic Life
The continent’s flora and fauna, adapted to a stable, frozen environment, face challenges from warming temperatures and altered ice conditions that affect breeding, food, and habitat. The most visible impacts are on penguin populations, whose distribution has shifted with changing sea ice. Species like Adélie and chinstrap penguins, which rely on sea ice for breeding and food access, have seen colonies shrink on the warming Antarctic Peninsula. The loss of ice cover has also led to the “greening” of some areas, with increased growth of native mosses.
Antarctic krill, a primary element of the food web, are also under threat. These small crustaceans are a food source for whales, seals, and penguins. Their populations have declined in the Southwest Atlantic sector of the Southern Ocean, a change associated with reduced sea ice cover, which serves as a nursery for juvenile krill. Warming and acidifying ocean waters further stress these populations, creating a cascading effect through the marine ecosystem.
Antarctica’s Role in Global Climate Regulation
Antarctica plays a significant part in regulating Earth’s climate, and changes there can trigger global feedback loops. One primary function of the continent’s ice and snow cover is reflecting solar radiation back into space, known as the albedo effect. As this reflective white surface shrinks, the darker land and ocean underneath absorb more heat, which in turn accelerates warming.
The continent is also a driver of global ocean circulation. The formation of cold, dense Antarctic Bottom Water is a process that helps power the planet’s ocean currents, including the Meridional Overturning Circulation. The influx of fresh water from melting glaciers can disrupt this process. By making surface water less salty and dense, meltwater can slow the sinking of water in polar regions, altering ocean circulation and weather systems worldwide.
This alteration of deep-ocean currents impacts the transport of heat around the globe. The Southern Ocean is also a significant sink for atmospheric carbon dioxide, absorbing a large portion of human emissions. Changes in water temperature, circulation, and biological activity could alter the ocean’s capacity to absorb CO2, further influencing global climate change.