page_title: Sea level rise
section_title: Antarctica
hierarchical_section_title: Sea level rise / Contributions / Antarctica
caption_attribution_description: English: Sketch of the Antarctic coast with glaciological and oceanographic processes. Deutsch: Schematische Darstellung glaziologischer und ozeanographischer Prozesse an der Küste der Antarktis. Über dem antarktischen Eisschild fällt Niederschlag in Form von Schnee (Precipitation). Der Eisschild (Ice sheet) ist weitgehend am Untergrund festgefroren (back stress) und hat sich bis zu einer Mächtigkeit von über 4000 m aufgebaut. Das Eis fließt nach allen Seiten vom Kontinent ab, z.T. konzentriert in Eisströmen (Ice stream). An der Küste verliert das Eis im Bereich der Aufsetzlinie (Grounding line) den Kontakt zum Untergrund, wird deutlich dünner (einige 100 m) und bildet über dem Schelf (Continental shelf) ein Schelfeis (Ice shelf) = Eis, das noch mit dem Eisschild verbunden ist, aber bereits schwimmt. Fließt das Schelfeis über eine Untiefe, entstehen Eisrücken (Ice rise). An der Schelfeiskante brechen Tafeleisberge ab (Calving line, Iceberg calving), die auf ihrem Weg um die Antarktis in wärmerem Wasser schmelzen. Eine Küstenpolynya entsteht, wenn kalte ablandige Winde (Catabatic wind) das Meereis (Sea ice) von der Küste wegtreiben. In Verbindung mit der Neueisbildung entsteht kaltes, salzreiches und damit schweres Wasser, das den Kontinentalhang (Slope) herabfließt und den wesentlichen Mechanismus für die Bildung des ozeanischen Bodenwassers in der Tiefsee (Deep sea) darstellt.
context_page_description: Since at least the start of the 20th century, the average global sea level has been rising. Between 1900 and 2016, the sea level rose by 16–21 cm. More precise data gathered from satellite radar measurements reveal an accelerating rise of 7.5 cm from 1993 to 2017, which is a trend of roughly 30 cm per century. This acceleration is due mostly to human-caused global warming, which is driving thermal expansion of seawater and the melting of land-based ice sheets and glaciers. Between 1993 and 2018, thermal expansion of the oceans contributed 42% to sea level rise; the melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Climate scientists expect the rate to further accelerate during the 21st century.
  Projecting future sea level is challenging, due to the complexity of many aspects of the climate system. As climate research into past and present sea levels leads to improved computer models, projections have consistently increased. In 2007, the Intergovernmental Panel on Climate Change projected a high end estimate of 60 cm through 2099, but their 2014 report raised the high-end estimate to about 90 cm.
context_section_description: The large volume of ice on the Antarctic continent stores around 70% of the world's fresh water. The Antarctic ice sheet mass balance is affected by snowfall accumulations, and ice discharge along the periphery. Under the influence of global warming, melt at the base of the ice sheet increases. Simultaneously, the capacity of the atmosphere to carry precipitation increases with temperature so that precipitation, in the form of snowfall, increases in global and regional models. The additional snowfall causes increased ice flow of the ice sheet into the ocean, so that the mass gain due to snowfall is partially compensated. Snowfall increased over the last two centuries, but no increase was found in the interior of Antarctica over the last four decades. Based on changes of Antarctica's ice mass balance over millions of years, due to natural climate fluctuations, researchers concluded that the sea-ice acts as a barrier for warmer waters surrounding the continent. Consequently, the loss of sea ice is a major driver of the instability of the entire ice sheet.
  Different satellite methods for measuring ice mass and change are in good agreement, and combining methods leads to more certainty about how the East Antarctic Ice Sheet, the West Antarctic Ice Sheet, and the Antarctic Peninsula evolve. A 2018 systematic review study estimated that ice loss across the entire continent was 43 gigatons (Gt) per year on average during the period from 1992 to 2002, but has accelerated to an average of 220 Gt per year during the five years from 2012 to 2017. Most of the melt comes from the West Antarctic Ice Sheet, but the Antarctic Peninsula and East Antarctic Ice Sheet also contribute. The sea-level rise due to Antarctica has been estimated to be 0.25 mm per year from 1993–2005, and 0.42 mm per year from 2005 to 2015. All datasets generally show an acceleration of mass loss from the Antarctic ice-sheet, but with year-to-year variations.
caption: Processes around an Antarctic ice shelf
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