Although Antarctica is the most remote region on Earth, it is intimately coupled to the rest of the climate system. Thus, the future of Antarctica is tied to that of the planet and human society.
From the perspective of an observer looking back from 2070, there are two possible narratives on the future of Antarctica and Southern Ocean: i) greenhouse gas emissions remained unchecked, climate continued to warm and policy response was ineffective, leading to profound changes in Antarctica and the Southern Ocean, with worldwide impacts; ii) ambitious action was taken to limit greenhouse gas emissions and to establish policies that reduced anthropogenic pressure on the environment, slowing the rate of change in Antarctica.
Looking back from 2070 under the high emissions scenario: air temperatures over Antarctica have warmed by about 3°C; Southern Ocean waters have warmed everywhere but surface waters freshened in response to increased sea and glacier ice melting; nearly a quarter of the volume of Antarctica’s ice shelves has been lost, leading to more than 10 meters of sea-level rise in the longer term; summer sea ice extent has decreased by almost half and winter sea ice reduced by 40%; Southern Ocean waters have become corrosive to shells and other biological structures made of this form of calcium carbonate; acidification and warming waters lead to the reorganization of communities; biological invasions have increased substantially.
Under the low emissions scenario, the physical environment of Antarctica and Southern Ocean remained similar in many respects to that of 50 years ago; surface air and sea temperatures warmed by less than 1°C; sea ice extent declined slightly (<15%) in both summer and winter; the mass loss from the Amundsen Sea ice shelves continued, contributing to 6 cm of sea-level rise between 2000 and 2070; the pH of Southern Ocean slightly decrease but eventually stabilised and Ocean waters remained super-saturated with respect to aragonite; some populations declined but others adapted, resulting in less change than was initially forecast; none of the world’s most invasive species have established.
Although both scenarios are highly speculative, the narrative that eventually plays out will depend on the choices made over the next decade. Actions need to be taken to slow the rate of environmental change, increase the resilience of Antarctica and reduce the risk of out-of-control consequences.
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Source: S. R. Rintoul, S. L. Chown, R. M. DeConto, M. H. England, H. A. Fricker, V. Masson-Delmotte, T. R. Naish, M. J. Siegert and J. C. Xavier, Choosing the future of Antarctica. Nature, 2018, 558, 233–241. doi: 10.1038/s41586-018-0173-4
Author: Guilherme Jeremias
