• Antarctica and the Southern Ocean are experiencing “abrupt changes” due to human-caused climate change, according to research published in Nature.

• The research review shows that multiple rapid changes across the Antarctic environment are already underway, or imminent.

• These abrupt changes include a rapid decline in sea-ice coverage, weakening of ice sheet and ice shelf stability, and population declines in some marine and terrestrial species, due to habitat loss.

• Human-caused climate change worsens with every increment of additional warming, although some impacts can develop abruptly. 

• A regime shift has reduced Antarctic sea-ice extent far below its natural variability of past centuries, and in some respects is more abrupt, non-linear and potentially irreversible than Arctic sea-ice loss. 

• A marked slowdown in Antarctic Overturning Circulation is expected to intensify this century and may be faster than the anticipated Atlantic Meridional Overturning Circulation slowdown. 

• Deep ocean currents, known as the Antarctic Overturning Circulation, help regulate the climate by transporting heat, carbon, nutrients and oxygen to other areas.

• Regime shifts are occurring in Antarctic and Southern Ocean biological systems through habitat transformation or exceedance of physiological thresholds, and compounding breeding failures are increasing extinction risk. 

• Amplifying feedbacks are common between these abrupt changes in the Antarctic environment, and stabilising Earth’s climate with minimal overshoot of 1.5°C will be imperative alongside global adaptation measures to minimise and prepare for the far-reaching impacts of Antarctic and Southern Ocean abrupt changes.

• Sea-ice loss also exposes glacial ice shelves, which fringe the Antarctic continent, to damaging ocean swells and storms that weaken them, promoting iceberg calving from their front.

• As ice shelves reduce the flow of glacial ice from the Antarctic interior to the coast, increased iceberg calving will speed the flow of glacial ice from the continent, directly contributing to sea-level rise.

• The unseasonal or complete absence of sea ice, along with other climate-related changes such as atmospheric warming and ocean acidification, also contribute to habitat loss for marine and terrestrial species.

• Emperor penguins, for example, which depend on land-fast sea ice to raise their chicks, are struggling to adapt to rapid changes in their environment, with several studies warning of their potential extinction by 2100.

• Scientists are also reporting a regime shift in phytoplankton species, with a decline in those preferred by Antarctic krill — a critical food source for other marine creatures.

(The author is a trainer for Civil Services aspirants.)