East Antarctica recorded an extraordinary increase in ice mass of 695\nbillion tonnes between 2021 and 2023. This phenomenon temporarily slowed\nthe long-term decline of the Antarctic ice sheet, and researchers have\nnow discovered the surprising reason behind the event.<\/p>\n
Based on a recent study published in the journal Nature on 19 August,\nscientists found that warming in tropical oceans thousands of miles away\nhas altered atmospheric circulation. This change channelled large\namounts of moisture towards the continent, which subsequently triggered\nvery heavy snowfall.<\/p>\n
The Antarctic ice sheet is a primary source of uncertainty for\nscientists in estimating future global sea-level rise. Over the last two\ndecades, Antarctica has lost an average of approximately 140.5 billion\ntonnes of ice per year.<\/p>\n
However, this pattern shifted briefly during the 2021-2023 period.\nThis 695 billion tonne mass addition was recorded as the largest\nAntarctic mass increase ever observed by the GRACE satellite\nmission.<\/p>\n
The research, led by the Institute of Oceanology of the Chinese\nAcademy of Sciences (IOCAS), analysed gravity satellite measurements,\nsnow accumulation records from ice cores, and atmospheric circulation\nsimulations to understand this phenomenon.<\/p>\n
The research team identified sustained warming in the tropical warm\npool during 2021-2023, a region where the western tropical Pacific meets\nthe eastern Indian Ocean. This warming triggered what scientists call a\n\u201cRossby wave train\u201d, a large-scale atmospheric wave pattern capable of\ntransmitting weather changes across vast distances.<\/p>\n
This disturbance moved towards high southern latitudes and rearranged\natmospheric conditions around Antarctica. This resulted in a north-south\ndipole circulation pattern, with unusual low pressure south of Australia\nand high pressure along the East Antarctic coast.<\/p>\n
This pressure pattern strengthened the transport of water vapour from\nthe mid-latitude Indian Ocean to East Antarctica through \u201catmospheric\nrivers\u201d.<\/p>\n
Atmospheric rivers are narrow corridors in the atmosphere that carry\nlarge amounts of water vapour. When they reach cold regions such as\nAntarctica, this moisture falls as heavy snowfall. Simulations show that\nthe dipole circulation directed more atmospheric rivers towards the\nQueen Mary Land-Wilkes Land region, adding significant mass to the ice\nsheet.<\/p>\n
Interestingly, researchers found that the contribution from\nanthropogenic factors (human activity) accounted for only 9% of the\nobserved snowfall anomaly. This suggests that the general increase in\natmospheric moisture due to global warming is not the primary\nexplanation for this specific event.<\/p>\n
Researchers described the tropical warm pool as a long-distance\n\u201cregulator\u201d that can influence the East Antarctic ice mass over\nmulti-year periods. Similar phenomena are estimated to occur\napproximately once per decade.<\/p>\n
\u201cWe have found a previously under-recognised \u2018tropical warm pool-East\nAntarctic Ice Sheet\u2019 teleconnection pathway,\u201d said Yunhe Wang from\nIOCAS, the lead author of the study.<\/p>\n
Despite the striking increase, researchers emphasised that this event\nis temporary. The long-term decline of the overall Antarctic ice sheet\ncontinues. The West Antarctic ice sheet is still losing mass, and\nseveral glaciers in East Antarctica remain vulnerable to melting from\nbelow due to warming seawater.<\/p>", "url": "https:\/\/jawawa.id\/newsitem\/record-695-billion-ton-increase-in-antarctic-ice-scientists-discover-the-trigger-1788882771", "image": "" }, "sponsor": "Okusi Associates", "sponsor_url": "https:\/\/okusiassociates.com" }