Up until 2014, Antarctic Sea Ice Area exhibited a slow yearly increase. Then the system broke.
Since then, there have been three years of record low sea ice and two years of very high sea ice; basically variability or whiplashing has more than doubled.
The major problem for the global climate is that with record low sea ice formation and record low sea ice area circumventing Antarctica, there is much less dense water created from salt rejection as sea ice forms. Thus, less water sinks to the abyss, in fact over 30% less in the Weddell Sea; thus formation of Antarctica Bottom Water (AABW) is reduced about 15%. This slows the Global Meridional Overturning Circulation (Global MOC) and has profound effects on global climate stability.
Very serious indeed.
There are also many problems local to Antarctica as well, such as enhanced wave action erosion (melting) and calving of ice sheets, disruptions to phytoplankton, mass mortality of emperor penguins, to name a few.
However, by far the most profound and far-reaching problem is the MOC reduction and global climate instability, with cascading feedbacks much more likely.
Most important articles discussed in this video:
“There are growing fears of an alarming shift in Antarctic sea ice”: [ Ссылка ]
“Slowdown of Antarctic Bottom Water export driven by climatic wind and sea-ice changes”:
Antarctic Bottom Water (AABW) is pivotal for oceanic heat and carbon sequestrations on multidecadal to millennial timescales. The Weddell Sea contributes nearly a half of global AABW through Weddell Sea Deep Water and denser underlying Weddell Sea Bottom Water that form on the continental shelves via sea-ice production. Here we report an observed 30% reduction of Weddell Sea Bottom Water volume since 1992, with the largest decrease in the densest classes. This is probably driven by a multidecadal reduction in dense-water production over southern continental shelf associated with a greater than 40% decline in the sea-ice formation rate…”:
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“Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater”: [ Ссылка ]
“Extensive melting of West Antarctic ice sheet now looks unavoidable”: [ Ссылка ]
“Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century”: …We find that rapid ocean warming, at approximately triple the historical rate, is likely committed over the twenty-first century, with widespread increases in ice-shelf melting, including in regions crucial for ice-sheet stability...”:
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“Emperor penguin colonies lost all their chicks due to ice breakup”: [ Ссылка ]
“Large-scale drivers of the exceptionally low winter Antarctic sea ice extent in 2023”: [ Ссылка ]
“Impacts of recent Antarctic Sea-Ice Extremes”: [ Ссылка ]
“Observational Evidence for a Regime Shift in Summer Antarctic Sea Ice”: In recent years, the Southern Ocean has experienced extremely low sea ice cover in multiple summers. These low events were preceded by a multidecadal positive trend that culminated in record high ice coverage in 2014. This abrupt transition has led some authors to suggest that Antarctic sea ice has undergone a regime shift… We find that the standard deviation of the summer sea ice record has doubled from 0.31 million km2 in 1979–2006 to 0.76 million km2 for 2007–22. This increased variance is accompanied by a longer season-to-season sea ice memory. The atmosphere is the primary driver of Antarctic sea ice variability, but using a linear predictive model we show that sea ice changes cannot be explained by the atmosphere alone. Identifying whether a regime shift has occurred is difficult without a complete understanding of the physical mechanism of change. However, the statistical changes that we demonstrate (i.e., increased variance and autocor- relation, and a changed response to atmospheric forcing), as well as the increased spatial coherence noted by previous re- search, are indicators based on dynamical systems theory of an abrupt critical transition. Thus, our analysis is further evidence in support of a changed Antarctic sea ice system.”:
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