Antarctic sea-ice expansion in a warming climate:

[beecee]

https://phys.org/news/2022-04-antarctic-sea-ice-expansion-climate.html

Antarctic sea-ice has expanded over the period of continuous satellite monitoring, which seemingly contradicts ongoing global warming resulting from increasing concentrations of greenhouse gasses. In a study, published in Nature Climate Change, an international team of scientists from the University of Hawaiʻi at Mānoa, National Oceanic and Atmospheric Administration (NOAA) and South Korea shows that a multi-decadal swing of the tropical sea surface temperatures and its ability to change the atmospheric circulation across large distances is in large part responsible for the observed sea-ice expansion since the late 1970s.

Sea ice, which covers a substantial portion of the ocean surface in the polar regions, plays an important role in controlling global temperatures by reflecting incoming solar radiation. Decreases in sea-ice coverage, therefore, are expected to amplify greenhouse gas-induced global warming. Changes in sea ice also affect energy exchanges between the ocean and atmosphere, carbon uptake by the ocean, ecosystems and the thermohaline oceanic circulation.

more at link...........................

 

the paper:

https://www.nature.com/articles/s41558-022-01339-z

Antarctic sea-ice expansion and Southern Ocean cooling linked to tropical variability

Abstract:

A variety of hypotheses, involving sub-ice-shelf melting, stratospheric ozone depletion and tropical teleconnections, have been proposed to explain the observed Antarctic sea-ice expansion over the period of continuous satellite monitoring and corresponding model–observation discrepancy, but the issue remains unresolved. Here, by comparing multiple large ensembles of model simulations with available observations, we show that Antarctic sea ice has expanded due to ocean surface cooling associated with multidecadal variability in the Southern Ocean that temporarily outweighs the opposing forced response. In both observations and model simulations, Southern Ocean multidecadal variability is closely linked to internal variability in the tropics, especially in the Pacific, via atmospheric teleconnections. The linkages are, however, distinctly weaker in simulations than in observations, accompanied by a marked model–observation mismatch in global warming resulting from potential model bias in the forced response and observed tropical variability. Thus, the forced response dominates in simulations, resulting in apparent model–observation discrepancy.

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Any ideas? Any errors, alterations and/or corrections?

[MigL]

It's going to be a hell of a job to relocate all the polar bears whose habitat is shrinking/disappearing in the Arctic, to Antartica.

[beecee]

49 minutes ago, MigL said:

It's going to be a hell of a job to relocate all the polar bears whose habitat is shrinking/disappearing in the Arctic, to Antartica.

Never thought of that! 🤤

[Ken Fabian]

Yet it is currently smaller in extent than at any time since records were kept. Big swings, from record high to record low over a short period. https://www.scientificamerican.com/article/antarctic-sea-ice-hit-a-record-low-now-scientists-think-they-know-why/

The recent extraordinary record high temperatures in Antarctica - coincidentally at the same time as breaking temperature records in the Arctic - came after the record low ice extent, so was not a factor. Antarctica's ice sheets are also losing about 200 billion metric tons of ice a year.

[beecee]

35 minutes ago, Ken Fabian said:

Yet it is currently smaller in extent than at any time since records were kept. Big swings, from record high to record low over a short period. https://www.scientificamerican.com/article/antarctic-sea-ice-hit-a-record-low-now-scientists-think-they-know-why/

The recent extraordinary record high temperatures in Antarctica - coincidentally at the same time as breaking temperature records in the Arctic - came after the record low ice extent, so was not a factor. Antarctica's ice sheets are also losing about 200 billion metric tons of ice a year.

Thanks for that. It appears we have still much to figure out. An important extract from your link.......

"It’s the latest event in a puzzling trajectory for Southern Ocean sea ice. For most of the satellite record, beginning in the 1970s, Antarctic sea ice was actually expanding. That’s in stark contrast to the trend at the other end of the world, where Arctic sea ice has been swiftly declining for decades in response to global warming.

But beginning around 2014, the pattern abruptly reversed. Antarctic sea ice started shrinking rapidly. It hit a record-low minimum in 2017, rebounded slightly around 2020, and then plummeted to another record low in 2022.

These trends have perplexed Antarctic scientists, who are still debating the exact causes. Many experts believe natural climate cycles have probably played a large role.

The recovery of the infamous Antarctic ozone hole, which has been gradually healing for the last three decades, may have also had a hand in things. Some studies suggest that the closing of the ozone hole has influenced wind patterns in the Southern Hemisphere, which in turn can affect the movement and behavior of Antarctic sea ice.

And human-caused climate change may have also played a part in recent events, although its exact effect is still uncertain.

Unlike the Arctic, where warming has had a clear and devastating long-term influence on sea ice, conditions are more complicated in the Antarctic. The Southern Ocean is much more vulnerable to the impacts of other natural climate fluctuations, which don’t always have the same kinds of effects as human-caused warming.

For now, climate change may not be the strongest influence out of all the elements affecting Antarctic sea ice. But eventually, as the world continues to warm, it’s likely to become a more dominant factor".

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I also found this.......................

https://www.climate.gov/news-features/understanding-climate/understanding-climate-antarctic-sea-ice-extent#:~:text=Overall%2C the long-term trend,trends have been statistically significant.

Overall, the long-term trend in Antarctic sea ice is nearly flat. The satellite record spans over four decades, and although the ice has shown increasing and decreasing trends over portions of that record, few of those trends have been statistically significant. 

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and this................................

https://www.antarcticglaciers.org/glaciers-and-climate/changing-antarctica/antarctic-sea-ice/

 Last updated 02/06/2021

Increasing Antarctic Sea Ice:

Characteristics of Antarctic sea ice

The Antarctic continent is surrounded by seasonal, floating sea ice. This sea ice, which comprises mainly frozen sea water, with occasional icebergs from glaciers and ice shelves, covers a minimum of 3×106 km2 in February to a maximum of 18×106 km2 in September. This effectively doubles the size of Antarctica in the winter. Most of the summer sea ice stays in the Weddell Sea, where it is relatively protected from the ocean currents.

Summary:

Antarctica is a unique environment, and the complex interactions between ice, ocean and atmosphere have led to a unique set of circumstances that have resulted in sea ice growth. It may be explained by many factors, or most probably by a combination of several. Climate change is a complex process governed by multiple feedbacks between different parts of the system; complex interactions between the melting land ice and ice shelves fringing the continent and changes in wind stress are all implicated in controlling Antarctic sea ice extent. Further, more work is required to ascertain the reliability of observations of sea ice increase given the recent discovery of an error in the algorithm used to quantify and map sea ice over the last few decades.

Edited April 25, 2022 by beecee

[beecee]

https://phys.org/news/2022-04-diminishing-arctic-sea-ice-impacts.html

Diminishing Arctic sea ice has lasting impacts on global climate:

As the impacts of climate change are felt around the world, no area is experiencing more drastic changes than the northern polar region. Studies have shown the Arctic is warming at two to three times as fast as the rest of the planet, resulting in a rapid loss of its sea ice volume.

That sea ice loss, declining at an average rate of about 13 percent per decade, is having a long-lasting climatic impact in the Arctic and beyond, according to a new study published this month in Nature Communications.

The research team, led by University at Albany atmospheric scientist Aiguo Dai, analyzed observational data and climate model simulations to show how fluctuations in Arctic sea ice cover are able to amplify multi-decadal variations in surface temperatures not only in the Arctic, but also in the North Atlantic Ocean.

more at link...............................................

the paper:

https://www.nature.com/articles/s41467-022-29810-7

Sea ice–air interactions amplify multidecadal variability in the North Atlantic and Arctic region:

Abstract:

Winter surface air temperature (Tas) over the Barents–Kara Seas (BKS) and other Arctic regions has experienced rapid warming since the late 1990s that has been linked to the concurring cooling over Eurasia, and these multidecadal trends are attributed partly to internal variability. However, how such variability is generated is unclear. Through analyses of observations and model simulations, we show that sea ice–air two-way interactions amplify multidecadal variability in sea-ice cover, sea surface temperatures (SST) and Tas from the North Atlantic to BKS, and the Atlantic Meridional Overturning Circulation (AMOC) mainly through variations in surface fluxes. When sea ice is fixed in flux calculations, multidecadal variations are reduced substantially (by 20–50%) not only in Arctic Tas, but also in North Atlantic SST and AMOC. The results suggest that sea ice–air interactions are crucial for multidecadal climate variability in both the Arctic and North Atlantic, similar to air-sea interactions for tropical climate.