Antarctic sea ice [image credit: BBC]
Sea ice levels are notorious for misuse by climate alarmists. Thankfully no mention of climate red herrings in this study.
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Antarctic sea ice is an important component of the climate system [snip – redundant climate waffle] — [and] significant changes in Antarctic sea ice have been observed, says Phys.org.
Specifically, it experienced a slow increase during 1979–2014, but a rapid decline thereafter.
Despite a modest recovery after the record minimum in 2017, the sea ice area during austral summer 2022 (December 2021 to February 2022) again hit a new record minimum, at 3.07 million km2, which is approximately a 25% reduction compared with its long-term mean during 1981–2010.
The largest decline occurred in two regions: the central-eastern Ross Sea to western Amundsen Sea, and the eastern Bellingshausen Sea to the northern Weddell Sea.
This latest record low occurred just five years after the preceding record low in summer 2017, which is surprising and has raised concern about climate change in the Antarctic.
In a paper recently published in Atmospheric and Oceanic Science Letters, Prof. Shuanglin Li from the Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, and Dr. Chao Zhang from the China University of Geosciences, Wuhan, China, attempt to uncover the underlying mechanisms of this record-low sea ice area.
“We found that the combination of stronger positive sea surface temperature anomalies in the Maritime Continent during July–September 2021 and the preceding near-strongest positive-phase Southern Annular Mode during August–October 2021 induced a deepened and southwestward-shifted Amundsen Sea Low, causing sea ice retreat via horizontal wind anomalies,” explains Prof. Li.
The former persisted into summer and favored the development of La Niña, which triggered an atmospheric wave train emanating from eastern Australia and propagating southeastward, deepening the Amundsen Sea Low remotely. The latter remained strongest or close to strongest due to the stratospheric cooling effect of unprecedented ozone reduction, which induced a deepened and southwestward-shifted Amundsen Sea Low.
“The unprecedented ozone reduction also played a role through the induced surface warming in the West Antarctic by increasing downward shortwave radiation. Additionally, positive feedback between sea surface temperatures, net shortwave radiation, and cloudiness, along with the Ekman heat transport, amplified the surfacing warming,” adds Prof. Li.
Source here.
Tallbloke's Talkshop 
Did they consider the underwater volcanoes and the fact they might have something to do with their real world observations?
Reblogged this on Climate Collections.
The Antarctic sea-ice data only goes back as far as 1979, which is too short to be making assertions about ‘climate change’ – or ozone. The Nimbus data from the 60s shows that Antarctic sea ice is highly variable.
“We were shocked by what we discovered in these images,” says Gallaher. “We thought, OK, all reports from the 1960s were that it was colder, so we expected to see a lot more sea ice. In fact, 1964 was the largest sea ice extent until 2014. Then in 1966 we saw the lowest ice extent that was ever seen. This was totally unexpected. There’s a lot more variability in sea ice extent than we ever could have imagined.”
https://www.earthdata.nasa.gov/learn/articles/new-data-from-old-satellites-a-nimbus-success-story
As JJ’s quote shows, alarmists talking up temporary sea ice conditions with no long term trend to back it up is just another wind-up.
More comedy modelling here…
Antarctic ocean currents headed for collapse, say scientists
March 30, 2023
A new study says that rapidly melting Antarctic ice could impact oceans “for centuries to come.”
https://www.dw.com/en/deep-ocean-currents-around-antarctica-headed-for-collapse-say-scientists/a-65176623
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*could* impact… 🥱
Really…
I’m far more worried by the late, great Terry Pratchett’s more credible theory that the Earth is about to be swallowed by a giant intergalactic sky goat.
[…] From Tallbloke’s Talkshop […]
APRIL 4, 2023
The ice in Antarctica has melted before, says study
by Steinar Brandslet, Norwegian University of Science and Technology
“From the evidence we presented in our study, we concluded that the East Antarctic ice sheet in Queen Maud Land also melted rapidly along its margins between 9,000 to 5,000 years ago, in a period we call the mid-Holocene. At this time, many parts of the world experienced warmer-than-present summers,” Rogozhina said.
https://phys.org/news/2023-04-ice-antarctica.html
SAM index with commentary here…
https://climatedataguide.ucar.edu/climate-data/marshall-southern-annular-mode-sam-index-station-based
The idea that warming leads to more moisture in the atmosphere, and thus higher rainfall, doesn’t work in Patagonia and the Antarctic under a positive SAM – as described below. Graphic says: ‘decreased precipitation’.
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From AntarcticGlaciers.org:
Today, glaciers in Patagonia and Antarctica are receding. In both cases, this has been attributed to changes in the Southern Westerly Winds and the Southern Annular Mode (SAM).
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The Southern Annular Mode is a key climatic component that will strongly affect how glaciers in the Southern Hemisphere respond to climate change. It explains the key drivers for glaciation in the Southern Hemisphere, and why glacier advances are asynchronous with those in the Northern Hemisphere.
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Antarctic Circumpolar Current
The Antarctic Circumpolar Current (ACC) is the World’s strongest current. It is able to flow unimpeded through the Drake Passage and around the continent of Antarctica. The winds over the channel and the flow of the ACC are aligned for the length of the channel. The ACC is getting stronger as the Westerly Winds have contracted poleward during the current positive phase of the Southern Annular Mode, as the winds are more directly aligned with the current.
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In a Positive Southern Annular Mode (the situation today), the belt of strong westerly winds strengthens and contracts towards Antarctica. It weakens at the northern boundary in the mid-latitudes (40-50°S). It is drier over Patagonia, driving glacier recession. In Antarctica, increased Circumpolar Deep Water upwells onto the continental shelf, driving glacier and ice sheet recession.
https://www.antarcticglaciers.org/glaciers-and-climate/changing-antarctica/southern-annular-mode/
Wait for it…
The positive trend in the Southern Annular Mode since ~AD 1940 has been attributed to rising greenhouse gas levels and ozone depletion, and the long-term average SAM index is now at its highest level for the last 1000 years.
But the SAM always existed and varied before that 🙄
It’s admitted their data is patchy, based on few stations and only goes back to 1957. So any talk of the last 1000 years must be suspect.