Antarctic Sea Ice

[GordMay]

Antarctica ice, melted this season to the smallest extent seen since record keeping began over 40 years ago.

"For the first time since the satellite record began in 1979, extent fell below 2 million square kilometers," the National Snow and Ice Data Center wrote in their latest report [1], "reaching a minimum extent of 1.92 million square kilometers on February 25."

After a fairly mediocre summer minimum last February, the sea ice extent quickly grew throughout the southern autumn and winter to reach an exceptionally early winter maximum at the beginning of September. At that time, it was in the top five extents seen in the satellite era.

In past years, the ice around Antarctica would have continued to expand for at least another few weeks, reaching a maximum extent in late September. However, after Sept. 1, 2021, the ice instead began to dwindle — slowly at first, but by mid-October the numbers plummeted. Ice extent measured through the rest of the southern spring and into southern summer tracked among the lowest seen so far.

Typically, the decrease in Antarctic sea ice extent levels off in late January or early February. However, this year, we didn't see that same levelling-off. Instead, the ice continued to melt.

On Feb. 8, Antarctic sea ice extent set a new daily record for the lowest extent ever measured — beating out the previous record lows set back in 2017 and 2018. For over two weeks after, new daily records were set until the melting finally slowed to a halt.

Feb. 25, 2022 now holds the new record for lowest summer minimum extent of Antarctic sea ice since 1979.

While the Arctic shows a clear long-term trend of dwindling sea ice, and global sea ice is shrinking as well, the situation in the waters around Antarctica is more complex. Sea ice extent in the Southern Ocean varies much more widely, year to year. Also, yearly minimum extents showed a generally increasing trend from the mid-1990s through the mid-2010s.

The reason for this? Based on the changes we are seeing, it appears that global warming is in the process of turning Antarctic land ice into Antarctic sea ice.

It starts with warming air and water temperatures causing more melting of the glaciers and ice sheets along the continent's coastlines. The freshwater produced from this melting then pours into the ocean, where it floats atop the denser saltwater and quickly refreezes. This additional sea ice is then spread farther away from the coastlines by wind and ocean currents, increasing the overall extent measured by satellites.

However, if ocean temperatures are high enough, it impacts the formation of sea ice. The ice doesn't form as quickly in the fall and winter seasons, and it melts away more quickly in spring and summer. For this reason, climate scientists have been warning that increasing ocean temperatures will eventually take their toll on Antarctic sea ice, just as we are seeing in the Arctic.

"The temperature of the ocean limits how much area the ice can cover," Dr. Marilyn Raphael, director of the UCLA Institute of the Environment and Sustainability and coauthor of new research [2] into Antarctic sea ice published in January, stated in a UCLA press release last month. [3]

Perhaps coincidentally, the top 7 warmest years for ocean heat content have all been since 2015, with 2021 setting a new record [4 & 5].
However, it's possible it may not be a coincidence. Instead, it could be a sign that we've passed a tipping point, and the years of increasing sea ice minimums in the Southern Ocean are, indeed, over.


[1] “Arctic sea ice approaches maximum; record low minimum in the south” ~ by National Snow and Ice Data Center [March 8, 2022]
➥ https://nsidc.org/arcticseaicenews/2...-in-the-south/



[2] “A regime shift in seasonal total Antarctic sea ice extent in the twentieth century” ~ by Ryan L. Fogt et al [January 10, 2022]
➥ https://www.nature.com/articles/s41558-021-01254-9

[3] “Antarctic sea ice level could reach record low in 2022, UCLA climate scientist says” ~ by David Colgan, UCLA Newsroom [February 2, 2022]
➥ https://newsroom.ucla.edu/releases/a...ecord-low-2022

[4] “World's oceans broke heat records again in 2021" ~ by Scott Sutherland, The Weather Network [January 20, 2022]
➥ https://www.theweathernetwork.com/en...-again-in-2021

[5] “Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions” by Lijing Cheng et al [January 11, 2022]
➥ https://link.springer.com/article/10...376-022-1461-3



See also:
“Significant Climate Anomalies & Events in 2021" ~ NOAA [January 2022]
➥ https://www.ncdc.noaa.gov/sotc/global/202113

[mako]

@Gord, I speaka da inglisi pretty good, but honestly I have no idea what this means:

" ice, melted this season to the smallest extent seen since record "

Does that mean that the ice melted so much that there is very little left, or does it mean that it melted the least amount and now we have happy penguins?

[GordMay]

Originally Posted by mako

@Gord, I speaka da inglisi pretty good, but honestly I have no idea what this means:

" ice, melted this season to the smallest extent seen since record "

Does that mean that the ice melted so much that there is very little left, or does it mean that it melted the least amount and now we have happy penguins?

Not exactly "very little" left, but "the least left" [smallest surface area], on record.

[roverhi]

Records only go back 40 years according to the report. One positive, the reduced sea ice sheet allowed them to find Shackleton's Endurance.

[Bycrick]

40 years. That’s really a long-term trend that we should worry about. It’s warmer than yesterday. That proves …… nothing.

[GordMay]

Antarctic sea ice extent set a record low minimum, for the satellite data era [1979 = 43 yrs. ago].
However, two regions of high interest, to researchers, remained locked in ice: Thwaites Glacier and the central Weddell Sea.

Sir Ernest Shackleton’s “Endurance was located at a depth of ±10,000 Ft, in the Weddell Sea at 69° 39' 30″ S x 52° 26' 30″W, about 3.5 nm south of Worsley's original calculated location*.
The sea ice, which covers the Weddell Sea year-round, and usually makes underwater exploration nearly impossible, due to its thickness, was recorded as being at the lowest levels around Antarctica, since space satellite records began.
This couldn't have hurt.

* Ship’s Captain & Navigator, Frank Worsley had fixed the original position as 68° 38.5' S x 52° 58'W.

The cited papers are about Antarctic Sea Ice Extent - Not temperature.

[Mal Reynolds]

Here is more data on sea ice extent at the poles. https://nsidc.org/data/seaice_index/
It's all laid out so even laymen like me can get the gist. One thing about Antarctica that makes this complex is volcanic activity.

Another data source I go to is the University of Alabama Huntsville that collates satellite data: https://www.nsstc.uah.edu/climate/index.html
In the satellite data you can find variances from average by latitude ranges. These show temperatures below 60S have changed very little, and the Southern hemisphere generally much less than the Northern hemisphere.

[GordMay]

Antarctic sea ice hits lowest minimum on record

Natural variability is probably the cause, although global warming could have a role.

Antarctic sea ice this year shrank to its lowest minimum extent since satellite records began in 1979. The minimum extent of 1.92 million square kilometres, recorded on 25 February, was 190,000 square kilometres less than the previous record in 2017.

Researchers say the low was partly caused by strong winds pushing the ice to warmer waters, where it melted. Scientists attribute the extreme to natural variability — but add that, over the long term, climate change will result in declining sea ice there.

More ➥ https://www.nature.com/articles/d41586-022-00550-4

[GordMay]

This looks like 'good' news, for a change:

Glaciers Hold Less Ice Than Previously Thought

Unprecedented research [1], into 250,000 glaciers, has found they hold less ice, and water, than originally thought.
Scientists now estimate there is 20 percent less glacial ice present [less ice in some regions and more ice in others = less overall], with the potential to melt into the ocean, and raise sea levels. Currently, glaciers are responsible for 1 millimetre of annual sea level rise, or 30 percent of the yearly increase.

Scientists at France’s Institute of Environmental Geosciences [IGE], and Dartmouth College, say [1] it means melting glaciers will have less impact on rising sea levels. The revised estimate reduces global sea level rise by 3 inches (7.62 centimetres), from 13 inches to just over 10 inches, if all glaciers were to melt.

But it raises concern, for some communities ,that rely on seasonal melt from glaciers, to feed rivers and irrigate crops. If glaciers contain less ice, fresh water [for drinking, agriculture, & power generation, etc] will run out sooner than expected.

The study [1] does not include Greenland, and the Antarctica, which in the long-term will be the major drivers of sea-level rise. If all Antarctica would melt, it has the potential to increase the sea-level rise by more than 50 metres, which is way more than the 25 centimetres from the glaciers

Much more about:
New Atlas Says Most Glaciers Hold Less Ice Than Thought ~ by Dartmouth College
Findings have implications for freshwater availability and sea levels.
➥ https://home.dartmouth.edu/news/2022...ss-ice-thought

[1] “Ice velocity and thickness of the world’s glaciers” ~ by Romain Millan et al [Feb. 7/22]
Abstract ➥ https://www.nature.com/articles/s41561-021-00885-z

[GordMay]

“Scientists report complete collapse of East Antarctica’s Conger Ice Shelf” ~ by The Woods Hole Oceanographic Institution (WHOI)

Satellite data has confirmed that an ice shelf, about the size of Manhattan, has completely collapsed in East Antarctica within days of record high temperatures. The Glenzer Conger ice shelf, which had an approximate surface area of 1,200 square km (463sq miles), collapsed [off iceberg C-38] around March 15, scientists confirmed today.

Catherine Walker*, a glaciologist at the Woods Hole Oceanographic Institution says this was a surprise because, while ice shelf collapse is something predicted to happen in West Antarctica (e.g., Thwaites Glacier) East Antarctica is the highest, coldest, driest place in the world, and mostly thought of as stable, and not much affected by climate change.

More ➥ https://www.whoi.edu/press-room/news...ger-ice-shelf/

Thinning Antarctica ice shelf collapses after heatwave
The 1,200sq km (463sq miles) Conger Ice Shelf crumbled [off iceberg C-38], after temperatures in the East Antarctic surged to 40C above normal, earlier this month.
➥ https://www.aljazeera.com/news/2022/...after-heatwave


Extremes of 40C above normal: what’s causing ‘extraordinary’ heating in polar regions?

Antarctic and Arctic temperatures have shocked researchers. How unusual are they? What are the consequences?

Concordia station, high on the Antarctic Plateau, hit a record temperature of -11.8C on Friday, more than 40C warmer than seasonal norms. Vostok station registered a temperature of -17.7C, beating its record by 15C.

At the same time, some stations near the north pole reached 30C above normal, with records broken in Norway and unusually warm temperatures recorded in Greenland and the Russian archipelago of Franz Josef Land.

The Antarctic continent as a whole on Friday was about 4.8C warmer compared to a baseline temperature between 1979 and 2000, the Associated Press reported. On the same day, the Arctic as a whole was 3.3C warmer than the 1979 to 2000 average.

More ➥ https://www.theguardian.com/environm...-polar-regions

Alarming heat waves hit Arctic and Antarctica at the same time
Temperatures peaked at least 50 degrees higher than average in both polar regions.
➥ https://www.livescience.com/arctic-a...eous-heatwaves

* Catherine Colello Walker Mar 24
Complete collapse of East Antarctica's Conger Ice Shelf (~1200 sq. km) ~ March 15, seen in combo of #Landsat and #MODIS imagery. Possible it hit its tipping point following the #Antarctic #AtmosphericRiver and heatwave too?
➥ https://twitter.com/hashtag/CongerIc...=hashtag_click

[JPA Cate]

There are a few sailors from Tasmania (Australia) every summer who go to Antarctica. Does anyone have any recent iceberg reports? or know of a source?

Ann

[GordMay]

The Southern Ocean isn't an important commercial shipping route, like the North Atlantic; so I don't expect there's the same economic/safety concerns with Antarctic icebergs.

There is scientific interest:

The ‘SCAR International Iceberg Database’ was terminated, in the 2009/2010 season.
➥ https://www.scar.org/resources/iceberg-database/

“The SCAR International Iceberg Database” ~ by Olav Orheimemail, Barry Giles, Geir Moholdt, Jo Jacka, Are Bjørdal
Dataset published 2021-04-19 by Norwegian Polar Institute
➥ https://data.npolar.no/dataset/e4b9a...1-56b5589807c4

The ‘Antarctic Report’ offers News & information, on Antarctica & the Southern Ocean.
➥ https://www.antarcticreport.com/

[GordMay]

ATCM Yachting Guidelines for Antarctic Cruises
Each country Party to the Antarctic Treaty is responsible for the regulation of visits to the Antarctic Treaty area organized by its nationals, but the Environmental Protocol requires that an environmental impact assessment be prepared for all activities planned to take place south of 60°S.
More ➥ https://iaato.org/wp-content/uploads...nes_090020.pdf

Information for Yachts
Information on guidelines, preparation and requirements for traveling to Antarctica by yacht.
At the 35th Antarctic Treaty Consultative Meeting (Hobart, 2012), Treaty Parties adopted Resolution 10. This resolution recommends that all those intending to undertake a yacht visit to Antarctica utilize an agreed checklist of yacht-specific items for preparing safe Antarctic voyages. The Parties also recommended the use of agreed Guidelines for Antarctic Cruises. Contact details of national competent authorities and relevant Maritime Rescue Coordination Centers (MRCCs) were also made available for Antarctica-bound yachts.
Much more ➥ https://iaato.org/visiting-antarctic...on-for-yachts/

[GordMay]

“Powerful 'rivers in the sky' could cause Antarctic Peninsula's biggest ice shelf to collapse” ~ by Angela Dewan, CNN

When temperatures in Antarctica soared to 38 degrees Celsius above normal -- around 70 Fahrenheit -- in March, a teetering ice shelf [‘Conger Ice Shelf’ 2] the size of Los Angeles collapsed. Scientists don't know what role the extreme temperatures may have played in the event, but the heat rushed in through what's known as an atmospheric river, a long plume of moisture that transports warm air and water vapor from the tropics to other parts of the Earth.

A new study [1] published Thursday [April 14/22] shows that these "rivers in the sky" -- which dump rain and snow when they make landfall -- are also causing extreme temperatures, surface melt, sea-ice disintegration and large ocean swells which are destabilizing ice shelves on the Antarctic Peninsula, a long, spindly mountain chain that points northwards to the tip of South America.

These conditions were observed during the collapse of two of the peninsula's ice shelves -- Larsen A and B -- in the summers of 1995 and 2002, respectively. And now, as the climate crisis is projected to warm the Earth further, the biggest remaining ice shelf, Larsen C, is also at risk of total collapse, the study [1] says.

The authors of the study [1], published in the Nature journal Communications Earth & Environment, used algorithms, climate models and satellite observations to determine that 60% of the peninsula's calving events -- where an iceberg breaks off an ice shelf or glacier -- were triggered by atmospheric rivers between 2000 and 2020.

More reporting about ➥ https://www.cnn.com/2022/04/14/world...ntl/index.html



[1] “Intense atmospheric rivers can weaken ice shelf stability at the Antarctic Peninsula” ~ by Jonathan D. Wille et al

“Abstract
The disintegration of the ice shelves along the Antarctic Peninsula have spurred much discussion on the various processes leading to their eventual dramatic collapse, but without a consensus on an atmospheric forcing that could connect these processes. Here, using an atmospheric river detection algorithm along with a regional climate model and satellite observations, we show that the most intense atmospheric rivers induce extremes in temperature, surface melt, sea-ice disintegration, or large swells that destabilize the ice shelves with 40% probability. This was observed during the collapses of the Larsen A and B ice shelves during the summers of 1995 and 2002 respectively. Overall, 60% of calving events from 2000–2020 were triggered by atmospheric rivers. The loss of the buttressing effect from these ice shelves leads to further continental ice loss and subsequent sea-level rise. Under future warming projections, the Larsen C ice shelf will be at-risk from the same processes ...”

Full paper ➥ https://www.nature.com/articles/s43247-022-00422-9



[2] See also “Collapse of East Antarctica’s Conger Ice Shelf” [March 26/22]
➥ https://www.cruisersforum.com/forums...ml#post3597625

[GordMay]

Meanwhile:

Why Iceland’s seas are falling

Melting ice in Iceland is flowing away, lightening the load on the rock below, and causing the ground to rise. The huge scale of melting, in nearby Greenland, is also causing water to move away, because of the reduced gravitational pull on the ocean. In parts of Iceland, the land is rising by almost 4 centimetres a year, threatening the livelihoods of fishers, who face the risk of shipwreck. Meanwhile, the lost ice contributes to sea-level rise elsewhere.

“A drop in the ocean” ~ by Ivana Kottasová and Temujin Doran, for CNN
As the world experiences sea level rise, Iceland’s waters are falling — and flowing to the other side of the planet.

“... Sea lagoons that surrounding the village of Höfn — pronounced hup, as if you have the hiccups — are becoming shallower and harder to navigate. The tides come in and out with less force than they used to, causing the channel that fishing boats pass through to slowly fill up with sediment ...
... As the fishermen in Höfn grapple with the consequences of shallower seas, people on the Marshall Islands have been watching the sea around them rapidly rise.
The Marshalls are made up of five islands and 29 low-lying, ring-shaped atolls. As ice melts on the other side of the globe in places like Greenland and Iceland, the resulting sea level rise has forced people here to change their way of life and think about their future in a more existential way ...”

More ➥ https://edition.cnn.com/interactive/...ands-cmd-intl/