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Aluminium

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Re: Sea Ice Extent around Antarctica
« Reply #950 on: September 27, 2018, 08:00:26 AM »
September 22-26.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #951 on: September 28, 2018, 09:46:12 AM »
JAXA EXTENT 18,043,406 km2(September 27, 2018)

Changed to a story of "what goes down, must go up"

The Antarctic continues to demonstrate its unpredictability

Extent is
- 414 k (2.3 %) above 2017,
- 124 k (0.7 %) above 2016, and
- 694 k (3.8%) below the 2010's average

Melt has not got going, with extent loss from the current maximum of 18.10 million km2 a mere 60k, 195 k less than the average extent loss to date.
 
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
"Para a Causa do Povo a Luta Continua!"
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Aluminium

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Re: Sea Ice Extent around Antarctica
« Reply #952 on: September 29, 2018, 11:34:55 AM »
September 24-28.

Aluminium

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Re: Sea Ice Extent around Antarctica
« Reply #953 on: October 01, 2018, 08:17:54 AM »
September 26-30.

colchonero

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Re: Sea Ice Extent around Antarctica
« Reply #954 on: October 01, 2018, 08:17:05 PM »
The new yearly maximum was reached today.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #955 on: October 02, 2018, 07:31:10 AM »
JAXA EXTENT 18,113,345 km2(October 1, 2018)

Changed to a story of "what goes down, must go up"

The Antarctic continues to demonstrate its unpredictability

Extent is at a new maximum and
- 395 k (2.2 %) above 2017,
- 127 k (0.7 %) above 2016, and
- 637 k (3.5%) below the 2010's average

Melt has not got going at all, while average extent loss from maximum to date is 256k.
 
Maximum is already 15 days later than average, which is uncommon, though an October maximum occurred in 2015 (Oct 2) and 2003 (Oct 3)
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Aluminium

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Re: Sea Ice Extent around Antarctica
« Reply #956 on: October 03, 2018, 06:50:34 AM »
September 28 - October 2.

Aluminium

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Re: Sea Ice Extent around Antarctica
« Reply #957 on: October 05, 2018, 07:49:51 AM »
September 30 - October 4.

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #958 on: October 14, 2018, 10:26:59 AM »
JAXA EXTENT 17,884,410 km2(October 13, 2018)

Changed to a story of "what goes down, must go up, or maybe stays the same"

The Antarctic Sea Ice continues to demonstrate its unpredictability by being late to very late in commencing melt .

Extent is
- 46 k (0.3 %) above 2017,
- 147 k (0.8 %) above 2016,
- 574 k (3.1%) below the 2010's average
- third lowest in the satellite record,
Extent loss to date from maximum is 0.3 million km2 less than the average of 0.53 million km2, but with merely 3.4% of the melting season over.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Stephan

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Re: Sea Ice Extent around Antarctica
« Reply #959 on: October 14, 2018, 11:43:21 AM »
I am not completely convinced that the melting start is too late this year. The daily change wobbles around the blue polynomial line.
I wonder whether a "2016 like" melting will set off soon or whether a more moderate/average melt season will be in the pipeline. This will also decide whether the GSI area/extent graph will follow the very low 2016 line or the higher 2017 line.

steve s

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Re: Sea Ice Extent around Antarctica
« Reply #960 on: October 14, 2018, 08:50:34 PM »
I suspect the sea ice concentration has been low this year, causing the total volume of ice to remain low. At least, that is the way I've been reading the AMSR2 data. The link is to the current reported image:
https://seaice.uni-bremen.de/data/amsr2/today/Antarctic_AMSR2_nic.png

The low concentration probably allowed winds to repeatedly spread the ice. The temperatures remaining below freezing, new (but thin) ice would have formed soon after each breakup. The result would enlarge sea ice extent as measured. Obviously there are other assumptions involved -- including sea surface temperatures, outflows from glaciers, air temperatures near the surface, and cloud cover.

I expect a fast and large decline in extent during this Antarctic summer -- jf other things, such as temperatures, are similar to those of the last few years.
« Last Edit: October 15, 2018, 06:45:26 AM by steve s »

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #961 on: October 20, 2018, 10:48:56 AM »
JAXA EXTENT 17,630,067 km2(October 19, 2018)

Melt is starting to accelerate, faster than 2017, and slower than 2016.

Extent is
- 5 k (0.0 %) below 2017,
- 368 k (2.1 %) above 2016,
- 568 k (3.1%) below the 2010's average
- 2nd lowest in the satellite record,

Extent loss to date from maximum is 0.3 million km2 less than the average of 0.78 million km2, but with merely 5.2% of the melting season over. The time of year has come when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #962 on: October 25, 2018, 12:31:07 PM »
JAXA EXTENT 17,190,030 km2(October 24, 2018)

Melt is cointinuing to accelerate, faster than 2017, and slower than 2016.

Extent is
- 309 k (1.8 %) below 2017,
- 265 k (1.6 %) above 2016,
- 759 k (4.2%) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice extends well north of the Arctic Circle. There is 3/4 million Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 92 k km2 (9.1%) less than the average, but with merely 6.8% of the melting season over. The time of year is coming when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #963 on: November 03, 2018, 10:11:44 AM »
JAXA EXTENT 16,663,144 km2(November 2, 2018)

Melt at around average in the last week.

Extent is
- 336 k (2.0 %) below 2017,
- 260 k (1.6 %) above 2016,
- 750 k (4.3%) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice extends well north of the Arctic Circle. There is 3/4 million Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 68 k km2 (4.5%) less than the average, but with merely 10.5% of the melting season over. The time of year is coming when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #964 on: November 04, 2018, 07:33:01 AM »
JAXA EXTENT 16,544,480 km2(November 3, 2018)

Extent loss on this day 119k, 1st century break of this melting season, and 30 k > averge (last 10 years)
Extent is
- 395 k (2.3 %) below 2017,
- 219 k (1.3 %) above 2016,
- 780 k (4.5%) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice extends well north of the Arctic Circle. There is 780k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 36 k km2 (2.2%) less than the average, but with just 11.2% of the melting season over. The time of year is coming when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #965 on: November 06, 2018, 10:31:43 AM »
JAXA EXTENT 16,304,104 km2(November 5, 2018)

Extent loss on this day 122k, 3rd century break in a row of this melting season, and 50 k > average (last 10 years). This has changed the picture somewhat.
Extent is
- 325 k (2.3 %) below 2017,
- 316 k (2.3 %) above 2016,
- 833 k (4.9%) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice extends well north of the Antarctic Circle. There is 830k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 22 k km2 (1.2%) greater than the average, but with just 12.7% of the melting season over. The time of year has almost arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
« Last Edit: November 06, 2018, 08:47:14 PM by gerontocrat »
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #966 on: November 07, 2018, 12:40:09 PM »
JAXA EXTENT 16,142,891 km2(November 6, 2018)

Extent loss on this day 161k, 4th century+ break in a row of this melting season, and 80 k > average (last 10 years). This continues to chang the picture somewhat.
Extent is
- 434 k (2.6 %) below 2017,
- 233 k (1.5 %) above 2016,
- 916 k (5.4 %) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice extends well north of the Antarctic Circle, most north of 60 degrees South. There is 816k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 106 k km2 (5.7%) greater than the average, but with just 13.3% of the melting season over. The time of year has arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
[/quote]
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #967 on: November 08, 2018, 11:08:06 AM »
JAXA EXTENT 16,012,390 km2(November 7, 2018)

Extent loss on this day 130k, 5th century+ break in a row of this melting season, and 26 k > average (last 10 years). This continues to change the picture somewhat.
Extent is
- 442 k (2.7 %) below 2017,
- 241 k (1.5 %) above 2016,
- 941 k (5.6 %) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice at this time of year extends well north of the Antarctic Circle, much north of 60 degrees South. There is 941k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is 132 k km2 (6.7%) greater than the average, but with just 14.1% of the melting season over. The time of year has arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

wdmn

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Re: Sea Ice Extent around Antarctica
« Reply #968 on: November 08, 2018, 01:10:37 PM »
Thanks gerontocrat.

Why is it that the arctic sea ice went so many decades without losing extent, but now seems to be on the decline suddenly? Were there losses in volume in previous decades, or just the way that the ocean currents work less heat was getting to the Antarctic?

thanks

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #969 on: November 08, 2018, 01:52:38 PM »
Thanks gerontocrat.

Why is it that the arctic sea ice went so many decades without losing extent, but now seems to be on the decline suddenly? Were there losses in volume in previous decades, or just the way that the ocean currents work less heat was getting to the Antarctic?

thanks
There are hyotheses galore. But remember nearly all of sea ice in the Antarctic is one year ice. 2.2 million km2 minimum, 18.1 million km2 maximum in 2018. So it must be all about the fierce circumpolar currents (air and ocean) that block warmth from getting south. Are they weakening?

This is so far the third year of significant decline compared with 1979 to circa 2015. So too early to claim there has been a permanent change.
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Sleepy

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Re: Sea Ice Extent around Antarctica
« Reply #970 on: November 08, 2018, 03:35:28 PM »
It happened in the 60's as well, check out the recovered Nimbus missions.
Regarding my comments above in #40 & #51 around the recovered Nimbus missions, I'll quote the cires article in #40 to highlight what I personally think is the thing to look for within a couple of years. A record low.
Quote
“And the Antarctic blew us away,” he said. In 1964, sea ice extent in the Antarctic was the largest ever recorded, according to Nimbus image analysis. Two years later, there was a record low for sea ice in the Antarctic, and in 1969 Nimbus imagery, sea ice appears to have reached its maximum extent earliest on record.
Only one weak La Nina during the 60's.
https://www.ggweather.com/enso/oni.htm
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Gray-Wolf

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Re: Sea Ice Extent around Antarctica
« Reply #971 on: November 08, 2018, 05:59:30 PM »
I worry that we have 'turned the corner' with regard the impacts the Ozone hole was having on the circumpolar ( winds and current) so allowing the warming into Antarctica ( and not just the peninsula poking out into the warming world).

To see the extent fall away, as we have this past few years, and now the concentration start flagging I have to worry about the loss of the damping it used to provide to the shelfs over winter there?.

Are we setting up for some rapid changes there over the coming years?

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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #972 on: November 08, 2018, 06:35:53 PM »
I worry that we have 'turned the corner' with regard the impacts the Ozone hole was having on the circumpolar ( winds and current) so allowing the warming into Antarctica ( and not just the peninsula poking out into the warming world).

To see the extent fall away, as we have this past few years, and now the concentration start flagging I have to worry about the loss of the damping it used to provide to the shelfs over winter there?.

Are we setting up for some rapid changes there over the coming years?
Probably not - a slow process, it seems.
But maybe a slow change is all that is needed.

https://www.theguardian.com/environment/2018/nov/05/ozone-layer-healing-after-aerosols-un-northern-hemisphere
Quote
Recovery from the holes and thinning caused by aerosol chemicals has progressed at a rate of about 1% to 3% a decade since 2000, meaning the ozone layer over the northern hemisphere and mid-latitudes should heal completely by the 2030s, if current rates are sustained.

Over the southern hemisphere and in the more problematic polar regions, recovery will take longer, until the middle of this century in the former and about 2060 in the latter case.

https://www.nasa.gov/feature/goddard/2018/nasa-study-first-direct-proof-of-ozone-hole-recovery-due-to-chemicals-ban
Quote
Looking forward, the Antarctic ozone hole should continue to recover gradually as CFCs leave the atmosphere, but complete recovery will take decades. “CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time,” said Anne Douglass, a fellow atmospheric scientist at Goddard and the study’s co-author. “As far as the ozone hole being gone, we’re looking at 2060 or 2080. And even then there might still be a small hole.”
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #973 on: November 13, 2018, 09:31:01 AM »
JAXA EXTENT 15,528,701 km2(November 12, 2018)

Extent loss on this day 157k, and 36 k > average (last 10 years). Overall last few days is below average.
Extent is
- 160 k (1.0 %) below 2017,
- 773 k (5.2 %) above 2016,
- 857 k (5.2 %) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice at this time of year extends well north of the Antarctic Circle, much north of 60 degrees South. There is 857 k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is only 44 k km2 (1.7%) greater than the average, but with just 19.0 % of the melting season over. The time of year has arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #974 on: November 17, 2018, 11:56:11 AM »
JAXA EXTENT 14,976,699 km2(November 16, 2018)

Extent loss last 2 days 158k per day, > average (last 10 years).
Extent is
-     45 k (0.3 %) below 2017,
- 1,065 k (7.7 %) above 2016,
-    887 k (5.6 %) below the 2010's average
- 2nd lowest in the satellite record,

Antarctic Sea Ice at this time of year extends well north of the Antarctic Circle, much north of 60 degrees South. There is 887 k Km2 of open sea compared with the 2010's average absorbing significant warmth as opposed to nearly zero (albedo effect).

Extent loss to date from maximum is only 85 k km2 (2.8%) greater than the average, but with just 23.8 % of the melting season over. The graph is following 2017, well above 2016 extent and rate of loss. The time of year has arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #975 on: November 25, 2018, 08:53:08 AM »
JAXA EXTENT 13,987,722 km2(November 24, 2018)

Extent loss in the last week has been mostly well below average.
As a result extent is now
-    586 k (6.0 %) above 2017,
- 1,390 k (15.5 %) above 2016,
-    482 k (4.9 %) below the 2010's average
- 3rd lowest in the satellite record,

Extent loss to date from maximum is only 10 k km2 (0.2%) greater than the average, with 35.2 % of the melting season over. The graph is now well above 2016 and 2017 extent and rate of loss. The time of year has arrived when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #976 on: December 01, 2018, 08:59:13 AM »
JAXA EXTENT 13,099,117 km2(November 30, 2018)

Extent loss in the last week has been mostly a bit below average.
Extent is now
-    299 k (2.3 %) above 2017,
- 1,401 k (12.0 %) above 2016,
-    712 k (5.2 %) below the 2010's average
- 3rd lowest in the satellite record,

Extent loss to date from maximum is 79 k km2 (1.6%) less than the average, with 47 % of the average extent loss from max to min melting season done. The graph is now well above 2016 and 2017 extent and rate of loss. This is the time of year when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
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gerontocrat

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Re: Sea Ice Extent around Antarctica
« Reply #977 on: December 07, 2018, 09:24:50 AM »
JAXA EXTENT 11,959,349 km2(December 6, 2018)

Extent loss in the last week has been mostly a around average.
Extent is now
-    227 k (1.9 %) above 2017,
- 1,508 k (14.4 %) above 2016,
-    780 k (6.1 %) below the 2010's average
- 3rd lowest in the satellite record,

Extent loss to date from maximum is 17 k km2 (0.3%) less than the average, with 63.3 % of the average extent loss from max to min melting season done. The graph remains well above 2016 but a bit closer to 2017 extent and rate of loss. This is the time of year when sea ice extent plunges.
______________________________________________________________
Antarctic Sea Ice is often dismissed of little importance in the grand scheme of things. The following is a quote from the June 2018 sea ice analysis from NSIDC.

Per NSIDC:-
Quote
Antarctica’s sea ice and ice shelf disintegration[/b]
.... sea ice—a component of the cryosphere that is very sensitive to changing climate and ocean—has an important protective effect on the Antarctic ice sheet.
_______________________________________________________________
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Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #978 on: December 09, 2018, 12:07:24 AM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.

https://sites.google.com/site/cryospherecomputing/daily-data-antarctic

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Re: Sea Ice Extent around Antarctica
« Reply #979 on: December 09, 2018, 12:48:58 PM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.
More than interesting.

But it has not started yet.
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Re: Sea Ice Extent around Antarctica
« Reply #980 on: December 10, 2018, 11:36:25 AM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.
More than interesting.

But it has not started yet (8th Dec).
But now it has.

JAXA ANTARCTIC Sea Ice Extent - 11,320,251 km2(December 9, 2018)

A drop of 317k on this day, though not a rarity at this time of year, is uncommon. Extent is 3rd lowest, though still 1.6 million km2 greater than 2016 on this day. Extent loss from maximum is very close to average so far, with on average 74% of extent loss for the season done.

Being at the beginning of the Austral summer, low extent and area means once again with insolation high, albedo warming potential in the Antarctic is also high and above average. Will this acceleration in extent and area loss continue?
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Re: Sea Ice Extent around Antarctica
« Reply #981 on: December 10, 2018, 07:37:58 PM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.
More than interesting.

But it has not started yet (8th Dec).
But now it has.

JAXA ANTARCTIC Sea Ice Extent - 11,320,251 km2(December 9, 2018)

A drop of 317k on this day, though not a rarity at this time of year, is uncommon. Extent is 3rd lowest, though still 1.6 million km2 greater than 2016 on this day. Extent loss from maximum is very close to average so far, with on average 74% of extent loss for the season done.

Being at the beginning of the Austral summer, low extent and area means once again with insolation high, albedo warming potential in the Antarctic is also high and above average. Will this acceleration in extent and area loss continue?

Yet sea ice compaction went lower still because sea ice area went to just above 2016. I wouldn't be surprised if extent losses continued at this high rate. On the albedo front 2018 is clearly is second place for daily values. For cumulative values since September 2018 is just about to overtake 2017 because of a slow start.

sea ice area:
https://sites.google.com/site/cryospherecomputing/daily-data-antarctic

albedo data:
https://sites.google.com/site/cryospherecomputing/awp/antarctic-graphs

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Re: Sea Ice Extent around Antarctica
« Reply #982 on: December 10, 2018, 07:42:24 PM »
Tealight must be a mind-reader. I was just about to beg for the albedo warming potential data.
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Re: Sea Ice Extent around Antarctica
« Reply #983 on: December 10, 2018, 07:50:02 PM »
Tealight must be a mind-reader. I was just about to beg for the albedo warming potential data.

you already asked for it in the previous post  ;)

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Re: Sea Ice Extent around Antarctica
« Reply #984 on: December 10, 2018, 08:57:23 PM »
Tealight must be a mind-reader. I was just about to beg for the albedo warming potential data.

you already asked for it in the previous post  ;)
Ho hum, meanwhile, I posted this on the Ice Apocalypse thread, but why not here as well

Quote from: AbruptSLR on Today at 06:55:25 PM

Quote
This defined layering of temperatures is exactly what is happening now around the Antarctic.
"The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface," said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England an author of the paper.
"At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers on Pine Island and Totten. It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.""

There is a consistent narrative -

AGW is causing land-based ice to melt faster, adding massive additional amounts of freshwater to the ocean surface.

You would think that cold surface water (also low salinity with a higher freezing temperature) would encourage sea ice freeze as winter approaches and discourage sea ice melt as summer commences. Since 1979 up to recently, there has been a slow but measurable increase in Antarctic sea ice extent (maximum extent in 2014). Hypothesis confirmed ?

BUT since then the opposite. Antarctic sea ice extent is in decline, not just at max and min but during the melt season. Temporary aberration? Or is something  extra going on?

ps :Found this post from Jim Pettit on an old Antarctic Thread

https://forum.arctic-sea-ice.net/index.php/topic,178.msg2754.html#msg2754
Quote
New paper explains the recent growth of Antarctic sea ice.
« on: March 31, 2013, 10:20:40 PM »

Nature Geoscience published a new study online today that I found very interesting. It sheds some more light on the reasons behind the seemingly paradoxical growth of Antarctic sea ice (Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion) From the abstract:


"Changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature. In contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded, with record extent in 2010. This ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling. Here we show that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion. Specifically, we present observations indicating that melt water from Antarctica’s ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves. Simulating these processes in a coupled climate model we find that cool and fresh surface water from ice-shelf melt indeed leads to expanding sea ice in austral autumn and winter. This powerful negative feedback counteracts Southern Hemispheric atmospheric warming. Although changes in atmospheric dynamics most likely govern regional sea-ice trends, our analyses indicate that the overall sea-ice trend is dominated by increased ice-shelf melt. We suggest that cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise.
« Last Edit: December 10, 2018, 09:03:30 PM by gerontocrat »
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Re: Sea Ice Extent around Antarctica
« Reply #985 on: December 11, 2018, 11:48:11 AM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.

Tealight's prediction continues to be spot on

JAXA ANTARCTIC Sea Ice Extent - 10,981,865 km2(December 10, 2018)

A drop of 338k , 107k greater than average on this day. Though not a rarity at this time of year, 2 days above 300k in a row is more uncommon. Extent is 3rd lowest, though still 1.6 million km2 greater than 2016 on this day, but only 135k above 2017. Extent loss from maximum is very close to average so far, with on average 78.6% of extent loss for the season done and just 71 days to minimum.

A record low minimum is a real possibility.

Being at the beginning of the Austral summer, low extent and area means once again with insolation high, albedo warming potential in the Antarctic is also high and well above average. Will this acceleration in extent and area loss still continue ?
« Last Edit: December 11, 2018, 11:54:07 AM by gerontocrat »
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Re: Sea Ice Extent around Antarctica
« Reply #986 on: December 12, 2018, 09:33:26 AM »
Antarctic Sea Ice Area & Compaction went into freefall in early December. Sea Ice Area is now just above 2016. Judging from the compaction graph, the extent cliff should soon follow and be at least as impressive as the area cliff.

Tealight's prediction continues to be spot on

JAXA ANTARCTIC Sea Ice Extent - 10,628,551 km2(December 11, 2018)

A drop of 353k , 124k greater than average on this day. Though not a rarity at this time of year, 3 days above 300k in a row is more uncommon. It happened in 2004, 2015, and 2016 within a day of this year's occurrence. In 2004, a few days later a +300k daile extent loss was followed by 2 days at +400k. This week is the week of maximum extent loss.

Extent is 3rd lowest, though still 1.55 million km2 greater than 2016 on this day, but only 39k above 2017. Extent loss from maximum is 252k (3.5%) greater than average so far, with on average 83.3% of extent loss for the season done and just 70 days to minimum.

A record low minimum (of below 2 million km2) is a real possibility, making 3 years in a row. So much for increased Antarctic Ice Sheet melt causing increased sea ice extent.

Being at the beginning of the Austral summer, low extent and area means once again with insolation high, albedo warming potential in the Antarctic is also high and well above average.
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wdmn

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Re: Sea Ice Extent around Antarctica
« Reply #987 on: December 12, 2018, 09:57:30 AM »
Two simple questions (they could go in the stupid question thread, but are on topic here):

1) Shouldn't there be some minimum % that compaction can reach if it is a ratio of two measurements that are not independent? I'm trying to make sense of how the compaction data over the last two weeks can be so different from previous years. Clearly it has to do with rate of melt; again, you'd think that area can only get so far ahead.

2) Compared to extent, isn't area the better metric for thinking about albedo? Extent seems like it's faster to calculate, but otherwise has no advantages over area.




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Re: Sea Ice Extent around Antarctica
« Reply #988 on: December 12, 2018, 10:27:08 AM »
Two simple questions (they could go in the stupid question thread, but are on topic here):

1) Shouldn't there be some minimum % that compaction can reach if it is a ratio of two measurements that are not independent? I'm trying to make sense of how the compaction data over the last two weeks can be so different from previous years. Clearly it has to do with rate of melt; again, you'd think that area can only get so far ahead.

2) Compared to extent, isn't area the better metric for thinking about albedo? Extent seems like it's faster to calculate, but otherwise has no advantages over area.
1) Don't know - it's that 15% rule for extent again, so at minimum each pixel can still register as 100% extent while area is only registering 15%. If every pixel is the same the ratio can be the same - which would be ridiculous.

Compared with extent, area is a leading indicator during the melting season, and a lagging indicator during the freezing season.

2) Area is the only measure used, certainly by tealight, for calculating albedo. But my posts use JAXA extent data going back to 1979. And extent is what is used for most published information, especially on maximum and minimum. That's just the way it is.
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Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #989 on: December 12, 2018, 12:46:24 PM »
Two simple questions (they could go in the stupid question thread, but are on topic here):

1) Shouldn't there be some minimum % that compaction can reach if it is a ratio of two measurements that are not independent? I'm trying to make sense of how the compaction data over the last two weeks can be so different from previous years. Clearly it has to do with rate of melt; again, you'd think that area can only get so far ahead.

2) Compared to extent, isn't area the better metric for thinking about albedo? Extent seems like it's faster to calculate, but otherwise has no advantages over area.
1) Yes compaction can't go below 15% for NSIDC and JAXA data. Some other algorithims use 30% as threshold. In that case compaction can't go below 30%.

2) In my view extent use has historical reasons from the early 80s when the world was more concerned about ships getting stuck in sea ice instead of thermodynamic behaviour of the oceans in the light of climate change.


I made a detailed comparison between sea ice extent and area on my website.
https://sites.google.com/site/cryospherecomputing/documentation/area-vs-extent

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Re: Sea Ice Extent around Antarctica
« Reply #990 on: December 12, 2018, 12:46:57 PM »
Two simple questions (they could go in the stupid question thread, but are on topic here):

1) Shouldn't there be some minimum % that compaction can reach if it is a ratio of two measurements that are not independent? I'm trying to make sense of how the compaction data over the last two weeks can be so different from previous years. Clearly it has to do with rate of melt; again, you'd think that area can only get so far ahead.

Theoretical minimum is 0.15, for this to be true the maximum concentration in any gridcell is 15%.  Grid cells with concentration less than 15% are neither counted in the area or the extent totals.

Quote
2) Compared to extent, isn't area the better metric for thinking about albedo?

For albedo yes. Here the calculation of area is actually underestimating the true value of melting ice, whetting the surface causing pools, is actually an advantage because those conditions also cause lowering of the albedo.

Quote
Extent seems like it's faster to calculate, but otherwise has no advantages over area.

Extent is much less sensitive to the melting surface. Historic observations where mostly the position of the ice-edge from which only extent can be estimated. Area measurements are only available in the satellite era.


wdmn

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Re: Sea Ice Extent around Antarctica
« Reply #991 on: December 12, 2018, 07:00:21 PM »
Thank you all for the great answers.

I would imagine that 15% may be mathematically possible, but physically impossible, and that based on geographical patterns of melt there is probably a much higher minimum % for compaction.

In any case, the graphs posted by Tealight (though they do not show very many years) suggest that the rate of melt we're now seeing is at least unusual if not unprecedented. I still haven't seen anyone give an answer to gerontocrat's question about whether we're witnessing a bigger change in the last few years, to bring cause this decline in Antarctic sea ice extent, or whether this is just an anomaly. The rate of melt occurring now may seems like an important piece of evidence to be considered.

Tealight

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Re: Sea Ice Extent around Antarctica
« Reply #992 on: December 12, 2018, 08:34:19 PM »
In any case, the graphs posted by Tealight (though they do not show very many years) suggest that the rate of melt we're now seeing is at least unusual if not unprecedented. I still haven't seen anyone give an answer to gerontocrat's question about whether we're witnessing a bigger change in the last few years, to bring cause this decline in Antarctic sea ice extent, or whether this is just an anomaly. The rate of melt occurring now may seems like an important piece of evidence to be considered.

Generally Antarctic sea ice is more variable from year to year, but doesn't have a clear trend like the Arctic. As far as I know it is more sensitive to weather patterns as the Arctic because it isn't constraint by continents on all sides, only one in the middle. In the last two years we got weather favoring low sea ice and with the addition of greenhouse gases it looks like an extreme warming. My cumulative albedo warming maps look completely different from year to year and I don't see a clear trend. This year will most likely end up in second place so the top 3 years in accumulated solar energy are the last 3 years.

https://sites.google.com/site/cryospherecomputing/awp/Antarctic-Overview

On my compaction graphs I only show record high and record low years (apart from recent years). The middle contains over 30 years zig-zagging around the mean. For this time of the year sea ice compaction is unprecedented. The second lowest compaction value for 11th December is 60.7% in 2010. Is the graph with two standard deviations any better?

« Last Edit: December 12, 2018, 10:40:07 PM by Tealight »

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Re: Sea Ice Extent around Antarctica
« Reply #993 on: December 12, 2018, 09:07:40 PM »
Great chart...looks unprecedented.

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Re: Sea Ice Extent around Antarctica
« Reply #994 on: December 12, 2018, 10:27:58 PM »
I still haven't seen anyone give an answer to gerontocrat's question about whether we're witnessing a bigger change in the last few years, to bring cause this decline in Antarctic sea ice extent, or whether this is just an anomaly. The rate of melt occurring now may seems like an important piece of evidence to be considered.

I tried to hint to the recovered Nimbus missions above when you asked the first time about losses in previous decades wdmn:
It happened in the 60's as well, check out the recovered Nimbus missions.
Regarding my comments above in #40 & #51 around the recovered Nimbus missions, I'll quote the cires article in #40 to highlight what I personally think is the thing to look for within a couple of years. A record low.
Quote
“And the Antarctic blew us away,” he said. In 1964, sea ice extent in the Antarctic was the largest ever recorded, according to Nimbus image analysis. Two years later, there was a record low for sea ice in the Antarctic, and in 1969 Nimbus imagery, sea ice appears to have reached its maximum extent earliest on record.
Only one weak La Nina during the 60's.
https://www.ggweather.com/enso/oni.htm

Article and links to the data here:
https://earthdata.nasa.gov/new-data-from-old-satellites-a-nimbus-success-story

A bit more here, including a link to a video with Frank Shapiro who was the operations manager back then:
http://www.moonviews.com/nimbus/

Edit; also adding the paper that I linked to back in 2014 below.
« Last Edit: December 12, 2018, 10:39:05 PM by Sleepy »
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Re: Sea Ice Extent around Antarctica
« Reply #995 on: December 12, 2018, 11:29:11 PM »
It does look kind of cheesy, doesn't it?
Compare, compare, compare

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Re: Sea Ice Extent around Antarctica
« Reply #996 on: December 13, 2018, 12:05:11 AM »
Here are a couple of charts from NASA data on Antarctic temperature anomalies. The 64-90 temps are not much use as regards sea ice as south of 64 it is mostly the continental ice sheet. The 44 to 64S also is partly where sea ice does not reach.

But temperature changes 44 to 64 south are relatively low. But the Roaring Forties is the barrier to AGW heading South? Hence no strong signal in Antarctic Sea Ice decline at least until now?

There is a marked contrast with the Arctic where temperatures have risen far more strongly. See second graph.

ps: I had totally forgotten I had the data and the graphs. Nurse!
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Re: Sea Ice Extent around Antarctica
« Reply #997 on: December 13, 2018, 12:11:00 AM »
It does look kind of cheesy, doesn't it?

Even worse than your jokes. The ice is doomed.

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Re: Sea Ice Extent around Antarctica
« Reply #998 on: December 13, 2018, 07:55:56 AM »
Detecting the statistical significance of the trends in the Antarctic sea ice extent: an indication for a turning point.
https://link.springer.com/article/10.1007/s00382-018-4579-3
Quote
In the past decades, the Antarctic sea ice extent (SIE) has been steadily increasing, but recently showed a sharp decline. Here we address the questions whether (1) the observed changes in the Antarctic SIE can be fully explained by natural variability and (2) whether the recent unprecedented decline in the SIE can serve as an indication that the long-term positive trend has reached a turning point entailing further decline. To study these questions, we extended the analysis period of previous studies (until 2013) by considering data until May 2018 and applied a statistical model which accurately reflects the natural variability of the SIE. Contrary to earlier detection studies we find that none of the annual trends of the SIE in whole Antarctica and its five sectors are statistically significant. When studying the seasonal changes, we find that the only trends in the Antarctic SIE that cannot be explained by natural variability and are probably tied to the warming of the Antarctic Peninsula, are the negative trends of the SIE in austral autumn (p=0.043) and February (p=0.012) in the Bellinghausen and Amundsen Seas (BellAm). In contrast, when the recent decline is omitted from the analysis and only data until 2015 are included, the (annual and seasonal) increases of the SIE in whole Antarctica and the Ross Sea become significant, while the significance of the decreasing trends in BellAm is slightly decreased. We consider this as a first indication that the Antarctic SIE may have reached a turning point towards a further decrease.
Attaching the paper below.
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Re: Sea Ice Extent around Antarctica
« Reply #999 on: December 13, 2018, 08:21:49 AM »
Stumbled over this so why not add it here as well?
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