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Arctic Sea Ice 2020

Re: Arctic Sea Ice 2020

Unread postby JuanP » Sat 28 Nov 2020, 14:38:02

Tanada wrote:
JuanP wrote:As of yesterday, November 26th, there is slush all the way to the North Pole. Also, sea ice extent has been at an all time record low for this time of the year for over a month. 2020 could still be an all time record low for average yearly sea ice extent, even if it didn't have the all time record sea ice extent low in the Summer.

This means that 2021 could start with the lowest sea ice extent, thickness, and volume of any year ever! I can't wait to see how low the extent will be next Summer! Will we hit an all time record low in 2021? It wouldn't be surprising at all.

https://nsidc.org/arcticseaicenews/


If you check the interactive chart sub page you can see for yourself that 2016 was actually slushier than 2020 starting on or around November 3, 2016, which set the record sea ice lows for the month of November solidly in 2016, not 2020.
https://nsidc.org/arcticseaicenews/char ... ice-graph/


Thanks for the correction, Tanada! :)
I wonder which year will have the lowest sea ice extent yearly average. Do you know of any place to check that? It looks like 2016 and 2020 are head to head on that metric.
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Re: Saved by the bell.....

Unread postby Whitefang » Sun 29 Nov 2020, 13:08:06

Tanada wrote:
Whitefang wrote:http://sci.sdsu.edu/how_volcanoes_work/Krakatau.html

A 310 dB blast instantly deafening everybody within a 10 mile radius. Heard in Perth 1900 miles away.
That would grant humanity, mammals a few extra years of solid sea ice regrowth.
Several degrees av. temp. drop, worldwide.


While a super-eruption might delay things a few years all the CO2 already in the atmosphere would still be there when the dust cleared 5-7 years after the eruption. A minor blip on the scheme of things.


Yes indeed Tanada, alike a life extending treatment for a cancer patient facing the unknown.
Our dirty shield of aerosols should have been damaged by the corona crunch of human activity, might be some data on it.
Maybe the cause of the insane spike of temperatures last summer of Northern Asia.
You would expect a worldwide spike in average temp. as more solar energy reaches the surface.

https://www.reuters.com/article/us-clim ... SKBN21Z1RA

(Reuters) - To contain the coronavirus pandemic, billions of people have been told to stay at home. In China, authorities placed almost half a billion people under lockdown, the equivalent of nearly 7% of the world’s population. Many other countries have since taken similar measures, initially in hard-hit Italy and Spain, and more recently in the United States and India.
The restrictions have sent financial markets into free fall. But they have also given residents in some of the world’s most polluted cities something they have not experienced in years: clean air.


https://arctic-news.blogspot.com/

In other words, all polluting emissions need to be reduced. Moreover, a recent paper by Jorgen Randers et al. points out that, even if all greenhouse gas emissions by people would stop immediately, and even if CO₂ levels in the atmosphere would revert back to pre-industrial levels, and even if with relatively modest rises in methane levels, overall temperatures would still keep rising for centuries to come. Another recent paper, by Tapio Schneider et al., points out that solar geoengineering may not prevent strong warming from direct effects of CO2 on stratocumulus cloud cover.


Arctic blog always looks a bit grim.....I should get back on topic asap.
Just look at that above freezing at the peninsula, Northshore Siberia on Earthnullschool:

https://earth.nullschool.net/#current/w ... 949,73.015

Plus 1 degrees C. at 73 NL, 84 E.
No deep purple on the arctic ocean but a stretch close to Greenland/Ellsmere Island.
Bit of air moving from the Atlantic to Pacific ocean, transpolar surface drift.
We can expect more of that in the near future.
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Re: Saved by the bell.....

Unread postby Tanada » Mon 30 Nov 2020, 12:52:39

Whitefang wrote:
Tanada wrote:
Whitefang wrote:http://sci.sdsu.edu/how_volcanoes_work/Krakatau.html

A 310 dB blast instantly deafening everybody within a 10 mile radius. Heard in Perth 1900 miles away.
That would grant humanity, mammals a few extra years of solid sea ice regrowth.
Several degrees av. temp. drop, worldwide.


While a super-eruption might delay things a few years all the CO2 already in the atmosphere would still be there when the dust cleared 5-7 years after the eruption. A minor blip on the scheme of things.


Yes indeed Tanada, alike a life extending treatment for a cancer patient facing the unknown.
Our dirty shield of aerosols should have been damaged by the corona crunch of human activity, might be some data on it.
Maybe the cause of the insane spike of temperatures last summer of Northern Asia.
You would expect a worldwide spike in average temp. as more solar energy reaches the surface.


Indeed it has been known for a couple decades now that the climate does not move as a smooth integral from one state to the next. Instead the climate moves stepwise in jumps of several degrees at a time after a long pause. This phenomenon was confirmed by deeply drilled ice cores in both the Antarctic and Greenland ice sheets that show how we go into and out of ice age major glaciation periods.
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Re: Arctic Sea Ice 2020

Unread postby dissident » Tue 01 Dec 2020, 13:58:29

Pinatubo is actually a good enough lab test of what really happened with Krakatoa and similar. Dust loading of the stratosphere is not on the scale of a decade but two years. The exponential (e-folding at 7 km) attenuation of density with height means that even submicron particulate sediments extremely fast. At the same time, in the troposphere you have rapid wet-scavenging. There is no way that dust would be suspended for 7 years in the troposphere. There would be a residual tail of particulate with a few nanometers in diameter that would persist this long. At this scale the particles are acting almost like a gas and the stratospheric Brewer-Dobson circulation has a turn-over timescale of 7 years.

When it comes to SO2, then we have a different story. It forms H2SO4 and sulfate aerosol particles that are in the few nanometer size range through nucleation. So the long term impact of Pinatubo, Krakatoa, etc., is through SO2 which is injected at and above 30 km in the tropics. Near-equatorial injection is important since the SO2 then follows the streamlines of the Brewer-Dobson circulation with ascent at low latitudes and descent at high latitudes. This way it spreads out covering both hemispheres by loading the sulfate or Jung layer.

https://www.albany.edu/faculty/rgk/atm101/junge.htm
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Re: Arctic Sea Ice 2020

Unread postby JuanP » Sat 05 Dec 2020, 17:21:46

The latest NSIDC report is out.
https://nsidc.org/arcticseaicenews/

"As reported in our previous post, sea ice extent averaged for October 2020 was the lowest in the satellite record. While extent increased through November as part of the annual cycle of autumn and winter growth, the November average extent of 8.99 million square kilometers (3.47 million square miles), ended up as second lowest in the satellite record for the month, just above 2016."

It looks like December's sea ice extent will be close to the all time record low for the month or maybe even a new record. And, as of today the North Pole is till slushy, though Russia's Northern Sea Route is finally iced. What a year for the Arctic!
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Re: Arctic Sea Ice 2020

Unread postby jawagord » Sat 05 Dec 2020, 19:28:45

JuanP wrote:The latest NSIDC report is out.
https://nsidc.org/arcticseaicenews/

"As reported in our previous post, sea ice extent averaged for October 2020 was the lowest in the satellite record. While extent increased through November as part of the annual cycle of autumn and winter growth, the November average extent of 8.99 million square kilometers (3.47 million square miles), ended up as second lowest in the satellite record for the month, just above 2016."

It looks like December's sea ice extent will be close to the all time record low for the month or maybe even a new record. And, as of today the North Pole is till slushy, though Russia's Northern Sea Route is finally iced. What a year for the Arctic!


Or not.

Through the month of November 2020, sea ice grew by an average of 116,000 square kilometers (44,800 square miles) per day, which is the fastest daily average growth on record for the month, and 46,400 square kilometers (17,900 square miles) above the 1981 to 2010 average rate.
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Re: Arctic Sea Ice 2020

Unread postby JuanP » Sat 05 Dec 2020, 19:52:29

jawagord wrote:
JuanP wrote:The latest NSIDC report is out.
https://nsidc.org/arcticseaicenews/

"As reported in our previous post, sea ice extent averaged for October 2020 was the lowest in the satellite record. While extent increased through November as part of the annual cycle of autumn and winter growth, the November average extent of 8.99 million square kilometers (3.47 million square miles), ended up as second lowest in the satellite record for the month, just above 2016."

It looks like December's sea ice extent will be close to the all time record low for the month or maybe even a new record. And, as of today the North Pole is till slushy, though Russia's Northern Sea Route is finally iced. What a year for the Arctic!


Or not.

Through the month of November 2020, sea ice grew by an average of 116,000 square kilometers (44,800 square miles) per day, which is the fastest daily average growth on record for the month, and 46,400 square kilometers (17,900 square miles) above the 1981 to 2010 average rate.


One thing does not negate the other. You should go back and read the whole thing again and check the corresponding graphs to try and get the full picture. I had already read the part you quoted and fully understood it. I wonder if you read the whole thing and checked the charts because you don't seem to have understood the whole thing.
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Re: Arctic Sea Ice 2020

Unread postby evilgenius » Sun 06 Dec 2020, 09:32:07

2016 was the only year with less ice than this one at this time of year. I thought by December 1 that this year would rejoin the others from the last twenty years at a level closer to three standard deviations below the old average. It's still close to them, but is that little bit lower. I wonder if this will have implications for the sea ice maximum?
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Re: Arctic Sea Ice 2020

Unread postby Azothius » Sun 06 Dec 2020, 11:05:48

PIOMAS gridded data was updated upto day 335, which is 30th Nov or 1st of December depending on your calendar. On day 335 volume, calculated from this thickness, reached 9/86 [1000]km3], which is the lowest value except for 2016.

https://forum.arctic-sea-ice.net/index. ... l#lastPost

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Re: Arctic Sea Ice 2020

Unread postby jawagord » Sun 06 Dec 2020, 11:37:54

JuanP wrote:
jawagord wrote:
JuanP wrote:The latest NSIDC report is out.
https://nsidc.org/arcticseaicenews/

"As reported in our previous post, sea ice extent averaged for October 2020 was the lowest in the satellite record. While extent increased through November as part of the annual cycle of autumn and winter growth, the November average extent of 8.99 million square kilometers (3.47 million square miles), ended up as second lowest in the satellite record for the month, just above 2016."

It looks like December's sea ice extent will be close to the all time record low for the month or maybe even a new record. And, as of today the North Pole is till slushy, though Russia's Northern Sea Route is finally iced. What a year for the Arctic!


Or not.

Through the month of November 2020, sea ice grew by an average of 116,000 square kilometers (44,800 square miles) per day, which is the fastest daily average growth on record for the month, and 46,400 square kilometers (17,900 square miles) above the 1981 to 2010 average rate.


One thing does not negate the other. You should go back and read the whole thing again and check the corresponding graphs to try and get the full picture. I had already read the part you quoted and fully understood it. I wonder if you read the whole thing and checked the charts because you don't seem to have understood the whole thing.


I think making monthly predictions about sea ice extent is a crapshoot, which is evident when looking at the October summary which completely missed predicting the biggest ever November ice gain.

What I do find interesting is the amount of heat loss from open water, the natural negative feedback to all that open water heat gain in the summer.

These air temperature “hot spots” correspond to areas of open water, where the ocean is still releasing large amounts of heat to the lower atmosphere; temperatures at the surface in these areas are locally more than 12 degrees Celsius (22 degrees Fahrenheit) above long-term November averages.

And there’s the above average Antarctica ice cover.

Antarctic sea ice extent for November 2020 continues to be well above the 1981 to 2010 average, a shift that began in August, with particularly above average extent in the Weddell Sea.

And there’s the return of the Arctic Oscillation to near normal.

Recall from a previous post that much of the 2019 to 2020 winter was characterized by a positive AO phase. As of late November 2020, the AO index had regressed back to a neutral phase; whether this is temporary remains to be seen.

All interesting.
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Re: Arctic Sea Ice 2020

Unread postby evilgenius » Sun 06 Dec 2020, 12:14:53

Antarctica is cut off from the rest of the world's land. This allows something I think they call they "Rolling Forties." That's the ring of storms that circulates around Antarctica. There is a lot of debate over whether global warming might actually contribute to that, insulating it from the warming that the Arctic is experiencing. I don't know enough about it, except to say that it is an important enough difference not to consider what is happening in Antarctica in the same conversation as the Arctic. They can be considered separately because the Arctic doesn't have that additional delaying mechanism. That makes the Arctic a better canary, I guess.
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Re: Arctic Sea Ice 2020

Unread postby dissident » Sun 06 Dec 2020, 13:49:56

Indeed, Antarctica has a dynamical barrier around it both in the atmosphere and the ocean. In both, there is a strong zonal flow due to lack of land disruption (hence roaring 40s in the atmosphere). This strong zonality is reflected in the Antarctic polar vortex in the stratosphere which creates conditions for the formation of the ozone hole by blocking transport of ozone-bearing air from lower latitudes.

Zonal jets act as barriers in a way that can be more easily understood using Potential Vorticity (PV) gradients. PV has elastic properties and a clump of PV contours acts like a stronger elastic compared to cases with reduced PV gradient. Baroclinic eddies (in the fully nonlinear regime without any quasi-linear approximations) impinging on such bunched PV contours deform them but cannot wrap them up and entrain them and thus cannot propagate through them. So tracers which are typically mixed horizontally by barocolinc eddies remain confined (aside from smaller scale diffusion) on one side of the PV gradient or zonal jet.

PV applies to both ocean and atmosphere stratified rotating fluid dynamics. The Antarctic circumpolar flow blocks horizontal transport of warmer surface and subsurface waters from lower latitudes out. Slower transport by the over-turning or meridional circulation can bypass this rapid mixing barrier to some extent. But as we see in the stratosphere, if there is no forcing of this circulation inside the polar vortex, its streamlines (latitude-depth or latitude-altitude) are confined away from the vortex interior. For the ocean around Antarctica we have deep and intermediate water currents that do penetrate inside the zonal flow barrier.

https://theconversation.com/explainer-h ... zen-106164
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Re: Arctic Sea Ice 2020

Unread postby dohboi » Sun 06 Dec 2020, 14:02:42

Antarctica is a continent cut off by ocean. Arctic is an ocean mostly cut off by land. Besides both being polar, they could barely be more different.

But I have read that there are some surprising interactions between them.
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Re: Arctic Sea Ice 2020

Unread postby dissident » Sun 06 Dec 2020, 16:36:58

dohboi wrote:Antarctica is a continent cut off by ocean. Arctic is an ocean mostly cut off by land. Besides both being polar, they could barely be more different.

But I have read that there are some surprising interactions between them.


The land is not acting to cut off the Arctic. In fact, it is key to ventilating the Arctic polar cap compared the Antarctic polar cap. And the Arctic Ocean is not confined from the transport of warmer water from lower latitudes like Antarctica. In fact, without the land there would also be a circumpolar flow isolating the Arctic. The Antarctic land mass is not involved the formation of zonal jets in the ocean and atmosphere except as a second stage due to low temperatures induced by the dynamical isolation. The zonal jets are due to the Coriolis torque and are induced by the slow overturning circulation established by tropical heating and polar cooling. In the ocean the atmospheric circulation helps drive the circumpolar current.
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Re: Arctic Sea Ice 2020

Unread postby JuanP » Wed 09 Dec 2020, 20:53:16

"Arctic's Shift to a Warmer Climate is Well Underway, Scientists Warn"
https://www.nytimes.com/2020/12/08/clim ... e=Homepage

"...
The age of sea ice is declining as well as the region warms. Three decades ago, ice that was at least four years old made up about a third of the Arctic Ocean pack ice at the end of winter. This year, according to the assessment, old ice accounted for less than 5 percent of the pack ice.
The increasing dominance of younger, and thus generally thinner, ice has contributed to the reduction in sea-ice extent, Dr. Perovich said, since thinner ice is less likely to last through a single season.
The shift from old to young ice has also led to a decline in overall ice volume. Volume this year, measured at the end of the melt season in September, was the second-lowest in the 10 years that satellites have been making reliable measurements.
..."
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Re: Arctic Sea Ice 2020

Unread postby dissident » Fri 11 Dec 2020, 18:44:40

One year ice is also more salty than multi-year ice due to lack of sufficient time for brine rejection. So it melts faster compared to multi-year ice. It also has some albedo differences.

We have all sorts of effects piling on top each other to reinforce the melting trend. And almost none to stop it.

Funny that Lindzen's effort to invoke cloud albedo as an offsetting valve for global warming will work in the completely opposite sense in the polar caps where insolation is not the primary driver of local heating on an yearly average. Low altitude clouds and fogs that will amplify in response to more open water in early winter will form an IR trap that will keep the waters open longer into the winter. Eventually, this feedback will help lock in ice free waters year round in the Arctic.
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