Author Topic: Global sea ice area and extent data (Read 518771 times)

gerontocrat · « **Reply #250 on:** March 25, 2018, 10:47:17 AM »

Data does not request to be a good scientific metric - it simply is.

Yes, Antarctic Sea Ice varies enormously in extent - and this has corresponding high impacts on insolation and why does it switch so violently?

Ok, and the Sea ice surrounds a continent with about 90% of the world's fresh water on top of it.
And yes, Hansen's predictions are that when the glaciers melt, sea ice will actually grow due to freshening of the top layer of the southern ocean. And this sea ice growth could actually increase glacial melt as it keeps a lid on the ocean and helps increase the temperature of the water lapping at the marine glaciers. But this is speculation? hypothesis?

We know more and more about the Northern Hemisphere cryosphere, and the comparison with our lack of knowledge of the Southern Hemisphere cryosphere (and the oceans) gets more and more extreme even as we know that in the long-term Antarctica and the Oceans may well be the real drivers of our climate.

So ignoring Antarctic Sea Ice data as not a good metric seems a bit odd. Unconscious bias to select data that is a good metric for the opinions of those on ASIF?

oren · « **Reply #251 on:** March 25, 2018, 11:44:32 AM »

A. Hansen's is published research, not mere speculation or hypothesis. I can't find the link atm but it's here on the site and was discussed ad nauseum in a dedicate thread.
B. I'm not saying Antarctic sea ice extent isn't a good metric. I am saying bunching it together with arctic sea ice, though they are of opposite seasons by definition, to create Global sea ice extent, is not a good metric.

gerontocrat · « **Reply #252 on:** March 25, 2018, 12:03:03 PM »

Quote from: oren on March 25, 2018, 11:44:32 AM

A. Hansen's is published research, not mere speculation or hypothesis. I can't find the link atm but it's here on the site and was discussed ad nauseum in a dedicate thread.
B. I'm not saying Antarctic sea ice extent isn't a good metric. I am saying bunching it together with arctic sea ice, though they are of opposite seasons by definition, to create Global sea ice extent, is not a good metric.

My understanding was that the field data about the Antarctic was extremely limited - so while Hansen (and other scientists) are able to produce predictions based on closely worded argument and mathematics, testing these predictions against field data was a big problem.

Even Einstein had to wait for the eclipse of the Sun and the better astronomical instruments then available before he could demonstrate that gravity bent light and from that the theory of relativity was tested against real world data.

I would not be surprised if Hansen in his paper or abstract made an impassioned plea for more resources to get the data ? Meanwhile here is my data.

JAXA GLOBAL EXTENT AS AT 24 MARCH

The increases since minimum are nearly all down to the Antarctic. I have seen no convincing explanation of these radical changes in recent years that is backed by data. Vague references to the PDO etc but nothing to get hold of and try to understand.

oren · « **Reply #253 on:** March 25, 2018, 12:07:45 PM »

Gerontocrat, don't take me wrong. First, I agree with what you say, there's a lot of unknown about Antarctic sea ice, and Hansen is not a prophet. And I do look in this thread mostly every day out of curiosity anyway... in spite of my scientific misgivings.

Sleepy · « **Reply #254 on:** March 25, 2018, 03:14:47 PM »

The recovered Nimbus data covers both poles. The link to the paper can also be found here:
https://forum.arctic-sea-ice.net/index.php/topic,904.msg36905.html#msg36905
There are posts about the Hansen paper all over but Lennart van der Linde was probably the first poster in the Sea Level Rise and Social Cost of Carbon thread in 2015, then Sigmetnow started the dedicated thread, Hansen et al paper: 3+ meters SLR by 2100. Both under Consequences.

And here's the link:
https://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016-discussion.html

gerontocrat · « **Reply #255 on:** March 25, 2018, 03:32:51 PM »

Quote from: oren on March 25, 2018, 12:07:45 PM

Gerontocrat, don't take me wrong. First, I agree with what you say, there's a lot of unknown about Antarctic sea ice, and Hansen is not a prophet. And I do look in this thread mostly every day out of curiosity anyway... in spite of my scientific misgivings.

Sorry about the crabby tone of my post. Having a crabby day. Sometimes I think the concentration on Arctic Sea Ice (and yes, I know it is the Arctic Sea Ice Forum) could be like looking out left and right for traffic while the truck out of control is coming up the rear.

When my brain comes to rest I will have to have another read of Hansen's stuff, and also look at all the new data - e.g.s the astonishing depth of bedrock being shown on the new maps, the evidence for relatively warm water at considerable depth gnawing away at the glaciers from below (which might make the assumption that the circumpolar vortex stops ocean heat heading South at least partly invalid?) .......

gerontocrat · « **Reply #256 on:** April 05, 2018, 03:28:36 PM »

JAXA DATA AS AT 4 April 2018

Since my last post on 24th March data, what a difference. Antarctic extent gain well below average and Arctic sea ice extent at a new record low for the date has made a new record low global maximum a real possibility. (and another week could change it all back again).

On 24th March global extent was 1.4 million greater than 2017, now it is 0.8 million.

Archimid · « **Reply #257 on:** April 06, 2018, 02:42:59 AM »

I'm glad to see you up and running again gerontocrat.

gerontocrat · « **Reply #258 on:** April 06, 2018, 04:44:49 PM »

Quote from: Archimid on April 06, 2018, 02:42:59 AM

I'm glad to see you up and running again gerontocrat.

Me 50%, Technology 25%.

NSIDC Daily Extent Data 5 April

The attached table shows how 2018 global sea ice extent maxed out at 1.5 million km2 greater than 2017 on 26th March and how in the 10 days since then the difference has shrunk to 0.6 million km2.

This could go into reverse just as quickly or the low Antarctic increases could be matched by persistent Arctic decreases.

Ktb · « **Reply #259 on:** April 07, 2018, 02:14:56 PM »

Another ~7 days of this and 2018 would be pushing for 1st lowest once again.

gerontocrat · « **Reply #260 on:** April 13, 2018, 02:29:45 PM »

NSIDC DATA AS AT 12 APRIL

(JAXA is on holiday today)

2017's extent above 2017 has gone down from 1.5 million on 26 March to 0.6 million km2 on 12 April. Extent is on a par with 2006 (a very low extent year).

Graph from https://sites.google.com/site/arctischepinguin/home/global-sea-ice

gerontocrat · « **Reply #261 on:** April 14, 2018, 11:31:28 AM »

JAXA DATA AS AT 13 APRIL 18,978,219 KM2

Extent gain continues well below average.
2018 now just 0.77 million km2 greater than 2017.
On average 41% of extent gain done.

gerontocrat · « **Reply #262 on:** April 17, 2018, 11:19:53 AM »

JAXA DATA AS AT 16 APRIL 19,058,671 KM2

Extent gain continues well below average.
2018 now just 0.53 million km2 greater than 2017.
On average 44% of extent gain done.

The data history suggests a second lowest November maximum is likely, though getting lower than the 2016 maximum looks unlikely.

gerontocrat · « **Reply #263 on:** April 19, 2018, 11:17:34 AM »

JAXA DATA AS AT 18 APRIL 19,096,469 KM2
Extent gain continues well below average. On 18th April was an extent reduction of 11k, and extent gain to date since the minimum is 530,000 km2 less than the average of the last 10 years. In addition, during this period in 2017 extent gain was greater than average.

As a result 2018 is now just 0.44 million km2 greater than 2017, compared with a maximum of 1.44 million on 27th March.

On average 46% of extent gain done. The historical data suggests a second lowest November maximum is likely of around 24 million.

Ktb · « **Reply #264 on:** April 20, 2018, 08:39:16 AM »

Global area once again threatening to be lowest on record

gerontocrat · « **Reply #265 on:** April 20, 2018, 09:44:57 AM »

JAXA DATA AS AT 19 APRIL - EXTENT 19,087,420 KM2

What a difference even one day can make. On 18 April 2018 was 0.44 million km2 greater than 2017, on the 19th April 0.33 million km2, (compared with a maximum of 1.44 million on 27th March).

The graph shows well the contrast between what is happening at the moment compared with "normal".

gerontocrat · « **Reply #266 on:** April 20, 2018, 02:30:31 PM »

NSIDC DATA says the same

closing on 2017 very quickly.

gerontocrat · « **Reply #267 on:** April 21, 2018, 09:00:26 AM »

JAXA DATA AS AT 20 APRIL - EXTENT 19,104,604 KM2

I was not expecting to post every day at this time of year, but the data is changing significantly every day. What a difference even one day can make.
On 18 April 2018 extent was 0.44 million km2 greater than 2017, on the 19th April 0.33 million km2, and on the 20th April 0.21 million km2, (compared with a maximum of 1.44 million on 27th March). Extent gain from minimum is 0.68 million (15%) less than the average of the last ten years..

The graph shows well the contrast between what is happening at the moment compared with "normal".

gerontocrat · « **Reply #268 on:** April 21, 2018, 03:34:33 PM »

NSIDC GLOBAL daily EXTENT AS AT 20 APRIL 2018 19.886 million km2

Just a mere 6k increase. See the graph!

gerontocrat · « **Reply #269 on:** April 22, 2018, 02:46:29 PM »

NSIDC GLOBAL daily EXTENT AS AT 21 APRIL 2018 19.934 million km2

Now only 0.232 million km2 above 2017 extent (down another 100k)

Neven · « **Reply #270 on:** April 22, 2018, 08:32:12 PM »

Area seems to be lowest on record:

gerontocrat · « **Reply #271 on:** April 23, 2018, 01:12:31 PM »

JAXA DATA AS AT 22 APRIL - EXTENT 19,225,891 KM2

Daily increases going up over the last 2 days, however 2018 extent is now reduced to 0.17 million km2 greater than 2017 - down from 0.22 million on 20 April. It looks more likely than not that 2018 extent will become lowest by the end of the month.

gerontocrat · « **Reply #272 on:** April 23, 2018, 03:12:02 PM »

NSIDC GLOBAL daily EXTENT AS AT 22 APRIL 2018 19.865 million km2

Now only 0.135 million km2 above 2017 extent (down another 100k)

gerontocrat · « **Reply #273 on:** April 24, 2018, 02:34:41 PM »

NSIDC GLOBAL daily EXTENT AS AT 23 APRIL 2018 19.952 million km2

Now only 0.087 million km2 above 2017 extent (down another 47 k)

Neven · « **Reply #274 on:** April 24, 2018, 03:11:18 PM »

Area clearly lowest now:

Pmt111500 · « **Reply #275 on:** April 24, 2018, 04:35:50 PM »

*** Flashbacks from 1998...*** Sorry, I don't know what that was.

But, that global graph looks like the freezing over on southern ocean and melting of ice in northern ocean do not work as they used to.

Buddy · « **Reply #276 on:** April 24, 2018, 05:04:36 PM »

Quote

But, that global graph looks like the freezing over on southern ocean and melting of ice in northern ocean do not work as they used to.

I certainly can't disagree with that....

gerontocrat · « **Reply #277 on:** April 25, 2018, 11:19:18 AM »

JAXA DATA AS AT 24 APRIL - EXTENT 19,392,904 KM2

Daily increases a bit above average due to low extent loss in the Arctic, but arewell below 2017. , 2018 extent is now reduced to 0.15 million km2 greater than 2017 - It looks more and likely than not that 2018 extent will become lowest by the end of the month.

gerontocrat · « **Reply #278 on:** April 26, 2018, 08:23:37 AM »

JAXA DATA AS AT 25 APRIL - EXTENT 19,419,695 KM2

Daily increases return to below average, and below half that of 2017. 2018 extent is now 0.087 million km2 above 2017 compared with 1.438 million km2 on the 27th March. It looks more and likely than not that 2018 extent will become lowest in the satellite record by the end of the month.
[/quote]

gerontocrat · « **Reply #279 on:** April 27, 2018, 11:35:21 AM »

JAXA DATA AS AT 26 APRIL - EXTENT 19,419,695 KM2

Daily increases remain well below average, and actually reduced by 1,513 km2 on the 26th. 2018 extent is now 7,395 km2 below2017 compared with 1.438 million km2 above on the 27th March.

On average, extent gain is 50% complete. A record low maximum is definitely a possibility. That the maximum will be amongst the lowest in the satellite record seems almost inevitable. (Another hostage to fortune?)

Interesting times.

charles_oil · « **Reply #280 on:** April 27, 2018, 12:31:31 PM »

Gero.. your graph in the above post is quite hard to read - could 2018 be highlighted (bold / dashed maybe) or could the one from 26th be used (less individual years)? Thanks for keeping these coming in!

gerontocrat · « **Reply #281 on:** April 27, 2018, 12:36:40 PM »

Quote

Posted by: charles_oil
« on: Today at 12:31:31 PM » Insert Quote
Gero.. your graph in the above post is quite hard to read - could 2018 be highlighted (bold / dashed maybe) or could the one from 26th be used (less individual years)? Thanks for keeping these coming in!

JAXA Graphs are a bit of a pain to work with. Might do my own to match the daily extent change graph.

HapHazard · « **Reply #282 on:** April 28, 2018, 10:16:30 AM »

Quote from: charles_oil on April 27, 2018, 12:31:31 PM

Gero.. your graph in the above post is quite hard to read - could 2018 be highlighted (bold / dashed maybe) or could the one from 26th be used (less individual years)? Thanks for keeping these coming in!

Yeah, it's kinda cluttered - took me a bit to find the 2018 track. I took the liberty of doing a quick edit to help out, though:

gerontocrat · « **Reply #283 on:** April 28, 2018, 02:17:35 PM »

NSIDC GLOBAL daily EXTENT AS AT 27 APRIL 2018 20.289 million km2

Now 0.017 million km2 below 2017 extent (cf with 1.467 million km2 above 2017 on 26th March)

gerontocrat · « **Reply #284 on:** April 29, 2018, 02:55:37 PM »

NSIDC GLOBAL daily EXTENT AS AT 28 APRIL 2018 20.307 million km2

Now 0.063 million km2 below 2017 extent (cf with 1.467 million km2 above 2017 on 26th March)

gerontocrat · « **Reply #285 on:** May 01, 2018, 03:49:11 PM »

NSIDC GLOBAL daily EXTENT AS AT 30 APRIL 2018 20.307 million km2

Now 0.065 million km2 below 2017 extent (cf with 1.467 million km2 above 2017 on 26th March)

gerontocrat · « **Reply #286 on:** May 03, 2018, 03:30:35 PM »

JAXA DATA - Extent as at 2 May = 19,924,895 km2, 109k above 2017

On average, a maximum of 24 million km2, second lowest, is on the cards.
On average, 55% of extent gain done, but with 6 months to go.

gerontocrat · « **Reply #287 on:** May 09, 2018, 02:36:10 PM »

JAXA DATA - Extent as at 8 May = 20,346,216 km2, 73k above 2017

On average, a maximum of 24 million km2, second lowest, is on the cards, with a relatively low range of 23 million to 25.2 million outcomes from the last 10 years remaining extent gain.
On average, 59% of extent gain done, but with 6 months to go.

gerontocrat · « **Reply #288 on:** May 09, 2018, 06:53:47 PM »

NSIDC Global Extent as at 8 May 20.88 Million Km2, 0.2 million Km2 below 2017

Interesting difference with JAXA.

gerontocrat · « **Reply #289 on:** May 11, 2018, 11:10:27 AM »

JAXA DATA - Extent as at 10 May = 20,375,167 km2, 110k below 2017

In the last two days above average extent loss in the Arctic and below average extent gain in the Antarctic has meant that global extent gain has stalled.

On average, a maximum of 24 million km2, second lowest, is on the cards, with a relatively low range of 23 million to 25 million km2 outcomes from the last 10 years remaining extent gain.
On average, 60% of extent gain done, but with 6 months to go.

kiwichick16 · « **Reply #290 on:** May 11, 2018, 11:26:48 PM »

la nina/ neutral year .....yet again flirting with lowest on record levels .....Miocene here we come?

jdallen · « **Reply #291 on:** May 12, 2018, 06:49:44 PM »

Quote from: kiwichick16 on May 11, 2018, 11:26:48 PM

la nina/ neutral year .....yet again flirting with lowest on record levels .....Miocene here we come?

That's on my mind as well. I will hasten to add that 2010, 2011 and 2012 were La Nina years.

litesong · « **Reply #292 on:** May 12, 2018, 08:46:14 PM »

Quote from: jdallen on May 12, 2018, 06:49:44 PM

Quote from: kiwichick16 on May 11, 2018, 11:26:48 PM
la nina/ neutral year .....yet again flirting with lowest on record levels .....Miocene here we come?
That's on my mind as well. I will hasten to add that 2010, 2011 and 2012 were La Nina years.

Its best to consider that the solar TSI has been languid for 50 years & low for 11+ years (including a 3+ year period, setting a 100 year record low radiation level). Yet, global sea ice continues near its least quantities.

kiwichick16 · « **Reply #293 on:** May 13, 2018, 03:35:20 AM »

Historical reconstruction of TSI

http://lasp.colorado.edu/home/sorce/files/2011/09/TIM_TSI_Reconstruction-1.png

gerontocrat · « **Reply #294 on:** May 13, 2018, 12:06:14 PM »

JAXA DATA - Extent as at 12 May = 20,498,076 km2, 166k below 2017

In the last two days above average extent loss in the Arctic but above average extent gain in the Antarctic has meant that global extent gain has increased again.

On average, a maximum of 24 million km2, second lowest, is on the cards, with a relatively low range of 23 million to 25 million km2 outcomes from the last 10 years remaining extent gain.
On average, 61% of extent gain done, but with 6 months to go.

ps:- Due to the different timings of Antarctic gain and Arctic loss, there is a secondary minimum of global extent in late August or September. At the moment, this also looks like a record low is very possible. See last table attached.

josh-j · « **Reply #295 on:** May 13, 2018, 02:35:56 PM »

Quote from: litesong

Its best to consider that the solar TSI has been languid for 50 years & low for 11+ years (including a 3+ year period, setting a 100 year record low radiation level). Yet, global sea ice continues near its least quantities.

Forgive the straying off topic but just one question for litesong - I don't see a languid 50 years in kiwichick's link. But I don't know much about the subject; could you link your source?

gerontocrat · « **Reply #296 on:** May 19, 2018, 01:08:53 PM »

JAXA DATA - Extent as at 18 May = 21,044,896 km2, 67k below 2017

On average, a maximum of 24.25 million km2, a bit higher but still second lowest, is on the cards, with a relatively low range of 23 million to 25 million km2 outcomes from the last 10 years remaining extent gain.
On average, 65% of extent gain done, but with 170 days to go.

ps:- Due to the different timings of Antarctic gain and Arctic loss, there is a secondary minimum of global extent in late August or September. At the moment, this also looks like a record low is very possible. See last table attached.

gerontocrat · « **Reply #297 on:** May 19, 2018, 02:06:26 PM »

NSIDC Global Extent as at 18 May 21.195 Million Km2, 0.284 million Km2 below 2017

Graph from https://sites.google.com/site/arctischepinguin/home/global-sea-ice

gerontocrat · « **Reply #298 on:** May 23, 2018, 08:27:56 PM »

NSIDC Global Extent as at 22 May 22.064 Million Km2, 0.079 million Km2 above 2017

Strong sea ice gain in the Antarctic has changed the picture somewhat.

Graph from https://sites.google.com/site/arctischepinguin/home/global-sea-ice

gerontocrat · « **Reply #299 on:** May 25, 2018, 02:18:10 PM »

NSIDC Global Extent as at 24 May 22.012 million km2, 0.189 million Km2 below 2017

Sea ice gain in the Antarctic sort of stopped and changed the picture again.

Graph from https://sites.google.com/site/arctischepinguin/home/global-sea-ice

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Author Topic: Global sea ice area and extent data (Read 518771 times)

Pmt111500