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Stephan

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Re: Global sea ice area and extent data
« Reply #500 on: May 19, 2019, 01:45:16 PM »
I use to compare the actual JAXA worldwide sea ice extent with the 2000-2009 average. Today it is -2,46 M km², almost seven times the size of Germany...

magnamentis

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Re: Global sea ice area and extent data
« Reply #501 on: May 19, 2019, 06:50:19 PM »
I use to compare the actual JAXA worldwide sea ice extent with the 2000-2009 average. Today it is -2,46 M km², almost seven times the size of Germany...

yeah it's good to look at and mention mid and long term comparisons before we get lost in tiny
seasonal talks  8)

how many times would that make the "Saarland" ? [just kidding]
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b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #502 on: May 19, 2019, 07:29:16 PM »
how many times would that make the "Saarland"?

(357.386km3/2.570km3)*7=973

That's almost a thousand Saarlands.

magnamentis

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Re: Global sea ice area and extent data
« Reply #503 on: May 19, 2019, 07:59:46 PM »
how many times would that make the "Saarland"?

(357.386km3/2.570km3)*7=973

That's almost a thousand Saarlands.

thanks. i opt for saarlands then, way more impressive numbers and then the size of the saarland is quite stable while the size of germany has been subject to significant changes over time LOL
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Stephan

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Re: Global sea ice area and extent data
« Reply #504 on: May 19, 2019, 09:00:20 PM »
Off-topic:
For those who are not familiar with the 16 German states: Saarland is the smallest state within Germany (apart from the three "city states" Berlin, Hamburg and Bremen). Saarland joined Germany in 1957, eight years after the foundation of the Federal Republic of Germany.

b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #505 on: May 20, 2019, 09:20:23 AM »
... and was French prior to that. And prior to that, it was German. And prior to that, it was French. And so on... You get the idea.

GoSouthYoungins

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Re: Global sea ice area and extent data
« Reply #506 on: May 20, 2019, 10:29:37 PM »
Back to actual global ice area and extent...

This time of year has historically seen the least variance from the mean. This year the area (in particular) and extent are drastically lower than ever before.

But hey, people say global sea ice doesn't matter. The northern and southern hemis are on different sides of a made up line, and the systems are some what separate. Who cares?

<snip, N.>
« Last Edit: May 21, 2019, 11:01:16 AM by Neven »
big time oops

Neven

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Re: Global sea ice area and extent data
« Reply #507 on: May 24, 2019, 11:17:48 AM »
Two more days and everything will be back to normal again.

Right?
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Juan C. García

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Re: Global sea ice area and extent data
« Reply #508 on: May 24, 2019, 01:02:49 PM »
Two more days and everything will be back to normal again.

Right?
Normal?
Well, it seems that the new normal is being the lowest (or second lowest) and out of the twice standard deviation range [which statistically, it is not normal].
« Last Edit: May 24, 2019, 01:09:44 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

magnamentis

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Re: Global sea ice area and extent data
« Reply #509 on: May 24, 2019, 02:49:32 PM »
Two more days and everything will be back to normal again.

Right?

if you consider the very lowest range of the bandwidth as normal, yes, nevertheless bad

[suppose you were kidding but just in case]
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gerontocrat

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Re: Global sea ice area and extent data
« Reply #510 on: May 24, 2019, 02:57:31 PM »
JAXA Global Sea Ice Extent as at 23 May 2019 :  20,842,190 km2

Low Arctic extent loss and high Antarctic extent gain the last few days, but extent has remained lowest, now for the 44th day this year, 38 days in a row, 486 k below 2017, 577k below 2018.

- extent gain on this day 141k, 90k more than the the average gain of 51k on this day,
- extent gain from minimum to date is 4.59 million km2, 1.46 million km2 (24%) less than the average gain of 6.06 milllion km2 by this day,
-on average 67.1% of extent gain done and 165 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.81 million km2,  a
 174k more than the record low maximum in 2016 and 2nd lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
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Neven

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Re: Global sea ice area and extent data
« Reply #511 on: May 28, 2019, 11:33:25 AM »
Dodge!
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gerontocrat

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Re: Global sea ice area and extent data
« Reply #512 on: May 28, 2019, 11:58:32 AM »
JAXA Global Sea Ice Extent as at 27 May 2019 :   20,954,768  km2

A change in the last 3 days. Very low Arctic extent loss increasing to average, and very high Antarctic extent gain decreasing to below average. Extent has remained lowest, now for the 48th day this year, 42 days in a row, 563 k below 2017, 581k below 2018.

- extent LOSS on this day 16k, 78k different from the the average gain of 62k on this day,
- extent gain from minimum to date is 4.71 million km2, 1.52 million km2 (24%) less than the average gain of 6.23 milllion km2 by this day,
-on average 69.0% of extent gain done and 161 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.75 million km2,  113k more than the record low maximum in 2016 and 2nd lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
« Last Edit: May 28, 2019, 12:04:39 PM by gerontocrat »
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ArcticMelt2

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Re: Global sea ice area and extent data
« Reply #513 on: May 29, 2019, 06:46:44 AM »
JAXA Global Sea Ice Extent as at 27 May 2019 :   20,954,768  km2

A change in the last 3 days. Very low Arctic extent loss increasing to average, and very high Antarctic extent gain decreasing to below average. Extent has remained lowest, now for the 48th day this year, 42 days in a row, 563 k below 2017, 581k below 2018.

This is a terrible situation. The planet continues to overheat. Each daily record increases the likelihood of the collapse of our fragile climate system.

roger white

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Re: Global sea ice area and extent data
« Reply #514 on: May 29, 2019, 05:16:58 PM »
The decadal figs given above your quote indicate either little or no decrease in sea ice from the 80's the 90's ( some days show an increase in global sea ice between those decades ) & a 2% decrease in sea ice over the past 40 years.
Do these stats justify your comments?
Do we have for example comparisons ( accurate ) of global sea ice changes between - say - the 1910's ^ the 1950's? To judge if a 2% swing is worth remarking upon? Or the 1880s - 1920's?
Or the 1840's to the 1880's?


jdallen

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Re: Global sea ice area and extent data
« Reply #515 on: May 30, 2019, 03:41:15 AM »
For the moment, I will assume your questions are in earnest rather than posting an invitation to start a fight.

The decadal figs given above your quote indicate either little or no decrease in sea ice from the 80's the 90's ( some days show an increase in global sea ice between those decades ) & a 2% decrease in sea ice over the past 40 years.
Do these stats justify your comments?
I will presume you are speaking to the graph in gerontocrat's post (#512)

The lines for those decadal averages merge like that because that is the middle of the transition between seasons - max at one end, minimum at the other.  There's been much more than a 2% decrease over 40 years.  That becomes more obvious as you follow the graph to mid-season - melt and refreeze - in late June and July.  There you can see the averages diverge by over 4 million km2 and more - a 15-20% decline - and that's before we begin to appreciate what's been happening since 2010.

I'm curious where you are deriving that 2% figure.


Do we have for example comparisons ( accurate ) of global sea ice changes between - say - the 1910's ^ the 1950's? To judge if a 2% swing is worth remarking upon? Or the 1880s - 1920's?
Or the 1840's to the 1880's?

"accurate" data that I think would satisfy your requirements is hard to come by before WW2.  There is some derived historical estimates, which really aren't bad, but have a fairly high uncertainty.  There's some discussion of that here:

https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850

... from which even with that uncertainty, its very clear the ice has gone into a very serious decline.

Unfortunately information of a similar nature for the Antarctic is sparse to non-existent because of it's relative remoteness and very hazardous sea.
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b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #516 on: May 30, 2019, 07:45:22 AM »
The decadal figs given above your quote indicate either little or no decrease

Zoom out! > https://sites.google.com/site/pettitclimategraphs/sea-ice-volume

Do you see little to no decrease decade over decade there?

oren

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Re: Global sea ice area and extent data
« Reply #517 on: May 30, 2019, 08:00:15 AM »
b_l, the original question was about global sea ice extent, not just about the Arctic as in Pettit's graphs, although the advice itself is correct, zooming out will give better results. The back pages of this thread have Gerontocrat's graph at various points of the year, with decadal averages.

In any case, I remind again about the problematic nature of the global sea ice extent number, which is a combination of two very different figures. In NSIDC's words:
Quote
Why don’t you publish a global sea ice extent number?
The combined number, while easy to derive from our online posted data, is not useful as an analysis tool or indicator of climate trends. Looking at each region’s ice extent trends and its processes separately provides more insight into how and why ice extent is changing. Sea ice in the Arctic is governed by somewhat different processes than the sea ice around Antarctica, and the very different geography of the two poles plays a large role. Sea ice in the Arctic exists in a small ocean surrounded by land masses, with greater input of dust, aerosols, and soot than in the Southern Hemisphere. Sea ice in the Southern Hemisphere fringes an ice-covered continent, Antarctica, surrounded by open oceans. While both regions are affected by air, wind, and ocean, the systems and their patterns are inherently very different. Moreover, at any point in time, the two poles are in opposite seasons, and so a combined number would conflate summer and winter trends, or spring and autumn trends, for the two regions.

b_lumenkraft

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Re: Global sea ice area and extent data
« Reply #518 on: May 30, 2019, 09:02:59 AM »
the original question was about global sea ice extent

Damn, i missed that. Sorry folks.

Stephan

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Re: Global sea ice area and extent data
« Reply #519 on: May 30, 2019, 10:29:42 AM »
The decadal figs given above your quote indicate either little or no decrease in sea ice from the 80's the 90's ( some days show an increase in global sea ice between those decades ) & a 2% decrease in sea ice over the past 40 years.
[...]

If you go to JAXA (https://ads.nipr.ac.jp/vishop/#/extent/&time=2019-05-29%2000:00:00) and zoom in the month of May you will see a different behaviour of Arctic and Antarctic. Whereas the Arctic Sea Ice Extent is steadily reducing, the Antarctic Sea Ice Extent rose from the 80s, the 90s, the 00s and into 2014. If you build a sum of both, these differences average out for the 80s and the 90s. The 00s show a decline by about 0.3 M km², the 10s average is lower, due e.g. to the smaller 10s average since 2016 Antarctic Sea Ice Extent reached record lows.

Wipneus

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Re: Global sea ice area and extent data
« Reply #520 on: May 31, 2019, 02:43:41 PM »
NSIDC NT global sea ice area and extent both now  4 sigma below the 1981-2010 normal.

'long' graphs => you must click.

Tor Bejnar

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Re: Global sea ice area and extent data
« Reply #521 on: May 31, 2019, 05:36:39 PM »
Wipneus's graph suggests a 'transformation' may have occurred in 2015 or 2016 (2015 might show a low-ice expression of the pre-existing paradigm, given previously expressed variation, or a slide into a new paradigm), but the paradigm shift was solidified in late 2016.

Being Arctic centric in my thinking, the warm Arctic winter of 2016-17 (where DMI 80N temps show more High Arctic heat than ever before) suggests a NH cause.  However, there was also a shift in Antarctic ice extent: starting in 2016 (IIRC), winter max extent has started going down (where it had been slowly increasing).

So, was there a global paradigm shift at that time?
« Last Edit: May 31, 2019, 07:26:11 PM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

oren

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Re: Global sea ice area and extent data
« Reply #522 on: May 31, 2019, 05:51:47 PM »
4 SDs came from the terribly late refreeze of 2016-2017, and 4 SDs came from a phase change in the Antarctic (that is still with us).
The only possible global linkage I can think of is the Monster El Nino of 2016, but it could also be random - when you add together two not very related figures you could get what looks like a pattern but may be just noise.

bbr2314

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Re: Global sea ice area and extent data
« Reply #523 on: May 31, 2019, 06:57:34 PM »
I would suggest both accumulation of heat in the High Arctic and the impact of clean energy (due to reduction in SO2 emissions) are dually to blame.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #524 on: May 31, 2019, 07:06:59 PM »
As pointed out above, it is mostly about the Antarctic sea ice.. which after gradually increasingfor decades to a major max in 2014, seems to have experienced a sea-change.
Read all about it here (though I am not totally convinced)

Sustained ocean changes contributed to sudden Antarctic sea ice retreat in late 2016
https://www.nature.com/articles/s41467-018-07865-9

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Observer

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Re: Global sea ice area and extent data
« Reply #525 on: May 31, 2019, 07:43:42 PM »
A comment from a member of the (hopefully) observant public on global extent: More than 2 years out of 40 continuously (almost) outside of 2 sigma (and all negative) seems unlikely to be random fluctuation or noise in the data--even if the data are simultaneously measuring 2 unrelated processes. Cause for concern? If I could not recall the times I have been wrong I wold vote for panic.
« Last Edit: May 31, 2019, 07:56:21 PM by Observer »

gerontocrat

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Re: Global sea ice area and extent data
« Reply #526 on: June 01, 2019, 09:28:19 AM »
JAXA Global Sea Ice Extent as at 31 May 2019 :    21,168,865  km2

In the last week very low Arctic extent loss increasing to average, and very high Antarctic extent gain decreasing to mostly below average. Extent has remained lowest, now for the 52 days this year, 46 days in a row.

Extent is 638 k below 2017, 695k below 2018.

- extent gain on this day 48k, 8k less than the the average gain of 48k on this day,
- extent gain from minimum to date is 4.92 million km2, 1.52 million km2 (24%) less than the average gain of 6.44 milllion km2 by this day,
-on average 71.3% of extent gain done and 161 days to maximum, but before that there is a false maximum and minimum before the (usually) true maximum around the 4th of November.

The Perils of Projections
- last 10 years average remaining extent gain would give a maximum of 23.76 million km2,  120k more than the record low maximum in 2016 and 2nd lowest in the satellite record.

Being a combination of two separate pieces of data volatility is often very high.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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ArcticMelt2

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Re: Global sea ice area and extent data
« Reply #527 on: June 01, 2019, 09:39:39 AM »
A comment from a member of the (hopefully) observant public on global extent: More than 2 years out of 40 continuously (almost) outside of 2 sigma (and all negative) seems unlikely to be random fluctuation or noise in the data--even if the data are simultaneously measuring 2 unrelated processes. Cause for concern? If I could not recall the times I have been wrong I wold vote for panic.

The reason is simple. The ocean begins to warm up with acceleration (in recent years and the average ocean level is growing much faster than before).

gerontocrat

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Re: Global sea ice area and extent data
« Reply #528 on: June 01, 2019, 09:50:15 AM »
Being at opposite ends of the earth, as Arctic Sea Ice declines, Antarctic Sea ice increases, and vice versa. So twice a year the two extents cross each other. This is about to happen now.

So I thought let's have a look to see if there is a trend in the date this occurs. And the answer is - there was. The decadal averages show it happening earlier and earlier. This was presumably because Arctic sea ice was declining while Antarctic sea ice was very gradually increasing.

In 2017 to 2019 this clear trend has been messed up mainly due to the steep decline in Antarctic Sea Ice. See attached graph.

I will do a similar graph when Arctic Sea Ice increase overtakes Antarctic Sea Ice decline.
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oren

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Re: Global sea ice area and extent data
« Reply #529 on: June 01, 2019, 11:18:30 AM »
A comment from a member of the (hopefully) observant public on global extent: More than 2 years out of 40 continuously (almost) outside of 2 sigma (and all negative) seems unlikely to be random fluctuation or noise in the data--even if the data are simultaneously measuring 2 unrelated processes. Cause for concern? If I could not recall the times I have been wrong I wold vote for panic.
The Arctic trend is very clear - downward. The Antarctic has been trending upwards and then crashed in late 2016. The combination appeared stable by coincidence, and then went to minus 8 sigma and stabilized at 4. This is what I meant by "noise", bad terminology, in reality the Antarctic has see a yet-unexplained major multi-sigma phase change, while the Arctic has not - it just went on declining.
I suggest a sigma graph for each region separately would clarify my load of words into something more coherent.

roger white

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Re: Global sea ice area and extent data
« Reply #530 on: June 02, 2019, 02:51:00 PM »
There are all sorts of very clever replies explaining why any increase in the antarctic sea ice is not significant, while the decrease in the arctic is very significant.
Yet the total for global sea ice which are published on this site continue to show:

No change ( sometimes tiny + or tiny -) in global sea ice between the 80's & 90's
2-3% decrease in global sea ice between the 80's & 2010's.

Contributors have confirmed there are no really accurate measures for global sea ice rise or fall in previous 40 year periods, to see if a 2-3% decrease is unusual.

So we seem to be left with observed very short term ( 40 years ) record of a decline in global sea ice of between 2 & 3%.

I wonder what, in a purely objective world, with no emotional commitment to hypotheses of warming, whether a scientific ( or indeed lay ) observer would make of such a trend.


Neven

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Re: Global sea ice area and extent data
« Reply #531 on: June 02, 2019, 05:51:04 PM »
Roger White, your comment smacks of climate risk denial, but maybe that's just my interpretation. Did you read Wipneus' comment and have a look at the graphs he posted:

NSIDC NT global sea ice area and extent both now  4 sigma below the 1981-2010 normal.

'long' graphs => you must click.




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Sterks

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Re: Global sea ice area and extent data
« Reply #532 on: June 02, 2019, 06:14:23 PM »
There are all sorts of very clever replies explaining why any increase in the antarctic sea ice is not significant, while the decrease in the arctic is very significant.
Yet the total for global sea ice which are published on this site continue to show:

No change ( sometimes tiny + or tiny -) in global sea ice between the 80's & 90's
2-3% decrease in global sea ice between the 80's & 2010's.

Contributors have confirmed there are no really accurate measures for global sea ice rise or fall in previous 40 year periods, to see if a 2-3% decrease is unusual.

So we seem to be left with observed very short term ( 40 years ) record of a decline in global sea ice of between 2 & 3%.

I wonder what, in a purely objective world, with no emotional commitment to hypotheses of warming, whether a scientific ( or indeed lay ) observer would make of such a trend.
Arctic sea ice has been declining for 40 years and the scientific explanations based on AGW, albedo amplification, ocean heat input and MYI loss seem straightforward for a grade-5 level intellect (meaning Trump and his average follower could grasp it with a bit of brain exercise).
Antarctic sea ice is subject to very different constraints. It basically surrounds a huge ice sheet instead of being land-locked.
That is why I dislike mixing it with Arctic.
Scientists have provided AGW-based theories to explain apparent insensitivity and even increase of Antarctic sea ice over the years. Now SH sea ice extent has decided to go south, apparently disproving these AGW-based shifts of ocean and wind currents. I simply believe first order amplification of NH heat is absent in SH, and search of 2nd order effects is not for 5-grade brains and probably unimportant with respect to what goes on at the other side.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #533 on: June 02, 2019, 06:41:46 PM »
So we seem to be left with observed very short term ( 40 years ) record of a decline in global sea ice of between 2 & 3%.
NO we are not.

If I had the energy I would go to skepticalscience.org, look at "most common deniers claims #10" and post some of the rebuttal. (https://skepticalscience.com/antarctica-gaining-ice.htm). But I can't be bothered.

But I will say,

The satellite record is 40 years, but the years between 80's average and 2010's averages is 30 years.
I do not get the 2-3% from the JAXA data. The change from 80's to 10's average..
Global sea ice extent maximum -6%,
Global sea ice extent minimum - 7%.
- Obviously the rate of change has accelerated remarkably in the last 4 years and does not show fully in the percents quoted above.. Currently global sea ice is at record lows again.

You also ignore the loss of mass from the Greenland and Antarctic ice sheets and the world's glaciers https://climate.nasa.gov/vital-signs/ice-sheets/.
But what's a few trillion tons in the world of denial ?

You also ignore the special characteristics of the Antarctic - the circumpolar current - that insulates the ice-cap, and recent events such as the ozone hole.

One could go on forever, but that's all I'm going to say about that.
"Para a Causa do Povo a Luta Continua!"
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jdallen

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Re: Global sea ice area and extent data
« Reply #534 on: June 02, 2019, 08:24:12 PM »
Roger White, your comment smacks of climate risk denial, but maybe that's just my interpretation. Did you read Wipneus' comment and have a look at the graphs he posted:

NSIDC NT global sea ice area and extent both now  4 sigma below the 1981-2010 normal.

http://file.scirp.org/Html/2-2801014_63707.htm

I think you'd find that increased total system enthalpy is responsible for the (temporary) increase seen in Antarctic ice... something that is counter-intuitive unless you study the science... and which will reverse quite as suddenly.
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roger white

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Re: Global sea ice area and extent data
« Reply #535 on: June 04, 2019, 05:15:08 PM »
Which data are you using to get to the 6% decline in global sea ice from the 80's to 10's?
I am only calculating on the stats used on this site.

The latest post showed:
1980's 24,033,325
2010's 23,331...

3%.

Of course this varies from day to day. Other stats show 2-3% decline.

I'm not impressed by throwaway lines about " denial" or " sceptics."

My question simply follows the stats released on this forum. 

Neven

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Re: Global sea ice area and extent data
« Reply #536 on: June 04, 2019, 10:47:29 PM »
I'm not impressed by throwaway lines about " denial" or " sceptics."

How convenient, now you can just ignore my question and the graphs with the trend lines in 4SD territory.

Quote
Which data are you using to get to the 6% decline in global sea ice from the 80's to 10's?

Are words like 'maximum' and 'minimum' too complicated for you?
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Michael Hauber

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Re: Global sea ice area and extent data
« Reply #537 on: June 05, 2019, 01:38:52 AM »

I wonder what, in a purely objective world, with no emotional commitment to hypotheses of warming, whether a scientific ( or indeed lay ) observer would make of such a trend.

No one is truly objective with no commitment to a particular hypothesis.  But I can at least claim to have been accused of being a denier in this forum on multiple occasions, whatever that may be worth in your opinion.

My opinion on the overall global sea ice trend is that it is pretty much what you expect in a world that is warming at a rate close to what was predicted some 40 years ago.  If you want to look at questions of whether the world is warming or not look at the global temperature trend, and not sea ice, which reflects temperature over a limited portion of the globe, and is also influenced by winds etc.  Its not a particularly important stat, and more interesting might be combined sea ice + snow cover, which then relates to global albedo, and one of several important feedbacks on global temperature change.  But important or not it is still interesting to look at from time to time.
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oren

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Re: Global sea ice area and extent data
« Reply #538 on: June 05, 2019, 03:28:44 AM »
I wonder what, in a purely objective world, with no emotional commitment to hypotheses of warming, whether a scientific ( or indeed lay ) observer would make of such a trend.
Just to clarify: so in your opinion the global warming widely discussed is a hypothesis?

Ktb

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Re: Global sea ice area and extent data
« Reply #539 on: June 05, 2019, 08:18:12 AM »
Being 8σ from the mean is so insanely rare. It should occur NATURALLY once every 100 billion or so.

So what is more likely; that humans just happened to be here to witness a one in 100 billion chance, or that something else has tipped the scales forcing this event to occur?
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DavidR

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Re: Global sea ice area and extent data
« Reply #540 on: June 06, 2019, 04:06:54 AM »
The latest post showed:
1980's 24,033,325
2010's 23,331...

3%.

Of course this varies from day to day. Other stats show 2-3% decline.

My question simply follows the stats released on this forum.
Roger, When we look at  the trend we generally consider the decline in the maxima and minima for the year rather than day to day values. As you can see in the table below based on these figures the decline in Global Maxima and Minima are both 7%.  However you can also see that the Arctic decline is much  greater than this at 41% for the minima and the Antarctic trend is actually an increase.

What  a reasonable person who knew nothing about AGW would say to this is "Why is it so?". 

The answer for the NH is seems obvious once you check the temperature records and discover that  both the Arctic and the Globe are warming rapidly. Obviously the more heat the less ice.

However in the Antarctic the picture is quite different Although the trend in temperatures is up there was a period from 1988 to about 2010 where the trend was flat or even in decline. A reasonable person will then ask why does this contradict expectations. As our temperature measures are consistently measured it is unlikely inaccurate measures are the reason. 

The two explanations I have heard are that:
a. ice melt water off the land is decreasing the salinity  of the water causing more freezing because fresh water freezes at a higher temperature than salt water.
b. the ozone hole that  was created in the 20Cent has changed the wind patterns so that stronger winds are blowing the ice further of the coast causing a greater extent.
Both these explanations are supported by relevant measurements.  But they may not be the complete answer. 

What we have seen since the 2015/6 El Nino is that Antarctic extent has dropped to extremely low levels, where only one day since Sept 9th 2016 has been ranked at 11 or above in the 31 year record. Prior to 2017 every year had at least 25 days ranked 20 or above.  So we appear to  be seeing a significant change.

PS. While you might not like being called a denier suggesting the Global warming is anything but a well documented fact is a clear sign of denial or ignorance. You can check out the temperature record here: http://www.woodfortrees.org/plot/ if you  actually are unaware of global temperature trends but don't try and dispute them here as Neven sensibly doesn't allow the forum to be corrupted by people arguing nonsense.
« Last Edit: June 06, 2019, 04:24:52 AM by DavidR »
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Dharma Rupa

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Re: Global sea ice area and extent data
« Reply #541 on: June 06, 2019, 01:09:05 PM »
I have read in passing that the circulation of the Southern Ocean has changed, but I don't really follow Antarctica so I don't know where I read about it.  I think that basically the surface current is more offshore and the next layer down is more onshore leading to more ice moving north in Winter and more melt under the ice shelves.  (A situation which cannot persist...)



roger white

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Re: Global sea ice area and extent data
« Reply #542 on: June 06, 2019, 05:08:55 PM »
Thanks to all for comments.

You seem to agree that on the stats regularly published on this site showing the decadal day to day changes, the figure is around 3% over 30 years from the satellite data.

But 7% or so when comparing maxima & minima.

Leaving aside all the snide comments, & responses to unasked questions- such as why the arctic decreases are quite large whereas the antarctic increases ( decadally) are also quite large - this still seems a small ( ish ) figure, without context of previous comparable measurements.

The comments that the picture has changed in the last 4 years seem remarkably silly. 4 years is no basis to measure such things. 30 years hardly seems very long..when there is no proper answer to the question.

Is a 3 or 7% variation unusual comparing several 30 year periods?

It also must seem suspicious that whenever a stat goes in the direction of a hypothesis ( the arctic ) the trend is real. But when it doesn't ( the antarctic ) special factors must be at play.




Neven

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Re: Global sea ice area and extent data
« Reply #543 on: June 06, 2019, 09:14:37 PM »
It has become quite clear now that Roger White didn't receive the climate risk denier memo that sea ice must be ignored. I don't think he has bought a new calendar since 2010 at least.  ;D

I'm willing to find out myself and get the data from NSIDC, but does anyone have Arctic minimum SIE+Antarctic minimum SIE, and the same for maximum? Just by eyeballing this graph the decrease seems to be at least 25% for the minimum:



But even then, 7% in such a short time for something that normally takes place at geologic timescales (think ice ages), is quite mindblowing. Unless you have the mind of a climate risk denier that fits plenty of cognitive dissonance, that is.
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oren

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Re: Global sea ice area and extent data
« Reply #544 on: June 06, 2019, 11:19:13 PM »
I've grown tired of this particular game.

Neven

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Re: Global sea ice area and extent data
« Reply #545 on: June 07, 2019, 01:08:56 AM »
I'm amazed that there are still climate risk deniers who play it. Again, didn't they get the memo on sea ice?  ::)

But to go back on-topic: Global sea ice area still lowest on record, extent by a larger margin.

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DavidR

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Re: Global sea ice area and extent data
« Reply #546 on: June 07, 2019, 04:44:19 PM »
Thanks to all for comments.

You seem to agree that on the stats regularly published on this site showing the decadal day to day changes, the figure is around 3% over 30 years from the satellite data.

But 7% or so when comparing maxima & minima.

Leaving aside all the snide comments, & responses to unasked questions- such as why the arctic decreases are quite large whereas the antarctic increases ( decadally) are also quite large - this still seems a small ( ish ) figure, without context of previous comparable measurements.

The comments that the picture has changed in the last 4 years seem remarkably silly. 4 years is no basis to measure such things. 30 years hardly seems very long..when there is no proper answer to the question.

Is a 3 or 7% variation unusual comparing several 30 year periods?

It also must seem suspicious that whenever a stat goes in the direction of a hypothesis ( the arctic ) the trend is real. But when it doesn't ( the antarctic ) special factors must be at play.
Roger you seem to want a simple answer to a complex question. We don’t know for certain that this decline is unusual however we do know that their is no evidence suggesting it is not unusual. We do know that global warming is a fact not an hypothesis, and that decline in sea ice is a likely consequence of AGW. But the decline in the sea ice does not prove that AGW is occurring and it is not an objective of this forum to prove anything about AGW. We want to know what is happening with the ice and identify short term and long term causes. What are you trying to observe? Or are you just trying to waste our time by refusing to consider the answers you are given?  A reasonable person seeing the changes in the sea ice would sky “why is it so”, and when given reasonable answers would accept them or dispute them with evidence. You don’t seem to have any evidence to refute the responses you are given.
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ArcticMelt2

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Re: Global sea ice area and extent data
« Reply #547 on: June 07, 2019, 05:14:18 PM »
The comments that the picture has changed in the last 4 years seem remarkably silly. 4 years is no basis to measure such things.

I think your opinion is an excellent proof of why a climatic catastrophe happens. Most people will regard climate change as random fluctuations until it is too late to change something. In connection, I think the creation of space colonies is the most sensible way solving climate problems.

ArcticMelt2

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Re: Global sea ice area and extent data
« Reply #548 on: June 07, 2019, 06:24:59 PM »
Now the global ice area is less than the past record of half a million square kilometers. This is the area of such a large country as France.

At this moment, I recall the following image:



Each month, the anomalous area of ice this year adds several times more energy to climatic system than human civilization consumes.

This is a visual representation of the magnitude of climate change.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #549 on: June 07, 2019, 06:58:23 PM »
I've grown tired of this particular game.
Me too. Nevertheless, worth a recap or two on the Antarctic Sea Ice thread since it was it happening there that is causing a scientist or three to scratch their heads.

Wait small (South Pacific Pidgin English)


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"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)