2016 melting momentum, part 1

Melting momentum, it's what I call the absorption of heat and solar radiation during May and June that does not directly lead to melt and a reduction in ice cover, but rather comes into play during July and August (I had a more wordy explanation last year).

As important as it seems to be for the final outcome of the melting season, it is one of those aspects of Arctic sea ice that has proven to be really difficult to measure. Observations based on satellite images have been developed in the recent past, but for some strange reason, this research didn't receive further funding.

I will discuss some indirect and experimental measurements further below, but start off with the best tool we have by far to get a feel for how much melting momentum is being built up during this crucial period in the melting season: the melt pond fraction simulation model developed by CPOM researchers at the University of Reading (more info).

Again this year, Dr David Schröder has been so kind as to send me the May melt pond fraction maps he uses for his SIPN 2016 Sea Ice Outlook prediction, showing melt pond anomalies for the years 2012, 2014, 2015 and 2016 compared to the average for the last 10 years:

Caveat: This is a model result, and so the distribution of melt ponds doesn't necessarily reflect reality.

This past May has been similar to last year's, but nowhere near May 2012. Here are two more maps that show the difference in melt pond fraction with May 2012 and 2015 (red = more melt ponds now, blue = less melt ponds now):

Here's the text accompanying Dr Schröder's entry to the 2016 Sea Ice Outlook:

We predict the September ice extent 2016 to be slightly lower than last year and slightly below the trend line from 1979 to 2015: 4.5 +/- 0.5 million km2. Given the exceptional low May sea ice extent, one might expect a stronger decline this summer. In our prediction the Arctic mean May melt pond fraction is not strongly affected by the low May sea ice extent, but it will be an intriguing question whether and to what extent the current Arctic sea ice and SST conditions might result in a lower sea ice minimum.

Looking at the May 2016 melt pond fraction in our sea ice simulation, the pond fraction is higher in the Kara Sea, north of Svalbard and in the Fram Strait compared to May 2015 and with a lesser extent to May 2012, but lower in the East Siberian Sea and the Arctic Basin (see attached figures). The weighted Arctic wide mean May pond fraction 2016 is higher than in 2015, but much lower than in 2012. While the ice thickness is generally thinner in May 2016 compared to previous years, the air temperature has been several degrees above the last 10 year mean in the northern North Atlantic and the Beaufort Sea, but slightly colder in the Eastern Siberian Sea causing the described melt pond pattern.

I want to mention that the observed positive SST anomalies are not accounted for in our sea ice simulation in which the mixed layer ocean temperature is restored to climatology. This shortcoming had not been important in the past, but might have a stronger impact this year due the magnitude of the positive SST anomalies.

Nevertheless, we do not expect a new record low for September 2016.

So, that's May. How about June so far? As we've seen in the latest ASI update, clouded skies have been blocking the Sun's rays from reaching large parts of the Arctic. Here too, the difference with 2012 weather conditions for the first half of June has been quite large. The image below shows surface air temperature anomalies on the left, and average sea level pressure on the right (from the ESRL daily composites page):

In 2012, temperatures were much higher over all of the Arctic during the first two weeks of June, and pressure was much higher too, which means solar radiation wasn't blocked by clouds. A very large amount of melting momentum came into being, the foundation on which the 2012 record minimum was built.

What is the effect of all this on melting momentum, you may ask. We'll have to wait a month for Dr Schröder to share his melt pond fraction maps for June. In the meantime there's a melt pond extent map on the Arctic Data archive System website that has taken over the role of IJIS in providing AMSR2 data from the JAXA GCOM-W1 satellite. This map showing melt pond concentration on the ice pack is "an essentially experimental and research product" (hat-tip to Wipneus), so I can't vouch for its accuracy. It is an interesting piece of information nevertheless.

Below is an animation showing the progress of melt pond formation since the start of the month:

The ever prolific Wipneus is even producing a melt pond extent graph based on these images, so we can compare this year to 2013, 2014 and 2015 (AMSR2 data started coming on-line back in 2012, so that year isn't complete):

This year started out slow, melt pond formation then speeded up at the start of June, but has been slowing down again in the past few days (as can be seen on the animation as well), and is now below the 2013 and 2014 trend lines. Mind you, given the fact that 2016 sea ice extent is currently more than 250K, 500K and 800K lower than 2015, 2014 and 2013 respectively, there is also less ice cover for melt ponds to form on, in the peripheral regions where temps and solar radiation should be higher than in the ice pack's core.

Although 2016 has been leading in extent, volume and snow cover almost all year so far, the build-up of melting momentum isn't following suit. It doesn't look like June will be very different from May in this respect. Based on the evidence presented in this blog post, it already looks highly unlikely that the 2012 record low minimum will be broken in September. This also depends on what happens during July and August, of course. Last year a similar unspectacular preconditioning phase was followed by the warmest July on record, eventually leading to one of the lowest September extents on record.

And there's one other of those aspects that are largely invisible to us: ocean heat flux. We simply don't know how much heat is coming into the Arctic via the Atlantic and Pacific Oceans, and both seem to have been quite warm all winter. Despite a cloudier and colder June so far, sea surface temperature anomalies are considerably higher than they were in 2012 around this time of year, on both sides of the Arctic:

With the ice pack being dispersed as it is right now and all the open water in the Beaufort and Kara Seas, one or two periods of predominantly clear skies over the Arctic, combined with high SSTs, can still cause this melting season to go low. Provided these periods occur, of course. As things currently stand, and with the forecast in mind, a more apt question is: Can the 2016 September minimum end up among the 5 lowest on record?

I will be providing one more line of evidence in part 2 of this series, as enough has been said already.

Comments

[Artful Dodger]

"Obiwan, how can I do the Albedo Flip?"

"Luke, you must use your Melting Momentum"...

Cheers,
Lodger

[John Christensen]

Hi Neven:

"Mind you, given the fact that 2015 sea ice extent"

Should be 2016, right?
You can delete my comment then, thanks.

[Fixed now, thanks; N.]

[John Christensen]

Great entry, thanks Neven!

- And a great melt pond extent graph by Wipneus!

It is surprising that May did not come out more negative from a melt pond fraction perspective given very clear skies and high temps in April.

Given what we saw in July 2015, the impact of cloudiness/clear skies may be more centralized around mid-summer, i.e. May-July rather than April-June..

[P-maker]

In order not to confuse things more than they already are, I suggest some kind of housekeeping across this blog and the ASI Forum,

Wipneus has increasingly alluded to “melt ponds” seen in pictures of the marginal zone of the Greenland Ice sheet (see latest example here: http://forum.arctic-sea-ice.net/index.php/topic,154.msg80469.html#msg80469 ). He may have been looking in vain for melt ponds on the sea ice, but then turned to the ice sheet looking for some blue spots to show us. On the glacier, these are normally called melt lakes.

Judging from the absence of melt ponds on large swathes of sea ice this spring/early sumemr, one can only speculate whether a combination of thin, salty, rotten sea ice and heavy melting from “blow torches” may have led to an apparent absence of melt ponds this year. The melt water could have drained though the sea ice nearly immediately, since there have been no episodes of “flash freezing” this winter as judged from the DMI 80N graph.

On the glacier – au contraire – where the underlying glacier ice is thick, old and solid, these huge amounts of melt water have so far not been able to make it to the bottom, thus lakes are still blue and running full.

Just a thought…

[Sam]

P-maker,

I agree. The truly extraordinary fracturing of the entire arctic ice sheet this year makes it extremely difficult for the ice to support melt ponds. They simply drain away.

The big question is what that means to the melting of the ice. Does the thinning of the ice, which led to the fractures and draining then also become a late stage negative feedback as the absence of the lakes reduces the heat absorption of the ice? If so, is that in any way significant or important?

[John Christensen]

P-maker and Sam,

After the consecutive melt years of 2010 and 2011, the sea ice was in a terrible state also by May/June 2012, so if that ice could sustain the melt ponds, this year should be no different.

[P-maker]

John,

If you take a closer look at the DMI 80N graph for 2012, you will see a nice 10 K "flash freeze" around day # 75. That ought to be enogh to keep the sea ice back then in good shape for the melt season to arrive.

[crandles]

Melt ponds suggest no Arctic sea-ice record this year
http://www.bbc.co.uk/news/science-environment-36560548

Seems to also be covering Dr David Schröder's melt pond fraction SIPN submission. Similar conclusions reached.

[D]

The area with melt ponds in 2012, but not this May was very warm in 2012 but not this year. The clear correlation of the weather with the melt pond locations is strong evidence that the melt pond model is working well.

The real problem is that the heat this May was in the Beaufort sea where it melted out. The model is returning the ocean in the Beaufort sea to climatology after it took up huge amounts of heat. That methodology puts a hand on the scale for more ice and less melting in the Beaufort sea. And the same is true for the Barents Sea.

Ignoring increases in ocean heat content will eventually lead to forecast failure. This year might be the year when they need to update the model.

-Fish

[Ott Toomet]

Thanks, Neven, I have been following your updates with great interest for a while.

I have been thinking why do you focus so much on the melt ponds? They suck solar radiation and melt the ice, sure, but there are so many other factors too. Is this because melt ponds are easy to measure, or they have stronger impact on the final outcome than other factors we can measure? Or something else?

I am imagining running a regression like

ice extent in Sept = melt ponds in May, June + weather + SST + winter sea ice extent + ice thickness + ...

For me, it only makes sense to single out melt ponds if they are an exceptionally good predictor...

Do I miss something?
-Ott

[iceBunny]

The question for us is the sea ice extent.
Whether two-oh-one-six, so heated, is meant
To exceed the ice losses of twenty and twelve,
Or stall (from thick ice on Siberian shelves?)

Chris Reynolds thinks not and so does Doc Schroeder,
They predict a good melt but not much too further,
(In terms of a record to wake up the world)
Despite north-bound heating that El Nino's hurled.

Neven, our Hero! - oh go, be kind ;-)
Thought it good for a record but changes his mind.
Which means that he's not the most dogmatic kind,
For he follows the data, not wishes opined.

The bunny (iceBunny, not Eli the Great)
Is too much a novice to say what the fate
Of Arctic sea ice might be, later this year,
But next year, perhaps, an opinion you'll hear?

[Chris Reynolds]

P Maker,

"John,

If you take a closer look at the DMI 80N graph for 2012, you will see a nice 10 K "flash freeze" around day # 75. That ought to be enogh to keep the sea ice back then in good shape for the melt season to arrive."

Huh?

Around that day number (15 March 2012) it was roughly -20degC. 273K is roughly 0degC.

Icebunny,

I always have an early season panic.
But unlike others I tend not to get manic.
But to be fair.
I have to declare.
I conceded the chance of a summer titanic.

[P-maker]

Chris,

I was using a rounded number around and approximate date. To be precise I was referring to the drop in temperature from 258 K to 248 K over a handful of days close to the middle of the day 50 to 100 time frame. A few days later the DMI 80N temperature even dropped an additional 3 K to a level close to 245 K ( = -28 degrees C ). This winter we have hardly moved below 250 K.

Anyway, it was just a quick thought I had this morning. I suggest we move back on topic, which is supposedly this season's apparent lack of melt ponds.

[navegante]

Thank you for bringing to us these model results. As previous year I don't understand why the model covers such a limited area of the Arctic. But it is ok, I guess one day I will grab the related paper and read it myself :-)

[Robert S]

Although the differences in weather patterns between June 2012 and 2016 are clear, I've been reviewing the images for the two years on the EOSDIS Worldview platform, for the same calender days, and I'm not seeing massive differences in cloud cover between the two. It is clear that there was more "melt ponding" (green ice, as a proxy) in the Beaufort in 2012, but more fracturing, in general, in 2016, and about the same melt ponding north of Ellesmere and Greenland. I'm concerned that there are too may other factors at play to make a simple variable, like MSLP, useful. If I get time, I'll do some albedo comparisons, which might start to give some idea of the total solar heat absorbtivity.

[wayne]

More more more! model displays are very much wanted. I'd like to see sea ice animation sequence for the entire summer, and coming years. I don't know about the details for the displays above, but suspect it is based in part with satellite data. If so, it will likely fail capturing the melt ponds below snow cover in the regions with more snow depth. And
there is a lot of it

https://www.weather.gc.ca/data/analysis/352_100.gif

Perhaps over all extent is less but in some regions its not area which matters, but depth. I note with great interest the melt ponds in Kara are where there was less snow fall during winter just past.

[Rob Dekker]

Excellent overview, Neven, as always.
I trust that in part 2 you will cover other variables that affect melting momentum as well.

After all, the "melting ponds" in May, as Dr. Schoder's model uses, is not the whole story. For starters, there are not that many melting ponds in May, and while it is true that "melting ponds" act to amplify melt over time, things like polynia and leads and edge fragmentation also amplify ice melt because they are essentially 100% concentration "melting ponds", with the difference that they cause bottom-melt, so you don't see the effects until the floes around go "poof" much later on.

For example, Dr. Schroder's model does not capture the mess in the Beaufort at all, where during May massive amounts of heat were accumulated (some 50 TW as I estimated) and is currently a destruction zone for even the thick MYI floes that get pushed in there.

That is why I put more trust in Dr. Slater's model, which is based on 'ice-concentration', which captures melting ponds as well as leads and open water next to the ice. And for SIPN numbers in 2015, Dr. Slater's numbers were a lot closer than Dr. Schroder's numbers.

However, even ice-concentration in May (by itself) does not correlate very well with ice extent in September either. I don't have the numbers in front of me, but the correlation has something like R=0.35 for the 1992-2015 period (based on NSIDC ice concentration numbers).

What I would hope is that Dr. Schoder and Dr. Slater get together and figure out the strength and weakness in each of their models, then include "land snow cover" as a variable, and see if that improves the standard deviation of the predictions of their models.

[Fwmbrown]

Hi Neven,
You point out the complication of SIE vs MPF late in your article. So, who is going to rise to the challenge of producing a formula which incorporates extent, +/- anomaly, +/- MPF, =/- MPF anomaly? That could make the prognosis clearer...

[Shared Humanity]

With SST on the Atlantic side of the Arctic, this area has become a killing zone for ice. SLP in this area has been relatively high with sunshine so these anomalies will not be going away as open water heats up. What effect will this have on the minimums? It depends on ice mobility. Right now, not much ice is moving through the Fram.

[Shared Humanity]

"I always have an early season panic.
But unlike others I tend not to get manic.
But to be fair.
I have to declare.
I conceded the chance of a summer titanic."

Very nice but the meter is off to be a proper limerick.

[sofouuk]

Each spring I will feel a slight panic
As others around me go manic
And this year to be fair
I have to declare
The melting could well be titanic

[Artful Dodger]

sofouuk wrote:

...this year to be fair
I have to declare
The melting could well be titanic.

Aha, good one! Mind you, back in 1912 ice sank the ship. By 2012, coal sinks the ice. ;^)

Oh, see how NASA quanifies sea ice albedo change via satellite data:

Pistone K, Eisenman I, Ramanathan V. Observational determination of albedo decrease caused by vanishing Arctic sea ice. Proceedings of the National Academy of Sciences of the United States of America. 2014;111(9):3322-3326. doi:10.1073/pnas.1318201111.

Cheers,
Lodger

[Artful Dodger]

Hi folks,

I reckon each of us should take a few minutes to look at Pistone et.al (2014), free PDF from the link above.

Here's why: (bold is mine)

Significance:

"The Arctic sea ice retreat has been one of the most dramatic climate changes in recent decades. Nearly 50 y ago it was predicted that a darkening of the Arctic associated with disappearing ice would be a consequence of global warming. Using satellite measurements, this analysis directly quantifies how much the Arctic as viewed from space has darkened in response to the recent sea ice retreat. We find that this decline has caused 6.4 ± 0.9 W/m2 of radiative heating since 1979, considerably larger than expectations from models and recent less direct estimates. Averaged globally, this albedo change is equivalent to 25% of the direct forcing from CO2 during the past 30 y."

So there you have it: Arctic amplification due to the albedo flip. Just like Grandpa said it would. Now let's roll some coal (or perhaps not!)

Rolling Coal Videos - Blowing Up Prius Drivers

Cheers,
Lodger

[iceBunny]

The limerick version is good but I have to say that I like the extended verbal canter of "I conceded the chance of a summer titanic", so here's my verdict:

An unorthodox poet called Chris,
Wrote a rhyme wot Humanity dissed,
When he said of the form,
It's not true to the norm.
But a limerick-like doesn't miss.

:-)

[iceBunny]

The limerick version is good but I have to say that I like the extended verbal canter of "I conceded the chance of a summer titanic", so here's my verdict:

An unorthodox poet called Chris,
Wrote a rhyme wot Humanity dissed,
When he said of the form,
It's not true to the norm.
But a limerick-like doesn't miss.

:-)

[Chris Reynolds]

SH,

I knew it was when I posted it, what I missed were the two 'buts'. It was the best I could manage after working 6:45 to 20:00.

IceBunny,

Thanks, I did however have to resort to a webpage of rhymes with 'panic/manic' to get the 'titanic'.

Sofouk,

Titanic? If PIOMAS follows the behaviour of DMI Cice, this year's spring melt looks likely not to to be very strong.
http://ocean.dmi.dk/arctic/icethickness/thk.uk.php
In 2012 it was massive and probably played a role in preconditioning for the July/Aug losses.

[sofouuk]

in fact I wasn't sure what the intended meaning was in the last line - so

but this year to be fair
I'm prepared to declare
the melting will not be titanic(?)

we do need something to change soon if we're going to see an exciting end to season, that's for sure

[wayne]

The Titanic was an unexpected disaster, I foresaw less sea ice than 2012 minima, quite on track, despite munching open water Cyclones,
which are the latest fashion in a degrading sea ice kingdom. They are a bit underwhelmed by a much warmed Arctic. The days of Ice demolition by compaction also may be over, after all for an Arctic dipole to exist, there is a need for a warm and cold zone. What we are left with are weaker anticyclones driven towards Greenland, the last place for Cold. As a result it is mostly warming which slowly and less dramatically (for now) warm the pack for the August onslaught.

[Kevin O'Neill]

Over on the Forum Gray-Wolf writes: "This year we may be watching this slow evolution at play and some folk might find they need 'update' their current understandings of the working of the basin ( I know none of us know it all but some long held beliefs might be falling by the way side?)."

This is in keeping with wayne's latest comment. It's wise to remember that this is not your grandfather's arctic. It's not your father's arctic. And, if you're old enough, it's not even the arctic of your youth.

We are primates that excel at pattern-matching. While this is generally a very good trait, it can also mislead us. This is especially true if we're unable to understand that -- as the financial disclaimer goes -- "Past Performance is Not Necessarily Indicative of Future Results..."

When you're in unknown territory extrapolating from past performance becomes especially problematic. Given enough time and/or imagination we can always find an analog somewhere in the past or a reanalysis dataset or a GCM ensemble. The question is how appropriate is the analog for prediction?

As regards 2016 specifically the main questions that I see are: Was the June stall in SIE a physical reaction to the early losses (negative feedback)? Was the stall unrelated physically to the early season losses, but just the result of random weather? Or was the June stall simply non-existent; i.e., the manifestation of early season losses do not show up in SIE in June, but will be seen later in the season?

The answer as to what to expect going forward in the melting season depends largely on the correct answers to the questions above.

[jdallen_wa]

Picking up from where Kevin left off.

I think the key problems we wrestle with understanding changes in melt are three fold:

1) Limited detail in our data
2) Large numbers of related variables
3) Limited understanding of how they interact.

We really have only *3* relatively constant factors - Annual insolation, net CO2 forcing and convective heat transfer from the earth. All of these vary by less than 1% a year. CO2 forcing has the largest variability over the last 30 years, but the impact of that change is far more indirect.

Even with the most powerful computing engines ever created, we can't skillfully see ahead more than a few days, much less a season. Short term, almost like watching a pot coming to a boil, we have to fall back on a certain amount of intuition, and extrapolation from the paucity of long term data we have in our hands.

We know the pot *will* come to a boil. That's calculable from the mechanics of heat being applied. What we're trying to do is akin to determining what the surface of the water will look like getting there.

[John Christensen]

"If PIOMAS follows the behaviour of DMI Cice, this year's spring melt looks likely not to to be very strong."

Agreed Chris, according to DMI, the June volume melt has been less than the 2004-13 average, with extent dropping relatively more.
That extent has dropped more sharply than volume was to be expected with significant volume in the central areas, as discussed earlier.

Suspects IMO:

1) June weather/lows in the CAB
2) Lack of conditioning (melt ponds)
3) Relative lack of Laptev bite - and why would that be?

[wayne]

John and Chris

"If PIOMAS follows the behaviour of DMI Cice, this year's spring melt looks likely not to to be very strong."

Wrong wrong, 2015f core ice warmed to -2.2 C, + .4 C in one week,
compared same date similar position buoy +.3 ahead of 2013.

Despite a single buoy, thank goodness for those placing it there!
This is a hugely significant turn of events. For a good chunk of the pack to melt, core temps must be very warm, warmest, especially if Dipole compaction is on the fritz. If best thing for sea ice to survive occurs -a complete gyre stall with great cloud cover - the only thing left is heat tho do the job. And we know, there is more heat -in air and ocean- than 2013, logically despite best geophysics feature to preserve from now on, 2016 will race with 2012 throughout the summer. But clouds are not so prominent yet.

[wayne]

I consider 2016 Gyre having a great deal of momentum as well, there was a great spin of the current for months during late winter early spring, any relapse in contrarian winds should make the beast turn clockwise, not strongly but enough for mini compactions.

[Cato Uticensis]

Neven, thanks for the update, just great as usual. As you correctly guessed...I liked it a lot! :) but I remain aware that in spite of the good news about melting momentum, the extension still remains extremely low and the current weather conditions need to be maintained for several weeks more in order to avoid a replica of 2012 or likewise...July 2015 remains as a quite painful warning of what could still happen in the near future.

[Colorado Bob]

This is What A Fossil Fuel Dystopia Looks Like — The Arctic Sea Ice is Breaking Up North of Greenland in June

https://robertscribbler.com/2016/06/20/this-is-what-a-fossil-fuel-dystopia-looks-like-the-arctic-sea-ice-is-breaking-up-north-of-greenland-in-june/

[Rob Dekker]

This is a little bit off-topic, but William Connelly has put up a post about the sea-ice bet on the 2016 September minimum I made with him 5 years ago :

http://scienceblogs.com/stoat/2016/06/13/the-sea-ice-post/

Note that the bet's void range is 3.1 - 4.8, and considering that the September minimum will likely fall within that range, we likely both be wrong. But considering that this entire range is quite outside the IPCC projected range for 2016, the models still underestimate reality, which is a grave point of concern in my opinion.

[John Christensen]

"this entire range is quite outside the IPCC projected range for 2016"

Rob,

Please share the IPCC project range for 2016 with us ignorants, thanks.

[Rob Dekker]

John, you are no "ignorant".
Here is a graph of actual Arctic sea ice extent versus IPCC model projections :
http://www.realclimate.org/images/seaice10.jpg

[Rob Dekker]

And here is one that includes 2012 :
http://neven1.typepad.com/.a/6a0133f03a1e37970b017744cf5360970d-pi

[John Christensen]

Thanks Rob - and yes; I do not consider myself entirely ignorant about sea ice, but I was not aware that the IPCC had included sea ice extent projections in their publications, and have searched AR5 again, in vain.

Are you aware if the projections were in AR5, or have they been published separately?

[crandles]

>"I was not aware that the IPCC had included sea ice extent projections in their publications"

Yes AR5 says things like:

Sea Ice
Continuing the trends reported in AR4, the annual Arctic sea ice extent decreased over the period 1979–2012. The rate of this decrease was very likely1 between 3.5 and 4.1% per decade (0.45 to 0.51 million km2 per decade). The average decrease in decadal extent of Arctic sea ice has been most rapid in summer and autumn (high confidence2), but the extent has decreased in every season, and in every successive decade since 1979 (high confidence).
{4.2.2, Figure 4.2}

The extent of Arctic perennial and multi-year sea ice decreased between 1979 and 2012 (very high confidence). The perennial sea ice extent (summer minimum) decreased between 1979 and 2012 at 11.5 ± 2.1% per decade (0.73 to 1.07 million km2 per decade) (very likely) and the multi-year ice (that has survived two or more summers)
decreased at a rate of 13.5 ± 2.5% per decade (0.66 to 0.98 million km2 per decade) (very likely). {4.2.2, Figures 4.4, 4.6}

The average winter sea ice thickness within the Arctic Basin decreased between 1980 and 2008 (high confidence). The average decrease was likely between 1.3 and 2.3 m. High confidence in this assessment is based on observations from multiple sources: submarine, electro-magnetic (EM) probes, and satellite altimetry, and is consistent with the decline in multi-year and perennial ice extent {4.2.2, Figures 4.5, 4.6}

Satellite measurements made in the period 2010–2012 show a decrease in sea ice volume compared to those made over the period 2003–2008 (medium confidence). There is high confidence that in the Arctic, where the sea ice thickness has decreased, the sea ice drift speed has increased. {4.2.2, Figure 4.6}

It is likely that the annual period of surface melt on Arctic perennial sea ice lengthened by 5.7 ± 0.9 days per decade over the period 1979–2012. Over this period, in the region between the East Siberian Sea and the western Beaufort Sea, the duration of ice-free conditions increased by nearly 3 months. {4.2.2, Figure 4.6}

It is very likely that the annual Antarctic sea ice extent increased at a rate of between 1.2 and 1.8% per decade (0.13 to 0.20 million km2 per decade) between 1979 and 2012. There was a greater increase in sea ice area, due to decrease in the percentage of open water within the ice pack. There is high confidence that there are strong regional differences in this annual rate, with some regions increasing in extent/area and some decreasing {4.2.3, Figure 4.7}

Projections would likely be CMIP3 or CMIP5 analysis? I doubt that should be described as an IPCC projected range. It is more like what the models show and the models may not be good enough for the IPCC to agree that that is what will happen.

[Rob Dekker]

John,
Yes. the sea ice projections (using CMIP5 models) are in AR5, WG1 report, chapter 12 "Long-term Climate Change: Projections, Commitments and Irreversibility".

https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter11_FINAL.pdf

Check figure 12.28b, in section 12.4.6.1, on page 1088. I know. It's almost as if they want to hide it. But it's there at least.
And the 3.1 - 4.8 bet range in 2016 is still well below model projections (albeit a bit less below model projections from CMIP3 models compared to reality/observations.

[Rob Dekker]

Oops. That would be chapter 12 :
https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter12_FINAL.pdf

[John Christensen]

Got it, thanks Rob!

Agreed, that the projections used are much too conservative, and odd that the text admits that the projections 'might be' too conservative, although observations extent considerably beyond confidence bands.

Similarly, it seems their projections have no clear grasp on the SH sea ice cover, but let's not open that discussion here.

[Rob Dekker]

That's right, John.
At least " the magnitude of the CMIP5 multi-model
mean trend in September Arctic sea ice extent over the satellite
era is more consistent with, but still underestimates, the observed
one (see also Massonnet et al., 2012; Stroeve et al., 2012; Wang and
Overland, 2012; Overland and Wang, 2013)"

I have previously suggested that the underestimate of the ice extent decline in GCMs is rooted in the underestimate of decline in land snow cover, which is underestimated by a factor of 2 or 3 in CMIP5 models (Brutel-Vuilmet et al 2013), thereby significantly underestimating albedo feedbacks during the melting season.

[Artful Dodger]

wayne wrote | June 30, 2016 at 07:03

"Its 2102 all over again, until something more dramatic occurs."

Hi Wayne,

Not to Rush things, but with CICE models running aboot a century behind the actual sea ice, I think its more like "2112 redux".

"I wandered home though silent streets
And fell into a fitful sleep
Escape to realms beyond the night
Dream can't you show me the light?"

The True North has seen more change in the past 40 years than in the last 8,000. How dramatic is that?

Bonne fête du Canada! Happy Canada D'eh! ;^)

Cheers,
Lodger