The Slow Transition

[oren]

I can't access the paper, but I believe the authors are confusing correlation and direct causation. There is an almost linear rise in CO₂, and a somewhat linear decrease in Sep sea ice, therefore a nice correlation. But the causation is much more complicated, as the abstract explain. Were CO₂ to accelerate or decelerate significantly, I believe the direct linear "relationship" would break down. Even more, should emissions completely stop, I believe the climate will continue to warm and Sep sea ice will still go down for quite a while.
On a side note, not sure if this belongs in this thread, again haven't read the full paper.

[Csnavywx]

Abstract mentions total Sept. loss. Zero average Sept. ice is different from 1 day or a 5-day average of ice-free conditions (which will come at least several years earlier).

Also, correlation is vs. area, which misses the volume aspect. Area loss will approach zero non-linearly because it is a 2-dimensional measure of a 3-dimensional phenomenon. Will result in at least a slight overestimation of the date. Having said that, I understand why area was used as it has a much longer observational data set than volume.

[jai mitchell]

yes, the default use of Area or extent due to convention (and longer series) is a problem.  However, it could easily have been adjusted for aerosols (surface temperature) using the 1946 to 1978 cooling trend.

Once this outside influence on forcing was isolated, the temperature trend data could then be applied to the Piomas data series and a much more rapid decline per tonne of CO2 emitted could be determined. 

However, even this result is (in my opinion) a fool's errand as it does not include forcing feedbacks from albedo and cloud/water vapor pulses in both winter (suppressing sea ice growth) and summer (cooler surface temperatures suppressing summer melt)

[Jim Williams]

However, even this result is (in my opinion) a fool's errand as it does not include forcing feedbacks from albedo and cloud/water vapor pulses in both winter (suppressing sea ice growth) and summer (cooler surface temperatures suppressing summer melt)

I have to agree.  CO2 is the trigger, but H2O is the bullet.  (I also do not really expect a slow transition.)

[Steven]

I can't access the paper, but I believe the authors are confusing correlation and direct causation. There is an almost linear rise in CO₂, and a somewhat linear decrease in Sep sea ice, therefore a nice correlation. But the causation is much more complicated, as the abstract explain. Were CO₂ to accelerate or decelerate significantly, I believe the direct linear "relationship" would break down. Even more, should emissions completely stop, I believe the climate will continue to warm and Sep sea ice will still go down for quite a while.
On a side note, not sure if this belongs in this thread, again haven't read the full paper.

According to that paper, the linear relationship appears in the observational record, as well as in climate model simulations with CMIP5 models.  Quote from the paper:

... we here identify and examine
a fundamental relationship in which the CMIP5 models
agree with the observational record: during the transition to
a seasonally ice-free Arctic Ocean, the 30-year running mean
of monthly mean September Arctic sea-ice area is almost
linearly related to cumulative anthropogenic CO2 emissions
(Fig. 1). In the model simulations, the linear relationship
holds until the 30-year running mean, which we analyze to
reduce internal variability, samples more and more years of
a seasonally ice-free Arctic Ocean, at which point the relationship
levels off toward zero.

In the model simulations, they assume that future CO₂ emissions follow the business-as-usual emission scenario (RCP8.5).  The results in the paper would probably be invalid for other emission scenarios.  But anyway, most of the CMIP5 models seem to be too conservative regarding Arctic sea ice.

[iceman]

    ... winter volume growth is growing as the minimum volume declines. (Hence summer is declining faster than winter volume.)
    ....

Tamino does some Change point anlaysis on Arctic ice. 
    ....

Do we think that 2017 marks a change point in the summer vs. winter volume trends?
In other words, are we now seeing a new regime of stratospheric circulation (or some other tipping point in Arctic amplification) that will be sufficient to overcome the thermodynamic constraints that Chris R posited?

[Neven]

That's a very good question. Maybe we can lure Chris back into this. 

[Gray-Wolf]

Didn't we miss the boat on winter ice losses? The volume of ice lost over winter through the 80's was monsterous and most all of it Paleocryistic! We now fret over the loss of our 4 and 5 year old ice.

When folk have told me that 'recovery' is still possible I have to point them way back beyond 07' where they think the problems started.

I think we are somehow missing an opportunity to show the disinterested just what has been lost to the basin prior to us even entering this new century?

When we talk of a 'slow transition' we need be mindful just how slow it has been and just how much of the ice has now been destroyed as we discuss the final loss of the dregs?

If anyone out there has data on the kind of volume losses we have seen (as ice reserves dwindled) it might prove useful?

[crandles]

2016/17 winter FDD are way out of line with previous years. I think a large portion of this could well just be anomalous but even if just a small portion remains as a new trend or step it is bad news. Will take a few years to distinguish size of any parts which are anomalous, step or new trend.

[meddoc]

Don't even know why this thread exists.
No such thing as a slow transition if You are able to comprehend basic physics & mathematics

[Dave C]

Don't even know why this thread exists.
No such thing as a slow transition if You are able to comprehend basic physics & mathematics

Arctic Ice melt isn't remotely "basic" physics and mathematics.
And there is in fact a lot of disagreement by experts about how long it's going to take for the Arctic to become ice free.

I would say that through summer of 2016 that the slow transition theory seemed to have better support behind it than a Wadhams like alternative. But it's really going to get tested this summer- the collapse that gets predicted each year on message boards might actually happen.

[Archimid]

As a climate change alarmist, I came here believing we will lose the ice cover years ago. I have learned much but still have much more to learn. After some learning I believe that there is merit to the slow transition theory, but it is being tested thoroughly. So far is failing some tests, but it has passed others.   

I don't think this year is beyond hope. There is less ice than ever, with the lowest extent on record and what can be described as the worst winter on record. I believe that had to do with the Atlantic and Pacific undergoing a very hot cycle. If the ice survives until the oceans return to a cooler cycle, then the slow transition gains a lot of credibility.


But right now, the worst should be assumed and prepared for, always hoping for the best. If the pacific returns to even close to warm conditions, with the ice in the conditions it is now, the slow transition theory will be disproven.

[Gray-Wolf]

When 07' woke me up and forced me to look at the evolution of the situation 07' put us in it became clear , to me, that we might struggle come a repeat of the 07' synoptic.

I held onto these concerns right up until last year where it was made quite clear to me that we no longer needed a 'perfect melt storm' to bring us into low ice conditions but merely a poor growth winter and an 'average melt season' ( equal proportions of high melt and retentive forcings?).

One thing has become apparent. We do not see many sunny summers over the basin any more! I believe this is a situation augmented by ice loss and open water.

2017 is the earliest possible return of the 'Perfect melt storm' synoptic. I am not expecting it but what would an 07' type summer of high export /high melt do to the ice that is now only 3 or 4 weeks away from melt season?

The 'Slow transition' is now over and we are awaiting to final, unstoppable, melt out season over a melt season some time soon!

[crandles]

Don't even know why this thread exists.
No such thing as a slow transition if You are able to comprehend basic physics & mathematics

I am quite happy for people to say they disagree with the hypothesis.

But why say this? It seems to be saying 'not only do I disagree but I so don't want to agree, that people should not be allowed to discuss it'. That doesn't advance any understanding of the idea but moreover is only giving impression that environmentalist mind set is such that they totally believe disaster is just around every corner and will not be dissuaded from such a view so there is no point engaging with them. Just giving out info on your perception filters like this seems exactly the wrong thing to do.

But maybe I am just totally misunderstanding what you have written.

[oren]

Chris R's main assumption was that the freezing season remains mostly the same, with FDDs stable or perhaps undergoing a small decline, and that therefore arctic sea ice cannot just pass a tipping point and disappear following its first ice-free summer. Instead, even if a freak summer came along and melted all the ice, the refrozen arctic would still not necessarily melt out the year after. This is what he dubbed a "slow transition", as opposed to a one-way phase change.
The theory is very strong and Chris at the time gave many good arguments and explanations, but I believe this year has already shown its main flaw, and that is the FDD assumption. FDDs crashed this winter, leading to the possibility of a melt-out with a regular un-freakish summer.
What still remains open is whether this winter is freakish or not. If it's not a one-time phenomenon (perhaps Nino-related) but instead a result of continued AGW coupled with the feedback from too much open water during autumn, then the arctic may have indeed passed a tipping point.

[Gray-Wolf]

Hi Oren!
If this winter was some kind of 'outlier' then I'd need more evidence that this was to become the norm but I think we can trace a long evolution of this' new polar maritime' winter atmosphere over the period Jen Francis has looked at?

Since we started to see snow cover impacted by warming ( late 90's?) she has been noting impacts over the Autumn Arctic Ocean. As Sea ice peeled back to reveal the dark water below these impacts appear to ramp up and give impact to the polar Jet. Since 07' it has not just been 'final figure' open water measures but the amount of open water , over the season, that brought issues to the N.Hemisphere. I suppose the low angle sun of September does not have a lot to give to the final bits of water to open up but those patches of open water in June/July early Aug???

My interest in the 'Crackopalypse events' is that they appear to be a mechanism for exposing open water, and imparting a 'melt pool' type albedo flip?, early in the season? The ,very quickly old, notion that melt pool area can help with final ice numbers must now be replaced with a measure of leads and open areas to show how quickly the ocean is coming up to 'melt temps' now that the well fractured pack no longer has the contiguous expanses it used to boast?

I cannot help but think that we will see the pack 'dis-articulate' into small floes among rubble very early in the season and then, whatever the weather conditions, it will either melt into open water areas or be bashed about to form open areas?

We still have not seen a summer , post 2012, with good stretches of sunshine across the basin over high solar .Is the weather up there so changed as to preclude such an occurrence these days?
Should we see a more sunny summer over the pack this melt season just what would we expect of this pack?

I have moved from dreading the return of the 'Perfect melt storm' summer to dreading a 'pretty decent ' Summer across the Arctic! (lol)

[ktonine]

For those that have not read Chris Reynold's original post on the "Slow Transition" - it can be found at his Dosbat website - The Slow Transition

Distilling a long post with lots of data and caveats, especially nearing three years old, is difficult.  But for those who haven't read it here is what I think is the takeaway from Chris' post:

Critical to all this is that I am becoming convinced that the approximate levelling of PIOMAS volume over the last few winters is telling us that the pack is becoming dominated by FYI, whose thermodynamic equilibrium thickness is largely setting the peak volume in April. Even if one year, with exceptionally good melt weather, were to lead to extent below 1 million kmsq, this will be unlikely to be repeated, and for the record, I do not think this is likely anyway. To get to a state of near ice free conditions in late summer we will need to see significant thinning of the winter peak thickness, which needs far greater winter warming. I don't think this is likely to be a fast process.

So I do not expect to see a virtually sea ice free state until later in the next decade - at the earliest, I suspect that Overland and Wang may be proven right in pinning it on the 2030s. In terms of expectations amongst many in the amateur sea ice community this is a slow transition. However in geological terms it remains abrupt.

This year we *are* seeing significant thinning in winter thickness, but it still requires an even thinner pack to meet the requirements to get reliably under 1 million kmsq.  So, the question still remains: is this winter's lack of FDDs a step change or is it an anomaly?

I've always been an advocate of slightly faster timing than Chris for these processes, but the arctic has always managed to surprise me with it's resilience.  And in the end we're realistically talking about a difference of 10 to 15 years -- virtually no difference at all in scientific terms.

What I think we should also remember is that the scientist that first really went out publicly on a limb with an "over-the-top" prediction was Wieslav Maslowski.  Back in 2006 Maslowski predicted a nearly ice free arctic in 2016  +/- 3 years.  What many don't know is that Maslowski was not talking about sea ice are or extent - but volume. And 'nearly ice free' he defined as losing 80% of the 1979-2000 summer volume (see article by Joe Romm at ThinkProgress).   2012 came close.  2017 should come even closer - perhaps even make that prediction come true.

[Iceismylife]

Chris R's main assumption was that the freezing season remains mostly the same, with FDDs stable or perhaps undergoing a small decline, and that therefore arctic sea ice cannot just pass a tipping point and disappear following its first ice-free summer. Instead, even if a freak summer came along and melted all the ice, the refrozen arctic would still not necessarily melt out the year after. This is what he dubbed a "slow transition", as opposed to a one-way phase change.
The theory is very strong and Chris at the time gave many good arguments and explanations, but I believe this year has already shown its main flaw, and that is the FDD assumption. FDDs crashed this winter, leading to the possibility of a melt-out with a regular un-freakish summer.
What still remains open is whether this winter is freakish or not. If it's not a one-time phenomenon (perhaps Nino-related) but instead a result of continued AGW coupled with the feedback from too much open water during autumn, then the arctic may have indeed passed a tipping point.

Starting with an alternative theory on AGW.  Soot added to the snow pack of Europe at the start of the industrial revolution started an ongoing Albedo driven warming trend, (Reference the albedo warming potential thread)  The size and extent of the reduced salinity surface water in and around the Arctic Ocean has been in decline from say 1700 on.  Give or take a bit.

Draw a line from extent back then until now and see where it hits Zero.  Or see where the rate of change says it is likely to hit zero.

When will the gulf stream make it into the Arctic Ocean basin to sink and become bottom water?  That is the end of Arctic Sea Ice.

[DavidR]

Back in 2006 Maslowski predicted a nearly ice free arctic in 2016  +/- 3 years.  What many don't know is that Maslowski was not talking about sea ice are or extent - but volume. And 'nearly ice free' he defined as losing 80% of the 1979-2000 summer volume.   2012 came close.  2017 should come even closer - perhaps even make that prediction come true.

Applying a polynomial trend line to  the decline in minimum volume puts the trend value for 2016 equivalent to the actual  value for 2012(3673 km^3).  The trend value for 2017 is perhaps 500 km^3 below 2012.   

20% of the 1979-2000 average is 2740 km^3. This appears easily within reach this year given the current state of the ice.

[Neven]

And I believe the core of Maslowski's prediction is ocean heat flux, which is hard to measure. I suspect that this is what has driven last year's melting season (which should have ended up higher given cloudy conditions) and is probably also partly driving this winter's lack of freezing power.

If true, then the question here too is: Is this just a pulse or a new state? And is it caused by Arctic sea ice loss, or by something that is going on at lower latitudes? Chicken or egg?

[Gray-Wolf]

Hi Neven!

With things like the Stratospheric oddness ( both QBO....which looks to be trying again to go easterly presently.....a year late....and the QBO) , the sudden Antarctic reversal in fortunes and Sea ice retreat, the failed Nina (when all the signs pointed to a moderate event/), et al it is very hard for me to look at the Basin this winter as some kind of 'outlier'?

Where this winter ,across the Basin, an isolated event I'd be wondering what was occurring but it is occurring on the back of a decade and a half's worth of witnessing an altering N. Hemisphere atmosphere, that is increasing in impact over time.

From reading Jen Francis's early papers the impacts were once rooted over the Autumn Barents/Kara seas?  But now, with the addition of long 'open water' periods across Baffin/Beaufort/East Siberia has that impact spread more widely across the basin and so giving a more defined impact on the Troposphere/Stratosphere?

The impacts of low snow cover around the basin augmented by low ice cover in Barentsz/Kara, since the turn of the Century took a number of years to properly establish in impact over Barentsz/Kara so maybe we have now served the 'Lag time' for the more regular appearance of open waters in Beaufort/Baffin/ESS and these wider impacts are what is now driving weather weirdness around the Hemisphere with higher energy events now being witnessed more frequently ( cold plunges into Sub tropical regions but warmer air masking it into the basin).

I am firmly of the belief that this is an organic evolution of low snow/sea ice forcings and that this localised energy boost to the climate system is now maturing into a self feeding loop of poor winter growth leading to early open water and ever higher energy absorption leading to atmospheric disruptions ( weak PV /displaced PV /errant Polar Jet) over autumn early winter leading to storms guided into the basin, via Fram/Bering, leading to early open water......

These impacts might also be timed to low solar (and the forcing this places on High pressure over the Atlantic?) giving us 3 or 4 years where Atlantic/European 'blocking' pushes storm systems up over Greenland and into the basin. The increased moisture content of the atmosphere ( including the upper trop!) is a growing component of the system and not likely to reduce so if there is a 'solar component to this , and last years Arctic winters, then the next low solar will see an even higher moisture/heat component to the storms meaning even higher disruption within the basin come that solar low point?

Seeing how this pack reacts to the weather types over the coming summer will show us exactly what this means for the basin.

Should high insolation now mean a cloudy basin we might not need fear about 'torching events' but will the slow 'drip,drip' forcing of above zero temps be all that is needed for a vast portion of the pack?

This years low FDD's means the ice is both not as cold ( resilient) but also not as thickened as previous years.

By that understanding a carbon copy of last summer would leave us far lower in ice come seasons end?

[Jim Williams]

Should high insolation now mean a cloudy basin we might not need fear about 'torching events' but will the slow 'drip,drip' forcing of above zero temps be all that is needed for a vast portion of the pack?

With the jump at the end of 2015, I think that when the melt-out comes it isn't going to matter what time of year it is.  All that the Ocean needs is enough egg-beaters running over open water to stir up all the heat right below.

[meddoc]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

[dnem]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

No doubt that a decade or two is immaterial over geological time.  But it could literally mean the difference between the survival or failure of modern industrial civilization if a dramatic (and earlier) transition in the arctic translates into an earlier policy response to the climate crisis. 

[Gray-Wolf]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

Agreed! as I posted up thread the 'slow transition' was the past 150 years!!!

I'm more concerned by the ability of the area to soak up energy over summer than some notional covering that is meant to strike fear into us!

Last years smashed and mangled pack at seasons end surely begs the question " what would we be facing after a Sunny Arctic summer?" We could see the basin absorb plenty of energy yet still cling onto over 1 million esp. if it is the 15% or more measure where 16km2 of ice can be majicked into 100km2 covering.........

[ktonine]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

No doubt that a decade or two is immaterial over geological time.  But it could literally mean the difference between the survival or failure of modern industrial civilization if a dramatic (and earlier) transition in the arctic translates into an earlier policy response to the climate crisis.

The comment by meddoc neglects any of the context surrounding the original discussion.  Everyone involved in the original discussion knew that in geologic terms the change is near instantaneous.  'Slow' was used to differentiate an ice-free arctic "this year" or "by the end of the decade" from the state where negative feedbacks delay the process by a couple of decades.

It is also a position that gives little support to a tipping point since it's based on an energy budget that slowly changes and recognizes winter freeze isn't likely to end - just slowly get reduced.

[Jim Williams]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

No doubt that a decade or two is immaterial over geological time.  But it could literally mean the difference between the survival or failure of modern industrial civilization if a dramatic (and earlier) transition in the arctic translates into an earlier policy response to the climate crisis.

The comment by meddoc neglects any of the context surrounding the original discussion.  Everyone involved in the original discussion knew that in geologic terms the change is near instantaneous.  'Slow' was used to differentiate an ice-free arctic "this year" or "by the end of the decade" from the state where negative feedbacks delay the process by a couple of decades.

It is also a position that gives little support to a tipping point since it's based on an energy budget that slowly changes and recognizes winter freeze isn't likely to end - just slowly get reduced.

However, the tippingpoint was approximately December 27, 2015.

[Neven]

So, after reading the replies to my comment-
I'm pretty much amazed by some of You geologists claiming, that a couple of + Years would mean "slow transition' for You.

Cause that's called Abrupt Climate Change in scientific circles.

You obviously haven't read the replies, because one of them contained a direct quote from the guy who coined the term 'Slow Transition':

"In terms of expectations amongst many in the amateur sea ice community this is a slow transition. However in geological terms it remains abrupt."

And as you didn't read that, you probably didn't read this either:

For those that have not read Chris Reynold's original post on the "Slow Transition" - it can be found at his Dosbat website - The Slow Transition

Read it. It's perhaps the best amateur scientist stuff that has been done wrt Arctic sea ice. Chris Reynolds was one of the first I have read talking about things like FDD.

[Archimid]

I think that the core of the slow transition is that at some point there will be an inflection in the opposite direction and something closer to equilibrium is reached. That is what happened after 2007 and after 2012, but not after 2016. But there some days left for winter, or if you believe Phil, 5 weeks.

I think that instead there is a point when there is simply not enough ice (winter power) left to keep more energetic influences out. Once that point is reached, the same forces that reduced the ice to the current volume overwhelm the small amount of ice and the arctic enters a different state.

I think that the first year this happens, the freezing season will not start until very late if at all. If it starts, ice will grow slowly from the outside in. If we get lucky it may reach a rapid growth phase and close completely. Whatever happens next year the arctic ocean is mostly ocean for most of the year. Ice in the arctic becomes a rare and sparse occurrence.

I also think that there is a good chance (50%?) that we have not hit that spot yet. But El niño really needs to stay away.

[Jim Williams]

I think that the core of the slow transition is that at some point there will be an inflection in the opposite direction and something closer to equilibrium is reached. That is what happened after 2007 and after 2012, but not after 2016. But there some days left for winter, of if you believe Phil, 5 weeks.

I think that instead there is a point when there is simply not enough ice (winter power) left to keep more energetic influences out. Once that point is reached, the same forces that reduced the ice to the current volume overwhelm the small amount of ice and the arctic enters a different state.

I think that the first year this happens, the freezing season will not start until very late if at all. If it starts, ice will grow slowly from the outside in. If we get lucky it may reach a rapid growth phase and close completely. Whatever happens next year the arctic ocean is mostly ocean for most of the year. Ice in the arctic becomes a rare and sparse occurrence.

I also think that there is a good chance (50%?) that we have not hit that spot yet. But El niño really needs to stay away.

I disagree with you on only one point...I think the point in question happened about December 27 2015.

[gerontocrat]

El nino? Climate Prediction Center says la nina is no longer extant and 50-50 chance of some sort of el nino later this year (but with low confidence in forecast).

But it is hard not to think that given the last 12+ months data the slow transition has speeded up somewhat ?

[oren]

Please all make sure to read Chris R's blog as Neven has stressed. And even with low FDDs and an ice-free September the North Pole is expected to freeze in winter.
To pass a tipping point, some strong amplifying feedback needs to kick in and prevent a return to the previous state. Whether Dec 2015 was such a tipping point is still not proven in my mind, though it is quite likely. I would wait a couple more years before making a final judgment, to put some distance from the monster El Nino and make sure this winter is repeating itself as a new "normal".

[Shared Humanity]

I am definitely in the slow transition camp.

Yes, the polar winters are warming and have been for a couple of decades, most pronounced in the fall and early winter, and 2016 has been one, literally, for the record books. And while we are quickly approaching a seasonally ice free state using any of the three ice measures, SIE, SIA and volume, the simple fact is the Polar winters will still be cold enough for sea water to freeze rapidly. Over the past 40 years as SIE and SIA minimums have declined and winters have warmed, the amount of ice growth during the following freeze season has trended up such that SIE and SIA maximums have declined at a slower pace. Essentially, those very low minimums mean there is more open water to freeze. The dramatic drop in SIE and SIA minimums that occurred in 2007 has resulted in faster ice growth in the winters. The two charts below show the trend in SIE and SIA min and max for each year. The gray line is the trend line for annual SIE and SIA growth which I call BICOT (Bifurcated Intra-annual Cryosphere Oscillation Trend aka "Baby, It's Cold Out There").

(Sorry about the charts. Easier to read with a click.)

[Gray-Wolf]

I'd again stress that it is now no longer about seeing the empty basin but looking at the forcings all of the energy that is absorbed over summer is causing. With the switch to a highly fragmented pack we now see wide areas exploit any incoming solar and not just random open spots. If impacts do include Stratosphere peturbations then the planets weather patterns ( and not just N.Hemisphere) are at risk with Antarctica particularly vulnerable after 30 years of isolation from global warmed temps.

Sea ice followed the lead of Snow cover in the N.Hemisphere and what we see with snow cover is that no matter how much snow the winter leaves it is still all gone earlier than it used to. Many times we saw alaskan snow ( in the noughties) hit record amounts but it still went earlier than it used to. Sea ice is the same in that it does not matter how extensive the cover is over winter if it is broken apart or gone by june then we have problems.

[Jim Williams]

Please all make sure to read Chris R's blog as Neven has stressed. And even with low FDDs and an ice-free September the North Pole is expected to freeze in winter.
To pass a tipping point, some strong amplifying feedback needs to kick in and prevent a return to the previous state. Whether Dec 2015 was such a tipping point is still not proven in my mind, though it is quite likely. I would wait a couple more years before making a final judgment, to put some distance from the monster El Nino and make sure this winter is repeating itself as a new "normal".

I quite understand the seasonal theory, but that relies upon all the warm water in the Arctic staying well below the surface.  I think the train of storms (egg beaters) we have been seeing is the new norm, and that the halocline is being destroyed.

[Archimid]

I am definitely in the slow transition camp.
...
 the simple fact is the Polar winters will still be cold enough for sea water to freeze rapidly.
...

I disagree that is a simple fact. That assumes the same conditions as historical conditions will remain in the absence of the ice. I think that's a huge assumption. I don't think they will remain the same.

 I know there are already enough forcings to steadily reduce the ice volume, if those forcings are enough to reduce the volume to 0, then the physics change.  The forcings become even stronger, because of added albedo warming, ocean mixing and hot air intrusions. A different state. This of course does not happen instantaneously, but continually.

For me to believe the slow transition you would have to show me mechanisms that cancel out the forcing being experienced during the reduction of ice and the added forcings after there is no ice. I have not seen that. The  enthalpy argument was the only one that came close, but seeing the ocean mixing, hot air intrusions, export capacity of Nares etc,  I also don't think is enough.

Things like cloudy summers, maybe more spring snow cover, might do it, but they don't seem enough to me.

[ktonine]

I am definitely in the slow transition camp.
...
 the simple fact is the Polar winters will still be cold enough for sea water to freeze rapidly.
...

I disagree that is a simple fact. That assumes the same conditions as historical conditions will remain in the absence of the ice. I think that's a huge assumption. I don't think they will remain the same.

The laws of physics.
.... because Schröder and Connolley [2007]
.... because Tietsche [2011]

[Jim Williams]

Things like cloudy summers, maybe more spring snow cover, might do it, but they don't seem enough to me.

The problem with the "cloudy summer" argument is that it assumes the Summer is both cloudy and calm; which I doubt seriously.

[aslan]

This winter is making clear that Arctic is going to crash abruptly. We are almost at the end of the winter, and first year sea ice is still not consolitaded. Until this year, yes, the cold was enough to keep the ice growing and reach a "standard value", something like a slab of first year ice, a 14 millions km² by 2m thickness slab. But these year we are way beyond this. The first year sea ice is still 1m - 1.5m about everywhere and there is only 1 - 2 month left before melting season starts. There is no way this year will reach the equilibrium state of a slab of 14 millions km² by 2m.



For Canada Sea Ice Service, thin first year ice is up to 70 cms, medium is up to 120 cms, thick is above. This is in broad agreement with HYCOM :



And it is woth stressing again that Chukchi sea ice remains open in the polar night until the start of January...
It can seem crazy to think that the Arctic is ice free in winter, but it will probably the case in the second half of this century. We are all in denial -me too sometimes-; and acknolewding that Arctic can be ice free in winter brings to me a picture of a man at the edge of a cliff, looking down and seeing nothing than a dark abyss -yeah I am a visual guy-. But here we are, this winter 2016-2017 is shouting to us, yes it is possible, it is only a matter of time.

There is not a strong need for aditional forcings. A bit more of CO2, a bit help from oceanic circulation, yes probably. But the most important factor is already playing
In winter there is a quasi permanent inversion in the Arctic. This quasi permanent inversion means, for radiative reasons, that surface can warm widly while the free atmosphere barely becomes hotter :

http://www.nature.com/ngeo/journal/v4/n11/full/ngeo1285.html

With this, open waters means clouds and water vapor. Stratocumulus helps even more to destroy the surface inversion.
Only one uncertainty remains, the possible feedback from a stormier Arctic. If Arctic truly becomes a den for storms, wich is likely, this will fan the oceanic heat content, helping even more. The 2016-2017 winter was astonishing because the surface inversion was barely alive. With January 2016, January 2017 is the sole month were T at 1000 hpa were above T at 850 hpa over Arctic:



Again, even while we are only in 2017, Ostrov Vrangla and the Pacific side of Arctic was able to stay strong and open until early - mid January, making two third of the journey trough the "freezing season" without freezing.

[Archimid]

The laws of physics.
.... because Schröder and Connolley [2007]
.... because Tietsche [2011]

First, thank you much for the references.

Second, the references do not provide any of the mechanism I'm looking for. Their arguments is the same as the arguments presented in this thread. They used models of present and past arctic conditions to predict a recovery based on the models. From my perspective, that's akin to saying, it will cold in the future because it was cold in the past. That is not enough. Furthermore, the models are outdated by current events. See the date of publication. It was after the 2007 recovery but before the 2012 crash. Furthermore, from the second link, my emphasis:

We use ECHAM5/MPI-OM to perform a climate projection for the 21st century according to the IPCC-A1B emission scenario [Nakićenović et al., 2000]. In this reference run, annual mean surface air temperature in the Arctic rises from −14°C in the 1900s to −4°C in the 2090s. Arctic sea-ice extent declines, and the Arctic Ocean is typically ice-free by the end of summer from 2070 onward

Since we are already way worse than ice free by 2070, and this models run do not include 2012, and worse, they do not include 2016-present, the arguments fails even more.

If you have other references that points to a recovery of the ice after a BOE that includes descriptions of physical mechanisms that present a negative forcing that overwhelm current and future positive forcings, I would more than gladly check them out. Until then, the slow transition is probably wrong.

[Archimid]

Furthermore, there are assumptions in the secondt paper that are not reality. For example:

[17] The SST anomaly only lasts until November; by then sufficient heat has been extracted from the surface water to cool it to the freezing temperature. Sea ice then forms from open water very rapidly, and partly recovers. In the next summer the sea-ice cover is still below normal, and larger shortwave absorption leads to a second positive SST anomaly. However, after the second year the SST anomalies are not larger than the natural variability of the reference run.

 I have yet to see ice form on the open water. The closest thing to that is when an open ocean area is almost completely circumvented by ice.

Go here: https://ads.nipr.ac.jp/vishop/#/monitor  and play an animation of the freezing season.

Come back and tell if you ever see ice forming in the open ocean. I have looked and ice is always seeded by ice. Their analysis is flawed because they only consider things like temperatures and salinity. I doubt they are considering waves or the heat and salinity intrusions seen since last year. Hind sight is 20/20

So I do agree that ice will form the first time a BOE happens but it will probably grow from the coast in. That makes the growth process slower at first and much faster at the end, which is the exact opposite of what we have today.


For me to believe the slow transition I would need a mechanism for ice to grow fast enough to have even a semblance of an ice cap for the next summer. Greenland ice, Siberian cold, glacier meltwater run off would probably help in this. I would also need a mechanism to bring waves down to levels where ice can form. Right now the ice is doing that work, but when there is no ice what will kill the waves?

[Archimid]

Arghh. From the same paper:

[18] For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability. The warming is mainly restricted to the lower troposphere (see auxiliary material), which is a result that has also been found in GCM studies that prescribed permanent ice-free conditions in the Arctic Ocean [Royer et al., 1990; Winton, 2008] and in observations of recent Arctic climate change [Screen and Simmonds, 2010]. The peak of the SAT anomaly occurs about four months later than the SST anomaly; the reason for this becomes clear when considering the energy budget.

From my point of view, what we have seen this year shatters the bolded statement.

[Iceismylife]

I am definitely in the slow transition camp.

Yes, the polar winters are warming and have been for a couple of decades, most pronounced in the fall and early winter, and 2016 has been one, literally, for the record books. And while we are quickly approaching a seasonally ice free state using any of the three ice measures, SIE, SIA and volume, the simple fact is the Polar winters will still be cold enough for sea water to freeze rapidly. Over the past 40 years as SIE and SIA minimums have declined and winters have warmed, the amount of ice growth during the following freeze season has trended up such that SIE and SIA maximums have declined at a slower pace. Essentially, those very low minimums mean there is more open water to freeze. The dramatic drop in SIE and SIA minimums that occurred in 2007 has resulted in faster ice growth in the winters. The two charts below show the trend in SIE and SIA min and max for each year. The gray line is the trend line for annual SIE and SIA growth which I call BICOT (Bifurcated Intra-annual Cryosphere Oscillation Trend aka "Baby, It's Cold Out There").
<Snip>

Looking at the graph that shows % open water at the end of the melt season as a function of sea ice thickness.  If you have 2 meters of ice then at the end of the melt season you have 80% ice coverage.  If you have 1.5 meters then you have 90% open water at the end of the melt season. Fifteen hundred freezing degree days short is about 0.5 meters of ice not formed.  With predominantly first year ice then with an average melt season this year we will see a lot of melt.

This means open water dumping water vapor into the atmosphere reducing FDDs.  Tipping point.  The open water allows lots of area for the wind to act on to mix the lower salinity surface water with higher salinity and warmer deeper water.  The self protective layer is under sever attack.

We could be seeing 1.5 m of ice growth being the new normal.  That means large areas of open water at the end of the summer and much warmer falls and early winters.

Mix the top water with the deeper water and you mint get much reduced freezing in area and extent. The permanent sea ice use to be 35 miles north of the coast of Denmark in the little ice age.  We could be on the edge of seeing year round open water in the Arctic basin. 

[Tor Bejnar]

In the process of looking for feedbacks that will re-establish sea ice after an ice-free CAB is achieved, I wonder which scenario sends more heat into deep space:

• ice covered CAB with current winter atmospheric conditions (different from historic conditions - ice and snow insulate the surface)
  
• ice-free CAB with increased waves (slows freezing), humidity and clouds (slows venting) (Pancake ice, etc. will not likely cover the CAB for a while)

If significantly more heat is released, this could create a new 'stable' Arctic (for a while) with seasonally ice-free CAB.  If significant heat from the deep is brought to the surface (and not sent to ~Pluto), this could create a year-round ice-free CAB.

[Gray-Wolf]

I think the speed , and scope, of change across the basin mean folk should be very careful when looking at conclusions of studies? We really do need be mindful of the study period and date of conclusions.

The thinking may well have been sound and supported at the time but new developments might have overpowered those notions today?

Take melt ponds. Today's pack is so smashed up that you cannot get the extensive melt ponding that we did in the late noughties. The work done then on melt pond fraction compared to total pack as a measure of later losses is no longer useful. Less than half a decade of 'use' and then overtaken by the evolution of the basin?

I think the widespread exposure to swells and waves that the basin has seen over the past 5 years must have mixed the upper portion of the deep halocline even across the C.A.B. ? If we are also seeing changes in surface extension of Atlantic water into the European side of the basin then there is plenty of 'exotic' water to mix into this evolving ocean layer.

Waves in the open water off Hawaii were measured disturbing the water column 200m down.

I'm not suggesting the basin will ever see such mighty swells but it will see bigger and bigger ones and this new 'mixed layer' will eat away at the top of the paleo halocline  .

In the end the surface will no longer have the insulating help that the old Halocline provided it so as the atmosphere above becomes more hostile to the ice the medium below also become less welcoming as the ocean transforms into the same type as the rest of the worlds oceans.

I think the speed of the transition of the Arctic ocean into a 'normal' ocean ( roughly in line with the workings of the rest of the worlds oceans?) is tied to the speed we see ice free, year around, begin to occur?

[ktonine]

Second, the references do not provide any of the mechanism I'm looking for. Their arguments is the same as the arguments presented in this thread. They used models of present and past arctic conditions to predict a recovery based on the models.

Archimid - I am on record as one who fully believes that GCMs are not very reliable on Arctic processes, but that said, these are models based on *physical laws* -- not merely line fitting exercises on past and present behavior.  They are PIOMAS writ large.

Failing to understand this, that these are physical models, not curve fitting exercises, undermines your entire argument.

[Neven]

The Slow Transition as posited by Chris Reynolds is about how, when most of the multi-year ice is gone, the decline towards ice-free conditions slows down. Hence he suspected we would see an sea ice-free Arctic towards the end of the 2020's, and not before the end of this decade.

What you guys are discussing, is when the Arctic will go ice-free year-round, and whether this transition will be fast or slow. I'm sure there is a thread somewhere for this subject. In fact, I've already found it (by searching for 'year-round'): Year-round ice free Arctic.

Maybe you guys want to take it there?

[Archimid]

Archimid - I am on record as one who fully believes that GCMs are not very reliable on Arctic processes, but that said, these are models based on *physical laws* -- not merely line fitting exercises on past and present behavior.  They are PIOMAS writ large.

Failing to understand this, that these are physical models, not curve fitting exercises, undermines your entire argument.

I won't pretend I understand how these models are created,  but I imagine they use the laws of physics with values defined by historical values and boundaries. I bet they also depend on quite a number of omissions for the sake of computability and omissions of unknown phenomena.

Credibility should be determined on the merits of the evidence. That paper postulated a return of the arctic after a complete meltdown using a model that gives us ice on the arctic by 2070. Even the IPCC agreed that by 2050 the ice would be gone. So whatever values were used on the model were probably too low and they probably disregarded important physical phenomena.

The Slow Transition as posited by Chris Reynolds is about how, when most of the multi-year ice is gone, the decline towards ice-free conditions slows down. Hence he suspected we would see an sea ice-free Arctic towards the end of the 2020's, and not before the end of this decade.

What you guys are discussing, is when the Arctic will go ice-free year-round, and whether this transition will be fast or slow. I'm sure there is a thread somewhere for this subject. In fact, I've already found it (by searching for 'year-round'): Year-round ice free Arctic.

Maybe you guys want to take it there?

I understand. But I think this subject is intimately related to the slow transition. If there is no enough endogenous winter power in the arctic to regrow sea ice during winter, the transition will be much faster than the slow transition posits. It will also not regrow after it reaches certain threshold.

But as I said before, I think that we might not be there yet. If we get lucky this year, then next year we might see sea ice volume reach something closer to equilibrium. I'm hoping for an after el niño lull in global temperature that might gives at least 5 more years of ice, and could very well be up to 2030, if the Sun and the oceans throw us a huge bone for the next decade.

That said, I'll stop about it until it can be better tied to the slow transition.

[Neven]

I understand. But I think this subject is intimately related to the slow transition. If there is no enough endogenous winter power in the arctic to regrow sea ice during winter, the transition will be much faster than the slow transition posits. It will also not regrow after it reaches certain threshold.

You have a point there, but I don't believe Chris Reynolds has ever suggested that his Slow Transition (towards an ice-free September) affects the speed of the transition to a year-round ice-free Arctic. And I think it's important to stress the difference between the two.

And secondly, I think it's a very interesting discussion to have - ie when the Arctic will go ice-free year-round - and it would be a shame if it gets lost because it's more or less in the wrong thread. Especially as there already is a good thread on the subject that just needs a kick up.

[aslan]

Yep, the two subjects are tied. Still, the inability of this winter to built back a slab of ice which is 2 m thick is, in my opinion, a counter argument to the slow transition. C. Reynolds had a nice idea and put some good work. But the premisses of his hypothesis is that the winter will be able to erase the memory of the system if I am say, at least for some times. And so, it will still need some mighty weather during the summer to demolish the sea ice. So the minimum sea ice trend will tend to flatten somewhat, being more subjected to year to year variability.

But this winter it is clearly not the case. Chukchi sea was still open in early - mid January, and there is no way sea ice will be able to consolidate before the melting season. Over the freezing thread of this winter, about everyone agrees saying that the conditions at the start of the melting season will be the worst ever and that even a non-conducive weather pattern this Summer can lead to an extremly low sea ice minimum. And we are only in 2016 - 2017. Which bring us back to the winter. What we are seing is the transtion of the Arctic region to a oceanic climate (as a side note, Svalbard was almost in line with a continental climate in 2016, and not too far away from a subpolar oceanic climate, temperatures wise ...). And this is linked to stormier Arctic, to lapse-rate feedback, to clouds feedback, and so on, during the winter season. With to understand and acknowledged the factors playing for an ice free winter to refute the slow transition theory. There is no indications that that the winter will be able to maintain the rate of ice growth. Summer is probably going to be ice free in 5 - 10 years from now, and Winter will probably be ice free beetween 2050 an 2070 depending on emissions path, unknown unknowns etc...