Holy Sh!t: Year-Round Arctic BOE Imminent

[miki]

The trend is not in our favor 

[GoSouthYoungins]

The trend is not our friend.

Egg xactly. The trend is down, the trend points to an ice free arctic in the summer in the 2020's.

Bububububub but the model say 2200.

BOE will almost certainly occur in the next decade, and we should advocate for solutions accordingly. Global systems need to be made more decentralized and resilient. Otherwise it is  genuine apocalypse.

[Wherestheice]

The trend is not our friend.

Egg xactly. The trend is down, the trend points to an ice free arctic in the summer in the 2020's.

Bububububub but the model say 2200.

BOE will almost certainly occur in the next decade, and we should advocate for solutions accordingly. Global systems need to be made more decentralized and resilient. Otherwise it is  genuine apocalypse.

Policy makers, scientists behind computers, governments.... they will all think it wont happen till 2200. The real scientists who have actually been up their, there predictions are much more dire.

[sidd]

out of curiosity, what is the definition of BOE ? Blue ocean event ? Less that 1e6 sq km area ? less than 1e6 sq km extent ? or is it volume based ?

sidd

[jdallen]

Actually your data supports my point.  In your data, the Arctic sea ice minimum was in a slow decline for the the five years, but then accelerated from 2001-2010.  The sea ice minimum declined an average of 741 km3 / year.  Since then, the decline has stalled.  From 2010-2018, the minimum has not declined, but actually increased at a slight rate of 91 km3 / year.  As mentioned previously, I will reserve endorsement until the minimum starts to decline again.

Actually it doesn't. The first assumption you are making is the system is linear.  It's not.  The second mistake you are making is that there was a stall.  You are making the fundamental mistake of interpreting short term variability for a trend.  That's the same thinking that was used in some circles to use 1998 (an outlier year) as an anchor point against which to compare climate data - and proclaim loudly that the trend in global temperatures was going down.  I recommend against that sort of thing.  It will bite you in arguments.

[sark]

out of curiosity, what is the definition of BOE ? Blue ocean event ? Less that 1e6 sq km area ? less than 1e6 sq km extent ? or is it volume based ?

sidd

top of my untrained head, some people are using 1000 km^3 volume as a definition.  why?  I dunno.

[Human Habitat Index]

What is stalling is the jetstream, due to the Arctic warming faster than lower latitudes and this causes further warming in the Arctic, so the trend is reinforced.

Imagine Dr Jennifer Francis wins a Nobel award for her work on Arctic amplification.

[Wherestheice]

out of curiosity, what is the definition of BOE ? Blue ocean event ? Less that 1e6 sq km area ? less than 1e6 sq km extent ? or is it volume based ?

sidd

When most of the ice is gone through out the entire arctic ocean.

[Pmt111500]

Imagine Dr Jennifer Francis wins a Nobel award for her work on Arctic amplification.

It's been a while when a specific atmospheric scientist has been awarded but Dr.Francis is a good candidate. Can think a couple more of the generation too

[mostly_lurking]

The trend is not in our favor 

Maybe , but the short term trend is flat'ish since 2007 ( 11 years).

[Wherestheice]

The trend is not in our favor 

Maybe , but the short term trend is flat'ish since 2007 ( 11 years).

Not really. The big trend ended in 2012. What made the difference is 2013-2015. There is plenty of noise in the Arctic system. Between 2007-2012, there was a very great loss in ice. That period lasted about 5 years. 2013-2015 saw a gain in the ice. That period was 2 years. 2016 was the second lowest on record. and it looks to me like the trend will continue. I want to make the point clear that debating about the noise in the Arctic is a waste of time. It's mostly about the trend. Expect the great loss of ice to continue until we get a BOE, and there will be noise in between.

[crandles]

Actually it doesn't. The first assumption you are making is the system is linear.  It's not.  The second mistake you are making is that there was a stall.  You are making the fundamental mistake of interpreting short term variability for a trend.  That's the same thinking that was used in some circles to use 1998 (an outlier year) as an anchor point against which to compare climate data - and proclaim loudly that the trend in global temperatures was going down.  I recommend against that sort of thing.  It will bite you in arguments.

Point of inflection (think straight line) is around 2005/6. Since then it has been flattening. 11 years is quite a lot of data to suggest this is short term variability.

I try to remember to say I don't believe the flat trend at the end, I still believe trend is still going down.

Anyway how many years data do you want before you start admitting there appears to be flattening trend rather than continue to dismiss it as short term variability?

[wili]

"out of curiosity, what is the definition of BOE ? Blue ocean event ? Less that 1e6 sq km area ? less than 1e6 sq km extent ? or is it volume based ?"

My recollection is that it was the 1^6 sq km extent.

The name 'Blue Ocean' really is emphasizing the amount of open sea.

We will continue to have icebergs calving into the Arctic Ocean for some time, so a totally ice-free AO is probably a very long way off.

On the 'flattening curve' thing--this reminds me a bit of the 'pause in GW' claimed by denialists after the super El Nino of 1998. We had an extreme event due to the Great Arctic Cyclone and other weather events in 2012. If you take that out, you don't have much of a flattening. But really we should appeal to Tamino or someone with similar statistics chops to weigh in on this.

[ETA: Ah, I see that jda made the same point above...great minds...?  ]

In any case, it does make me wonder if the sequestering of heat the the lead article is about did accelerate in the last few years. If so, I find that more ominous than comforting...but maybe that's just me? 

[Ned W]

The big trend ended in 2012. What made the difference is 2013-2015. [...] 2016 was the second lowest on record. and it looks to me like the trend will continue.

Actually, 2011 was the second lowest volume on record.  (2016 was second lowest extent, but not volume).

Removing the years 2013-2015 doesn't really have much effect on the flattening.  Here's a LOESS model (10-yr timescale) both with and without the 2013, 2014, and 2015 data points:

Pretty similar flattening, IMHO. 

In general, I agree with crandles (as usual).  There does seem to have been a flattening of the downward volume trend, perhaps from the loss of multi-year ice and the switch to a first-year-ice-dominated Arctic.  It's certainly possible that this represents a brake on the rate of volume loss that will help reconcile the seemingly different blue-ocean dates that are projected using volume vs extent.

This is why I don't expect ice-free conditions in the next decade.  Maybe late 2030s?

Note that the above graph includes a projected 2018 Sept volume of 5.05.  As seen below, there is a very tight relationship between PIOMAS on 31 August and PIOMAS September volume.  The predicted 2018 value is 5.05 (95% CI 4.81 to 5.30).

I also agree with crandles on this:

I try to remember to say I don't believe the flat trend at the end, I still believe trend is still going down.

though in my case I'd clarify it as:

I don't believe the trend will stay flat; it will probably continue downward in fits and starts.

[mostly_lurking]

The trend is not in our favor 

Maybe , but the short term trend is flat'ish since 2007 ( 11 years).

Not really. The big trend ended in 2012. ...

One can look at it in different ways.  Slight down trend from 1980 to 2000, Big drop from 2000 to 2007 and then flat since ( with one outlier). Yes , you can call it noise if you want.If the current trend ( as I see it ) stays flat for another, let's say, 5 years- is it a new trend then?

[wili]

It's a good question how long to go before you can establish a trend, in this case. In most cases for climate you need decades. This certainly does not meet that standard.

In any case, isn't there always a distortion at the end of any smoothed graph toward the beginning and end since the the few years at the end have an outsize effect on the smoothed curve?

And of course the deeper and more important questions are: if there is a 'flattening,' what is causing it?  and what are likely to be the main forces driving extent and volume numbers over the next decade?

[sark]

Actually it doesn't. The first assumption you are making is the system is linear.  It's not.  The second mistake you are making is that there was a stall.  You are making the fundamental mistake of interpreting short term variability for a trend.  That's the same thinking that was used in some circles to use 1998 (an outlier year) as an anchor point against which to compare climate data - and proclaim loudly that the trend in global temperatures was going down.  I recommend against that sort of thing.  It will bite you in arguments.

Point of inflection (think straight line) is around 2005/6. Since then it has been flattening. 11 years is quite a lot of data to suggest this is short term variability.

I try to remember to say I don't believe the flat trend at the end, I still believe trend is still going down.

Anyway how many years data do you want before you start admitting there appears to be flattening trend rather than continue to dismiss it as short term variability?

I pray there is a flattening trend, although we seem to be within the range of natural variability now.

[Ned W]

And of course the deeper and more important questions are: if there is a 'flattening,' what is causing it? 

One possible answer, from my comment a few minutes earlier:

perhaps from the loss of multi-year ice and the switch to a first-year-ice-dominated Arctic.  It's certainly possible that this represents a brake on the rate of volume loss that will help reconcile the seemingly different blue-ocean dates that are projected using volume vs extent.

In other words, the rapid downward trend prior to 2005 was due to the loss of multi-year ice.  First/second year ice, which now dominates the Arctic, keeps re-forming itself every winter, so the rate of decline has slowed.

and what are likely to be the main forces driving extent and volume numbers over the next decade?

Continued warming, internal variability, and feedbacks both positive and negative.  That covers everything, right?   

[mostly_lurking]

I pray there is a flattening trend, although we seem to be within the range of natural variability now.

Wait- those points for 2018-2020 are hypothetical.

[crandles]

I also agree with crandles on this:

I try to remember to say I don't believe the flat trend at the end, I still believe trend is still going down.

though in my case I'd clarify it as:

I don't believe the trend will stay flat; it will probably continue downward in fits and starts.

Yes, that looks like a good extra clarification. Could be fits and starts or somewhat smooth trend and if a  smooth trend then I don't see any reason why it can't accelerate downwards again (even if I am saying I don't see any evidence for it in the observations yet).

Continued warming, internal variability, and feedbacks both positive and negative.  That covers everything, right?   

Increased GHG levels, increased water temperatures, increased air temperatures, any other forcings,  internal variability, and feedbacks both positive and negative.  That covers everything, right?   

[crandles]

I pray there is a flattening trend, although we seem to be within the range of natural variability now.

Doesn't seem to work the same on my graph, but maybe I have cut the natural variability too much.

[AbruptSLR]

Increased GHG levels, increased water temperatures, increased air temperatures, any other forcings,  internal variability, and feedbacks both positive and negative.  That covers everything, right?   

A few more considerations, that could further increase Artic Amplification, resulting in reduced Arctic Sea Ice, in coming decades :

1. Continuing atmospheric & oceanic telecommunication of energy into the Arctic, possibly including from the bipolar seesaw mechanism, due to ice mass loss in Antarctica.

2. Decreasing aerosol emissions; resulting in decreased negative forcing.

3. Increase wildfires & associated brown carbon emissions, resulting in increased positive forcing.

4. Possible pulsed discharge of low saline water from the Beaufort Gyre, BG, that might raise-up the relatively warm deep high saline water in the BG.

5. Pulsed increases in methane emissions from thermokarst lakes in permafrost regions; that are already being activated.

6. Decreased albedo due to the increase of plankton beneath thinning sea ice.

7. Projected increasing in regional rainfall in permafrost regions, leading to accelerating rates of permafrost degradation.

[Klondike Kat]

It's a good question how long to go before you can establish a trend, in this case. In most cases for climate you need decades. This certainly does not meet that standard.

In any case, isn't there always a distortion at the end of any smoothed graph toward the beginning and end since the the few years at the end have an outsize effect on the smoothed curve?

And of course the deeper and more important questions are: if there is a 'flattening,' what is causing it?  and what are likely to be the main forces driving extent and volume numbers over the next decade?

The cause may be climate change itself.  Warmer temperatures have led to greater cloud cover.  Greater cloud cover leads to warming in the Arctic winter, due to less heat loss during clear skies.  This has been quite prevalent in recent years.  Greater cloud cover in the summer leads to cooling, as less sunlight reaches the surface.  This has also been evident in recent years, although to a much less degree than winter warming.  Cooler summers in the Arctic may be the reason for the observed flattening.

[sark]

Doesn't seem to work the same on my graph, but maybe I have cut the natural variability too much.
[/quote]

I'm not arguing with you & your chart, which is very nice.  The point of looking for the natural extreme is to show the range of variability. 

Someone else suggested the years 2018-2020 on my chart are conjecture.  I'll allow that it's conjecture based on the current date of 2018.

I'll pray, along with the rest of humanity, that the sea ice time series makes Gompertz a household name.  If not, we'll experience a blue ocean arctic at least by 2035, but as soon as next year.  That's what I mean by being within the range of natural variability.

[crandles]

Increased GHG levels, increased water temperatures, increased air temperatures, any other forcings,  internal variability, and feedbacks both positive and negative.  That covers everything, right?   

A few more considerations, ...

Natural / internal variability, hmmm. Is there any unnatural/external variability? 
Do aliens aiming meteors at the Arctic count as unnatural? 

[Tunnelforce9]

I think this graph shows best when we can expect BOE

[crandles]

The point of looking for the natural extreme is to show the range of variability. 

Sure, that is sensible if that is what you want to do.

I don't believe the flat trend, so if BOE happened, more likely to be a bit of trend steepening and some natural variability.

Should we worry more about trend steepening than about it occurring due to variability? Possibly depends whether you expect serious consequences from a BOE that was just due to natural variability?

[AbruptSLR]

Natural / internal variability, hmmm. Is there any unnatural/external variability? 
Do aliens aiming meteors at the Arctic count as unnatural? 

Does natural forcing include an increase in high latitude wildfires due to anthropogenic forcing?

Does internal mean local Arctic forcings/feedback mechanisms, or does it include systemic telecommunication of energy from lower latitudes? 

Does variability consider that higher variability implies higher values of ECS (see the linked reference below)? 

"Dessler & Forster (2018) demonstrate rather convincingly that the likely range for ECS in the period from 2000 to 2017 was 2.4 to 4.6C as opposed to AR5's cited likely range of 1.5 to 4.5C.  Furthermore, it is important to remember that ECS is not a fixed value but rather is projected to increase with continued global warming, this century:

A. E. Dessler and P.M. Forster (07 August 2018), "An estimate of equilibrium climate sensitivity from interannual variability', Journal of Geophysical Research Atmospheres, https://doi.org/10.1029/2018JD028481

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028481?campaign=wolacceptedarticle

Abstract
Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate ECS is likely 2.4‐4.6 K (17‐83% confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty, but rather uncertainty in converting observations of short‐term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.

Plain language summary
Equilibrium climate sensitivity (ECS) is the amount of warming resulting from doubling carbon dioxide. It is one of the important metrics in climate science because it is a primary determinant of how much warming we will experience in the future. Despite decades of work, this quantity remains uncertain: the last IPCC report stated a range for ECS of 1.5‐4.5 deg. Celsius. Using observations of interannual climate variations covering the period 2000 to 2017, we estimate ECS is likely 2.4‐4.6 K. Thus, our analysis provides no support for the bottom of the IPCC's range."

You can obtain a copy of the paper here:

https://drive.google.com/file/d/1nt4YEMLc0AwWEAHtHAcwDEVzHkyKj1G-/view
"

[Ned W]

Possibly depends whether you expect serious consequences from a BOE that was just due to natural variability?

I don't expect "serious consequences" from a BOE per se, given that we've defined a BOE as just crossing some arbitrary threshold (1 million km2 extent or 1 thousand km3 volume).  Going from 1.1 to 0.9 in either case will be small in effect, compared to the much larger change that has already happened.  In fact, I think the whole concept of "eek, a BOE!" is misplaced.  What matters is the long-term decline.  But people want excitement and drama...

[jacksmith4tx]

Possibly depends whether you expect serious consequences from a BOE that was just due to natural variability?

I don't expect "serious consequences" from a BOE per se, given that we've defined a BOE as just crossing some arbitrary threshold (1 million km2 extent or 1 thousand km3 volume).  Going from 1.1 to 0.9 in either case will be small in effect, compared to the much larger change that has already happened.  In fact, I think the whole concept of "eek, a BOE!" is misplaced.  What matters is the long-term decline.  But people want excitement and drama...

I would only add that the decline of polar ice biggest knock on effect will be the long term change in ocean chemistry. Changes in saline ratios, oxygen depletion, higher water temperatures and species migration will have much bigger negative feed backs. Once you screw up the plankton and zooplankton food chain the falling dominoes really start to accelerate. We have very few in situ sensors to monitor these conditions and rely increasingly on remote sensing via satellites, aerial surveys and a few surface expeditions.

[Dharma Rupa]

Possibly depends whether you expect serious consequences from a BOE that was just due to natural variability?

I don't expect "serious consequences" from a BOE per se, given that we've defined a BOE as just crossing some arbitrary threshold (1 million km2 extent or 1 thousand km3 volume).  Going from 1.1 to 0.9 in either case will be small in effect, compared to the much larger change that has already happened.  In fact, I think the whole concept of "eek, a BOE!" is misplaced.  What matters is the long-term decline.  But people want excitement and drama...

I don't know about the immediate effects of a BOE, but I expect there to be very large and sudden changes when the DMI 80N in Summer is no longer pinned near 0.

Kind of guessing that a BOE will be at about the same time -- or possibly immediately following.

[Phil.]

While the drop below, say, 1000km³ doesn't mean there will suddenly be a change at that point.  However, some point between the present september value just below 5,000km³ the volume will become small (and fragmented?) so that its behavior will almost certainly change.  The data shows a fairly consistent drop of ~18,000km³ during the year, as the maximum continues to drop the fall minimum will likely drop into into this new regime.

[SimonF92]

I think this graph shows best when we can expect BOE

One generally wouldn't fit a linear regression to a complex system (nor expect it to be the best fit)

[Ned W]

the long term change in ocean chemistry. Changes in saline ratios, oxygen depletion, higher water temperatures and species migration will have much bigger negative feed backs.

It would be interesting to see more about effects of seasonally ice-free conditions a few thousand years ago, during the early-mid Holocene.  This has happened before, it would be nice to know what to expect.

[Klondike Kat]

I think this graph shows best when we can expect BOE

One generally wouldn't fit a linear regression to a complex system (nor expect it to be the best fit)

Hence, those linear fits are meaningless.

[harpy]

I think this graph shows best when we can expect BOE

One generally wouldn't fit a linear regression to a complex system (nor expect it to be the best fit)

Hence, those linear fits are meaningless.

Do you have any reference that the arctic was ice free during the Holocene?

[Ned W]

Do you have any reference that the arctic was ice free during the Holocene?

I think that was meant as a reply to me.  Sure, there's a fair bit of evidence for very-low or ice-free conditions during summers in the early-mid Holocene, e.g.,

https://www.sciencedirect.com/science/article/pii/S0277379113004162

https://www.geo.umass.edu/faculty/jbg/Pubs/Polyak%20etal%20seaice%20QSR10%20inpress.pdf

https://www.sciencedirect.com/science/article/pii/S0277379110003185?via%3Dihub

and a fair bit more, if you look around.

Wish I'd seen this AGU talk last year.  It hypothesizes a connection between loss of sea ice in the Holocene and epic drought in the US Southwest.  Seems like it could be relevant, since we're now again experiencing both reduced sea ice and Southwestern drought:

http://adsabs.harvard.edu/abs/2017AGUFMPP33D..07L

[Ned W]

This doesn't directly address whether the Arctic Ocean was "ice-free" or just "low-ice", but it does make the point that Milankovitch forcing made the Arctic Ocean very warm during the early/mid Holocene:

Shallow marine molluscs that are today extinct close to Svalbard, because of the cold climate, are found in deposits there dating to the early Holocene. The most warmth-demanding species found, Zirfaea crispata, currently has a northern limit 1000 km farther south, indicating that August temperatures on Svalbard were 6°C warmer at around 10.2–9.2 cal. ka BP, when this species lived there. The blue mussel, Mytilus edulis, returned to Svalbard in 2004 following recent warming, and after almost 4000 years of absence, excluding a short re-appearance during the Medieval Warm Period 900 years ago. Mytilus first arrived in Svalbard at 11 cal. ka BP, indicating that the climate was then as least as warm as present. This first warm period lasted from 11 to 9 cal. ka BP and was followed by a period of lower temperatures 9–8.2 cal. ka BP. After 8.2 cal. ka, the climate around Svalbard warmed again, and although it did not reach the same peak in temperatures as prior to 9 ka, it was nevertheless some 4°C warmer than present between 8.2 and 6 cal. ka BP. Thereafter, a gradual cooling brought temperatures to the present level at about 4.5 cal. ka BP. The warm early-Holocene climate around Svalbard was driven primarily by higher insolation and greater influx of warm Atlantic Water, but feedback processes further influenced the regional climate.

http://journals.sagepub.com/doi/abs/10.1177/0959683617715701

As I said, it would be interesting to know more about what effects that warm Arctic had.  For example, on northern hemisphere circulation patterns. 

[bluesky]

Intrigued that there could still have been sea ice in the Arctic during the LIG at 125K 120K bp, with warmer temperature according to this Nature research paper, which nevertheless shows some contradictions; still thinking that LIG conditions were not comparable to today's unique forcing based on very rapid increase of GHG emissions unmatched for the last 60 million years or so, a BOE could probqbly happen from the mid late 2020ies early 2030ies onward depending on climate variability (e.g. , 2007 perfect storm conditions, 2012 GAC ...).


Arctic Ocean sea ice cover during the penultimate glacial and the last interglacial
Ruediger Stein et al August 2017

https://www.nature.com/articles/s41467-017-00552-1

abstract:
"Coinciding with global warming, Arctic sea ice has rapidly decreased during the last four decades and climate scenarios suggest that sea ice may completely disappear during summer within the next about 50–100 years. Here we produce Arctic sea ice biomarker proxy records for the penultimate glacial (Marine Isotope Stage 6) and the subsequent last interglacial (Marine Isotope Stage 5e). The latter is a time interval when the high latitudes were significantly warmer than today. We document that even under such warmer climate conditions, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Our proxy reconstruction of the last interglacial sea ice cover is supported by climate simulations, although some proxy data/model inconsistencies still exist. During late Marine Isotope Stage 6, polynya-type conditions occurred off the major ice sheets along the northern Barents and East Siberian continental margins, contradicting a giant Marine Isotope Stage 6 ice shelf that covered the entire Arctic Ocean."

[Dharma Rupa]

the long term change in ocean chemistry. Changes in saline ratios, oxygen depletion, higher water temperatures and species migration will have much bigger negative feed backs.

It would be interesting to see more about effects of seasonally ice-free conditions a few thousand years ago, during the early-mid Holocene.  This has happened before, it would be nice to know what to expect.

Yes, and what I have read on the subject was just coarse enough that we can't really know what to expect in a 5-year timespan.

[Klondike Kat]

Intrigued that there could still have been sea ice in the Arctic during the LIG at 125K 120K bp, with warmer temperature according to this Nature research paper, which nevertheless shows some contradictions; still thinking that LIG conditions were not comparable to today's unique forcing based on very rapid increase of GHG emissions unmatched for the last 60 million years or so, a BOE could probqbly happen from the mid late 2020ies early 2030ies onward depending on climate variability (e.g. , 2007 perfect storm conditions, 2012 GAC ...).


Arctic Ocean sea ice cover during the penultimate glacial and the last interglacial
Ruediger Stein et al August 2017

https://www.nature.com/articles/s41467-017-00552-1

abstract:
"Coinciding with global warming, Arctic sea ice has rapidly decreased during the last four decades and climate scenarios suggest that sea ice may completely disappear during summer within the next about 50–100 years. Here we produce Arctic sea ice biomarker proxy records for the penultimate glacial (Marine Isotope Stage 6) and the subsequent last interglacial (Marine Isotope Stage 5e). The latter is a time interval when the high latitudes were significantly warmer than today. We document that even under such warmer climate conditions, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Our proxy reconstruction of the last interglacial sea ice cover is supported by climate simulations, although some proxy data/model inconsistencies still exist. During late Marine Isotope Stage 6, polynya-type conditions occurred off the major ice sheets along the northern Barents and East Siberian continental margins, contradicting a giant Marine Isotope Stage 6 ice shelf that covered the entire Arctic Ocean."

Seems reasonable.  However that time frame is about 10x what some posters here are claiming.

[Wherestheice]

The big trend ended in 2012. What made the difference is 2013-2015. [...] 2016 was the second lowest on record. and it looks to me like the trend will continue.

Actually, 2011 was the second lowest volume on record.  (2016 was second lowest extent, but not volume).

Removing the years 2013-2015 doesn't really have much effect on the flattening.  Here's a LOESS model (10-yr timescale) both with and without the 2013, 2014, and 2015 data points:

Pretty similar flattening, IMHO. 

In general, I agree with crandles (as usual).  There does seem to have been a flattening of the downward volume trend, perhaps from the loss of multi-year ice and the switch to a first-year-ice-dominated Arctic.  It's certainly possible that this represents a brake on the rate of volume loss that will help reconcile the seemingly different blue-ocean dates that are projected using volume vs extent.

This is why I don't expect ice-free conditions in the next decade.  Maybe late 2030s?

Note that the above graph includes a projected 2018 Sept volume of 5.05.  As seen below, there is a very tight relationship between PIOMAS on 31 August and PIOMAS September volume.  The predicted 2018 value is 5.05 (95% CI 4.81 to 5.30).

I also agree with crandles on this:

I try to remember to say I don't believe the flat trend at the end, I still believe trend is still going down.

though in my case I'd clarify it as:

I don't believe the trend will stay flat; it will probably continue downward in fits and starts.

If 2013-2015 had continued the trend from 2007-2012,  we wouldn't be having this debate. Noise in the system. I don't expect that trend to just flatten out or slow down. 2013-2015 didn't slow the trend, its just noise. Late 2030's seems very very conservative. We're on thin ice (pun intended).

[Ned W]

If 2013-2015 had continued the trend from 2007-2012,  we wouldn't be having this debate.

If 2013-2015 had followed the previous trend, then 2016, 2017, and 2018 would have been even more out of place. 

I do agree that if 2013, 2014, 2015, 2016, 2017, and 2018 had all followed the previous trend, we probably wouldn't be talking about a slowdown or flattening.

[Wherestheice]

If 2013-2015 had continued the trend from 2007-2012,  we wouldn't be having this debate.

If 2013-2015 had followed the previous trend, then 2016, 2017, and 2018 would have been even more out of place. 

I do agree that if 2013, 2014, 2015, 2016, 2017, and 2018 had all followed the previous trend, we probably wouldn't be talking about a slowdown or flattening.

2013-2015 are the problem. After the gain in ice, 2016-2018 are reaching the equilibrium of what was before 2013-2015. If 2013-2015 didn't have the gain that we saw, 2016-to now would have certainly been lower. Noise in the system. The volume is pretty low now. Another drop like 2007-2012 and we will have a BOE.  Infact we really only need half of what 2007-2012 was to reach a blue ocean event.

[magnamentis]

if is see this correctly the title of this thread contains "year-round"

and most of the reasoning and discussion is once more about when BOE will happen the first time which is a totally different topic and for which there exist various threads with slightly different titles but discussing the same thing after a few initial posts.

this is mostly due to the fact that the title does not allow for a meaningful discussion because:

a) year round will take a long time (intentionally don't name my idea of how long)

b) is certainly NOT IMMINENT ?

which is why there is not much more to say hence the rest is chatter and noise about something nobody can predict except the fact that year-round is not imminent.

[jdallen]

It's a good question how long to go before you can establish a trend, in this case. In most cases for climate you need decades. This certainly does not meet that standard.

*Exactly*,  and thank uou.

[sark]

if is see this correctly the title of this thread contains "year-round"

we're supposed to be talking about this paper: https://phys.org/news/2018-08-archived-deep-arctic-interior.html

"This means the effects of sea-ice loss are not limited to the ice-free regions themselves, but also lead to increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well beyond the summer season," Timmermans said. "Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year."

Well, for a long time people have been talking about how that halocline cold water lens in the arctic could be mixed with warmer atlantic/pacific water layers below.  waves at the surface are a big factor.  however briefly the arctic is ice-free, we can demonstrate that it'll have more waves than it did with sea ice.

also, the latent heat of fusion of ice should play a large role.  I don't want to get my numbers mixed up, but it takes a lot more heat to raise the temperature of water 1 degree C through the melting point than it takes to raise water 1 degree C above the melting point?

and finally, of course, albedo goes from (very roughly) reflecting 80% of heat to absorbing 80% of heat.

there are quite a few reasons why the first loss of sea ice in the arctic could hypothetically mean drastic changes for the arctic, the earth's pattern of climate, and I think many people expect the first blue ocean event to be a step change in global climate...

Nobody really has any clue what's going to happen, but paleo-climatology would suggest this system has an ability to transition quickly and grow cycads in the arctic circles.  So, let's not pretend to be foolish and act like the ice age climate will be happily circulating heat in the same ways when the atmosphere has a hothouse quantity of greenhouse gas.

Nobody has modeled abrupt climate change to give us any idea what it looks like.  that's probably why reports such as the one being discussed in this thread are rather interesting... and it is extremely alarming, but it's hard to see it as particularly unlikely.

[Ned W]

which is why there is not much more to say hence the rest is chatter and noise about something nobody can predict except the fact that year-round is not imminent.

Yes, well, that's pretty much it.  Despite the thread title, a year-round BOE is not imminent, so we fall back on speculating about when the Arctic might become ice-free in the summer.  And you're right that this has already been the topic of many threads, sometimes multiple ones simultaneously. 

[sark]

which is why there is not much more to say hence the rest is chatter and noise about something nobody can predict except the fact that year-round is not imminent.

Yes, well, that's pretty much it.  Despite the thread title, a year-round BOE is not imminent, so we fall back on speculating about when the Arctic might become ice-free in the summer.  And you're right that this has already been the topic of many threads, sometimes multiple ones simultaneously.

Will you qualify "imminent?"  what about 2035?

[wili]

As I say in the first post in the thread, if you want to replace 'imminent' with 'could basically happen any time' that's fine, and I think the evidence still supports the statement.

There has always been a vast body of relatively hot and salty water below the freshwater 'lens' in the Arctic Ocean that makes sea ice possible.

We now know that this vast body of hot salty water has gotten much hotter (and presumably saltier...do we know about that?).

And as the authors of the study also point out, they expect major disturbances of the layering structure that has been keeping the hot, salty lower water from interacting with the surface, fresh(er)-water lens...basically at any time.

The article also points out that there is enough heat (and salt, presumably) in that lower level to keep the region ice-free for most of the year.

Add those all together, and I think you can defend at least a version of the title of the thread, especially since at the same time 'Atlantification' and plain old feedbacks are also assaulting the same ice from every other direction.

If anyone doesn't like the title of the thread, though, they are of course free to start their own thread with their own more sensible title, and then they can enjoy being the target of slings and arrows of skeptics!