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iceman

Good post as usual, Neven. When considering the linear anomaly trend by itself, the excursion into +2 STD territory is remarkable. In another sense, it's an eventuality if a sigmoid function is taking over as a better representation of reality, as Chris R and others have asserted.
Anyway my guess is that November will mark the anomaly peak for the near term, as above-normal Arctic temperatures exert a delayed effect on the refreeze, and Fram Strait export picks up markedly.

Chris Reynolds

Iceman,

To be clear, what is going on with volume at present is not, in my opinion, part of the emergence of a long(ish) tail of the 'sigmoid' form.

The last two years of poor summer melt weather could have happened at any time in the last ten years or so and have had a similar effect. That weather issue is seperate from my argument that winter volume had hit a floor with a slower rate of volume loss dictated by the tending of winter thickness to the thickness of thermodynamic growth (roughly 2m thick ice).

As I have said before, actually it's a nuisance for me because I will probably have to wait several more years for the floor in winter volume to be regained.

Ostepop1000

CR:

I have yet to see a convincing summary of the different factors of weather and their relative contribution to seasonal melting, and I am not convinced that random weather events is the FULL explanation for what we have seen over the last couple of melting seasons.

And by weather I of course mean isolated events as opposed to changes in longer term patterns.

So is the uptick over the last couple of seasons isolated weather events, or are they the beginning of what may be a shift in the general trend, which will last for some years to come?

I tend to favour the latter, eyeballing soem of the trends in temperature and sea ice extent, but of course have no more conclusive proof than those who think that it is all just weather and will return to the downward trend soon.

D_C_S

Ostepop1000:

The trend is actually still downward. This uptick didn't change that.

Chris Reynolds

I've had to correct the regional volume graph at the start of my blog post.
http://4.bp.blogspot.com/-BuwFfRShAA8/VIXhj7ado6I/AAAAAAAABPg/KYy3dnoFDvU/s1600/PIOMAS%2BRegional.png
The data displayed reverted to September data after copy and paste - odd Excel bug.

Osteopop,

You tend to favour a shift that drives a reverse of sea ice loss because, as amply demonstrated in the past, you are driven by an agenda which dictates your conclusions.

I do not have enough information to say either way whether a changed of typical summer atmospheric regime is starting. I think we will know in a few years if summer considitions continues to be adverse to ice loss.

However, given that sea ice extent loss is so clearly correlated with increases in CO2. And given that the loss of volume from 1995 to 2012 has been driven by the ice/ocean albedo feedback. And given the wide variety of weather that has not led to a recovery of the summer sea ice. The conservative position remains that the process of sea ice loss will continue. Although of course I think we will enter a long(ish) tail of persistence of the summer sea ice that is not implied by statistical extrapolation of volume loss.

jdallen_wa

Ostepop1000 ... Assertions based on anecdote and/or unfounded speculation tend to get short shrift here. You even admit you have nothing to support yours beyond a hunch. They will dismissed.

Chris Reynolds

I forgot to add to the above.

Whilst there may be something subtle that indicates a common cause to the weather patterns of summer 2013 and summer 2014, the largescale pattern doesn't seem to me to indicate a common new pattern due to a regime shift.

Jun to Aug 2013
https://farm8.staticflickr.com/7465/15791815057_9acc599277_o.png

Jun to Aug 2014
https://farm8.staticflickr.com/7511/15951778986_a4a67ab3f1_o.png

Ostepop1000

Careful reading of my above post will reveal that I am not making any conclusions (CR) or any assertions (jdallen). "I tend to favour" were the words I used, and they can hardly be less assertive.

True, I am speculating here, but why not. My main position or agenda, as CR puts it, is that we actually know very little and that too brash conclusions have been drawn on such a flimsy foundation.

But it is not just a hunch. One of my arguments is that the winter maximum has not been going down now for 10 years:

http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi_range_ice-ext.png

This year it seems likely that this trend will continue.

And it seems unlikely that 10 years of halt in the winter extent is caused by a series of diverse and scattered weather events.

And when the winter extent stops decreasing and even grows - what is more natural than this also affecting the summer minimum in due time?

It seems a reasonable and logical argument to me, not just a "hunch".

Chris Reynolds

Osteopop,

Where is the winter maximum in extent or area set?

1) Inside the Arctic Ocean.
or
2) Outside the Arctic Ocean.

George Phillies

"the winter maximum has not been going down"

Yes, Lake Erie still freezes.

Until the winter in the Arctic is uniformly warmer than around -2C, there will still be a local skim coating of ice in places.

Chris Reynolds

Damn, didn't think I'd posted the above, while pondering how to follow up I changed my mind and did some graphs. All this is done using Wipneus's calculation of regional extent.

Osteopop,

Here is the decline in extent on day 90 (late March) from 1979 to 2013.
https://farm9.staticflickr.com/8664/15984536852_0e91651117_o.png

I've not done the calculations, but I'd be surprised if the claimed levelling is outside the error bounds of the linear trend. That said, there might be a levelling, to examine this I break down the data into regions.

First, here is the Arctic Ocean (Beaufort, Chukchi, ESS, Laptev, Kara, Barents, Greenland, Central, CAA).
https://farm9.staticflickr.com/8564/15362944314_14a347ff5e_o.png

There is no sign of a levelling within the Arctic Ocean, why is this?

I have broken down the Arctic Ocean into two subsets, land bounded seas are Beaufort, Chukchi, ESS, Laptev, Central and CAA. The Atlantic seas are Kara, Barents, Greenland, the regions most exposed to Atlantic influence.
https://farm8.staticflickr.com/7524/15797924490_f97d5626a3_o.png
The landbound Arctic Ocean extent in March is 'maxed out' with minimal variation and negligible trend. However in the Atlantic sector, under the influence of warming Atlantic ocean waters the downward trend is significant. This Atlantic sector decline account for virtually all Atlantic ocean extent decline, and 55% of the decline slope of overall northern hemisphere extent decline for day 90.

There is no evidence of a cessation in decline during recent years in the Arctic Ocean.

So what of decline in the rest of the northern hemisphere? I have plotted the total extent for the northern hemisphere excluding the above defined Arctic Ocean.
https://farm9.staticflickr.com/8640/15985198135_731ebc8c15_o.png

In this graph we see an increase in extent in the timeframe (~2005 onwards), against the long term trend, though not necessarily outside the assoicated error bounds. What is going on here?

I have graphed extent for the Pacific (Okhotsk & Bering), the Atlantic (Baffin & Gulf of St Lawrence), and Hudson Bay.
https://farm8.staticflickr.com/7541/15983208961_5ec54af991_o.png

Hudson Bay plays no role, it is 'maxed out' by day 90 (late March). The extra-Arctic Atlantic can be viewed as having a pause in loss since 2005, while the extra-Arctic Pacific can be seen as having an uptick.

So based on this I don't see any grounds for claiming that conditions within the Arctic are driving a pause in winter peak sea ice extent.

Note that none of this data is hidden. The entire dataset is available here:
https://sites.google.com/site/arctischepinguin/home/sea-ice-extent-area/data
I use "nsidc_nt_nrt_detail.txt"

Wipneus has put a lot of work into producing it (I know from the work I put into my PIOMAS derived data), yet people continue to assert things without first referring to such data. When they do so they may be challenged with the data. However as it is the job of those proposing ideas to do the hard work, and as the data to do that work is available, do not be surprised if people get a bit short with your use of their time.

Ostepop1000

CR:

"So based on this I don't see any grounds for claiming that conditions within the Arctic are driving a pause in winter peak sea ice extent."

And I agree. There are no conditions arising from within the Arctic which could explain the ten year pause in winter sea ice extent.

Quite the contrary:

Ostepop1000

It has to come from the outside.

jdallen_wa

Outside? Bah.

A rather obvious answer is... That the environment hasn't cooled down... But rather the central basin and peripheral seas ran out of extent they can easily refreeze.

The Arctic is constrained by land surface; once the annual Refreeze has dropped back either a land or basin constraint, we won't see heat content inside that boundary rises sufficiently to retard freezing.

I think the Greenland/Svalbard/Franz Joseph/ Nova Zemlya boundary might be testable for this thought experiment. There has been huge retreat of the winter extent back to approximately this line, which presents a considerable barrier to the intrusion of warmer more saline water into the central basin. Beyond it, SSTs and net ocean heat content has continued to increase. The ice is saved because the shelves and islands constrain flow into the basin.

Further, at the higher ranges of the arctic (above 67N) may represent a bastion where the net loss of heat still remains sufficient to cause a refreeze even with increasing heat content. (Yet...)

I shall have to work up a thumbnail sketch of ocean surface north of 67 degrees and compare that to maximum extent, and see how they compare.

jdallen_wa

Edit... Extent that can easily refreeze should read extent which can remain unfrozen.

Chris Reynolds

Crandles has posted a poll on the forum asking when people think we will start to regularly see no ice (at all, as I understand it) in the Arctic Ocean, which would be during late summer.

I think it would be very interesting if all forum members could vote.

Note, this is for no ice at all, not virtually ice free (e.g. <1M km^2 extent).


Osteopop,

But there is no cessation of loss(levelling) within the Arctic Ocean, just regional effects outside the Arctic. So I see no evidence for your initial claim that: "...when the winter extent stops decreasing and even grows - what is more natural than this also affecting the summer minimum in due time?"

Chris Reynolds

Ooops,

Forgot the link to the poll.
http://forum.arctic-sea-ice.net/index.php?topic=1086.0

Frank

Chris, I don't full agree with you ( weather...). Let's habe a look at the Volume-data from PIOMAS ( monthly) and the trend of the autumn data from 2000 on. http://up.picr.de/20387070mj.gif . We see a slope of about -0.5 T kmĀ³ per year. Anyway, there is a great autocorrelation and so let's analyze the residuals: http://up.picr.de/20387095xe.gif . The data of 2014 are a 2.4-sigma-event. The seaice-volume of SON is only located in the Arctic ocean, so I thing that something happend beyond weather.

NeilT

It seems to me that incessant focusing on the Max extent figures does not show the whole picture.

Surely the figures which are changing most right now are the onset of re-freeze, how late Max Extent arrives and how long the new ice is frozen.

There will come a time when the max arctic extent is significantly less than it is today, but that will require increasing heat absorption in the ocean and a significant change in the cloud cover over winter. Both of which take time.

Focusing on whether or not some coverage of ice reaches the same extent as it did 10 years ago, whilst ignoring the crash in overall volume and continuing trend of both extent and area losses at ice minimum, seems to me to be somewhat myopic at best and somewhat dishonest at worst.

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