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SATire

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Year-round ice-free Arctic
« on: April 03, 2013, 01:53:11 PM »
After reading other threads in this forum and Neven's blogs I assume some agreement about the prediction of an ice-free arctic in summer between this year and 2017 (e.g. caused by exponential decline of ice volume due to albedo-feedback, https://sites.google.com/site/arctischepinguin/home/piomas). I also assume some agreement from climate paleontology, that current atmospheric CO2 content of 400 ppm is similar to the Pliocene or even Miocene situation. Therefore, we are now in a transition period from (inter-)glacial clima to a glacial free clima at least in northern hemisphere. What is unclear and of interest are the major processes driving this transition and their time scale. I would like to describe a possible process for the transition to a year-round ice-free arctic basin below.

If you read this, please be aware, that I am not a climate specialist nor a ocean scientist. I am only an interested amateur in this field (instead I am an engineer with a PhD in physics, for the case you want to know that). But since the professionals are failing so badly predicting current situation in the arctis for 2050 using history-proofed complex models, we all have a chance to do better even with simple empirical pictures. So I am interested in your critics and thoughts, maybe we can find a proper description of probable transition schemes together.

As introduction I would like to point to an article describing the waters and the halocline in the arctic ocean very nicely und readable: http://www.polarresearch.net/index.php/polar/article/view/6278
In figure 1 in that paper you find salinity- and temperature profiles in the Eurasian basins (Nansen basin (yellow) and Amundsen basin (green)), the Makarov basin in the center of the arctis (violet) and the Canada basin next to Alaska (blue). Some possible origins of the haloclines there are described quite understandable.

In the Eurasian basin below a depth of ~100m warm waters of atlantic origin are hold back by the halocline. Since the halocline is a result of sea-ice e.g. north of Svalbard and in Barents sea, an ice-free arctic can result in a slow "atlantification" of the arctis. An absence of a halocline in the Eurasian basin would result in a mixing with deeper warm waters preventing the formation of ice in winter.

An additional mechanism able to destroy the halocline could be vaporization of water over an ice-free Eurasian basin in autumn: Since the salinity is only 1 PSU lower in the top 100 m (yellow curve for Nansen basin) and 1 PSU is 0.1% salt content, only 10 cm of water need to be vaporized to result in disappearing halocline there (0.1% x 100 m = 0.1 m) after some mixing. The heat needed to vaporize this water has to be stored in the upper water layer, e.g. the top 10 m. Since 2700 kJ/kg are needed (2256 kJ/kg vaporization enthalpy + 420 kJ/kg for 0->100 °C), for comparison that is the energy needed to melt 0.8 m ice (334 kJ/kg) or to heat a 10 m water culumn by 6.4 °C. I think that amount of heating is well in reach for an ice-free ocean in the summer.

In the Amundsen Basin this numbers would be 0.15 m to vaporize (0.15% x 100m, heat equal to 10 m water heated by 10 °C), in Makarov basin 0.3m (2 PSU x 150 m) and in the Canada basin 1 m (8 PSU x 50 m plus 3 PSU x 200 m). Therefore, I estimate the transition time to an all-year ice-free ocean 1-2 years for the Eurasian basin and 1-2 decades for the Canada basin. Both transitions would start after the ice melted early enough to result in a surface temperature of 5-8 °C  (7-10 °C above melting temperature there).


To conclude, I have drawn a picture to describe how and when evaporation could result in a perennial ice-free state above the deep basins in the arcits and I am asking for your thoughts. This is not a proper prediction for the bays (e.g. Hudson) and the shelf waters (Siberian seas, Kara, Tschuktschen, Makenzie delta,...) - I think some ice will be grown in that areas under the influence of fresh-water inflow and cold air from continents.

Since open sea in the arctis will kill the polar vortex, the jet stream and the atmospheric flux of energy to the arctis the oceans currents must cool the equator on the long run. Evaporation will suck the Atlantic water north and cover the continents with a ton of wet snow. The persistent depression over the artic ocean will kill the jet stream and the westerlies - leaving only the Antarctis to cool the Equator by air. What would that mean for monsuns, westerly, northern trade wind, ... persistent winter weirdness globaly, I guess. 
And what would that mean to Greendlands ice -  that last memory of the glacial periode? Probably some more water to motivate our dykers.
 
Erratum: Since the change of salinity by vaporization is calculated wrong in this message (see comment from Peter Ellis below), vaporization is not reasonable to destroy the halocline. Instead other processes could be discussed in this thread. I am sorry for that mistake.
« Last Edit: April 05, 2013, 07:12:52 PM by SATire »

Jim Williams

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Re: year-round ice-free artic basin by vaporization?
« Reply #1 on: April 03, 2013, 02:18:51 PM »
In the Amundsen Basin this numbers would be 0.15 m to vaporize (0.15% x 100m, heat equal to 10 m water heated by 10 °C), in Makarov basin 0.3m (2 PSU x 150 m) and in the Canada basin 1 m (8 PSU x 50 m plus 3 PSU x 200 m). Therefore, I estimate the transition time to an all-year ice-free ocean 1-2 years for the Eurasian basin and 1-2 decades for the Canada basin. Both transitions would start after the ice melted early enough to result in a surface temperature of 5-8 °C  (7-10 °C above melting temperature there).

If you get a significant fraction of the Arctic ice free over winter I think you change the dynamics of the entire ocean.   If I buy into your argument for the Eurasian basin then I doubt the 1-2 decades required to test your hypothesis for the Canada basic will be available.

Neven

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Re: Year-round ice-free Arctic
« Reply #2 on: April 03, 2013, 02:21:13 PM »
SATire, I think this is a very useful thread that will lead to an interesting discussion, now and in years to come, which is why I took the liberty of giving it a more generic title. I hope that's okay!

Last week there was a teleconference in New York with some prominent Arctic sea ice experts such as Wieslaw Maslowski and Walt Meier. I asked them when we can expect a year-round ice-free Arctic as soon as the Arctic sees its first ice-free September day. I will put up a blog post with the audio later this week.
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Peter Ellis

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Re: Year-round ice-free Arctic
« Reply #3 on: April 03, 2013, 02:58:52 PM »
In the Eurasian basin below a depth of ~100m warm waters of atlantic origin are hold back by the halocline. Since the halocline is a result of sea-ice e.g. north of Svalbard and in Barents sea, an ice-free arctic can result in a slow "atlantification" of the arctis. An absence of a halocline in the Eurasian basin would result in a mixing with deeper warm waters preventing the formation of ice in winter.

This is not the whole story.  The halocline is not only due to sea ice formation, but also due to large amounts of freshwater influx from rivers draining into the comparatively closed Arctic basin. 

Even if it were true that the halocline formation was driven primarily by sea ice, then the halocline will get stronger, not weaker, as summer sea ice declines.  More ice melting each summer means more fresh water getting added to the surface layers.  More ice re-forming each autumn means more cold salty brine getting rejected and sinking down to the lower layers.

An additional mechanism able to destroy the halocline could be vaporization of water over an ice-free Eurasian basin in autumn: Since the salinity is only 1 PSU lower in the top 100 m (yellow curve for Nansen basin) and 1 PSU is 0.1% salt content, only 10 cm of water need to be vaporized to result in disappearing halocline there (0.1% x 100 m = 0.1 m) after some mixing.
Your calculation is wrong by a factor of 286.  To increase salinity from 34 PSU to 35 PSU, you need to lower the volume by a factor of 1/35, i.e. evaporate away 2.86 metres from the top 100 metres.

In any event, evaporation is low at Arctic temperatures.  I'm not quite clear what you're aiming at by comparing it to the heat taken to warm the water up by a few degrees.  If you start with water around freezing point and warm it up a few degrees, you get slightly warmer water, not great clouds of water vapour.

SATire

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Re: Year-round ice-free Arctic
« Reply #4 on: April 03, 2013, 05:30:08 PM »
Your calculation is wrong by a factor of 286.  To increase salinity from 34 PSU to 35 PSU, you need to lower the volume by a factor of 1/35, i.e. evaporate away 2.86 metres from the top 100 metres.
Peter Ellis, you are right with that. What a shame - this thread is bs.

The halocline is not only due to sea ice formation, but also due to large amounts of freshwater influx from rivers draining into the comparatively closed Arctic basin. 
There are no rivers in Svalbard or Barents - the various processes for halocline formation are described nicely in that linked paper.

In any event, evaporation is low at Arctic temperatures.  I'm not quite clear what you're aiming at by comparing it to the heat taken to warm the water up by a few degrees.  If you start with water around freezing point and warm it up a few degrees, you get slightly warmer water, not great clouds of water vapour.
Are you sure with that? Cold air from continents getting warmed over the ocean are very dry and can take significant water from evaporation. E.g. look at the "smoke" next to leads in the ice. But there is of course not enough heat for vaporization of 2.86 m water column - so I would agree to close this thread and delete it, at least until I have lost the red color from my face  :-[

TerryM

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Re: Year-round ice-free Arctic
« Reply #5 on: April 03, 2013, 05:43:21 PM »
SATire


Don't ditch the thread due to a little embarrassment.


I made a most horrific mistake in basic arithmetic last year and found that no one harassed me about it - ever. Neven's sites have attracted a group that is much more interested in learning about the Arctic ice than repeatedly screaming "GotCha".


You've brought up a subject that is of interest to most on the forum & a glitch coming out of the gate is really no big deal.


Terry

DrTskoul

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Re: Year-round ice-free Arctic
« Reply #6 on: April 04, 2013, 02:37:29 AM »
I will second that. It is much more important that we all learn and learning from the process of correcting mistakes is the single best way to really open your eyes and understand. Keep up the good thinking...
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
― Richard P. Feynman

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #7 on: April 04, 2013, 03:22:41 AM »
Even if it were true that the halocline formation was driven primarily by sea ice, then the halocline will get stronger, not weaker, as summer sea ice declines.  More ice melting each summer means more fresh water getting added to the surface layers.  More ice re-forming each autumn means more cold salty brine getting rejected and sinking down to the lower layers.

It is the rejected brine sinking which may be the death of the halocline as it sinks and causes the Atlantic layer to rise.  The last of the ice may very well melt in mid-winter rather than late summer.

Peter Ellis

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Re: Year-round ice-free Arctic
« Reply #8 on: April 04, 2013, 03:54:30 PM »
It is the rejected brine sinking which may be the death of the halocline as it sinks and causes the Atlantic layer to rise.  The last of the ice may very well melt in mid-winter rather than late summer.
Surely not.  The Antarctic manages to form sea ice each winter and it has no halocline other than that generated by seasonal melt.

frankendoodle

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Re: Year-round ice-free Arctic
« Reply #9 on: April 17, 2013, 05:44:37 AM »


I saw this video on YouTube and it made me realize I've been underestimating the effects a totally ice free arctic would have on the jet stream. I've been thinking more about the trans oceanic currents. It looks like the prevailing winds might not prevail in the end :)
In the past 3 years, central North America has experienced extended periods of D3-D4 (extreme to exceptional) drought. 2009  was also a much worse than average year.
http://droughtmonitor.unl.edu/archive.html
 This has coincided with the worst 5 year stretch for corn crops as well. This has caused the price of corn to increase, thus making it a less attractive agro-industrial product. Farmers in the upper plains states have already started going back to planting other less water intensive grains than corn (and to a slightly lesser extent soy beans) due to lack of water. So a yearly ice free arctic will probably mean the US will no longer be the world's bread basket.   

slow wing

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Re: Year-round ice-free Arctic
« Reply #10 on: April 17, 2013, 10:00:07 AM »

That is an excellent video! Thanks for posting it, FrankenDoodle.

Neven

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Re: Year-round ice-free Arctic
« Reply #11 on: April 17, 2013, 02:42:04 PM »
Thanks from me too, FD. I had watched that Francis presentation, but it's cool that someone has taken out that particular segment. I'll use it at one point on the blog.
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frankendoodle

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Re: Year-round ice-free Arctic
« Reply #12 on: April 17, 2013, 06:18:05 PM »
You're welcome slow wing.
Glad to be of service to you Neven. Also, I was wondering whether it would be appropriate or not to have a section on this forum about wildfires, drought stages and/or crop failures. As the dramatic change in Arctic temperatures affects weather in the Northern Hemisphere, these things are seen as secondary effects. 

Vergent

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Re: Year-round ice-free Arctic
« Reply #13 on: April 17, 2013, 06:47:53 PM »
You're welcome slow wing.
Glad to be of service to you Neven. Also, I was wondering whether it would be appropriate or not to have a section on this forum about wildfires, drought stages and/or crop failures. As the dramatic change in Arctic temperatures affects weather in the Northern Hemisphere, these things are seen as secondary effects.

FND,

Thanks for the video. Those topics would be appropriate in AGW in general » Consequences

V

Neven

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Re: Year-round ice-free Arctic
« Reply #14 on: April 17, 2013, 07:13:32 PM »
Also, I was wondering whether it would be appropriate or not to have a section on this forum about wildfires, drought stages and/or crop failures. As the dramatic change in Arctic temperatures affects weather in the Northern Hemisphere, these things are seen as secondary effects.

AGW in general -> Consequences
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Nightvid Cole

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Re: Year-round ice-free Arctic
« Reply #15 on: April 19, 2013, 12:27:45 AM »
Presumably, in a year-round ice free Arctic, the SST 's in the Arctic Ocean could begin to warm up very early in the spring (March or April??) and reach very high levels by late summer, especially over the shallow continental shelf portions. Since there are presumably a lot of clathrates on the sea floor there, storms during the summer which produce mixing will cause the warmth to reach the bottom and destabilize the clathrates, causing runaway hothouse Earth...

Vergent

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Re: Year-round ice-free Arctic
« Reply #16 on: April 19, 2013, 08:36:56 PM »
Presumably, in a year-round ice free Arctic, the SST 's in the Arctic Ocean could begin to warm up very early in the spring (March or April??) and reach very high levels by late summer, especially over the shallow continental shelf portions. Since there are presumably a lot of clathrates on the sea floor there, storms during the summer which produce mixing will cause the warmth to reach the bottom and destabilize the clathrates, causing runaway hothouse Earth...

Cole,

With a ice free Arctic Ocean, Atlantic water from the Barents sea would be free to flow into the Arctic Basin and displace the denser that is there. The MET office global model thought it was happening last fall. The dense water would flow out the Fram. The potential is to have the Arctic Basin filled with warm water down to 2,000m.

V

Dromicosuchus

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Re: Year-round ice-free Arctic
« Reply #17 on: April 20, 2013, 04:37:11 AM »
Vergent:  Would you mind providing a link going into further detail on that?  That's an extremely unnerving possibility that I hadn't really heard of before, and I'd be very much interested in learning more about it.

Neven

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Re: Year-round ice-free Arctic
« Reply #18 on: June 02, 2016, 10:53:30 PM »
Comments moved from 2016 Melting Season thread:

...
First, even if there was a full melt out of the arctic (sub 1,000,000KM2 of ice at minimum), the refreeze in fall would recover completely, and will continue to do so for decades to come.   It will be the best part of a century before we have a year round ice free Arctic, at the least.

Apologies for a lengthy post not exactly related to current melt, but i felt i have some general ideas to share in terms of the nearest future of ASI after this melt season is complete, which may also relate to how _long_ this 2016 season may end up be... Please cut the post mercilessly if it's too bothersome, but if it will be done, please consider keeping the quote above and links presented, as i dare think they may still remain interesting for quite many people in here.

Not completely, no. And certainly not for "decades to come".

Even been to lake Baikal? It's frozen desert alright in winter, some 0.8...1.0 meters ice thickness - quite possibly very close to observable-future Arctic ice thickness. More details about it can be found in this paper. But now to my point: despite such a solid ice cover for much of any given year (~half a year), and despite the fact Baikal gets less insolation than Arctic waters/ice summer-time, - waters of this huge and massively _deep_ lake are warmed up to 15...18°C for 3 summer months, as you can see in a table on this page. In the same table, you can see Baikal surface temperatures in winter, which go ~-20°C.

This is, i guess, the mode to be set for the Arctic few seasons after it first goes mostly ice-free (<1M km2 area): thinner winter ice, much longer ice-free summer time, and quite warm waters for much of the summer.

Thing is, without ice, and especially with massive Arctic insolation, SSTs go up very quickly under any significant sun. More interesting what happens after they do, though. There is relatively little convection, since above +4°C, the warmer water is, the less dense it is - so much warmer water will tend to stay surface layer. But this does not prevent deeper layers from warming up - both sunlight direct (much of which hits for many dozens meters into water column, and some for more than 100 meters deep), and also via secondary IR from surface water itself (slowly creeping out in all directions, as usual for IR - including downwards).

This process will create big-time "heat reserves" for autumn times. The more "much above 4°C" water will be produced by summer times "meters / dozens meters" below surface, the more _convection_ there will be once surface water will start to approach freezing temperatures: very same conditions which previously led to direct formation of surface ice - now will lead to heavier "cooled down" surface water to "sink" instead, as warmer (less dense) water would be replacing it. Then the process will repeat, until there would be no sufficiently warm "much below surface" water remaining at any given location.

One can even attempt to quantify it, napkin-style: if say there is just 8.3 deep meters layer of water with +10°C anomaly through it by the end of the summer, sitting "a bit below" surface layer (of say 1 meter deep), then that 8.3 meters colum will have enough energy in it to melt 1m thick ice, should _all_ the energy be spent for it; and napkin-style, one may then muse that in such a location, any signs of ice on surface would appear only when "normally" ice would be getting over 1m thick - that 1m thickness was not formed exactly because that 8.3 deep "extra 10°C" water was spending its extra energy _preventing_ formation of 1m-thick ice.

As you can see in the paper linked above, Baikal _begins_ to form its ice (depending on specific region of it) in late October (its northern parts) to January (southern parts). So we still talk completely open water in its southern parts during beginning of average January. However, air temperatures typically shift to negatives MUCH earlier for Baikal on average - late October / early november (source, ru). So there is lengthy gap between "freezing air" and actual start of water freeze, for most of the lake. It is exactly because of dozens meters of warmer water formed summer-time, - it needs plenty time to convect up, give away its extra heat, become dense and sink down (giving place to the "next" layer of still-warm water from below, until there is no such layers left). One would expect lots of evaporation in such conditions, - and indeed, it is reported that most intensive evaporation from Baikal happens during November and December months (source, ru).

So you see, we have quite a "real world model" for the "cold climate, long winter, thick ice, but open-water for most of summer" big water body. In fact, lake Baikal is so big that climate of nearby lands is more like sea climate than continental (the latter being the norm for most of Siberia).


(...)
Thing is, without ice, and especially with massive Arctic insolation, SSTs go up very quickly under any significant sun. More interesting what happens after they do, though. There is relatively little convection, since above +4°C, the warmer water is, the less dense it is
(...)


So - I entirely agree with you, and this is what I suspect/am concerned will happen in an entirely ice free arctic. As you mentioned, the southern reaches don't refreeze until January, even long after being exposed  to lower temperatures.  I expect this delayed (not prevented) refreeze would happen in the arctic as well for most of the reasons you mentioned.  A basically open arctic ocean will be absorbing solar heat into the water, not just putting it  into existing ice; therefore there'd be a delay before it can refreeze as it loses that heat.  That, I think, will have big effects. It will prevent "complete" recovery. 

However I do have to point out that the +4C density peak applies only to freshwater - saline water has a density peak at a lower temperature, even all the way down to its freezing point.  Of course the freezing process creates brine which tends to sink because of salinity - but the hydrodynamics are significantly changes by the presence of salt, and it drives a huge amount of the mixing, etc


If you want an idea of what the Arctic Ocean will be like under ice-free conditions in the fall, simply look at the Great Lakes for a halfway decent analog. Anybody who lives near them can tell you -- a tremendous alteration of local climates occurs there (via tempering of early cold air outbreaks, lake effect rain and snow and lots of cloudiness).

The warmer the lakes start, the more vigorous the convection when continental cold air outbreaks start. In fact, we forecasters have a metric we use for helping determine whether lake effect precipitation is likely and how intense it is likely to be. It's based on the height of the lowest inversion and delta-T (or simply the difference of the lake surface temperature and the temperature at 850mb). Change in wind speed and direction with height also determine how the precip becomes organized (bands, etc). A delta-T of 13C is often enough to start the process. Any deltas over 18 or so can be good enough to generate lightning (and actual thunderstorms). This brings up an interesting issue. We know the deeper the convection, the more effective it is in trapping outgoing infrared. This slows down the cooling of the pole during autumn, delaying freeze-up and conditioning next year's ice to be thinner.

More important, I think, will be the (continuing) net change to atmospheric circulation during this phase. High delta-Ts and rampant convection will result in a big release of latent heat via water vapor condensation to the atmosphere, causing a "monsoon"-type circulation to appear annually as surface pressures will tend to be lower over the low-to-no ice Arctic Ocean than on surrounding continental land, which tends to cool much faster. Indeed, we're already seeing signs of this since the collapse of the MYI pack several years ago. The heat and moisture flux from the basin tends to dump snow over neighboring Siberia, strengthening the high that forms there and helping to disrupt the polar vortex and depress the Arctic Oscillation during winter. I think this will become far more pronounced over time as we transition to seasonal ice-free conditions. The earlier the melt-out, the higher the basin SSTs will become and the stronger the disruption to circulation. Even a week or two of extra sun makes a big difference at this point.
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Tor Bejnar

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Re: Year-round ice-free Arctic
« Reply #19 on: February 11, 2017, 11:23:06 PM »
Neven suggested this is where certain comments made in The Slow Transition thread should go, so I cross post mine (edited):
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 (that may be different from historic conditions [stormier?] - basically, ice and snow insulate the surface preventing venting of heat, and stratified waters beneath the ice)
  • ice-free CAB with increased waves & de-stratified water (slows freezing), humidity and clouds (slows venting) (Pancake ice, etc. will not likely cover the CAB quickly, so a longer ice-free surface)

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.
Arctic ice is healthy for children and other living things.

Iceismylife

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Re: Year-round ice-free Arctic
« Reply #20 on: February 11, 2017, 11:29:32 PM »
<snip>
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.

IMO  When the Arctic goes ice free year round is a function of how much rebound we get next year.  If we get a good ice year or not a really bad one and a bad melt season then it could be several decades until year round ice free.

Global warming is step up slow decline, step up slow decline.  If we get sea ice rebound next year then we are at the end of this step up and in for several decades of decline before the next step up.

If we don't get rebound next year then before then end of this decade is possible.  Sorry to say that.

Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #21 on: February 12, 2017, 12:17:04 AM »
I don't understand what you mean by rebound as it relates to ice free year round.

I do believe that we are quickly moving to a seasonally ice free Arctic. Hell, look at the visuals at minimum of the past 10 years and one could make the case that most of the Arctic Ocean proper already is seasonally ice free.

This winter has been a wild one. While polar winters have been warming for a couple of decades, this winter has deviated from the trend line in a manner that can only mean one thing. There are special causes that have resulted in this abrupt shift from trend line.  I am not sure if this is a special cause, one season type of thing or a phase change which will persist.

So what do we know.

Minimums are trending down and polar winters are warming and these trends have been in place for a couple of decades. So how have the freeze seasons reacted to this?

For both SIE and SIA, as the melt season minimums have declined, the amount of ice freezing has increased such that the freeze season maximums have declined at a slower pace. In fact, these charts show that the amount of ice that freezes in a season (gray line) is inversely correlated with the minimum reached for that season. The effect is to smooth the variability of the maximum reached even as the SIE and SIA minimums fluctuate wildly.

With this wildly warm winter, it will be interesting to see if this trend holds true. It might not but I expect that this tendency for more ice to freeze when the minimums are low will continue into the future.

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #22 on: February 12, 2017, 03:04:19 AM »
OK.  I say the Arctic will be ice free year round the same year it is ice free in September, and there will be no slowdown as the ice gets closer to gone -- and possibly a speedup.  It will be caused simply by the increased humidity and storminess of an open Arctic.  I also say we saw this process begin abruptly at the end of December 2015, and are now watching it happen in realtime.

James Lovejoy

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Re: Year-round ice-free Arctic
« Reply #23 on: February 12, 2017, 04:37:56 AM »
I say the Arctic will be ice free year round the same year it is ice free in September

I really doubt that, unless the year that it is ice free in September it is also ice free in July.  Which is possible.

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #24 on: February 12, 2017, 02:21:06 PM »
I say the Arctic will be ice free year round the same year it is ice free in September

I really doubt that, unless the year that it is ice free in September it is also ice free in July.  Which is possible.

Actually, I need to correct myself.  It will be the same year unless it goes ice free during Oct-Dec, in which case it will be the year before it goes ice free in Sept.

I don't think the season will matter when it decides to melt out.

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #25 on: February 12, 2017, 02:34:47 PM »
On the question of definition of Ice Free:

In accord with a conversation recently had, I propose that the Arctic ocean in Summer is ice free when there is no longer enough ice to keep the DMI 80N graph of temperature from going above 3C for 10 or more straight days.

I don't yet have a good idea for defining ice free in Winter.

Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #26 on: February 12, 2017, 03:30:50 PM »

I don't yet have a good idea for defining ice free in Winter.

The definition of ice free in the winter should be the same as ice free in September. I believe we are already getting a hint of what the winter that follows the 1st ice free Arctic in September will look like. There has been little transport into the Beaufort this winter after a very early ice free this past melt season. The Beaufort is now comprised of highly mobile, small floe sea ice that is continuously stitched together by newly frozen ice as the larger floes are jostled about by storms and waves. This ice should and I believe will completely melt out this melt season. The entire Arctic Ocean will behave this way. Once we get a seasonally ice free Arctic, it will likely be seasonally ice free or nearly ice free from that point forward but -15C or -20C with periodic intrusions of -2C will still cause ice to form in the ocean.
« Last Edit: February 12, 2017, 04:20:01 PM by Shared Humanity »

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #27 on: February 12, 2017, 04:59:07 PM »

I don't yet have a good idea for defining ice free in Winter.

The definition of ice free in the winter should be the same as ice free in September. I believe we are already getting a hint of what the winter that follows the 1st ice free Arctic in September will look like. There has been little transport into the Beaufort this winter after a very early ice free this past melt season. The Beaufort is now comprised of highly mobile, small floe sea ice that is continuously stitched together by newly frozen ice as the larger floes are jostled about by storms and waves. This ice should and I believe will completely melt out this melt season. The entire Arctic Ocean will behave this way. Once we get a seasonally ice free Arctic, it will likely be seasonally ice free or nearly ice free from that point forward but -15C or -20C with periodic intrusions of -2C will still cause ice to form in the ocean.

First, I doubt it will be averaging -15 to -20C.  Second, I expect the Arctic to be in a nearly continuous storm -- with large waves.

Just Take the Arctic as a large bay of the Atlantic.  This is what I'm expecting to happen at some point rather suddenly.  At least at first Greenland will create a localized break, and as long is there is permafrost the continents will continue to be cold in Winter.  The Arctic Cell is already failing, and night will provide no relief from the wind transport of heat from mid-latitudes.

I might buy into the idea of 80N being above 3C on average for the year -- or something like that -- as a definition of ice free.

Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #28 on: February 12, 2017, 05:04:17 PM »
If we look at the insanely warm winter we are currently experiencing and the nearly as warm winter that preceded it which I believe is becoming the new normal, how can these ridiculously warm temperatures which still bounce around -20C north of 80 degrees not cause ice to form?

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #29 on: February 12, 2017, 05:13:42 PM »
If we look at the insanely warm winter we are currently experiencing and the nearly as warm winter that preceded it which I believe is becoming the new normal, how can these ridiculously warm temperatures which still bounce around -20C north of 80 degrees not cause ice to form?

I think the step change in 80N in Dec 2015 was basically when the Atlantic Climate (ocean and air) made it to 80N.  What is the historic temperature in the North Atlantic (open water) off Norway in Winter?   Whatever that is, that is what I expect for the bulk of the Arctic waters in a few (or fewer) years.


Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #30 on: February 12, 2017, 05:18:46 PM »

First, I doubt it will be averaging -15 to -20C.  Second, I expect the Arctic to be in a nearly continuous storm -- with large waves.

Just Take the Arctic as a large bay of the Atlantic.  This is what I'm expecting to happen at some point rather suddenly.  At least at first Greenland will create a localized break, and as long is there is permafrost the continents will continue to be cold in Winter.  The Arctic Cell is already failing, and night will provide no relief from the wind transport of heat from mid-latitudes.

I might buy into the idea of 80N being above 3C on average for the year -- or something like that -- as a definition of ice free.

The definition of ice free is an ocean lacking ice. Anything else makes no sense.

With regards to a stormy Arctic, we have had a cyclone cannon firing strong lows with high winds into the Arctic for the entire winter. We have seen persistent intrusions of warm air on the Pacific side as well, all a result of a Polar Vortex that is nearly absent. How stormy are you expecting it to be as compared to this year and will it just be a strengthening of the current behavior or something that looks entirely different? Finally, how will an above 3C average north of 80 degrees exist in the long polar night?

Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #31 on: February 12, 2017, 05:29:52 PM »
A quick glance at the Arctic and I can only conclude that the intrusions of warm air on the Atlantic and Pacific sides of the Arctic is directly related to to the presence of large expanses of water, the Barents and the Bering Seas. This is not a coincidence. I would be very surprised if we were to see persistent lows penetrating the Arctic from a cold, snow covered central Siberia or North America. The patterns we are seeing will persist and likely strengthen. I simply don't believe this strengthening pattern will result in a year long, ice free Arctic Ocean anytime soon.

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #32 on: February 12, 2017, 05:31:26 PM »
The definition of ice free is an ocean lacking ice. Anything else makes no sense.

Then the Arctic will be ice free when Greenland is glacier free.

With regards to a stormy Arctic, we have had a cyclone cannon firing strong lows with high winds into the Arctic for the entire winter. We have seen persistent intrusions of warm air on the Pacific side as well, all a result of a Polar Vortex that is nearly absent. How stormy are you expecting it to be as compared to this year and will it just be a strengthening of the current behavior or something that looks entirely different? Finally, how will an above 3C average north of 80 degrees exist in the polar night?

A little bit stronger....but there will be no ice already there.

Well...I told you I didn't have a good definition for night...but...I expect the air which currently rises in the Gulfs (Gulves?) to fall at the Pole rather than the Mid-Ocean.  At is...the deletion of the Polar Cell in the North.  So...I expect the air being transported to me here in Boston to instead be dumped right on top of the Arctic Ocean -- and they can have these Nor'easters.



Jim Williams

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Re: Year-round ice-free Arctic
« Reply #33 on: February 12, 2017, 05:33:42 PM »
A quick glance at the Arctic and I can only conclude that the intrusions of warm air on the Atlantic and Pacific sides of the Arctic is directly related to to the presence of large expanses of water, the Barents and the Bering Seas. This is not a coincidence. I would be very surprised if we were to see persistent lows penetrating the Arctic from a cold, snow covered central Siberia or North America. The patterns we are seeing will persist and likely strengthen. I simply don't believe this strengthening pattern will result in a year long, ice free Arctic Ocean anytime soon.

We are both taking a bet.  The "science" isn't there to answer the question....  Now, if we had a hundred billion earths to experiment on...

Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #34 on: February 12, 2017, 05:38:43 PM »
Yep. Not sure how this plays out but it will be riveting to watch.

Pass the popcorn.  :o

Jim Williams

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Re: Year-round ice-free Arctic
« Reply #35 on: February 12, 2017, 05:40:53 PM »
BTW -- The only real "scientific" basis I have for my position is that we have some evidence that seems to indicate extremely large past climate changes in extremely short times (decades or less). I am interpreting what I see in terms of the best available evidence about past climatic behavior.


Shared Humanity

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Re: Year-round ice-free Arctic
« Reply #36 on: February 12, 2017, 05:47:27 PM »
Neven----I have been struggling with and annoyed by off topic streams of comments occurring on these threads and would like to thank you for redirecting us to this annual ice free. It has breathed life into a topic that is extremely important. I also think it has pointed us to a potential solution. How difficult would it be to monitor threads and move any stream of comments to the appropriate thread? Don't bother with a single off topic remark but if a discussion ensues, everything gets moved. It would preserve the discussion on the thread freed of the off topic discussion and energize discussions that are very important.

Would we need a number of individuals appointed as monitors in order to manage this?

Don't pick me. I'd simply move all the comments with which I disagree.

All kidding aside. If it would require more than one monitor, you would need to be very careful with who you designated. They would have to be very knowledgeable to know where comments should be moved. Perhaps you could test this on only the most active threads.

Archimid

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Re: Year-round ice-free Arctic
« Reply #37 on: February 12, 2017, 07:07:52 PM »
The definition of ice free is an ocean lacking ice. Anything else makes no sense.

Then the Arctic will be ice free when Greenland is glacier free


I agree with that. Once Greenland is glacier free an "ice free" arctic ocean will literally be true.  The timing for such an event  is hard to guess but, here is the latest I've read on that.

https://www.sciencedaily.com/releases/2016/12/161207133453.htm

FTA talking about the Greenland ice sheet:

The scientists say that in the most conservative interpretation, there might have been only one ice-free period that ended 1.1 million years ago. But, more likely, they say, the ice vanished multiple times for shorter periods closer to the present.

I think it is plausible that the Greenland  ice sheet disappeared during the hottest interglacials in the past half million years. But unlike this time around that warming happened over hundreds, or perhaps thousands of years. The warming projected for Earth will exceed that of the peak of the Eemian in 100 years. Will the Greenland glaciers melt at the same pace that the temperatures are rising? Probably, with some lag given mostly by the speed of SLR and global temperatures.

 That's when we will have a literally ice free arctic ocean. Until then, some ice will form in the long arctic night along the coast of Greenland.



I might buy into the idea of 80N being above 3C on average for the year -- or something like that -- as a definition of ice free.



I like that.



I would also like to recognize Neven's moderation. It is spot on. Thanks Neven.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Iceismylife

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Re: Year-round ice-free Arctic
« Reply #38 on: February 12, 2017, 09:52:26 PM »
If we look at the insanely warm winter we are currently experiencing and the nearly as warm winter that preceded it which I believe is becoming the new normal, how can these ridiculously warm temperatures which still bounce around -20C north of 80 degrees not cause ice to form?
We are looking at the old new normal not the new, new normal.  If we get enough open water it wont get to minus 20C.  Minus 5C max. 

If there is enough wave action to brake up the sea ice next to Greenland then it wont extend and it will melt.

I had a mini stroke (this year) and some things just turn to mush sorry.

F.Tnioli

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Re: Year-round ice-free Arctic
« Reply #39 on: August 01, 2017, 10:03:45 PM »
The subject of year-round ice-free Arctic surfaced in the ongoing Melt Season thread, and it is best we continue the discussion in this topic.

... Even with much higher temperatures, there will probably always be freeze in winter, that's why there will probably never exist zero ice all over the year...


What you are discussing is the transition of the Arctic Ocean from being perennially ice covered, through seasonally ice covered, and ending up in a perennially ice free condition.

One such study appeared last year in the Journal of the American Meteorological Society. Their findings, in a nutshell, were that the vast bulk of winter sea ice could be a thing of the past by as soon as ~2130.

I'll put more flesh on this later, but I'm off to sink a few pints.


Bill, excellent spotting about that paper! But i am sure their result is a vast underestimation. I am not familiar with the paper, but i could bet authors did not take the biosphere influence into much consideration when making their calculations. If so, then that is perhaps the biggest flaw of their work. Because, obviously, in real world, we _do_ have the biosphere. So far. Thank God for that, if i might add.

As you can see in this lecture by no other than James Lovelock himself - the "father" of Gaia theory, inventor of the detector which allowed to detect ozone holes, etc, - he predicts a distinct state change into "Hot House Earth" (a.k.a. "Jurassic Park Earth") some time during 2050s. I recommend you hear his own explanations about how and why he produces such a graph; they are very good, you can hear them at the beginning of the video i provided the link for.

Further, what James does not say is full version of why there are higher and higher volatility in his graph before 2050, and why there is smaller volatility after the state change (2060s and beyond). The reason for that is that biosphere attempts to regulate temperatures using its ability to do so, but with greater and greater positive forcing and (not changing in James' model - static) ability of the biosphere to regulate it, the regulation becomes less and less potent, thus producing wilder and wilder swings.

Obviously after the state change, positive forcing becomes much reduced (becase new quasi-equilibrium temperature is higher, so Stefan-Boltzman law does much bigger work radiating extra amounts of energy into space without biosphere having to deal with it). Thus less volatility after the state change.

Next, while i agree with James about everything he says in this (3rd) part of his lecture, i can't help but be sure that there is one thing James' model did not yet completely account for: the ongoing 6th great extinction of species. In particular importance, ongoing deforestation, rapidly increasing amount and scale of forest fires, and ongoing loss of phytoplankton in the oceans. All those trends are most likely to continue into observable future, thus further reducing biosphere's ability to regulate temperature of Earth surface at large.

In turn, that reduced ability means that the state change will happen sooner than predicted by James' model he presents in the lecture. So, we're talking something like "some time during 2040s, in best case as late as year 2050 or so".

And that's even before we start to take into account vast uncertainty presented by melting permafrosts and associated methane releases. Clathrate gun hypothesis, you know. Obviously nobody can quantify its effects any well - for now. But the thing is, nearly everyone calculates things as if Clathrate Gun would be minor and/or distant factor. What if it's not either minor nor distant? 2030s for state change of the kind James talks about?

You get the picture. 2130s? I wish. But nope. It'll be much, much sooner. Certainly this century, if you'd ask me.

Thoughts?

P.S. i vastly disagree with few things James says in other parts of that lecture, even though i respect him extremely much. I just can't agree; notably the one about his proposal to tinker with the biosphere feedbacks: i'm extremely cautious about any such proposal. To me, it's like practicing middle ages medicine methods which can lead to death of patients. Simply because methods used would not be sufficiently safe. We should not attempt to regulate the climate via any biospheric methods unless we understand very well and in every detail how Gaia works. Which we don't. And which we won't for a long time ahead - Gaia is much more complex than "just a human body", and it took our civilization many centuries to learn the latter only. Did you know "doctors" could literally kill your kid just few hundreds years ago trying to treat the kid's stuttering, for example? But it's true, and feel free to scroll on this page to other similar examples of "medicine" methods widely practiced not so long ago, and in some cases even today; and that list was just a warm-up - if you appreciate black humor, them check this one, too. So, it is so tempting to genetically engineer some climate-change-preventing-algae or something, but i think we must not: unlike human patients, whos death is tragic but is not yet the end of the world, if we "mis-cure" Gaia - there won't be another patient to experiment on. If through our misunderstandings and limitations we end up destroying most of the Gaia (to the level of only remains of microbiota remaining) - then Guy McPherson will end up being right, i think: then we'd extinct as a species, ourselves.
« Last Edit: August 02, 2017, 12:41:05 AM by F.Tnioli »

Thawing Thunder

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Re: Year-round ice-free Arctic
« Reply #40 on: August 01, 2017, 11:21:44 PM »
I can agree on that there'll be a tipping point after which everything will look different. But when this is going to happen? Who am I to tell you or even make guess. We will probably see it in the rearview mirror and agree then (if we're not totally occupied with survival then, or even worse).

One of the things of the thawing Arctic that attracts me and lets me watch it, is exactly that: You can see a change with your own eyes (though enhanced by satellites) and all within a human timespan (I'm watching this for a decade now, so much has changed!).

Sometimes I doubt this is sane or helping anything. Sometimes It seems to me like a morbid fascination. But here I go. And go on watching ...

Dharma Rupa

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Re: Year-round ice-free Arctic
« Reply #41 on: August 01, 2017, 11:32:38 PM »
Sometimes I doubt this is sane or helping anything. Sometimes It seems to me like a morbid fascination. But here I go. And go on watching ...
Me too!

I do think that from a HuMan perspective the changes in both computer science and bioengineering are more important, but from a biosphere perspective the North Pole is the center of the Universe.

Thawing Thunder

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Re: Year-round ice-free Arctic
« Reply #42 on: August 02, 2017, 12:08:25 AM »
DR, to me it seems like a cataclystic singularity, all those events converging in the next years and decades. Peak ice, peak oil, peak humanity, peak brain power, peak species ... you name it.

Thinking about it ... exponential events probably tend to converge in a narrow window because of their limited expansion in time.

So no mysticism involved, just man, maths and the carbon age.


F.Tnioli

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Re: Year-round ice-free Arctic
« Reply #43 on: August 02, 2017, 12:09:45 AM »
I can agree on that there'll be a tipping point after which everything will look different. But when this is going to happen? Who am I to tell you or even make guess. We will probably see it in the rearview mirror and agree then (if we're not totally occupied with survival then, or even worse).
...
We will see it in the rearview mirror for quite a while, yes; global technological civilization we got has VAST reserves for survival as a system. Not to be underestimated. Then after a while (period of global civilization's "agony" or, if you prefer, "final struggle"), due to rapidly and massively deteriorating human and argicultural-grain habitats, that would collapse, and when it does, those of us who'd managed to survive would get very occupied, yes.

When the "tipping point" would happen - i still prefer "state change" in this context, but your term is doable, too, - that, we can in fact guesstimate rather well. We know current greenhouse forcing is roughly equivalent to +6 degrees celcius Earth climate, numerous and long periods in the geological past clearly demonstrate that. Plus, the Sun is not any colder than dozens and hundreds of millions of years ago - in fact, it's hotter now. So, we know we're heading for +6 Celcius to pre-industrial even if mankind ceases to emit GHGs right now and completely - "eventually".

We also know why we're not there "yet": thermal inertia of oceans is one big thing (i've seen few papers on the subject, estimates vary much, from ~20 years to over 50 years in one case). So in a way, we are a frog in the pot, the fire under the pot is already burning, but we're still alive because it takes time for the water to heat up enough to kill (most of) us; and we're so far unable (technologically and politically) to shut down the fire (i.e. to remove GHGs from the athmosphere quickly on a planetary scale). Analysing available literature on CO2 removal allows one to conclude we won't be able to do so for at least 3 more decades, too. Even as simple method as charcoaling all the plant matter after grain harvests and burying it into the soil (or dropping down to ocean floor) - even that most simple method is practically impossible to perform on a planetary scale, taking into account costs of doing so planet-wide and existing other uses of said plant matter by the farmers world-wide.

Therefore, the most likely frame for what you call "tipping point" is exactly 20...50 years from now, based on thermal inertia of oceans, known CO2 levels for the past 50 years (which have risen much during said period), and further ongoing deterioration of the biosphere which reduces its ability to stabilize surface temperatures. Personally, i think we're in for the lower end of said 20...50 years into-the-future moment as a tipping point, in no small part because of significant increase of methane outbursts in Siberia permafrosts very recently (it's not a secret). It is expected those processes, once started on this scale, will escalate with incredible speed, comparable to how quick gunpowder burns (in geological terms), which is why clathrate _gun_ hypothesis got its name in the 1st place.

But in any case, we're talking this century for the tipping point. Not even 2100 - much sooner. Unless some miracle technological fix would save us at very last moment. Chances of which are, in practice, as high as of real miracle happening, if you'd ask me - and not because nothing can be _invented_, but because nothing of the kind could realistically be _used_ on the planetary scale; i mean well known "tragedy of commons" here, of course. Gotta be realist these days, you know.
« Last Edit: August 02, 2017, 12:19:01 AM by F.Tnioli »

Thawing Thunder

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Re: Year-round ice-free Arctic
« Reply #44 on: August 02, 2017, 12:28:56 AM »
Yes, upon a time frame of 20 - 50 years I do agree. Even on 5 - 50 years, while I would not bet the farm on the nearest possible date of a state change (I agree on that term, too, as far as it implies a sudden change).

But 20 years, yes. Inertia is a big factor for us frogs in the kettle (and we are many, considering the population overshoot).

The only solution that is on its way to solve all this at least long term, IMO is solar energy. We'll see if this will save some kind of technological civilization, once humanity has shrunk to say a billion. Hope it will diminish in a controlled and conscious way, though I doubt it very much. By "controlled and conscious" I mean by voluntarily reducing the birthrate and giving the possibility to those who are alive to life their whole lifespan. But I think I'm getting off topic now.

F.Tnioli

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Re: Year-round ice-free Arctic
« Reply #45 on: August 02, 2017, 02:11:41 AM »
Yes, upon a time frame of 20 - 50 years I do agree. Even on 5 - 50 years, while I would not bet the farm on the nearest possible date of a state change (I agree on that term, too, as far as it implies a sudden change).

But 20 years, yes. Inertia is a big factor for us frogs in the kettle (and we are many, considering the population overshoot).

The only solution that is on its way to solve all this at least long term, IMO is solar energy. We'll see if this will save some kind of technological civilization, once humanity has shrunk to say a billion. Hope it will diminish in a controlled and conscious way, though I doubt it very much. By "controlled and conscious" I mean by voluntarily reducing the birthrate and giving the possibility to those who are alive to life their whole lifespan. But I think I'm getting off topic now.
We are less limited in terms of off-topic, as long as it somehow related, than in the melt thread, i believe.

Saving some kind of technological civilization is the only possible way for mankind to go on. Without it, we'd have to get back to non-civilized living, but for human organisms to be able to go something like hunter-gatherer, there need to be enough to gather and to hunt for. Yet biosphere will be in massive temporary decline during incoming thermal maximum, so that's not a way forward. Especially with wild fires, droughts, extreme winds, etc - which non-civilized society has very little to oppose with. Even some old civilizations were wiped out by such events, like Aztecs, Egypt, Easter island. So, we'll need agriculture, like it or not. And we'll need to maintain domesticated animals at good numbers, too. For transportation and to replace agriculture machinery (which is of no use without oil industries and won't function long without spare parts, which is high-tech these days), among other things. And we'll need to keep doing those despite and through any extreme weather events and other complications, which won't be easy.

Solar is obvious long-term, yes. But that's for future centuries. What we'll have to lean on after the global system collapse is, undoubtfully, Hydro for baseload capacity, and Wind for certain local intermittent applications. Both were used pre-industrial, widely, on local level, those can be done very low-tech. Solar is too high-tech - you need IT industry for solar (both voltaics and also solar-thermal, to control the mirrors at very least), yet it's way unlikely local self-sufficient semiconductor technologies would persist uninterrupted. Heck, possibly those would never be designed and installed, even. On the contrary, local metallurgy and simple electrics - which is all what's needed to run Hydro at significant scale, - are very doable.

Obviously only regions which will maintain substantial rainfall, and ones "downstream" from such, will remain able to do Hydro power. Lots of places won't. PDSI research done by Augio Dai et al and similar works are helpful to have a good guess about which ones are which, in advance. And in terms of dams - those pre-existing will be extremely valuable, because making any new big dams after global industries collapse (whatever reason) would be highly problematic. Fortunately, good modern dam has good chances to serve for centuries, provided good specialists maintain and service it.

Do not hope for non-violent, non-tragic human population reduction. Something like a half of 7 billion of people we have living today are likely to be still alive when tipping point happens - possibly more. Add a billion or few of kids born between now and then, and you have the picture. If you're seriously considering options, then certainly plan for violence during population die-out. Both individually and collectively. The best option at that (rather short) phaze, during die-out, is of course to outrun and avoid hostilities, moving out well in advance, and preferably never even being threatened by others. That's if one is modern urban dweller (most of us here are). Head to remote regions. Preferably know where you're heading. Become a part of remote but significantly large regional society before global system fails. Those will stand their ground firm, and distance from major dense-populated areas will be their best defense: the larger the distance, the safer it'll be.
« Last Edit: August 02, 2017, 02:48:18 AM by F.Tnioli »

oren

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Re: Year-round ice-free Arctic
« Reply #46 on: August 02, 2017, 07:34:25 AM »
Regarding the thread's topic, I believe ice will continue to form during midwinter in the central CAB long after ice-free Septembers arrive. Storminess can do only so much when the temperatures drop to minus 10, 20 and even 30 C. Even storms have a calm day or two every now and then. If the stormy and southern Bering sea manages to become ice-covered in winter, so will the North Pole for quite a while.

Thawing Thunder

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Re: Year-round ice-free Arctic
« Reply #47 on: August 02, 2017, 08:33:51 AM »
I have limited understanding of the dynamics, but that sounds reasonable. Ocean currents are limited regarding the Arctic, because ist's closely surrounded by land – though on the other hand the Golf current is a heavy weight.

And there are the jet streams. With their possible disappearing, warm air will reach much higher, even in winter, even in Bering. We had some extraordinary events of warm winter air at the north pole even with the jet streams still existing.

There are many variables in the future that could lead to a warmer arctic. But even a cold rush could be in the cards for some decades. Still the oceans accumulate most of the heat, we'll only see the whole picture when they start to "overflow".

Glenn Tamblyn

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Re: Year-round ice-free Arctic
« Reply #48 on: August 02, 2017, 09:39:54 AM »
Truly ice free year-round is a big, big step.

For 4-6 months there is ZERO solar insolation. That is of the order of 3 kwH/m^2 of energy missing each day during winter. So a few months of some ice, maybe 1/2 a meter thick, could persist for a very long time. Sure, each April/May it goes poof. And with the sun missing, that winter ice has almost no impact on the albedo of the planet.

But if the Arctic is ever 100% ice-free, year round, we won't notice because we will have loads more stuff to worry about.

Coffee Drinker

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Re: Year-round ice-free Arctic
« Reply #49 on: August 02, 2017, 11:01:13 AM »
Its hard to imagine any scenario that involves an ice free arctic year around.

When was the last time this happened? Right, back then the continents were at quite different positions.

With the current constellation of the land masses there will always be enough cooling during the long dark winters to produce ice and snow.

In fact if the arctic would remain ice free for a winter for whatever strange reason, the lake effect would produce so much snow that there would be no summer the next year.