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Author Topic: Damming Bering Straits to Restore Sea-ice - Reduction in Warmer Atlantic Water  (Read 40943 times)

timallard

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Erosion Control Construction Refinement Diagram
Phases and methods along with refining the technique with erosion control projects nearby.

A solution to slow down accelerating Arctic warming and to forestall the inevitable is damming Bering Straits to 1/100 its volume flow to create a year-round sea-ice refuge.

To do this using modified Dutch levee & dam methods for deeper water learning and refining the machines & technique by raising and restoring villages being lost.

When ready to then build a weir dam & shipping locks at St. Lawrence Island, then with reduced flow to build ice-polders protecting sections to allow the bottom to refreeze, that allowing the chance to remain all year in some areas.

Then to build atolls around the methane flares to refreeze them, this may be fairly fast as the bubbles create an up-flow pulling in colder water at the sides all winter.

Using the ice-polders and larger areas calmed by levee sections and shoals to then corral and sustain ice much longer if not year-round in half the Bering Sea, all of the Chukchi Sea and extend into the Beaufort on the Alaska side, to levee & shoal the entire Arctic Basin the goal.

It's time to get serious and try to stop the early melt-out by the ice each spring to-sea from the shoreline.

It's all heat-transfer physics doing this water is 13-times better at holding heat than air, we must stall and pond the runoff from permafrost melting inland until 2070 then it slows down, all the glaciers in Alaska and globally are gone by then for being late-season water supplies.

The reduction in volume into the Arctic Basin reduces the volume of warmer Atlantic water drawn in to just under 1-sverdrup of 3-sverdrup coming a 30% reduction, the North Atlantic Overturning Current is about 15-sverdrups [1-sverdrup = 1-million cubic-meters/second].

This counters the Gulf Stream disruption of the AOC by 30%, not trivial, and prevents 30-Terawatt-hours a year of heat coming in as fresher water staying on top melting ice from below to 300-Gigawatt-hours/year of heat, these facts why it can have a large effect globally.

All it takes is recognition of this needing to be done, and, emission reductions are too slow to matter now to the accelerating feedbacks including ocean acidification.

Finally, to close a loop I want to ship the brine from California's new desalination plants to Alaskan waters to dispense there to counter acidification, a fairly new shellfish farm can't grow 4-5 months of the year ...

[Original statements & first few pages are an archive, most recent Q&A on the last page]
Why even think of trying to reduce flow through Bering Strait?
Briefly, Archer, Zeebe et al. have shown a general rule that CO2 is persistent now with a 3‰ isotopic variation matching an extinction event from so much carbon so fast.

    The planetary rule is 25% of the carbon we emit lasts for 10,000-years, that's 1/4 of 37-Gt of CO2 just last year and this legacy carbon is cumulative due to being in a geologic carbon excursion shown by oceans acidifying 10-times faster than the PETM:
    Let addCarbon = carbon added in a year
    Let legacyCarbon = the excess in the atmosphere + oceans
    Total legacyCarbon: legacyCarbon += (0.25 * addCarbon)

    This is the reason for actions not connected to emissions that has the largest effect thermally to maintain the remnant of sea-ice left to forestall the gain in albedo-loss doubling Arctic heating.
************************************************************

    A previous screenshot of predicted aragonite saturation curves for the three main Alaskan fisheries all going below 1 by 2070, the last the Bering Sea affecting that crab fishery.

    First seeing that the Anadyr Current water had most of the nutrient supply used in the Chukchi Sea so the preferred flow to allow into the Arctic Basin, now add in the end of these fisheries by 2100 as commercially viable with no actions taken as part of the problem to solve.

    That leads to the problem of what to do with the freshwater outflow from the glaciers until about that time when they'll be fractions of today's volume so far less of a problem to fisheries?

   That led me to think of how to sustain the fisheries by diverting the freshwater intentionally away to the Pacific near shore at first then to join the surface currents in a way that doesn't put that water against the shoreline south as the long-term need to prevent it from acidifying those coastal waters.

    It seems the best way to confine the Yukon and rivers on the coast to a path that enters the Gulf through Etolin Strait with Nunivak Island offshore. The same idea is applied to the western shoreline the problem there to not mix into the nutrient flow currents when diverting it.

    This only changes the closure on the Alaska side to have a diversion dam the main closure abuts, it makes more work yet today a shellfish hatchery only has a 5-month window at their location to use the water due to runoff. [A design reaction is to create a vortex to sort out these to draw deeper water into them and funnel freshwater past them.]

    To extend a dam from Nunivak Island to St. Matthew Island would send this freshwater west all the way to join the excess freshwater from the Anadyr side going south to Kamchatka. So far and sketching in many miles of dams it can work to extend the fisheries for some decades beyond 2070 for crab.

    The very southern Chukchi Sea can be closed Cape Hope to Cape Serdtse-Kamen in a progression with ice-polders the intention to over time expand along the shoreline east and west to delay it going ice-free early, extending the frozen bottom zone.

Main categories of critique:
Extending Ice Season
        2015 - FEEM Lecture: "Arctic Amplification, Climate Change, Global Warming. New Challenges from the Top of the World"; 1:43:26;
        Sea-ice yearly animation; 3:27;
        Heat-gain metrics and processes; "Charles Kennel:The Impacts of Arctic Sea Ice Retreat on Contemporary Climate."; 21:59;
        "Ocean Heat Uptake: The Apparent Hiatus in Global Warming and Climate Sensitivity"; 29:01;
        "Assessing the Habitability and Physical Structure of Rotting First-year Arctic Sea Ice "; APL-UW; 6:38;
Routes
        St. Lawrence Island to Cape Romanzof: http://www.mallard-design.com/mdc2010/media/st-lawrence-to-cape3.jpg
        Original route Wales to Cape Nunyamo: http://www.mallard-design.com/mdc2010/media/dam-bering-route.jpg
        Extension after straits closed north: http://www.mallard-design.com/mdc2010/media/kotzube-sound.jpg
Construction
        Post on construction details: https://www.postwaves.com/posts/2739558625
        Dutch history totally relates this uses their concepts in deeper water; "Holland's Barriers to The Sea"; 44:21;
        Related proposesd dam building techniques; "Earth Under Water - Worldwide Flooding | Sea Level Rise (SLR)"; 45:08;
Habitats & Migration
        “Ridgwell and Schmidt found that ocean acidification is happening about ten times faster today than it did 55 million years ago.”; http://www.nature.com/ngeo/journal/v3/n3/abs/ngeo755.html; long article; http://e360.yale.edu/feature/an_ominous_warning_on_the__effects_of_ocean_acidification/2241/
        The circular shape puts the center of the whirlpool at the "V" of the backflow, this is a perfect location for a fish ladder of those going upstream into the Pacific.
        The design a vertical version of one made commercially for canals, works well for waterfalls since been installed demo tape from 2012.
        Note how non-damaging their design is versus standard blades for wildlife why I like it; "Hydrovolts hydrokinteic turbine in the Roza Canal"; 3:21;
Water Column Cooling
       "Methane Hydrates - Extended Interview Extracts With Natalia Shakhova"; 8:57;
Restore Beaufort Sea
Clathrate Atolls
        Carbon budgets versus carbon excursions, how large carbon releases work over time; Emiliani Lecture 2012, Dr. Zeebe; 52:47;
        "Fall Meeting 2015 Press Conference Alaska’s thawing permafrost Latest results and future projections; American Geophysical Union"; 42:45;
       "Global Warming 56 Million Years Ago: What it Means for Us"; 1:44:14;

Check current & sea-surface anomalies; nullschool: http://earth.nullschool.net/#current/ocean/surface/currents/overlay=sea_surface_temp_anomaly/orthographic=-167.37,66.43,3000[/size]
« Last Edit: December 23, 2016, 02:07:54 PM by timallard »
-tom

jdallen

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #1 on: May 17, 2016, 02:36:50 AM »
Wow... that would be the most massive engineering project in human history.

I'll have to mull this a bit.  The idea is intriguing, but I'm skeptical for two reasons.

First, I'm not sure the unintended environmental consequences of closing off the strait might not overshadow the net benefit.

Second, I'm not sure isolating the Arctic from either export or import of water will protect the ice from increasing heat.
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OldLeatherneck

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #2 on: May 17, 2016, 03:50:44 AM »
Certainly a novel concept, and not impossible to design and implement.  Don't know  about the costs and of course, the unintended consequences.

Shouldn't this thread be moved to Policy and Solutions??
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AbruptSLR

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #3 on: May 17, 2016, 04:37:43 AM »
Other people have had similar ideas for melting or preserving Arctic ice by damming the Bering Strait:

http://www.adn.com/article/could-massive-dam-between-alaska-and-russia-save-arctic
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6roucho

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #4 on: May 17, 2016, 05:08:01 AM »
Does heat advection through the Bering Strait contribute to the thermohaline conveyor cooling and thus sinking in the north Pacific? This would be one way to find out.
« Last Edit: May 17, 2016, 05:18:03 AM by 6roucho »

icy voyeur

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #5 on: May 17, 2016, 05:26:14 AM »
The idea put forward by the Soviets in the 50s was to damn the straight with locks to only admit warmer water in order to melt the Arctic, with the infamous advantages of added sea ports for the USSR. I rather view the idea of damning it to refreeze the Arctic as similar hubris.

sofouuk

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #6 on: May 17, 2016, 05:55:36 AM »
... if you like this sort of thing, see also:  http://onlinelibrary.wiley.com/doi/10.1029/97EO00180/pdf

i don't think it's any less farfetched   :o ::)

oren

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #7 on: May 17, 2016, 07:08:31 AM »
I quite suspect the Russians would prefer the sea ice to be gone and the local climate to warm so they can make better use of their vast frozen lands.
Not to mention all those unintended consequences. And this will not stop AGW just shift it to another canary in the coal mine,

DavidR

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #8 on: May 17, 2016, 09:48:14 AM »
... if you like this sort of thing, see also:  http://onlinelibrary.wiley.com/doi/10.1029/97EO00180/pdf

i don't think it's any less farfetched   :o ::)
Last time the Straits of Gibralta were dammed the Mediterranean dried out.  This would raise sea levels by 10  metres. Another weird idea to leave on the shelf.
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magnamentis

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #9 on: May 17, 2016, 11:15:57 AM »
cannot be compared because the arctic would not be closed, while the mediterranean is closed environment, same like the black seas that were sealed once.

that said i find the entire idea ridiculous for the reasons someone already mentioned. Huge side effect, some of them unaccounted for, no real benefit and then the huge costs and political impossibility.


DoomInTheUK

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #10 on: May 17, 2016, 11:48:31 AM »
Damming the Mediterranean I can just about accept. It would save all the cities around the Med from SLR for a very long time, and the inflow could be controlled to balance the evaporation losses. As projects go, it would certainly count as a 'big thing'. It would still have some serious side effects.

Damming the Bering is a much bigger prospect, for a far less certain result and potentially far worse side effects....and for that reason, I'm out.

Buddy

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #11 on: May 17, 2016, 12:46:15 PM »
ZERO chance of that ever happening.  It would take 5 years MINIMUM from the start time....and it would take 5 years to get to the start time.  By then.....the waters from the Atlantic have moved further into the Arctic.   And besides....Russia would NEVER do it with the US.

Aint happening....ever.
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DavidR

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #12 on: May 17, 2016, 02:23:10 PM »
Damming the Mediterranean I can just about accept. It would save all the cities around the Med from SLR for a very long time, and the inflow could be controlled to balance the evaporation losses. As projects go, it would certainly count as a 'big thing'. It would still have some serious side effects.

Damming the Bering is a much bigger prospect, for a far less certain result and potentially far worse side effects....and for that reason, I'm out.
Given that  the objective is to keep salt out and the Med probably evaporates at about 1-2 M per year, all those cities would be looking for the ocean in just  a few years. Aral Sea ring any bells?

Which means you's have to  let the Atlantic in which would rather defeat the purpose of the exercise. Like the Bering Dam the cost  would not be worth the benefit.
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DoomInTheUK

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #13 on: May 17, 2016, 03:47:55 PM »
The Med plan was to include turbines to produce electricity, and locks for shipping. Yes the idea was to let some of the Atlantic in, just not enough to flood the surrounding cities.

The big problem was that the Med would tend to get saltier due to evaporation - but it would take a while.

oren

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #14 on: May 17, 2016, 09:23:18 PM »
And just imagine, as sea levels rose higher and the dam in Gibraltar held back more and more water, one good bombing (or just dam collapse for whatever reason) - so many people dead, so many cities flooded. Bad idea. Seriously.

sofouuk

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #15 on: May 18, 2016, 04:26:35 AM »
'Nevertheless, if the conceptual model is ap­ proximately correct, a new ice age can be avoided if a partial dam is constructed on the sill across the strait 40 km west of Gibraltar (Figure 3a). By limiting the Mediterranean outflow to, for example, 20% of today's flow rate, the higher-velocity component of flow approaching the Scotland-Faeroe sill would be removed, upwelling would diminish, warm surface water now diverted to Labra­ dor would enter the Nordic Seas, Canada would remain dry, and Europe's climate would remain mild and stable'

the paper wasn't advocating draining the Mediterranean. it might not make it much more sensible, but it's not entirely stupid, either - it did get published, at least

6roucho

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #16 on: May 18, 2016, 06:16:53 AM »
The subject of geo-engineering came up on the 2016 melting season thread, and this is an example of geo-engineering: in this case to modify ocean heat flows.

While this idea (and the Mediterranean version) seems outlandish, it's worth discussing because it raises some interesting points. If we hope to shift a system as large as the climate, then unless we can identify a convenient chaotic attractor, such as that mythical butterfly, then interventions of this size (or greater) will be what has to happen.

Perhaps interrupting ocean flows is that attractor, and if we're going to interrupt ocean flows, then the Bering Straits is an obvious candidate.

As with all such ideas, I question our ability to predict scientifically what will happen. The outcome might in the range of preferable results, or it might not.

Entropy suggests that the range of preferable results is likely to be smaller, unless climate is somehow homeostatic to our needs, on the anthropic principle. Entering into a potentially biosphere-changing project on that assumption would be highly optimistic.

On the other hand, it might make no difference at all.

epiphyte

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #17 on: May 18, 2016, 06:58:45 PM »
Damming the Mediterranean I can just about accept. It would save all the cities around the Med from SLR for a very long time, and the inflow could be controlled to balance the evaporation losses. As projects go, it would certainly count as a 'big thing'.It would still have some serious side effects.


E.g. It would smell _really_ bad for about 200 years!
(just ask anyone who has ever passed within a mile of a salt pan...)

cesium62

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #18 on: May 18, 2016, 10:58:09 PM »
Wow... that would be the most massive engineering project in human history.

A Tailings dam seems like a comparable structure.  The largest of these seems like it would have roughly the correct height, but be about one-fifth of the necessary length of a dam across the Bering strait.

Other large structures, not necessarily a single project, include:

Dubai islands

More Dubai islands.

Bridges

Dams

Tunnels

The US interstate system or even just I-5 seem like they would easily be more massive, although not a single project.

crandles

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #19 on: May 19, 2016, 12:02:30 AM »
Wow... that would be the most massive engineering project in human history.

A Tailings dam seems like a comparable structure.  The largest of these seems like it would have roughly the correct height, but be about one-fifth of the necessary length of a dam across the Bering strait.

Other large structures, not necessarily a single project, include:

Dubai islands

More Dubai islands.

Bridges

Dams

Tunnels

The US interstate system or even just I-5 seem like they would easily be more massive, although not a single project.

No mention of Suez Canal or Panama Canal? They seem like more obvious larger scale engineering projects.

RoxTheGeologist

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #20 on: May 19, 2016, 01:11:18 AM »
Wow... that would be the most massive engineering project in human history.

A Tailings dam seems like a comparable structure.  The largest of these seems like it would have roughly the correct height, but be about one-fifth of the necessary length of a dam across the Bering strait.

Other large structures, not necessarily a single project, include:

Dubai islands

More Dubai islands.

Bridges

Dams

Tunnels

The US interstate system or even just I-5 seem like they would easily be more massive, although not a single project.

No mention of Suez Canal or Panama Canal? They seem like more obvious larger scale engineering projects.

Those projects had very obvious ROIs.

I'm not sure spending billions of putting a barrier across the strait is going to be top of anyone's list when it becomes clear the extent of coastal defenses that are going to be built around some VERY expensive real estate. There is no monetary gain, no political will. Perhaps if you could soften the political landscape with some sweet contracts to the engineers and construction companies you have a chance in hell of this ever happening.

The carbon cost of the project (and it's maintenance) would be enormous as well.

timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #21 on: May 19, 2016, 01:53:06 AM »
In response to critique, in no particular order:

The flow rate from the Pacific into the Arctic Basin is about 10^6m³/second and supplies about 30% of water input for the Basin, that volume will be removed from current forcing fresher water into the North Atlantic from rivers & precipitation I feel Greenland's meltwater will replace this; [http://www.colorado.edu/geography/class_homepages/geog_5241_f09/media/Readings/week_5_serreze_et_al_2006.pdf].

The main thermal issue is that sea-ice is being melted from below by warm water not as much by air temps [Pertinent to several questions; "Climate and Evolution:Charles Kennel:The Impacts of Arctic Sea Ice Retreat on Contemporary Climate."; 21:58; ].

To me on coastal civil engineering it's a simple project today using barge-dredges that place the output, depths are under 30-fathoms so moderate, recall that the land bridge was there until 12,000-years ago, the closure will assist restoring habitat for sea-mammals that's being lost and estuaries for birds.

How can sea-ice possibly be restored otherwise? We lost it in this area it's not coming back, there's no ice there now and should be at that latitude, warm Pacific water has currents east and west from the straits near shore that speed full melting to blue water and it expands into the Beaufort Sea.

The main dam is 40-miles or so in two sections, someone put out 5-years to build it & seems that's about right so very fast for a large project, most dams would take 4-5 times longer and the shipping canals & locks may take a decade.

Consider that the depth of Gibraltar is over 1,000ft, this is under 180ft so not comparable really, slabbing ice in winter part of why having most of the roadway-railroad separate from where the Pacific can stack it up.

Without restoring a refuge for the traditional longer season of ice ... it's gone already, functionally from the Eastern Basin, the Chukchi & Beaufort Seas and westward to the Lana River where methane stores are, land & clathrates.

Thus beyond sea-mammal concerns, how will one restore sea-ice to this area if the Straits are not dammed?

There is no substitute for albedo that's proven by others in 2007 the big deal was too much latent heat left in the water in fall, it couldn't cool fast enough so ended up degrading the ice, a storm finished it off yet to paraphrase, "It was on its way out anyway.".

So that's the serious concern, we can't restore sea-ice at this time and need to, my experience says this has a really good chance to keep ice in the straits much longer than today if we act soon.

Not likely, the global oceans are 1.6C warmer than pre-industrial if they go over 2C that means another big jump in heat retention by the Arctic Ocean, the video pointing out that it's a large portion of heat gain now separate from greenhousing thus a new thermal heat input & strong feedback.

As a historian of these things humanity will have to do this eventually, there's no way to restore sea-ice there without stopping both the warmer water and the ice movements from the Pacific, by having a relatively still-water refuge for the ice to not get pushed around much and currents weak below the ice in shallow water a miracle to refreeze the bottom to -2C.

What else can is why to present the idea and hash it out.

-tom

wehappyfew

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #22 on: May 19, 2016, 01:55:20 AM »
A better approach would be to make the dam out of ice - a la Game of Thrones - by pumping sea water on top of the ice floes in winter time, until they are grounded on the seafloor.  This has the advantage of increasing albedo during the construction phase, and being completely reversible if it turns out to be a bad idea.

And spray the water in the air near the end of winter to make artificial snow. This insulates the ice, and increases albedo further to protect the ice dam over the summer months.

timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #23 on: May 19, 2016, 03:30:53 AM »
A better approach would be to make the dam out of ice - a la Game of Thrones - by pumping sea water on top of the ice floes in winter time, until they are grounded on the seafloor.  This has the advantage of increasing albedo during the construction phase, and being completely reversible if it turns out to be a bad idea.

And spray the water in the air near the end of winter to make artificial snow. This insulates the ice, and increases albedo further to protect the ice dam over the summer months.

Ok idea in construction at times a reaction but no snow as you say it's insulation that's bad, the air is colder than the ice we want to cool the water below the ice to -2C to freeze the bottom, scratch the snow idea versus trying to freeze the seabed in winter to control clathrate releases, a most difficult task.

Then, consider this dam is reversible and built in phases, it should be obvious after the Wales to Fairway Rock section is roughed in what to do, in any case not hard to remove had the thought.

The design focus to be enduring is creating a longshore current west-to-east to maintain the beaches the entire span with a lot of estuaries, these where the slabs slide to on the Pacific side.

That's essential to create something that fits into ocean currents and works with them on that side and the goal still-water on the other.
-tom

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #24 on: May 19, 2016, 06:34:09 AM »
'Ok idea in construction at times a reaction but no snow as you say it's insulation that's bad, the air is colder than the ice we want to cool the water below the ice to -2C to freeze the bottom, scratch the snow idea versus trying to freeze the seabed in winter to control clathrate releases, a most difficult task.'

don't understand any of this - not sure how feasible it would really be to block the strait with artificially generated ice, but it would certainly be easier than building a dam. just keep pumping water from below the ice onto the ice throughout the winter, and you could generate a huge ice plug by springtime (and if you froze cables inside the new ice, you could presumably even try to hold it in place). can't really think of a downside - building a huge dam in that environment would be a horrendous task (too remote, too dangerous, too vulnerable to inevitable pollution, etc) but pumping and spraying water across a strait that's only a few kms wide is probably doable

LRC1962

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #25 on: May 19, 2016, 09:48:06 AM »
Laws of thermodynamics may come into play as far as being able to make any headway as far as retaining ice using ice dams and ice dams historically have been known to have catastrophic collapses that may make things worse. Using concrete would be IMO a nonstarter as the amount of heat given off by the chemical reactions setting the concrete are huge and that is not taking into account the amount of CO2 produced to make it.
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timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #26 on: May 19, 2016, 09:48:55 AM »
'Ok idea in construction at times a reaction but no snow as you say it's insulation that's bad, the air is colder than the ice we want to cool the water below the ice to -2C to freeze the bottom, scratch the snow idea versus trying to freeze the seabed in winter to control clathrate releases, a most difficult task.'

don't understand any of this - not sure how feasible it would really be to block the strait with artificially generated ice, but it would certainly be easier than building a dam. just keep pumping water from below the ice onto the ice throughout the winter, and you could generate a huge ice plug by springtime (and if you froze cables inside the new ice, you could presumably even try to hold it in place). can't really think of a downside - building a huge dam in that environment would be a horrendous task (too remote, too dangerous, too vulnerable to inevitable pollution, etc) but pumping and spraying water across a strait that's only a few kms wide is probably doable

Let me explain what sea-ice does. It stops winds and waves and transfers thermal energy & CO2-CH4 from recent findings.

Right now Bering Straits melts out first and forms last seasonally in the Eastern Arctic Basin, opening the Arctic Ocean from there to instigate widespread open water in the Beaufort Sea.

When the sea-ice is lost the ocean gains heat, to freeze the bottom the ocean water needs to be -2C/28.4F to freeze, if the seawater is 0C not happening, right now it's 0.9C in the straits so it's impossible to freeze saltwater, won't for sure alter the warmer water near the bottom with the present situation.

The seawater is too warm it'll melt the ice from above just like it melts it from below.

It's a fallacy to think the air will freeze it when water is such a high specific heat, the air can't remove enough heat in fall from the Arctic water and the Pacific water that flows north into the straits never is that cold is the problem.

The only prior situation that allowed sea-ice to grow to where it can freeze the bottom is persistence for much more of the season to not gain too much heat to be lost in fall to allow temps to drop to -2C for critical shallow sea areas like East Siberia's margin.

That's the geophysical reality to deal with. Why sea-ice works is that it keeps the wind & waves from distributing heat into the water column all the way to the bottom and this thaws the bottom, the present situation.

Thus we need a physical dam to keep this warmer water away from the entrance to the Beaufort Sea or it's game-over on having sea-ice persist to where it can refreeze the bottom in the Eastern Arctic Basin without still-water in Bering Strait to stop the instigation of sea-ice loss seasonally and the loss of the albedo of the sea-ice.

The method to construct is like China is using to create islands in the South China Sea, like that proposed for a dam across the Golden Gate to prevent salination of their freshwater supplies.

The Dutch did 11-miles to close the last stretch of water to prevent flooding with gates against the North Sea ... it can be done, to create a still-water refuge for ice to grow to where the water below it gets to -2C most of the year is the geophysical need.
-tom

sofouuk

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #27 on: May 19, 2016, 01:43:20 PM »
I think you're overestimating how fast ice melts - a block of ice 60 or so m high, several kms long and wide isn't going anywhere in a single summer, and could be quickly 'repaired' the following winter. there's no need to immediately freeze the ocean to the bottom - if you just keep adding ice to the pack floating on the surface, it will eventually ground itself when it gets thick enough. but never mind - this is never going to happen

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #28 on: May 19, 2016, 03:46:59 PM »
The ice dam is not built from the bottom up... but from the surface down. In the depth of winter, when air temps are -25C, wind 50km/hr, zero solar insolation, the surface freezes in seconds. Then pump another few cm of water on top of the floe. The cold wind carries away the phase change heat.

How fast can it accumulate? Not sure. Maybe some cold climate members can relates some experience with freezing rates. Maye 1 meter/day? 50m/winter?

The point of the artificial snow is to insulate the ice mass from summer warmth. Accumulate solid ice during winter, but slow enough that it can cool down to -10 or-15C. Then cap it off with several meters of snow in early spring. This will keep the ice cold (and strong) over the summer. Replace any melted ice the following winter.

Once the floe reaches full depth and is grounded in the sediment, it will no longer gain heat from the warm sea water below, and it can start to cool down and compress the permafrost and clathrates of the continental shelf, preventing them from releasing their CO2 and CH4.


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Re: Damming Bering Straits to Restore Sea-ice
« Reply #29 on: May 19, 2016, 06:52:50 PM »
Wait a minute, forget the dam.  If you can build massive amounts of ice by pumping water over the ice in winter, why not just do that for the whole ice pack?  Or strategic areas like the peripheral seas?

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #30 on: May 19, 2016, 07:27:58 PM »
Wait a minute, forget the dam.  If you can build massive amounts of ice by pumping water over the ice in winter, why not just do that for the whole ice pack?  Or strategic areas like the peripheral seas?
Scale, anotheramethyst.  The infrastructure required to do that is pretty vast, and would introduce additional feedbacks.  It would be an engineering project on a scale an order of magnitude larger than the dam, which in itself would be the biggest single engineering project in history.

While building an ice dam is attractive, I'm not sure the it could resist the tidal forces applied to it daily.  It would need to be an earthen bank structure eventually, and would require pretty staggering volumes of material - potentially 10's of cubic kilometers worth.  You would need 1000's of massive haulers working around the clock for years just to move it.  You would then need to surface the berm with durable material - concrete, rock fill, etc. - which would probably require the best part of a cubic kilometer of concrete - thousands of times more than used in some of the biggest dams ever built. 

For comparison, the largest tailings dams are about 500,000,000 M3 in size or less - that's only about 1/2 cubic KM3, and they took years to build.  A Bering dam would require more fill than all the dams ever built previously by humanity combined - All of them.

I think we need to better wrap our heads around the sheer scale of this.
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wehappyfew

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #31 on: May 19, 2016, 07:37:53 PM »
If the goal is to reduce heat flow to the CAB, then the dam doesn't need to be watertight, it doesn't even really need to be a dam - it just needs to block most of the flow. Leave gaps, maybe reinforced with concrete, or rocks to resist erosion.

Pykrete is an option where needed for additional tensile strength and heat resistance.

(Pykrete is a composite of ice and wood fiber/pulp)

Applying this to the whole basin? Not gonna happen. Much harder in deep water, Arctic is too big which means it doesn't scale, as jdallen points out. For some vital areas, like vulnerable clathrates or subsea permafrost? Maybe...

I remember a SciFi novel where an iconoclastic billionaire had built an artificial ice pack at the North Pole (hundreds of meters thick) to preserve a bit of ice. Once most ice is melting out in summer, I don't see how this artificial ice pack won't just get flushed out the Fram.

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #32 on: May 19, 2016, 08:03:57 PM »
Some reference information.

http://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-2300.pdf

Now, imagine building 82 of the larger dams humanity has constructed, and doing so in a region with no infrastructure, where work can only be done effectively about 4 months out of the year.  It would cost 10s of trillions of dollars to build, and require a direct workforce of well over a million.
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P-maker

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #33 on: May 19, 2016, 09:35:16 PM »
If Donald T can promise to build a wall towards the Mexicans, why can't the Americans promise to build a wall to keep the Arctic Basin cold. It is one of the better ideas flagged recently, and it will keep them occupied as long as the rest of the World is busy building energy efficient renewables...

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #34 on: May 19, 2016, 11:23:08 PM »
On the add-water-let-it-freeze concept, which is valid, yet, consider the whole time you're doing that the ice is actively being melted from below by the Pacific Ocean water so that decreasing the rate-of-gain this is why the ice goes so fast in spring.

Thus when that warmer water hits where one isn't adding seawater to thicken it, this same current will waste north of where you quit earlier in the season and keep it free of ice later like it does now.

Review any animation for the past decades and focus on the straits you'll see it gets to today where it goes first and returns last, leading the open water my thesis from this ocean current warmth.

So, there needs to be a surface-to-bottom damming of flow north, a full closure, to remove the Pacific water naturally being warmer so a higher sea-level combined with the new, persistent warm blob north of the Aleutian chain adding to that and wrapping the Alaskan coast into the straits from that sea-height difference.

To me the technique will be used, yet we must dam the flow, it's not just the sea-ice in the straits themselves, it's to prevent the spread early of open water.

-tom

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #35 on: May 19, 2016, 11:46:46 PM »
Now, imagine building 82 of the larger dams humanity has constructed, and doing so in a region with no infrastructure, where work can only be done effectively about 4 months out of the year.  It would cost 10s of trillions of dollars to build, and require a direct workforce of well over a million.

Sir, I have a strategy to operate and have based assumptions not on how the military operates which is the highest cost-per-watt of any known industry.

This is a dredge-n-fill project not a "dam" per se, it's a geophysical barrier not a pretty picture with smooth walls the railway-roadway not needed it's to handle Pacific Ocean fetch slabbing sea-ice onto it off-n-on during winter and storing that ice in estuaries before you get close to a roadway.

For budget, consider a rag-tag low-budget dredge operator wanting to make a killing types for a thought that'll out-compete your fancy stuff no problem, you build some railways laying the bed ahead of the train bubba and it doesn't matter what the weather is doing if one is on the lee side of the dam.

To drill the Arctic we have ice-breakers galore & iceberg movers and all kinds of vessels to use in support all winter we be doing this 365 24x7 if you got the cash honey.

This is a geophysical barrier not a wall, design decision is to lay in a shallows before the above sea-level part on the Pacific side to create slabbing and allow a longshore current development to deposit sand free-of-charge so one starts on the Russian side.

Think it over, China is building islands as we speak using this technique, perhaps the military is obsolete?
-tom

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #36 on: May 19, 2016, 11:47:58 PM »
Does first-year ice have enough strength to act as a dam?  Constructing a dam by adding layer upon layer of water to the top is essentially creating a giant block of first-year ice.  I could see an iceberg made from glacial ice having enough strength, but such ice has been compressed for decades.  It seems to me that first-year ice would easily break apart once it reaches a certain size.

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #37 on: May 20, 2016, 12:05:22 AM »
In Reply #24 of the "Possible Iceberg Wrangling in the Southern Ocean" thread, I discuss the possibility of towing icebergs from Greenland to the Bering Strait (to make a grounded iceberg barrier) sometime between 2030 & 2050 after policy makers become more motivated:

http://forum.arctic-sea-ice.net/index.php/topic,1389.msg63124.html#msg63124
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Re: Damming Bering Straits to Restore Sea-ice
« Reply #38 on: May 20, 2016, 12:14:25 AM »
Now, imagine building 82 of the larger dams humanity has constructed, and doing so in a region with no infrastructure, where work can only be done effectively about 4 months out of the year.  It would cost 10s of trillions of dollars to build, and require a direct workforce of well over a million.

Sir, I have a strategy to operate and have based assumptions not on how the military operates which is the highest cost-per-watt of any known industry.

This is a dredge-n-fill project not a "dam" per se, it's a geophysical barrier not a pretty picture with smooth walls the railway-roadway not needed it's to handle Pacific Ocean fetch slabbing sea-ice onto it off-n-on during winter and storing that ice in estuaries before you get close to a roadway.

For budget, consider a rag-tag low-budget dredge operator wanting to make a killing types for a thought that'll out-compete your fancy stuff no problem, you build some railways laying the bed ahead of the train bubba and it doesn't matter what the weather is doing if one is on the lee side of the dam.

To drill the Arctic we have ice-breakers galore & iceberg movers and all kinds of vessels to use in support all winter we be doing this 365 24x7 if you got the cash honey.

This is a geophysical barrier not a wall, design decision is to lay in a shallows before the above sea-level part on the Pacific side to create slabbing and allow a longshore current development to deposit sand free-of-charge so one starts on the Russian side.

Think it over, China is building islands as we speak using this technique, perhaps the military is obsolete?

Ooof.  I'm not talking about the price at "military levels" of inefficiency, I'm talking about private sector with their drive to profit and efficient delivery.

I'm not talking about smooth walls or any such nonsense.  I'm talking about a geophysical barrier large enough and robust enough to stand up to the pretty massive forces which will be applied to it, which will be non-trivial when you consider the effect of waves and current, much less ice being rammed into it.  And as to a road... you think we can just leave a pile of dirt in the Bering Strait and expect it to remain intact without actively maintaining it?

China making islands?  Not even in the same ballpark as building a typical dam much less this one.  They are piling up sand and coral over an area with water depths of well under 10 meters, generally under 5, and they've only gotten a couple of square KM.  You do not have a sense of the scale required for this, at all.

Dredge and fill?  Your project will fail if you use that method.  You need to show me what engineering you will use, and how it will stand up.  The Corps of Engineers is actually filled with a lot of really sharp people who understand what they are doing.  You are unwise to dismiss them out of hand.

Your expectation of cheap labor... really?!  Have you looked into the kind of effort required to support any kind of construction in the Arctic?  We're talking about the biggest project in human history, and trying to carry it out in terrain which 6 months out of the year is actively trying to kill people, destroys machinery and defies efforts to tame it.  It would take over a decade just to build the infrastructure required to support it.


The idea of having "rag tag workers" to reduce cost is just absurd, bluntly.  I really don't think you understand the necessary logistics, much less the engineering required.

Current deposit sand free of charge?  Then why isn't the strait filling now?  What makes you think it will stay?

I'm far from convinced. Very far.
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timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #39 on: May 20, 2016, 12:31:08 AM »
Quote

Ooof.  I'm not talking about the price at "military levels" of inefficiency, I'm talking about private sector with their drive to profit and efficient delivery.

I'm not buying your issues listed they don't address the underlying need.

People dredge for gold there, it's high-tech & efficient processing of materials with many innovations by small-timers, the input will be tested for archeological evidence to shut down quickly and move to the alternative sources, yeah things will be lost stating awareness.

Dredging is an expert local resource the only enterprise-level concern is supply-chain to parts for repairs being timely with a shop to make them along with said support for a global-scale project with living quarters and so forth.

You're not making a point on the need for the geophysical end to early ice loss from the Pacific water and late formation in the Beaufort Sea, address that sir.
-tom

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #40 on: May 20, 2016, 12:55:56 AM »
Let's make another pass at this, hopefully with a bit more patience on my part.

I'm not buying your issues listed they don't address the underlying need.

They are independent of the need.  I'm not questioning the need, I'm questioning your solution to it.  That's the nature of my issues.

People dredge for gold there, it's high-tech & efficient processing of materials with many innovations by small-timers, the input will be tested for archeological evidence to shut down quickly and move to the alternative sources, yeah things will be lost stating awareness.

Dredging is an expert local resource the only enterprise-level concern is supply-chain to parts for repairs being timely with a shop to make them along with said support for a global-scale project with living quarters and so forth.

So, lets break this down.

How many cubic meters of material are processed by dredging operations in Alaska on an annual basis?

How many cubic meters of material per worker per day do they move? (recall, to build this will require moving 10's of billions of cubic meters of material...)

How many people total are involved currently in Alaska dredge mining?

How transferable is the terrestrial technology you're talking about to a seaborne setting?

How many additional operators will we need to create an operation large enough to finish the project in a timely (less than 2 decades) fashion?

How much will it cost for us to train them?

How much will it cost for us to house them?

How will we provide them with the energy, equipment and materials to do the work?  How much will it cost?  How long will it take to get set up?

What I'm trying to get at, a few hundred sluice and dredge miners from Alaska are not going to be able to tinker together and scale an operation to build a dam across the Bering.

You're not making a point on the need for the geophysical end to early ice loss from the Pacific water and late formation in the Beaufort Sea, address that sir.

I'm not denying the need to stop early ice loss.  I'm pointing out the economic and logistical problems with your solution.  I haven't even started on the potential environmental ones.

It's not even clear that the proposed solution would work.  We haven't even established a case for building it in the first place.  It doesn't look at all like a magic bullet for the problem.

And in the face of that, you're talking about trying to marshal resources and manpower that would bankrupt most nations, and keeping it at work for at least 20 years. The political resistance to it will be immense, probably insurmountable.

I suggest you mull this over a little bit, considering the time scales, cost and resources required to carry it out.

https://en.wikipedia.org/wiki/Palm_Islands
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timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #41 on: May 20, 2016, 01:03:56 AM »
Let's make another pass at this, hopefully with a bit more patience on my part.

I'm not buying your issues listed they don't address the underlying need.
Quote
They are independent of the need.  I'm not questioning the need, I'm questioning your solution to it.  That's the nature of my issues.

That's ok then. Let people buy into your costs of operation versus mine. The big rigs are doing the main moving the small-timers provide the cladding and specialty stuff, what's your plan again?
-tom

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #42 on: May 20, 2016, 05:21:22 AM »
Let's make another pass at this, hopefully with a bit more patience on my part.

I'm not buying your issues listed they don't address the underlying need.
Quote
They are independent of the need.  I'm not questioning the need, I'm questioning your solution to it.  That's the nature of my issues.

That's ok then. Let people buy into your costs of operation versus mine. The big rigs are doing the main moving the small-timers provide the cladding and specialty stuff, what's your plan again?


Hmmm.  So we base whether we do this or not on feelings rather than logic.

Nice attempt at firing up a "Tu Quoque" fallacious argument; whether I have a solution or not is irrelevant.  What is relevant or not is whether the one you suggest will *work*.  That's far from proven.

Short form:  If you want to prove your point, you need to address my questions and criticisms.  Show your work.  Demonstrate how it will work.
« Last Edit: May 20, 2016, 05:39:39 AM by jdallen »
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Eli81

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #43 on: May 20, 2016, 05:23:43 AM »
With respect.... as jdallen says, it is very clear that you have absolutely no concept of the scales involved here.

Perhaps you're aware of our Herculean efforts to tame the Mississippi River, which at peak flow, represents 2% of the flow through the straight. By the way, that project has cost ~7 billion, and the upkeep of the structures is a constant uphill battle.

How exactly do you propose we tame the unfathomable forces behind the transport of 15.8 billion gallons of water per minute? With dredge? Seriously? That's 15 with nine zeroes behind it. You are vastly, vastly underestimating the power of water, the ocean and the harshness of the Arctic here...

We could probably do it - If all of humanity were to get behind the idea, and every nation that could were to pour money and resources into it. Manpower, equipment and money.

And we don't even know if it would work, nor the possible undesirable consequences. There is no way that this will ever happen.

That money and effort would be far better spent on 1) transitioning from fossil fuels or

2) More space exploration; Colonizing mars, etc.

We are well past the point of state change - in fact, it appears the state change happened way back in 1987http://onlinelibrary.wiley.com/doi/10.1111/gcb.13106/abstract.  An ice free arctic is inevitable with CO2 at 400PPM and climbing, just a matter of when the new stable regime is reached. That doesn't mean we should give up the good fight, but this is not the solution.

/delurk

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #44 on: May 20, 2016, 06:26:46 AM »
'Does first-year ice have enough strength to act as a dam?  Constructing a dam by adding layer upon layer of water to the top is essentially creating a giant block of first-year ice.'

I don't think it needs to be a contiguous, robust structure as such - the idea was just to create so much ice that the straits are choked with it, then it literally has nowhere to go, and the melting season would barely make a dent in it. the doubt would be how many (floating, obviously) pumping stations you would need in the first place - given the length of the freezing season I don't think there's much doubt you could generate 60 m thick ice, but it would be extremely difficult technologically (how to keep the pumps and pipes from freezing) and safety issues would be a nightmare (there would have to be human operators up there throughout the winter, and they'd be creating an unstable monster which they'd be right next to). again, I'm sure that it could be done, and it could work, but it's never going to happen

Flocke

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #45 on: May 20, 2016, 08:33:52 AM »
Drastic measures sometimes have unexpected consequences.

Thanks to cesium. In his post in this almost unnoticed thread he quotes the
Arctic Ocean wikipedia article, which surprisingly exactly fits:

Quote
In large parts of the Arctic Ocean, the top layer (about 50 m (160 ft)) is of lower salinity and lower temperature than the rest. It remains relatively stable, because the salinity effect on density is bigger than the temperature effect. It is fed by the freshwater input of the big Siberian and Canadian streams (Ob, Yenisei, Lena, Mackenzie), the water of which quasi floats on the saltier, denser, deeper ocean water. Between this lower salinity layer and the bulk of the ocean lies the so-called halocline, in which both salinity and temperature are rising with increasing depth.
[...]
During the winter, cold Alaskan winds blow over the Chukchi Sea, freezing the surface water and pushing this newly formed ice out to the Pacific. The speed of the ice drift is roughly 1–4 cm/s. This process leaves dense, salty waters in the sea that sink over the continental shelf into the western Arctic Ocean and create a halocline."

The low salinity of the cold top layer in the arctic prevents mixing with the warmer deep water. The cold layer is established by runoff of the arctic rivers and freezing in the Chukchi. A dam might prevent this to some extent ("pushed out to the Pacific"), weakening the layering in the Arctic Ocean. This might lead to a warmer sea surface and less sea ice.

Adam Ash

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #46 on: May 20, 2016, 10:48:07 AM »
This is very silly, but fun. 

Firstly re damming the Med.  You will have to put a plug in the Suez as well if you want to stop the eventual SLR sneaking in the back door...

http://the100metreline.blogspot.co.nz/2009/09/80m-sea-rise-maps-africa-middle-east.html

Secondly re the Damn Bering:  We have no idea what the water levels will stabilise at either side of the dam.  The outcome of a significant head differential and resulting inevitable dam failure would be another 'interesting' unintended consequence of humanity's great geoengineering-by-carbon-emissions project.  To date all we have done is caused our own extinction due to thermal stress.  Lets not get drowned in the process!

timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #47 on: May 20, 2016, 11:06:23 AM »
Responding to things, to some critique I'll employ Dutch engineers over American on a closure a first point on attitude.

A second point is technique used, the wicker mats worked with ballast for cladding and preventing the fill from being eroded, for this deeper water using a surface tube that descends to near the bottom for accuracy is the strategy, shooting it into the air won't work.

This technique will also be used to place the cladding & ballast rock, no clue yet on matting considering hemp.

If you study Andean hydrologic modifications the Dutch methods emulate those in principle in underwater construction being porous yet preventing sediment removal of the clays used for a water barrier, thus the thought to establish the foundations first on the bottom able to resist currents as they are placed.

The tidal closure in many ways is more difficult this closure the current is headed in one direction but doesn't have a slack water, it does have slower flows seasonally, and, for sure as it closes the scour increases.

The strategy of starting in the west is to develop a west-to-east current flow from the Cape, as this happens it redirects the northward volume obviously into what's left, the critical join at Fairway Rock.

So the deep foundation is laid followed by an ongoing stepped construction raising it so much more each step, cladded and able to take the current, creating a new longshore current as it grows; this should model.

Then, how wide are people thinking and what profile for the structure? I have my ideas stated using estuaries to catch slabbing sea-ice that can be a shoal then the above sea-level part on the north.

How does this compare to the proposed closure of Gibraltar for scale, that's quite a lot larger undertaking on the face of it?
-tom

timallard

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #48 on: May 20, 2016, 11:43:45 AM »
Drastic measures sometimes have unexpected consequences.

Thanks to cesium. In his post in this almost unnoticed thread he quotes the
Arctic Ocean wikipedia article, which surprisingly exactly fits:

Quote
In large parts of the Arctic Ocean, the top layer (about 50 m (160 ft)) is of lower salinity and lower temperature than the rest. It remains relatively stable, because the salinity effect on density is bigger than the temperature effect. It is fed by the freshwater input of the big Siberian and Canadian streams (Ob, Yenisei, Lena, Mackenzie), the water of which quasi floats on the saltier, denser, deeper ocean water. Between this lower salinity layer and the bulk of the ocean lies the so-called halocline, in which both salinity and temperature are rising with increasing depth.
[...]
During the winter, cold Alaskan winds blow over the Chukchi Sea, freezing the surface water and pushing this newly formed ice out to the Pacific. The speed of the ice drift is roughly 1–4 cm/s. This process leaves dense, salty waters in the sea that sink over the continental shelf into the western Arctic Ocean and create a halocline."

The low salinity of the cold top layer in the arctic prevents mixing with the warmer deep water. The cold layer is established by runoff of the arctic rivers and freezing in the Chukchi. A dam might prevent this to some extent ("pushed out to the Pacific"), weakening the layering in the Arctic Ocean. This might lead to a warmer sea surface and less sea ice.
Firstly the surface waters are too warm if free of sea-ice too long to give back all the heat absorbed in fall is the problem with the thermal budget.

The big melt in 2007 was almost entirely from bottom melting not warmer air or storms and it's adding 0.21-watts/m² on a global scale just from this flip of albedo with the sea-ice being gone from so much sea.

Then yes, definitely it stops that southerly flow and think about it, that's more likely a good thing on preserving sea-ice north of the dam, it'll pile up and thicken in storms and resist movement after that while not being affected by melting from below, the Pacific water is gone and the circulation in the embayment has river & runoff input of fresh water.

I'm not sure it'll get much interchange with the Chukchi as it's only 50m deep and the warmer water usually is a lot deeper but it may get shoved into the embayment.

So consider it can't lead to a warmer sea-surface where it piles up, south of the dam the ice budget will change and it should have a longshore current from west-to-east to move it around as well as the winds.

Someone may be able to model this scenario my hunch is that south of the dam it will go away sooner so help to melt out north of the dam yet it'll take a lot longer per season.
-tom

Adam Ash

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Re: Damming Bering Straits to Restore Sea-ice
« Reply #49 on: May 20, 2016, 12:21:19 PM »
So you are going to build a fish ladder for whales?  No?  Any other minor environmental or ecological catastrophes you have in mind?  Sigh.