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# Climate networks for MOC collapse detection

I ran across a paper I thought could be of interest to Azimuth climate network people: "Deep ocean early warning signals of an Atlantic MOC collapse". It uses a climate network approach, using methods developed in earlier work ("Interaction network based early warning indicators for the Atlantic MOC collapse" and "Are North Atlantic multidecadal SST anomalies westward propagating?").

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1.

Graeat, thanks! I'm behind on everything, but I should read and blog about these.

Comment Source:Graeat, thanks! I'm behind on everything, but I should read and blog about these.
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2.

Unfortunately these papers are paywalled. Can they be made available somehow?

Comment Source:Unfortunately these papers are paywalled. Can they be made available somehow?
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3.

Open versions here, here, here.

Comment Source:Open versions [here](http://www.climatelinc.eu/fileadmin/UG_ADVANCED/Publications/Qingyi-Dijkstra-2-FAMOUS_grl52004.pdf), [here](https://www.pik-potsdam.de/members/kurths/publikationen/2013/mheen_grl50515.pdf), [here](http://www.climatelinc.eu/fileadmin/UG_ADVANCED/Publications/QINGYI-and-Dijkstra--Are_North_Atlantic_multidecadal_SST_anomalies_west_propagating.pdf).
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4.

Thanks Nathan.

Comment Source:Thanks Nathan.
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5.

Henk Dijkstra's book Nonlinear physical oceanography: A dynamical systems approach to the large scale ocean circulation and El Niño has lots of details about ocean circulation, including box models for flow. He has a chapter called "The Dynamics and Physics of ENSO".

Comment Source:Henk Dijkstra's book [Nonlinear physical oceanography: A dynamical systems approach to the large scale ocean circulation and El Niño](http://rd.springer.com/book/10.1007/1-4020-2263-8) has lots of details about ocean circulation, including box models for flow. He has a chapter called "The Dynamics and Physics of ENSO".
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6.

I must have read about Thietsche et al. (2011) which somewhat discounted a disastrous MOC collapse and is cited in the first paper. That's why MOC in the title triggered my interest.

Thanks for the tip Paul. I've been considering buying Dijkstra's book but can no longer afford a fraction of the books I'd like to buy. I usually go for the latest raw stuff.

Comment Source:I must have read about Thietsche et al. (2011) which somewhat discounted a disastrous MOC collapse and is cited in the first paper. That's why MOC in the title triggered my interest. Thanks for the tip Paul. I've been considering buying Dijkstra's book but can no longer afford a fraction of the books I'd like to buy. I usually go for the latest raw stuff.
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7.

Tietsche et al. is about sea ice thresholds, not MOC collapse. I'm not sure why they cited it in this context.

Comment Source:Tietsche et al. is about sea ice thresholds, not MOC collapse. I'm not sure why they cited it in this context.
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8.

Tietsche et al. is about sea ice thresholds, not MOC collapse.

Ermm. I haven't got as far as reading the refs. Any idea who did the calculation that sea ice collapse wouldn't lead to the MOC stopping a few years ago? It took the item off my agenda.

Comment Source:> Tietsche et al. is about sea ice thresholds, not MOC collapse. Ermm. I haven't got as far as reading the refs. Any idea who did the calculation that sea ice collapse wouldn't lead to the MOC stopping a few years ago? It took the item off my agenda.
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9.

I haven't heard much about sea ice shutting down the MOC; most of the concern I've heard is over warming surface waters, as well as freshwater input from Greenland.

Comment Source:I haven't heard much about sea ice shutting down the MOC; most of the concern I've heard is over warming surface waters, as well as freshwater input from Greenland.
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10.
edited October 2014

I didn't know Arctic sea ice melt and Greenland freshwater exundatation had different causes. The 8.4k year event is claimed to be reasonably attributed to freshwater from Lake Agassiz.

The MOC collapse scare I'd read about sounds like something to do with a letter to Nature by an economist called Wunsch discussed on Real Climate which has details of various confusions in 2006 including conflating the gulf stream, thermohaline circulation and the MOC:

Since the winds will continue to blow and the Earth continue to turn, does this mean that there can’t be any changes to the MOC? Emphatically no. The circulation may well derive it’s energy from the winds and tides, but it is heavily steered by density contrasts and the stratification of the ocean (witness the difference between the North Pacific and the North Atlantic). Changes in that modulation can have profound effects on the currents, and in particular, additions of fresh water from massive lake drainages (i.e. the 8.2 kyr event) or ice sheet collapses (the Heinrich events) most likely caused severe slowdowns or shutdowns of the MOC in the past. Wunsch is a little sceptical of this research (he calls fresh water the ‘deus ex machina’ of climate change), but in this he is probably mistaken – for instance, there is enough information from the 8.2 kyr event to reasonably attribute it to the drainage of Lake Agassiz into Hudson Bay. - See more at: http://www.realclimate.org/index.php/archives/2006/10/carl-wunsch-the-economist-and-the-gulf-stream/#sthash.XqxbGHty.dpuf

Comment Source:I didn't know Arctic sea ice melt and Greenland freshwater exundatation had different causes. The 8.4k year event is claimed to be reasonably attributed to freshwater from Lake Agassiz. The MOC collapse scare I'd read about sounds like something to do with a letter to Nature by an economist called Wunsch discussed on [Real Climate](http://www.realclimate.org/index.php/archives/2006/10/carl-wunsch-the-economist-and-the-gulf-stream/) which has details of various confusions in 2006 including conflating the gulf stream, thermohaline circulation and the MOC: > Since the winds will continue to blow and the Earth continue to turn, does this mean that there can’t be any changes to the MOC? Emphatically no. The circulation may well derive it’s energy from the winds and tides, but it is heavily steered by density contrasts and the stratification of the ocean (witness the difference between the North Pacific and the North Atlantic). Changes in that modulation can have profound effects on the currents, and in particular, additions of fresh water from massive lake drainages (i.e. the 8.2 kyr event) or ice sheet collapses (the Heinrich events) most likely caused severe slowdowns or shutdowns of the MOC in the past. Wunsch is a little sceptical of this research (he calls fresh water the ‘deus ex machina’ of climate change), but in this he is probably mistaken – for instance, there is enough information from the 8.2 kyr event to reasonably attribute it to the drainage of Lake Agassiz into Hudson Bay. - See more at: http://www.realclimate.org/index.php/archives/2006/10/carl-wunsch-the-economist-and-the-gulf-stream/#sthash.XqxbGHty.dpuf
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11.

Hi Nathan,

I hadn't got climatelinc.org in my bookmarks although I'd heard of the LINC collaboration. Great.

Unfortunately I can't find the supplementary info there and that's what's of most interest to me for programming purposes.

Comment Source:Hi Nathan, I hadn't got climatelinc.org in my bookmarks although I'd heard of the LINC collaboration. Great. Unfortunately I can't find the supplementary info there and that's what's of most interest to me for programming purposes.
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12.

WRT to the sloshing model where I identified a break around 1980 in the quasi-periodic behavior of ENSO, I received this as a comment on my blog:

David Mellen on October 20, 2014 at 7:23 pm said: "You might want to look at this article http://www.dailykos.com/story/2014/03/05/1281907/-The-Antarctic-Half-of-the-Global-Thermohaline-Circulation-is-Collapsing it reports that the largest source of Antarctic Bottom Water in the global thermohaline circulation has ceased production around 1980 which might explain the break in 1980"

Problem with these kinds of connections is that they are largely circumstantial.

Comment Source:WRT to the [sloshing model](http://forum.azimuthproject.org/discussion/1504/symbolic-regression-machine-learning-and-enso-time-series/#Item_34) where I identified a break around 1980 in the quasi-periodic behavior of ENSO, I received this as a comment on my blog: > David Mellen on October 20, 2014 at 7:23 pm said: *"You might want to look at this article <http://www.dailykos.com/story/2014/03/05/1281907/-The-Antarctic-Half-of-the-Global-Thermohaline-Circulation-is-Collapsing> it reports that the largest source of Antarctic Bottom Water in the global thermohaline circulation has ceased production around 1980 which might explain the break in 1980"* Problem with these kinds of connections is that they are largely circumstantial.
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13.

Arctic sea ice and Greenland land ice melt do have common causes (surface warming). But they contribute differently to MOC slowdown.

Comment Source:Arctic sea ice and Greenland land ice melt do have common causes (surface warming). But they contribute differently to MOC slowdown.