Your first article makes this claim, but does not explain it. On the face of it, one would expect vigorous stirring to facilitate absorption of CO2 from the atmosphere. and lack of circulation to impede it. Any explanation? — unenlightened

When water absorbs CO2, it makes carbonic acid. A bottle of soda water has a high carbonic acid content until it's either warmed or shaken, both of which will make the water lose it's ability to dissolve CO2.

The second link is not accessible to the Institute for Retired Busybodies, unfortunately. — unenlightened

That's the one from Nature. I'll copy out the good bits. I've been wandering around the Potsdam website for a while. Fascinating stuff.

All in all, the more I find out, the more the whole affair looks like humanity as a mad scientist in the process of blowing up his laboratory and speculating about whether he will be roasted or frozen or both. — unenlightened

That's the reason I found the article about how we might have been tweaking the weather for the last 6000 years to be intriguing. It could be that something as fundamental to who we are as agriculture could be at odds with climate stability.

Sorry, it's from memory. I think I read it in relation to the little ice age. It's something I must've read in 2004-2010 when I was working at the ESA. Might even be obsolete nowadays to be honest.

When water absorbs CO2, it makes carbonic acid. A bottle of soda water has a high carbonic acid content until it's either warmed or shaken, both of which will make the water lose it's ability to dissolve CO2. — Tate

Yes so the effect of circulation is to cool surface water and allow increased absorption. So why the claim that it does the opposite?

Yes so the effect of circulation is to cool surface water and allow increased absorption. So why the claim that it does the opposite? — unenlightened

Circulation brings warm water up from the tropics. When the circulation stalls, it ceases to be a heat conveyor. Is that what you mean? I'll look at it again. I may be missing something.

Yes, which then leads to increased acidification again so not necessarily a good thing.

FYI, found a reference to the research about lower temperatures in the northern hemisphere: https://news.illinois.edu/view/6367/207427

Well, more the sinking and upwelling replacing the surface water, that is presumably reaching an equilibrium with the atmospheric CO2 saturation, with colder deep water that can absorb some more, as well as the cooling tropical water also able to absorb some more. Basically, absorbtion happens at the surface, so if the oceans are stably stratified, CO2 absorption would stop pretty quickly.

Thanks for that. The effect on Europe I suspect would be what we have seen this year; drought. My secondary school education tells me that the mediterranean climate is "warm wet winters with westerly wariables, and hot dry summers". Without the warm water in the Atlantic, that would I guess change towards "cold dry winters and even hotter dryer summers". Fun!

But a much larger question would be the effect on Antarctica. Intuitively, there would be heating of the tropics and cooling at the poles, with much complexification, and thus a loss of temperate climate which is what tiggers and tea drinking monkeys like best.

You seem to be suggesting that the slowing of the circulation may trigger re-glaciation. but this looks to be backwards. Rather it is the melting sea ice that is reducing the salinity and thus the density of the water and so slowing the circulation. Re-glaciation would increase the salinity and thus strengthen the circulation. — unenlightened

I think the situation is a lot more complex than this. Evaporation also increases salinity, and this makes denser warm water, possibly increasing water temperatures at greater depths. Further, increased evaporation increases the flow of fresh water, and this makes greater surface circulation. But, as I explained earlier, surface flow is insufficient to replenish the volume of surface water flowing way from equatorial areas, so there will always be an upwelling of colder water in equatorial areas.

It's slowing down now. here — Tate

That's highly speculative. As I've explained, such currents change, but it's impossible that the THC, on a global scale, could stop. And these speculations you refer to are very unscientific. First, the article admits that the evidence is "proxy" evidence, and this is extremely susceptible to confirmation bias. Ocean currents, especially those at various levels of depth, have not been adequately measured. And, they admit that only nine out eleven of those "proxy" observations actually confirm this "slowing" thesis. Furthermore, the description of the THC in that article doesn't even include the freezing factor described by unenlightened. It seems to only described increased salination due to evapouration:

The AMOC is driven by two vital components of ocean water: temperature and salt. In the North Atlantic, warm, salty water flows northward off the U.S. coastline, carrying heat from the tropics. But as it reaches the middle latitudes, it cools, and around Greenland, the cooling and the saltiness create enough density that the water begins to sink deep beneath the surface.

Read this article, exploring the possibility that the THC (thermohaline circulation) is responsible for longer and shorter term changes in climate. It also talks about the debate about how the Younger Dryas actually started. — Tate

The problem with this sort of so-called "science" is that when dealing with long time scales without direct observations, it is impossible to distinguish cause from effect. So, we see a change in THC as coincident with a change in climate. Yes, of course, the two go hand in hand as two parts of the same phenomenon. But it is a mistake to conclude that one is the cause of the other.

All in all, the more I find out, the more the whole affair looks like humanity as a mad scientist in the process of blowing up his laboratory and speculating about whether he will be roasted or frozen or both. — unenlightened

The THC cannot shut itself off. The fundamental feature is that warmed surface water will move away from equatorial areas. This is 'forced' by the spinning of the planet and the consequent Coriolis effect. The replenishment of water, via surface mechanisms is not equally 'forced'. There is a force away from the equator at the surface, but not an equal push back toward it. This will always create an upwelling of colder water from the depths. The same process is observed on lakes with a prevailing wind, without any influence salination.

I think the situation is a lot more complex than this. — Metaphysician Undercover

I think you may be right. I don't actually expect to model the climate in a paragraph.

The THC cannot shut itself off. — Metaphysician Undercover

I think the situation is a lot more complex than this. And in fact links already given and quoted suggest that it can shut itself off, and has done, which does not imply that no movement at all occurs, vertical or horizontal. So some published support is required for your pontifications as much as for the rest of us.

I found this a helpful broad summary of many of the issues in this thread. Carl Sagan from 1985 when things were slightly less political.

The cause of global warming is the sun obviously, with the input into the atmosphere being part of the equation and the amount unable to exit as the result of it being trapped in gasses caused by fossil fuel burning another.

So, of course, if sun input changes, we could see another ice age, and equally of course, if we increase heat capturing gasses into the environment, we'll increase global temperatures.

He acknowledges humans have been impacting global temperatures for thousands of years. My assumption is that all plant life does to some extent as well.

Pay attention to his solution, which I find interesting as it acknowledges an almost impossibility of universal political agreement. That is, it's not clear that complete elimination of green house gasses from the West will do anything without the same by China and Russia. You can't dam half a river.

It's slowing down now. here
— Tate

That's highly speculative — Metaphysician Undercover

I don't know about highly speculative, since there's a consensus that it's slowing, but you're still making an important point: everything talked about in this thread is pretty speculative. There are a variety of reasons for that, but one of the big ones is that we still have unanswered questions, such as a solution to the 100,000 year problem.

That's how science rolls, though. Speculate, model, test, repeat.

Read this article, exploring the possibility that the THC (thermohaline circulation) is responsible for longer and shorter term changes in climate. It also talks about the debate about how the Younger Dryas actually started.
— Tate

The problem with this sort of so-called "science" — Metaphysician Undercover

I'm going to push back on this. Climatology is science.

Here are some tidbits from the article in Nature that we were talking about:

"The possibility of a reduced Atlantic thermohaline circulation in response to increases in greenhouse-gas concentrations has been demonstrated in a number of simulations with general circulation models of the coupled ocean–atmosphere system. But it remains difficult to assess the likelihood of future changes in the thermohaline circulation, mainly owing to poorly constrained model parameterizations and uncertainties in the response of the climate system to greenhouse warming. Analyses of past abrupt climate changes help to solve these problems. Data and models both suggest that abrupt climate change during the last glaciation originated through changes in the Atlantic thermohaline circulation in response to small changes in the hydrological cycle. Atmospheric and oceanic responses to these changes were then transmitted globally through a number of feedbacks. The palaeoclimate data and the model results also indicate that the stability of the thermohaline circulation depends on the mean climate state.

"Most, but not all, coupled GCM projections of the twenty-first century climate show a reduction in the strength of the Atlantic overturning circulation with increasing concentrations of greenhouse gases13—if the warming is strong enough and sustained long enough, a complete collapse cannot be excluded14,15. The successful simulation of past abrupt events that are found in the palaeoclimate record is the only test of model fidelity in estimating the possibility of large ocean–atmosphere reorganizations when projecting future climate change.

"Paradoxically, although the THC in current models responds to freshwater forcings without delay, the largest deglacial meltwater event on record, referred to as meltwater pulse 1A (MWP-1A), occurs more than 1,000 years before the next significant change in the THC associated with the Younger Dryas cold interval39. This paradox may be resolved, however, if MWP-1A originated largely from the Antarctic Ice Sheet40, where its impact on the Atlantic THC would be substantially reduced.

"Some modelling experiments find that during the next few centuries, the THC moves to an ‘off’ state in response to increasing greenhouse gases14,15,65. A reduction of the meridional heat transport into the circum-Atlantic region would partially compensate the warming due to increasing greenhouse gases, although such a change could have serious climatic consequences for the climate in the circum-Atlantic region through modifying long-established regional air–sea temperature contrasts, seasonal variations in the direction and strength of wind patterns66 and the location of convective areas67. The implication of such changes on regional climate remains largely unexplored. Reorganizations in the THC would also change the distribution of water masses and hence the density in the world ocean. A warmer and more stratified North Atlantic would also take up less anthropogenic CO2 (ref. 68). On the other hand, other experiments suggest little or no reduction of the THC to the same greenhouse gas forcing13. This indicates the possible dominance of negative feedback mechanisms such as changes in the amplitude and frequency of ENSO69, or modifications of atmospheric variability patterns in the Northern Hemisphere70.

"The fate of the THC in the coming century largely depends on the response of air–sea heat and freshwater fluxes to the increased load of greenhouse gases. Uncertainties in modelled responses are particularly large for the latter13. Moreover, the threshold for the occurrence of an abrupt change in a particular climate model depends on poorly constrained parameterizations of sub-grid-scale ocean mixing57. Because a complete THC shutdown is a threshold phenomenon, the assessment of the likelihood of such an event must involve ensemble model simulations71, as well as continued efforts to simulate past abrupt climate changes that so remarkably affected the global climate system.

The role of the thermohaline circulation in abrupt climate change

Pay attention to his solution, which I find interesting as it acknowledges an almost impossibility of universal political agreement. That is, it's not clear that complete elimination of green house gasses from the West will do anything without the same by China and Russia. You can't dam half a river. — Hanover

If you look at the Potsdam Institute for Climate Impact Research website, it looks like the articles discussing adaptation to climate change are quite a bit more prevalent than articles about stopping it. I think both avenues are important, though.

This is another interesting factor: brine rejection

Yes I remember the brinicles now...

But that's what I was saying earlier; that sea ice formation increases salinity and drives circulation and sea ice melting reduces salinity and slows circulation (other things being equal).

You can't dam half a river. — Hanover

You can dam your contributory tributary to the river though which would have reduced the flow and shown that it could be done. The tragedy of democracy is that the next election is the event horizon of all democratic politicians. Oligarchs and dictators on behalf of the proletariat have no such excuse though.

Sad though to see how clear it was 37 odd years ago, and how very little has been done in that time.

But that's what I was saying earlier; that sea ice formation increases salinity and drives circulation and sea ice melting reduces salinity and slows circulation (other things being equal). — unenlightened

Yes. I'll have to look into further.

Sad though to see how clear it was 37 odd years ago, and how very little has been done in that time. — unenlightened

What he says needs to be done can happen only through universal cooperation, which is the panacea that will cure far more imminent threats than global warming.

Given that we'll not get China to allow Taiwan self determination, much less get it to abandon thoughts of mining and using its own coal, perhaps we should reconsider our paltry efforts of trying to do the right thing. Having the moral higher-ground is of what value if our efforts don't ultimately matter?

Having the moral higher-ground is of what value if our efforts don't ultimately matter? — Hanover

It's a better place to be than the moral pit, for as long as there is any place to be at all. Nothing ultimately matters and we're all ultimately dead, so it's just a question of having a good looking corpse, because fuck it why not.

Folks have been looking for a real world example ever since whichever pedant it was raised the 'grue' thing, and you have found it! My heartiest commiserations! — unenlightened

Ignorance is bliss.

Having the moral higher-ground is of what value if our efforts don't ultimately matter? — Hanover

The Chinese are building lots of nuclear power plants, which everyone should be doing. If Europe actually does wean itself off Russian oil and gas, that would help.

I agree that democracy isn't the organizational structure for this problem. Totalitarianism would work.

The Chinese are building lots of nuclear power plants, which everyone should be doing. If Europe actually does wean itself off Russian oil and gas, that would help. — Tate

The solution remains more political than scientific. Most of Europe is aligned, but not so much the US, and surely not beyond the West.

https://www.yahoo.com/news/shelling-ukraine-nuclear-plant-raising-144759494.html

What he says needs to be done can happen only through universal cooperation, which is the panacea that will cure far more imminent threats than global warming. — Hanover

The solution remains more political than scientific. Most of Europe is aligned, but not so much the US, and surely not beyond the West. — Hanover

Universal cooperation is a pipe dream. Also the idea that we can quickly de-carbonize is a fantasy it seems. The "political" part of the problem is the promulgation of impossible targets, but also, the unwillingness (due to the perceived unpopularity) to promote the idea that we (in the "developed" nations) should all use much less energy; drive much smaller cars, use public transport, do without air-conditioning unless absolutely necessary, stop traveling overseas, choose locally grown foods etc.

This Explains very clearly the problems involved with trying to de-carbonize rapidly.

I'm going to push back on this. Climatology is science. — Tate

Climatology is said to be a science, I do not deny that. And what you've presented here you seem to present as science, that's why I called it "so-called science". But the stuff you've presented and referenced, in this thread, if it is claimed to be science, is really pseudoscience. It's pseudoscience because the theories and predictions made cannot be verified or falsified

That's how science rolls, though. Speculate, model, test, repeat. — Tate

Yes, that's a fair representation of the scientific method, but what is lacking in your claimed scientific climatology is the "test" part. So all we have is 'speculate, model, repeat'. That's not science.

But the stuff you've presented and referenced, in this thread, if it is claimed to be science, is really pseudoscience — Metaphysician Undercover

If it was published in Nature, it's science.

So some published support is required for your pontifications as much as for the rest of us. — unenlightened

https://www.whoi.edu/news-insights/content/the-future-of-the-oceans-conveyor-belt/
https://www.whoi.edu/press-room/news-release/two-new-studies-advance-understanding-of-currents/
https://www.e-education.psu.edu/earth103/node/686

Notice, in the first reference, the changes to the THC currently observed are described as "natural variability". Beyond that, it's all speculation. And notice as well, the concluding paragraph of the third reference;

As it turns out, recent research on the detailed configuration of surface and deep currents shows that circulation is much more complex than the GCB. Floats deployed in the ocean don’t always follow expected pathways in the GCB model. Wind actually plays a more significant role in causing downwelling than previously thought. Moreover, mixing by small systems or eddies plays a large role in driving surface currents.

The THC (GCB) will not stop, the principles are simple. The earth's surface is heated unevenly by the sun. The earth spins therefore the Coriolis effect. Warm water will be moved from equator toward the poles, and cold water dropped to the depths, and moved by other forces toward the equator, to replenish surface water moved out from there by the Coriolis effect. The positioning of land masses has the greatest influence over how and where this occurs. Other factors also play a role.

The THC (GCB) will not stop, the principles are simple. The earth's surface is heated unevenly by the sun. The earth spins therefore the Coriolis effect. Warm water will be moved from equator toward the poles, and cold water dropped to the depths, and moved by other forces toward the equator, to replenish surface water moved out from there by the Coriolis effect. The positioning of land masses has the greatest influence over how and where this occurs. Other factors also play a role. — Metaphysician Undercover

Thanks for the references. You own summary above, though, is highly misleading. The principles are not at all simple in their interaction and you have entirely omitted the role of salinity. As I said before, no one is suggesting that all movement of water will stop under any scenario. However, radical changes in circulation can certainly happen due to climate change, that will in turn have a large influence on the climate. Models of complex systems are always simplifications, and always inexact. Like weather forecasts, climate forecasts are subject to error that increases with the timescale. But this does not make them unscientific.

The principles are not at all simple in their interaction and you have entirely omitted the role of salinity. — unenlightened

I omitted the role of salinity because it is a secondary feature. The point is, that as secondary, changes in salinity cannot cause the GCB to actually shut off. Some articles place salinity as a primary feature, implying that cooled water would not sink if there was no salinity. But this is not true, as we notice in fresh water lakes.

The online articles about the THC, or GCB, are not very consistent with each other. Where they place the underwater flow varies greatly. Also, I've noticed discrepancy in the time required to complete the cycle, with reports varying between 700 and 1500 years. How can they talk about a slight slow down when there is that much discrepancy already? Also, it is stated in the quote I took, that in the practise of measurement, the flow sometimes does not even follow the path presumed by the model.

However, radical changes in circulation can certainly happen due to climate change, that will in turn have a large influence on the climate. — unenlightened

Radical changes will happen, there is no doubt in my mind. The big factors are the earth's spinning, its interaction with the sun, and the positioning of land masses. The land masses we know to be changing, with volcanoes and plate tectonics. These features seem to be attributable to internal forces of the earth. Changes to the properties of the water itself (salinity, turbidity, etc.) could also causes lesser changes which could appear to us as large changes, due to our limited observational time scale. Changes to the properties of the atmosphere, since winds are a driving force, would also change the THC.

I see that a number of scientists now speak about the water in the oceans in terms of water masses, like meteorologists speak of air masses. These are masses of water with similar properties, which may move in away similar to air masses. So we can make an analogy between a polar air mass, and a polar water mass. The air masses have boundaries and the boundaries are areas of turbulent weather. Differences in salinity exaggerate the boundaries. In the case of air masses, portions of the polar air mass move toward the equator, sliding underneath portions of the warmer air mass moving poleward. Along the boundaries we have the jet streams, where the mixing occurs. (I acknowledge this as an over simplification.) The jet streams are not stable, always changing, and sometimes even totally breaking down to reform in a new location. This lack of continuity makes them difficult to predict. Scientists have produced some success in predicting the jet streams in the short term, through extensive observation of the air masses. but the discontinuity presents a real problem. Movement can be modeled, but a lack of movement won't indicate where the next movement will be. This means that features related to the cause of movement are missing from the theories, requiring some "guess work" in the modeling, making the models unscientific in that sense.

If we take the jet streams as analogous with the water flow, we see that these are mainly east/west directional, and are the product of the mixing of air masses to the north and south. The jet streams do not take heat from the equator to the north pole, or cold in an opposite direction, the flow represents the mixing of the heat differential. Therefore I believe that the GCB, or THC, ought to be modeled more like this. Rather than as transmitting heat from equator to poles, it ought to be described as currents produced from the mixing of water masses with different properties. A water mass in contact with another, with different properties, will flow.

Models of complex systems are always simplifications, and always inexact. Like weather forecasts, climate forecasts are subject to error that increases with the timescale. But this does not make them unscientific. — unenlightened

I disagree. The "guess work" which goes into these models is unscientific. That is the problem. True science is mixed with pseudoscience in a way where the outcome is models consisting of both. The true science does not have the required observational data, nor the required proven theories, to make the desired models. So the gaps are filled with pseudoscience. The simple issue is that the science required to make these models does not exist, yet the models are produced and presented as science. So they must be classified as pseudoscience due to the fact that the true science is contaminated within the model. Models contaminated with pseudoscience are not scientific. This is a problem which our computer driven society, which greatly facilitates model making, presents us with, unscientific models which people are inclined to call science.

I disagree. — Metaphysician Undercover

And I disagree with you. Weather forecasting has become hugely more accurate since the advent of computer modelling, but it hasn't become more scientific, just better informed and capable of faster calculation. Science includes speculation and guesswork in every prediction - the more mature the science, the better the predictions, but perfection - never. The estimation of error is an important aspect of experimental science.

I might be the only one, but I don't think a mere metaphysician should be getting involved in matters of science. @Metaphysician Undercover

I might be the only one, but I don't think a mere metaphysician should be getting involved in matters of science — Changeling

What are you saying here? We shouldn't have any opinions about anything scientific?