Ocean Circulation Doesn't Work As Expected

[Trakar]

I do understand that we are a group of many different time schedules and varied real life demands, so while I eagerly anticipate learning that which I do not know and adapting that which I do know through the exchange of information with other intelligent and thoughtful individuals in engaging discussion, perhaps this little excerpt of a statement by Dr Susan Lozier (one of the paper's principle authors) in an exchange with Dr Bill Chameides will help to stimulate further discussion:

"It has been quite surprising (and dismaying) that some global warming skeptics have argued that our research 'means that all the current climate prediction models are significantly wrong.'"

"This statement is clearly nonsense. Apparently, by stating that the conceptual model of the lower limb of the overturning circulation as a conveyor belt is broken, the skeptics took this to mean that there is no overturning circulation. From there, they concluded that all climate prediction models are wrong, an astoundingly erroneous interpretation of our work!"

Dr. Bill Chameides is the dean of Duke's Nicholas School of the Environment and a member of the National Academy of Sciences. He blogs regularly at theGreenGrok.com.

Without comment upon the "skeptical" blogosphere comments, as I generally don't have the time or inclination to surf around, particularly to such politically contrived sites, it seems to me that one of the paper's authors is arguing against any change of "significance" (there's that word again, I wonder if we could source that to the denialist blogosphere?) by these findings with respect to current climate models. Despite this repudiation, I believe that there might be some room for difference of opinion, and I would like to understand any alternative explanations and considerations.

[Ara Pacis]

Since the OP has already admitted and retracted his claims about models I see no reason to discuss it further. For the rest, if you don’t care for my characterization feel free to go ahead and say exactly what you think is important about this article. I’ve been asking for this for two pages now so it’s not like I’ll object.

Well, I thought it prompted more questions which might lead to new speculations, but that's all it is, questions and speculations based on a new observation, not a hypothesis.

[Argos]

Excellent!
What is your considered (lightly or in depth) opinion with regards to any important effect this new understanding would have upon the planet's climate, or our models of the climate?

However marginal the effect may be, it seems to indicate that the models are going to be better henceforth, since they were running on flawed data so far. The findings make our understanding of the oceanic heat transport better, so I expect refinements in the climate models, especially climate change models.

[Argos]

Since the OP has already admitted and retracted his claims about models I see no reason to discuss it further.

Why not? Even if I´m wrong the subject can yield an interesting discussion. It´s not about my opinions. As I said, I´m making no assumptions or hypothesis. It was just a wrong word choice. Excuse me, but I think you´re taking too hard on me. Such aggressivity is uncalled for.

[Trakar]

However marginal the effect may be, it seems to indicate that the models are going to be better henceforth, since they were running on flawed data so far. The findings make our understanding of the oceanic heat transport better, so I expect refinements in the climate models, especially climate change models.

I suspect that you may well be correct in this consideration, particularly with regards to longer term projections. In general, my take from this paper is that there is no real alteration in thermal transport mechanisms or effects, but there may be some effect in the CO2 sink capabilities, particularly with respect to longer term sequestration of absorbed CO2 in the deep-water leg of the thermohaline system. Apparently we can't depend upon the oceans remaining to be a sink for up to a third of human generated emissions into the future, as it has done up until the present.

[geonuc]

I'm no oceanographer, but wouldn't the change be realized in the deep water data we have been using, not at the northern latitudes, but in the tropics? In other words, we've been taking data at the southern end of this deep-water current under the assumption that it represented the bulk of the Labrador current. Turns out that's not the case, so we need to obtain (or use) data from the various other places that we now think the current flows to.

There are sure to be other implications. Deep water currents don't stay that way - they eventually rise somewhere, right? We now know that some data we attributed to other rising water actually represents rising Labrador current water, in part or whole. Probably the transport time will have to be adjusted.

[Trakar]

I'm no oceanographer, but wouldn't the change be realized in the deep water data we have been using, not at the northern latitudes, but in the tropics? In other words, we've been taking data at the southern end of this deep-water current under the assumption that it represented the bulk of the Labrador current. Turns out that's not the case, so we need to obtain (or use) data from the various other places that we now think the current flows to.

There are sure to be other implications. Deep water currents don't stay that way - they eventually rise somewhere, right? We now know that some data we attributed to other rising water actually represents rising Labrador current water, in part or whole. Probably the transport time will have to be adjusted.

This new data does not shorten the conveyor process to my understanding, it merely changes the pathway. Instead of a concentrated, steady current, it is more like a diffuse capillary flow, think of a river tributary system in reverse.

The major problem is that the overturn possesses a millenial lag, and while our measurements of atmosphere are fairly solid over the last century, the time lag of waiting for it to upwell once again so that we can compare the characteristics of the water that sank to the characteristics of the water that upwells, is still well into the future. Deep water sampling, is possible, particularly once the flow patterns are better understood.

[Ara Pacis]

Deep water currents don't stay that way - they eventually rise somewhere, right?

Or are there two hydrospheres with less interaction than we might think?

[lomiller1]

However marginal the effect may be, it seems to indicate that the models are going to be better henceforth, since they were running on flawed data so far.

It’s the surface behavior that climate models depend on, and they are already working off the best available research on how those surface currents behave. Deep ocean return will never trump the actual observations in the upper ocean that climate models depend on because whatever new theories arise for the deep ocean must fit with surface observations. Over the long term this could be significant for predicting how ocean currents may change but even this doesn’t impact the models themselves, just the scenarios you choose to run.

What the article does point out is that this may have impact for detecting climate signals in the ocean. IOW, it may be important when you go out to physically measure changes in ocean heat content, which should allow for more accurate data and help resolve some of the discrepancies in the different methods of measurement.

It’s worth pointing out that with the current generation of models discrepancies between measured and molded ocean heat changes In the last few rounds of climate model predictions of ocean heat content, vs the measured values the models won out. I.E. the discrepancy turned out to be caused by errors in measurement rather then deficiencies in the models.

[nauthiz]

It's also kind of neat to see how researchers are starting to discover new climate mechanisms by noticing unexpected results in the model runs and then collecting empirical data to confirm that the same thing happens in the real world.

(Though I suppose it's not particularly unique, since every theory is supposed to make testable predictions like that.)

[Ara Pacis]

It’s the surface behavior that climate models depend on, and they are already working off the best available research on how those surface currents behave. Deep ocean return will never trump the actual observations in the upper ocean that climate models depend on because whatever new theories arise for the deep ocean must fit with surface observations. Over the long term this could be significant for predicting how ocean currents may change but even this doesn’t impact the models themselves, just the scenarios you choose to run.

But might there be a GW tipping-point after which the deep ocean becomes relevant? I'm not sure I could speculate on a mechanism by which this would be important on human timescales. But long-term, I would think that large sea-level changes would alter the scope, if not the dynamics, of both the upper and deep ocean.

[lomiller1]

That’s a possibility, if fact there some potential tipping points have already been identified, and there is always the possibility of more. Permafrost, Greenland/Antarctic ice caps, methane hydrate deposits, CO2 uptake by the oceans are all examples of possible tipping points.

If we do hit a tipping point all bets are off because by their very nature they mean global climate will settle into a completely different range, and in many cases we simply lack the empirical data to know what that range will be. This is why tipping points tend to scare climate scientists.

On the surface of the issue though, I don’t see what tipping point could arise from this new information. If it does have long term implications for surface behavior, I’d speculate that those would occur well into the future where model uncertainty is already high.

[Trakar]

On the surface of the issue though, I don’t see what tipping point could arise from this new information. If it does have long term implications for surface behavior, I’d speculate that those would occur well into the future where model uncertainty is already high.

Again, as a speculation, and based upon some other discussion fo potentials that I've read concerning the THC, if this system is indeed as weak as this and other reports suggest, it is possible that the global conveyor system could break down into isolated local currents. This would potentially have several global climate impacts.

[lomiller1]

The surface circulation is primarily wind driven, and that’s a function of the planets rotation and the position of the continents it’s not fragile at all, in fact it’s almost as certain as you can get.

[Trakar]

The surface circulation is primarily wind driven, and that’s a function of the planets rotation and the position of the continents it’s not fragile at all, in fact it’s almost as certain as you can get.

I'm certain that winds play a major role in establishing and maintaining many ocean currents, but I'm unclear on how it acts as the primary driver of the Thermohaline circulation currents, could you please explain this in more detail?