Scivillage.com Casual Discussion Science Forum

Are Atlantic Ocean currents weakening? A new study finds no, but other experts aren't so sure.
https://www.livescience.com/planet-earth...nt-so-sure

INTRO: Scientists say there is a high chance that key Atlantic Ocean currents will weaken over the coming decades due to climate change — but whether they have already slowed is hotly debated. Now, a new study finds that Atlantic circulation has remained stable since the 1960s, suggesting the system may be more resilient to warming than scientists thought.

But the results are controversial. Previous studies show mixed results, with some papers concluding that the Atlantic Meridional Overturning Circulation (AMOC) is weaker now than at any point in the past millennium, and others finding little to no evidence for a decline in current strength.

"I would say that whether or not the AMOC has weakened is still an open question," Maya Ben-Yami, a climate researcher at the Technical University of Munich in Germany who was not involved in the new study, told Live Science in an email.

The AMOC is a system of Atlantic Ocean currents, including the Gulf Stream, that circulate in a giant loop from Antarctica to Greenland. It transports heat to the Northern Hemisphere. Should it weaken, it could trigger significant cooling in Northern Europe and dramatic disruptions to weather patterns worldwide.

Direct observations of AMOC's strength only go back to 2004. So to measure longer-term trends in Atlantic circulation, researchers rely on climate parameters, or "fingerprints," they think are linked to the AMOC. These include sea surface temperature, salinity, sea surface height, water density and data from marine sediments, Ben-Yami said.

"The reason we're not sure about the AMOC weakening is that all these different fingerprints can give us different results," she said.

The results of the new study, published Jan. 15 in the journal Nature Communications, suggest the AMOC has not weakened over the past 60 years... (MORE - details)
- - - - - - - - - - - - - - - -

COMMENT: The lack of agreement potentially illustrates the potency of pre-existing biases and motives.

If you have presuppositions that desire the AMOC to have weakened, then you'll be selective about or interpret data in a way that reinforces that view. As well as be choosy with regard to how you disparage interpretations that confict with that. If you have presuppositions that desire the AMOC to not have weakened, then similar with respect to facilitating for that.

Even if you have a neutral or dispassionate thought orientation, the impartial status of your conclusions may be muddled and obscured amidst the furious swordplay between the "interested" parties.

That experts supposedly assert "...there is no doubt that circulation will slow in the future" exemplifies the preset commitment of these impassioned or non-robotic researchers. Though probably the future will indeed output such, that potential yet-to-be-realized fact is independent of the moral dedication of these experts to save humankind from itself, to herald and amplify the magnitude of "threat" whenever permissably possible.

In the past, a vast array of invalid science was simply overlooked, enabling the idealized portrayal of science as indifferent and not laden with the preferences and career drivers of its human practitioners. That halcyon era no longer exists, now that science has finally acquired critical self-awareness of the frailty of its publishing industry: https://en.wikipedia.org/wiki/Retraction_Watch

Quote:If you have presuppositions that desire the AMOC to have weakened

.. a model. For example that cold water has to sink to draw water in from warmer regions. A model can be wrong for any number of reasons - where a model fails to predict (or simply 'model') you refine or discard the model in favour of a better one. Presuppositions are a religious thing.

Every model requires making assumptions about things you do not know. That's literally presupposition. It's those presuppositions that you "refine or discard."

I swear, English is a second language around here.

(Feb 1, 2025 02:50 AM)confused2 Wrote: [ -> ]

Quote:If you have presuppositions that desire the AMOC to have weakened

.. a model. For example that cold water has to sink to draw water in from warmer regions. A model can be wrong for any number of reasons - where a model fails to predict (or simply 'model') you refine or discard the model in favour of a better one. Presuppositions are a religious thing.

theory-ladenness: In the philosophy of science, observations are said to be "theory-laden" when they are affected by the theoretical presuppositions held by the investigator. [...] Theory-ladenness poses a problem for the confirmation of scientific theories since the observational evidence may already implicitly presuppose the thesis it is supposed to justify. This effect can present a challenge for reaching scientific consensus if the disagreeing parties make different observations due to their different theoretical backgrounds...

In the physical sciences, where the moral, social, and "being the savior of the world" issues (of the humanities) were traditionally remote, the background differences could still often find common ground (as pointed out in the last bits of the next section below). But the spillover of those literary intellectual concerns infecting the social sciences, and then creeping incrementally into the earth science disciplines that are adjacent to human and animal domains, makes personal political and philosophical influences and activism more kosher and weightier influences today [#1 footnote]. Again, though, even a broken doomsday clock will be correct twice a day -- AMOC will probably be altered, eventually.

Theory and value ladenness
https://plato.stanford.edu/entries/scien...eladenness

EXCERPTS: Empirical results are laden with values and theoretical commitments. [...] Do the theory and value-ladenness of empirical results render them hopelessly parochial? That is, when scientists leave theoretical commitments behind and adopt new ones, must they also relinquish the fruits of the empirical research imbued with their prior commitments too?

[...] If you believe that observation by human sense perception is the objective basis of all scientific knowledge, then you ought to be particularly worried about the potential for human perception to be corrupted by theoretical assumptions, wishful thinking, framing effects, and so on. Daston and Galison recount the striking example of Arthur Worthington’s symmetrical milk drops...

Perceptual psychologists, Bruner and Postman, found that subjects who were briefly shown anomalous playing cards, e.g., a black four of hearts, reported having seen their normal counterparts e.g., a red four of hearts. It took repeated exposures to get subjects to say the anomalous cards didn’t look right, and eventually, to describe them correctly [...] Kuhn took such studies to indicate that things don’t look the same to observers with different conceptual resources. [...] This would mean, for example, that when Priestley and Lavoisier watched the same experiment, Lavoisier should have seen what accorded with his theory that combustion and respiration are oxidation processes, while Priestley’s visual experiences should have agreed with his theory that burning and respiration are processes of phlogiston release.

The example of Pettersson’s and Rutherford’s scintillation screen evidence attests to the fact that observers working in different laboratories sometimes report seeing different things under similar conditions. It is plausible that their expectations influence their reports. It is plausible that their expectations are shaped by their training and by their supervisors’ and associates’ theory driven behavior. But as happens in other cases as well, all parties to the dispute agreed to reject Pettersson’s data by appealing to results that both laboratories could obtain and interpret in the same way without compromising their theoretical commitments.

Indeed, it is possible for scientists to share empirical results, not just across diverse laboratory cultures, but even across serious differences in worldview. Much as they disagreed about the nature of respiration and combustion, Priestley and Lavoisier gave quantitatively similar reports of how long their mice stayed alive and their candles kept burning in closed bell jars.

[...] Interests change, however. Scientists may eventually come to appreciate the significance of data that had not originally been salient to them in light of new presuppositions. The moral of these examples is that although paradigms or theoretical commitments sometimes have an epistemically significant influence on what observers perceive or what they attend to, it can be relatively easy to nullify or correct for their effects. When presuppositions cause epistemic damage, investigators are often able to eventually make corrections. Thus, paradigms and theoretical commitments actually do influence saliency, but their influence is neither inevitable nor irremediable.

- - - footnote - - -

[1] Science activism is surging – which marks a culture shift among scientists: ... scientists today are speaking out on a variety of political and social issues related to their own research fields and in solidarity with other social movements. [...] Science activism has long been considered taboo, as many in the field fear that politicizing science undermines its objectivity. ... We’ll need more research to determine how the resurgence of scientist activism is influencing politics and policy. But we can already point to some effects ... we also expect that impending crises, like climate change, may be driving acceptance of activism within the scientific community....

(Feb 1, 2025 03:14 AM)Syne Wrote: [ -> ]Every model requires making assumptions about things you do not know. That's literally presupposition. It's those presuppositions that you "refine or discard."

I swear, English is a second language around here.

I try not to get involved in this sort of discussion..

The science thing .. a theory .. starts with:

IF A is true [AND B,C..] then it it follows, by >this< line of reasoning, that P must be true.
A,B,C.. are 'postulates' .. close to assumptions but made without the assumption that they true .. if that makes any sense. If experiment shows P (the theory) matches (models) reality then it lends credibility to the notion that the postulates also match reality.

OR

Just join the dots and project the line further ahead in time.

presupposition - a thing tacitly assumed beforehand at the beginning of a line of argument or course of action

You cannot form a model without things "assumed beforehand."

Literally just plain English.

Compare:
postulate - a thing suggested or assumed as true as the basis for reasoning, discussion, or belief

So postulates are just as much a "religious thing" as a presupposition.
Just because the less used word has more of a "sciency" sound, doesn't actually change the meaning.