Global warming is now slowing down the circulation of the oceans

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[–]horvybaby 1515 points 11 hours ago*x3

Okay, so let's get a few things correct: because perhaps Nature is behind a paywall for some people. Rahmstorf et. al. show a decrease in THC/MOC variability for the period 1970-1990, which we have then partially recovered from. The title of the Nature article is inflammatory, but the Washington Post article is significantly more so.

We do not know nearly enough about THC variability to make millenial scale arguments. We only recently actually made a measurement system that can calculate the overturning (the RAPID array).

Rahmstorf and others had some issues with THC shutdown in the 90's when previous studies, which at one point suggested a shutdown in THC or meridional overturning, turned out to be incorrect because of an aliasing from a sampling error: they just happened to be measuring at points in the seasonal cycle that were spaced in such a way so as to show a decrease when there was none. This led to our modern understanding of inter-annual variability in the THC, so it all worked out well.

The nature paper takes pains to note that the RAPID array is just 11 years old and so we can't say anything from the results. But this proxy data must be referenced to something, and the only reasonable measurement apparatus to use is RAPID. It isn't.

Using proxy data to infer something about the overturning, while reasonable, doesn't give great coherence towards present understanding of complicated, long-timescale events like the heating of the deep ocean. Furthermore, even at theirs strongest the conclusions absolutely do not support the WaPo headline. This is the sort of things that makes climate scientists like myself furious. The results end up overhyped, overblown, and for soundbites like press releases and Nature papers. This just misinforms people. Unless I hear from RAPID that the MOC/THC is reducing, I'm not trusting the authors. Just because climate change is a hot-button issue, and we want ways to convince people about its impacts, doesn't mean MOC/THC shutoffs can be pulled out of nowhere.

edit: Just want to mention: this doesn't say anything about the method of analysis. The method seems to be well done and scientific and careful, given the data at hand. The issue is rather the paper title and subsequent inflation in popular media, which is silly.

I understand the scientist's desire for rigour, but ...

Most people won't bother reading the article at all. If it's up-voted or liked enough, the title is the truth. We all do it. We all accept a sentence as truth if we trust the source enough, without checking the facts. It's impossible to check all the facts all the time.

But the WaPo article isn't about the truth. It's about beliefs. The party line.

The belief that 'I, through my sinful actions am causing the ocean to slow down'. Ridiculous, but that is what most people will get from reading that headline. And maybe it's not that bad.

It doesn't matter what the truth is, it matters what you believe the truth to be.

The truth doesn't matter, nor does what you believe. The only thing that actually matters is how you act. You could happily say that there's only a 0.0001% chance that humanity is affecting climate change, but if that's enough to get you to stop doing things that might harm the planet just in case then that's brilliant.

The most important thing to remember with climate change is that there's no downside to being less wasteful.