Oh, sh*t, or, this is why it's called "Global *Climate Change*", not 'warming'

[purpletigron]

First observational evidence that the North Atlantic Conveyor ('Gulf Stream') is weakening. "Computer models have predicted that if it turned off completely, Europe would cool by perhaps four to six degrees Celsius."

Comments

[vgnwtch.livejournal.com]

Oh gods...

[purpletigron.livejournal.com]

Oddly, I thought of the Fimbulwinter earlier today...

[yonmei.livejournal.com]

Oh, great.

[purpletigron.livejournal.com]

And that's only the drop in average temperatures. Winter minima could drop twice and much or more.

However, the research is a bit less secure than the BBC report had lead me to believe.

On the gripping hand, this is probably going to happen in our livetimes.

[artela.livejournal.com]

To be fair - so far this is a one-off result. Listening to other scientists on R4 they want to do more prolonged testing before confirming anything as the University results are based on "spot checks" rather than on "continuous monitoring" so could actually be caused by anomolous flows just the same as you get with anomolous air current flows... doesn't mean it isn't happening - doesn't mean it is - does mean it needs more careful monitoring.

[del-c.livejournal.com]

Until I hear different, I'm going to assume this is periodic and not secular.

[purpletigron.livejournal.com]

It could be secular, short-period, long-period or 'chaotic'. I define 'short' as 'significantly shorter than an average human live-span'.

[purpletigron.livejournal.com]

I wouldn't describe this as a 'one-off' result:

"Their conclusions, reported in the scientific journal Nature, are based on 50 years of Atlantic observations."

I would describe this as 'one study'. Until I read the Nature paper, I will assume that the data are non-homogenous, and I agree that continuous monitoring is definitely required to test this preliminary result.

I'm also going to step up my efforts to bring my 100 year home up to 2005 Building Regulation standards for insulation.

[purpletigron.livejournal.com]

OK, I've now been able to access the 'News and Views' response to the study:

During a cruise in spring 2004 from the Bahamas to the Canary Islands, on board the British research vessel RRS Discovery, the team measured water temperature and salinity along a latitude of 25º North, taking samples roughly every 50 kilometres. They then calculated from the density and pressure differences between each sample, the volume and velocity of the circulation at various depths, assuming that from coast to coast the balance of water flowing north and south must be zero.

Similar measurements along the same latitude were previously made in 1957, 1981, 1992 and 1998. But until now, the data never showed any significant decline in circulation. "In 1998 we saw only very small changes," says Bryden. "I was about to give up on the problem."

So I see where your 'one result' comes from - sorry about before!

[artela.livejournal.com]

That's OK - apology not necessary.
As a scientist (in training) I cannot accept results such as those as there is no way to tell if the readings are anomolous (ie. they caught it in a bad season) or not - as I said, what is needed is continuous monitoring. Personally I think the results are probably what they're being billed as (due to the melting greenland glaciers, melting arctic polar ice cap, etc - which should lead to a drop in temperature _and_ a drop in salinity), but without the correct proof it is dangerous to assume that a result is what we want it to be to back up other theories.

[purpletigron.livejournal.com]

Oh, but it is - I'm a scientist too, a physicist. I have long railed against poor science journalism, and this is another example. There's a big difference between 'based on 50 years of observations' and 'based on a few spot samples over 50 years, where only the last one shows any change'. Grr.

Scientifically, I quite agree. However, politically, I think we need to follow the 'precautionary principle' - start planning for plausible difficult cases (not the same as 'worst case scenario').

[artela.livejournal.com]

Oh I absolutely agree on the political "we should do something" front :-)
It's just a shame that we can't force the world's largest problem to do something about it - it makes our own small efforts in this country seem so insignificant :-(

[purpletigron.livejournal.com]

I have to keep reminding myself that I can't single-handedly change the world. I do what I can do, I try to persuade my friends and family to do what they can do, I lobby my elected representatives to do what they can do... Remember, only half the USA are Republicans, and there are a lot of USA residents who want to do more. So, if the UK is setting a good example, we're helping by more than just our direct efforts... Also, we're 'heavy emitters' (four times the sustainable global level, even without any personal flights).

[artela.livejournal.com]

I forgot to say... how many people reading here have seen "The Day After Tomorrow"? *g*

Larger and larger hurricanes - check
Cooling of North Atlantic - check

...what was next? Ah yes, atlantic conveyor switches off suddenly... ;-)

[purpletigron.livejournal.com]

Even the BBC say:

"Computer models of climate have regularly predicted that the north Atlantic conveyor may well reduce in intensity or even turn off altogether, a concept that was pushed beyond credence in the Hollywood blockbuster The Day After Tomorrow."

:-)

[artela.livejournal.com]

It's still a good disaster movie though (and I absolutely adore disaster movies, especially GeoScience based ones where I can point and laugh)... well, a good movie apart from those ridiculous CGI wolves - what *were* they thinking!

[anthraxia.livejournal.com]

Just remember people, the Gulf Stream is the reason why London doesn't get as cold as Moscow, which is on roughly the same latitude.

Drakey described New Year's Eve in Moscow as minus 30 C. This is not a drop of 4 or 5 degrees for the UK - Europe as a whole, but the British Isles are REALLY going to suffer.

I think they meant average temperatures, not extremes!

[purpletigron.livejournal.com]

And there was me, trying not to be called a hair-shirt scare-monger :-)

Actually, Moscow has a continental climate, whereas the UK has a maritime one. So Blanc Sablon, Québec, Canada might be a closer analogue (51 deg N).

climate for Blanc Sablon climate station (http://climate.weatheroffice.ec.gc.ca/climate_normals/results_e.html?Province=QUE%20&StationName=&SearchType=&LocateBy=Province&Proximity=25&ProximityFrom=City&StationNumber=&IDType=MSC&CityName=&ParkName=&LatitudeDegrees=&LatitudeMinutes=&LongitudeDegrees=&LongitudeMinutes=&NormalsClass=A&SelNormals=&StnId=5669&) - still gets down to -20 C during mid-winter.