Alarm over dramatic weakening of Gulf Stream

[norml]

Alarm over dramatic weakening of Gulf Stream

· Slowing of current by a third in 12 years could bring more extreme weather
· Temperatures in Britain likely to drop by one degree in next decade

Ian Sample, science correspondent
Thursday December 1, 2005
The Guardian


The powerful ocean current that bathes Britain and northern Europe in warm waters from the tropics has weakened dramatically in recent years, a consequence of global warming that could trigger more severe winters and cooler summers across the region, scientists warn today.
Researchers on a scientific expedition in the Atlantic Ocean measured the strength of the current between Africa and the east coast of America and found that the circulation has slowed by 30% since a previous expedition 12 years ago.

The current, which drives the Gulf Stream, delivers the equivalent of 1m power stations-worth of energy to northern Europe, propping up temperatures by 10C in some regions. The researchers found that the circulation has weakened by 6m tonnes of water a second. Previous expeditions to check the current flow in 1957, 1981 and 1992 found only minor changes in its strength, although a slowing was picked up in a further expedition in 1998. The decline prompted the scientists to set up a £4.8m network of moored instruments in the Atlantic to monitor changes in the current continuously.

The network should also answer the pressing question of whether the significant weakening of the current is a short-term variation, or part of a more devastating long-term slowing of the flow.

If the current remains as weak as it is, temperatures in Britain are likely to drop by an average of 1C in the next decade, according to Harry Bryden at the National Oceanography Centre in Southampton who led the study. "Models show that if it shuts down completely, 20 years later, the temperature is 4C to 6C degrees cooler over the UK and north-western Europe," Dr Bryden said.


snip


http://www.guardian.co.uk/science/story/0,3605,1654803,00.html

[aquart]

1. While BushCo scammed us about TERRA, Mother Nature...

prepared to slap us upside the head.

I wouldn't buy Manhattan or Florida real estate for nuttin'

[lonestarnot]

2. Couldn't give me property in either state!

[lonestarnot]

3. CA, WA, TX , MS, Carolinas either...None of the costal areas...

[are_we_united_yet]

4. I'm not an alarmist so I have only one thing to say about this....

Oh shit.

[rurallib]

5. Blair supports W's war and gets an ice cube in return

How will British history treat Blair as this happens? Wish I could stick around and see.

[necso]

6. There are a number of

possible earth-changes that would not bode well for mankind -- or the ecosystem.

For example, if the earth's magnetic field drops off to zero (or near zero) in the process of shifting polarity, this could be bad (if only for a time), as the earth's magnetic field shields us from some of the stuff streaming out from the sun.

Ocean currents can have dramatic effects on climate (which dictates what foods can be grown, etc) and ocean populations.

The failure of the Gulf Stream would have pronounced effects on both sides of the Atlantic, but there are also important deeper currents.

A big issue is the speed with which the changes happen. Fast changes are much harder for plant and animal populations to adapt to, and even so for man.

And sometimes there is a critical point (this can be a critical point in the rate of change or in the basal measured quantity) where things go completely to hell.

[Odin2005]

7. The magnetic feild weakens, doesn't turn off completly during a flip.

The magnetic field lines just go loco for a few years. IIRC, It won't weaken enough to make the solar wind a threat

[Dead_Parrot]

8. Unless you work in IT...

...Then you're screwed (guess what I do? :)) Unlikely to be a problem for a few centuries, though.

[necso]

10. I've read

(or heard) it argued several different ways, and it's not like someone was there previous times taking detailed measurements and recording effects. We primarily rely on interpretations of residual magnetism in rocks, other extant indicators, models, etc, for our understanding of similar past events. Of course, what is taking place now (and what relevant data we have been historically collecting) is also useful and somewhat predictive, and I seem to remember reading someone's concerns about recent trends.

And the key words were "if", "or", "could" and "if" (in order of occurrence).

But perhaps you missed these.

And it could mostly be an issue for electronic stuff, magnetic orientation and navigation, etc, not organisms.

[Dead_Parrot]

9. Most currents are safe

The Gulf stream - or to be more precise, the "North Atlantic drift" part of it - is the only current that is vunerable to the fresh/salt density. Most of the others are driven more by Thermal density, rotation and prevailing winds.

Most of the Gulf Stream loops around at 40°N, between the Azores and Bermuda: it's only a branch that heats Western Europe. In the "shutdown" scenario, it all loops around, leaving Britain a rather chilly place.

I sometimes wonder if we could tap these currents: the Antarctic Circumpolar current carries enough energy to power the world about 50 times over...

AbE: All subject to the "IIRC" disclaimer, but a contributing factor in yours truly getting the hell out the UK before the rush.

[necso]

11. I've also

read concerns about other currents, including deep-water cold currents. And I have read it argued that there are certain linkages between currents, linkages which could have effects not typically accounted for in some of the models used.

The mathematical part of the science (as in the proof, not the models or measurements) involved in many of these sorts of things is rather thin for my taste, and this makes it hard to differentiate between the validity of different schools of thought in some cases.

However, if one can make a plausible argument for some risk, backed up by some reasonable science, then I am willing to factor this risk into a general risk analysis. Of course, assigning probabilities is rather more difficult, but there is a certain class of risks that just because of their potential magnitude warrant some attention, particularly if one can realistically address them as part of an effort to deal with other, more predictable disasters, and especially if this can be done at little or no extra cost.

[NickB79]

20. How do we tap into the power of sea currents?

Would it be feasible to build undersea "water turbines" that are spun as water flows through them? I ask because I remember an episode of SeaQuest: DSV that had a scenario like that powering undersea cities :-)

[Dead_Parrot]

21. Yeah, I guess...

I didn't see that, but it sounds like an almost-plausible idea. But the effects of a wind turbine hitting birds would be nothing compared to getting a whale caught in your sea turbine...

I've never heard this from any energy think-tanks. There's probably a good reason for that. :)

[Dogmudgeon]

12. This is happening a lot faster than most of us thought

I thought it would take a century or more, and that even small changes in the water flow would produce big change in the weather. As it's turning out, the weather isn't quite as immediately vulnerable, and the ocean's currents are capable of responding a lot more quickly.

Just three to five years ago, the talk was that Greenland would require a couple thousand years to melt free of ice, and over a century would be required to stop the thermohaline current process. Now, it looks like a century or less for Greenland, and theoretically 36 years for the thermohaline shut-down.

Of course, we now know that global climate changes can happen very quickly, as fast as a couple years. But with the situation we have now -- human-influenced climate forcing -- all bets are off. This process resembles a Heinrich event (superficially at least) but humans didn't have heavy industry during the last Heinrich event, which kicked off the Younger-Dryas. That was a "little ice age" that lasted 1000-1500 years.

--p!

[One_Life_To_Give]

13. Effect on Eastern Seaboard?

Researchers on a scientific expedition in the Atlantic Ocean measured the strength of the current between Africa and the east coast of America and found that the circulation has slowed by 30% since a previous expedition 12 years ago.

I presume that this general slowing of the entire gulf stream will cause temperatures to fall in the Mid Atlantic states?

Northern New England waters are on the Gulf of Maine current. So would much change be expected there?

And how about the SouthEast? Will Florida's winters turn noticably colder? Perhaps destroying it's Citrus Growing industry?

[NNadir]

14. I am no expert in this subject, but this is a huge planetary heat flow.

That heat has to go somewhere.

One wonders, where is it going?

[phantom power]

15. I have two predictions...

1) If you reduce the ability of heat to flow, then more of it stays where it is. So, we can expect an increase in ocean temps closer to the equator.

2) The heat will "try" to find some other way to flow. If not through the ocean, then through the atmosphere. So, we can expect more vigorous exchanges of warm equatorial air for cooler polar air.

[NNadir]

16. It seems that there were some dramatic airborne heatflows this summer.

[phantom power]

17. And many of them were fueled from the bottom by hot ocean water.

It's like I'm psychic or something.

Speaking of that, I was interested in Jeff Masters' blog yesterday. He says he thinks this season was a "once in 500 years" season. I don't think he really gets what's happening, yet.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=252&tstamp=200512

[NNadir]

18. Maybe this will be a "once in 25,000 years " 500 year period. 2004 was no

slouch as a hurricane season either.

However it is often difficult to separate the signal from the noise. That said, it is probably better to jump to conclusions under the circumstances. Sometimes people over emphasize the randomness of events.

The frequency of hurricanes is but one piece of data, though. Moreover, it's not exactly like the global climate change effect sprang from nowhere. It was a prediction based on physical data, the concentration of carbon dioxide and the absorption spectrum of the gas, something that is easily measurable. Under those circumstances unusual events certainly merit unusual attention. It is scientifically questionable to speculate that events of all kinds will occur with the same probability as they did under different conditions. In fact, three is good reason state the case that the old rules may never apply again.

To me, it's pretty damn clear what's going on.

[phantom power]

19. Masters is planning to post a write-up on why he thinks the last two years

were so intense. I'm looking forward to hearing what he thinks. I'm assuming he is attributing it to things other than systematic climate change, based on his comment yesterday, but maybe I'm assuming too much.

[Dead_Parrot]

22. Hmmm... Hurricane Epsilon...

No, I've no idea :)

My local papers coverage suggested flow in the short-loop part had increased by 30%. Of course, this doesn't get cooled like the N. Atl. loop, so the waters wind up back back in the gulf warmer than they would nomally do. The rest is history... (kinda like New Orleans)

Maybe we will need the Chinese alphabet, after all.

[phantom power]

23. That makes sense.

The current can't just "stop." especially all at once. It will re-route itself. When an ordered flow of water runs into an obstacle, turbulence results. The flow disperses itself into a fractal eddies. I imagine that we will get to witness this on a very large scale.

[philb]

24. What is supposed to happen to temperatures in the rest of N. Hemisphere?