The gulf stream is stopped......

[andyandy]

.....only for 10 days, but even so......a worry.....

Scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate by dragging warm water northwards from the tropics. The slowdown, which climate modellers have predicted will follow global warming, has been confirmed by the most detailed study yet of ocean flow in the Atlantic.
Most alarmingly, the data reveal that a part of the current, which is usually 60 times more powerful than the Amazon river, came to a temporary halt during November 2004.

snip. comparison with day after tomorrow...

Although no scientist thinks the switch-off could happen that quickly, they do agree that even a weakening of the current over a few decades would have profound consequences.

Warm water brought to Europe's shores raises the temperature by as much as 10C in some places and without it the continent would be much colder and drier.

Researchers are not sure yet what to make of the 10-day hiatus. "We'd never seen anything like that before and we don't understand it. We didn't know it could happen," said Harry Bryden, at the National Oceanography Centre, in Southampton, who presented the findings to a conference in Birmingham on rapid climate change.

Lloyd Keigwin, a scientist at the Woods Hole Oceanographic Institution, in Massachusetts, in the US, described the temporary shutdown as "the most abrupt change in the whole [climate] record".

He added: "It only lasted 10 days. But suppose it lasted 30 or 60 days, when do you ring up the prime minister and say let's start stockpiling fuel? How can we rule out a longer one next year?"

Prof Bryden's group stunned climate researchers last year with data suggesting that the flow rate of the Atlantic circulation had dropped by about 6m tonnes of water a second from 1957 to 1998. If the current remained that weak, he predicted, it would lead to a 1C drop in the UK in the next decade. A complete shutdown would lead to a 4C-6C cooling over 20 years.http://environment.guardian.co.uk/climatechange/story/0,,1932761,00.html

[The Atheist]

Go short-term buy on thermal underwear.

[This Guy]

Interesting.

[Schneibster]

Butthere'snoglobalwarming, right Diamond?

Yeahsureyabetcha.

[The Atheist]

Butthere'snoglobalwarming, right Diamond?

Yeahsureyabetcha.No way, mate - it's snowing in Chicago.

[robinson]

I don't think anyone but a complete brainwashed politico denies global warming. Seperate issue from WHY there is global warming.

While I'm sure there must be another deadthread about global warming, why bother to find it when this one will do for a thrash about.

heh

One thing I noticed over the many years the issue has come up. Both online and off. There seems to be, in the non-scientific mind, some belief that global warming, (or cooling), is about the ATMOSPHERE warming up.

While the hard nosed scientist knows that it is the ocean that is the real meat of the matter. What is happening with ocean currents, ocean ice, ocean temperatures, that is really the issue.

And, IMNSHO, that is what has scientist who know about such things, really concerned. While the ordinary person thinks global warming means the air will get warmer, that isn't the case at all. Air gets cool and warm quickly, as in, within a day or less. But the ocean is the real planet. And there is no doubt at all it is warming up, and has been for a while.

Of course I could be wrong. I actually hope I am. And all those really smart scientist are wrong too.

[Hawkeye]

Well… that’s bad news.
Whenever I try to tell people about the consequences of global warming, the first thing I mention is how screwed the U.K. is if a glacial runoffs shut down the Gulf Stream. I had no idea it actually stopped in 2004.

On the bright side; I like your “Red Meat” avatar, robinson.

[rockoon]

If it is the most detailed study yet, is it possible that this sort of slowdown has been common and we just didnt notice it before?

Think about it.

[CriticalThanking]

Prof Bryden's group stunned climate researchers last year with data suggesting that the flow rate of the Atlantic circulation had dropped by about 6m tonnes of water a second from 1957 to 1998.
Is there some way of figuring out after the fact that the current must have been stronger in the past or is it all direct current measurement? Sediment layer thickness? Fish "growth rings"? :D

CT

[andyandy]

If it is the most detailed study yet, is it possible that this sort of slowdown has been common and we just didnt notice it before?

Think about it.

true - the reaction is bafflement -

Researchers are not sure yet what to make of the 10-day hiatus. "We'd never seen anything like that before and we don't understand it. We didn't know it could happen," said Harry Bryden, at the National Oceanography Centre, in Southampton, who presented the findings to a conference in Birmingham on rapid climate change.

and the scientists aren't drawing any conclusions..

Is it the first sign that the current is stuttering to a halt? "I want to know more before I say that," Professor Bryden said.

even if it is a common occurance, it would still be pretty remarkable regardless of if it's linked to GW.....

[andyandy]

A 2001 report.....

http://www.gsfc.nasa.gov/topstory/20011116meltwater.html
At the end of the last Ice Age 13 to 11.5 thousand years ago, the North Atlantic Deep Water circulation system that drives the Gulf Stream may have shut down because of melting glaciers that added freshwater into the North Atlantic Ocean over several hundred years, NASA and university researchers confirm. Since the Gulf Stream brings warm tropical waters north, Western Europe cooled.

The National Science Foundation (NSF) funded study also finds that if a shutdown persisted for a long enough time, the entire Northern Hemisphere would eventually cool.

The computer model simulations of ocean and atmosphere processes used in this study imply a similar phenomenon has the potential to occur in the future due to freshwater additions from increased rain and snow caused by global climate change.

"For the first time, it is shown that realistic additions of glacial meltwater into the North Atlantic would have shutdown North Atlantic Deep Water production over a period of a few hundred years if the initial ocean circulation was somewhat weaker than that of today," said David Rind, lead author of the study and a senior climate researcher at NASA's Goddard Institute for Space Studies in New York, NY. The study appears in the November 16 issue of Journal of Geophysical Research - Atmospheres.

When Rind and his colleagues entered realistic estimates of freshwater from melting glaciers into their model, they found the North Atlantic circulation stopped completely after some 300 years. When the model was adjusted to make the circulation weaker than it is today, cessation of the Gulf Stream took only 150-200 years, matching current estimates based on paleo-climate records .

Freshwater additions into the ocean through the St. Lawrence River have a profound effect on the ocean circulation.

"The more freshwater you add, and the longer you add it, the greater reduction in the North Atlantic circulation," Rind said. "According to our model, this is a linear response."

When the Gulf Stream moves warm surface water from the equator north through the Atlantic, the water cools, gets saltier due to evaporation and becomes very dense. By the time it approaches the coast of Newfoundland, or further northeast in the Norwegian Sea, it becomes dense enough to sink. This process is called overturning. The dense water then slowly travels through the deep water southward into the Southern Hemisphere, with the return flow to the north occurring at the surface.

But when freshwater gets mixed with the salty water in the North Atlantic, it makes the water less dense and slows the overturning process and the ocean circulation.

While the study finds that freshwater input could slow and stop overturning, this would not stop the Gulf Stream entirely. That's because the stream is partially pushed by winds. As a result, the model shows the reduced Gulf Stream would only transport about half as much heat northward, thereby cooling Western Europe. Were this to occur in a global warming scenario, it would act to partly counter the effects of projected greenhouse warming in parts of Western Europe

but for an answer as to why a current "60 times more powerful than the amazon" would suddenly stop, have a break for a few days, and then resume, the possible gradual introduction of ice-melt fresh water doesn't seem to fit......

[andyandy]

Is there some way of figuring out after the fact that the current must have been stronger in the past or is it all direct current measurement? Sediment layer thickness? Fish "growth rings"? :D

CT

ice core data?

We know, from ice-core data, when the Gulf Stream has stopped flowing before. The most recent collapse, 15,000 years ago during the Younger Dryas, was caused by the sweetening of the North Atlantic Ocean, when glaciers covering North America melted and began flowing through the St. Lawrence waterway into the Atlantic, instead of into the Gulf of Mexico via the Mississippi. Today’s accelerated melting of the Arctic and Antarctic ice sheets may recreate these conditions, not just for the Gulf Stream but also for other parts of the global ocean circulation. http://www.theecologist.org/archive_detail.asp?content_id=522

don't ask me how ice core data would tell you though....:D

[Silly Green Monkey]

Salt concentration perhaps, and possibly accumulation rings.

[robinson]

I've been looking at some data on this. Anyone interested in data?

[This Guy]

I've been looking at some data on this. Anyone interested in data?

Let's don't confuse the issue with data! ;)


Seriously though, I'd be interested.

In my Navy days, as I've mentioned in other threads, I made submarine patrols. I worked on inertial navigators which provided the ships position/velocity/attitude data to the missile fire control system.

One of the automated plots we had to monitor was Velocity Difference. It compared the Navigator's velocity data to Electro Magnetic Log (EM Log) data - basically a thing that stuck out into the water, with two buttons, one on each side, that generated a mag field between the buttons, and then sensed the current generated by the salt water flowing through that field. That signal was amplified and resolved by the ships heading to give N/S and E/W Velocity, and compared to the Navigator's data, and plotted every few minutes.

During those patrols I made off the East coast, it was always fun to watch those plots as we went through the Gulf Stream.

Though, not as much fun as watching the bottom drop as we headed out of port from Guam, in the Big Ocean, and crossed the Mariana Trench :)

[robinson]

Sweet! Great story, very cool.

Yeah, data. OK but it is Saturday night and I am outa this place. Maybe in 24 hours.

[robinson]

Nov 2004 data

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/327/

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/328/


Nov 2004 data


http://www7320.nrlssc.navy.mil/altimetry/images/envt_images/arc_list_nat.html#Nov2004

And more Nov 2004 data

http://srbdata.jhuapl.edu/d0043/avhrr/gs/averages/04nov/index.html

With a little effort, and a lot of time, you can see the event for yourself

[andyandy]

Nov 2004 data

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/327/

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/328/


Nov 2004 data


http://www7320.nrlssc.navy.mil/altimetry/images/envt_images/arc_list_nat.html#Nov2004

And more Nov 2004 data

http://srbdata.jhuapl.edu/d0043/avhrr/gs/averages/04nov/index.html

With a little effort, and a lot of time, you can see the event for yourself

could you explain these a bit?

say this one ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n16_ch1_2004326_1day.gif

What's chanel 1 (or 2) reflectarce?

and this
ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_ssta_2004326_5day.gif

compared with this.....

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_sst_2004326_5day.gif

what exactly is it showing (in more detail than "a difference in temperature!)? They both seem to be taken over the same time frame (17-22Nov) so why the difference?

it looks really interesting - but i could do with some talking through it :D

[This Guy]

could you explain these a bit?

say this one ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n16_ch1_2004326_1day.gif

What's chanel 1 (or 2) reflectarce?

and this
ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_ssta_2004326_5day.gif

compared with this.....

ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_sst_2004326_5day.gif

what exactly is it showing (in more detail than "a difference in temperature!)? They both seem to be taken over the same time frame (17-22Nov) so why the difference?

it looks really interesting - but i could do with some talking through it :D

I'm still working on this also. But for me, this link - http://srbdata.jhuapl.edu/d0043/avhrr/gs/averages/04nov/index.html

gives a better picture of what the Gulf Stream is doing. I'm just not sure exactly how to interpret it. One thing that is confusing me is the white spots that show up in some of the pictures. Are those hot, or cold spots? Or clouds? Or something else? (http://srbdata.jhuapl.edu/d0043/avhrr/gs/averages/04nov/gs_04nov12_0250_multi.png)

Haven't had much time to spend going over the pictures yet. But hope to spend more time with them in the AM.

In any event, thanks for the links robinson!:)

[robinson]

Another data source (Nov 2004).

http://www.ncdc.noaa.gov/oa/climate/research/sst/2004weekly-sst.html

"what exactly is it showing ..."
When you see anomaly it is the difference from the mean temperature. The mean is gathered from worldwide temperature data. Here is a list of adjustments to get the mean.
ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/monthly.ocean.90S.90N.df_1901-2000mean.dat

Fun stuff eh? Now for some way easier to follow data.
In this animation
http://www.ncdc.noaa.gov/oa/climate/research/2004/nov/eaimages.html
you can see the cool readings where it should be normal or warm.
Compare with
http://www.ncdc.noaa.gov/oa/climate/research/2003/nov/eaimages.html
or
http://www.ncdc.noaa.gov/oa/climate/research/2005/nov/eaimages.html

In those cases, base temperature for those images is 1971-2000. (Obviously)

There is a lot more data available of course. White spots are usually no data (clouds). The reason for the combination of days is to overcome clouds, by adding days (sat passes) you eliminate missing data. Some data is also averaged in, and the polar regions are adjusted due to known problems with temperature measurements.


ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_ssta_2004326_5day.gif
compared with this.....
ftp://podaac.jpl.nasa.gov/near_real_time/sea_surface_temperature/avhrr_navo_mcsst/browse/historic/2004/326/mcsst_n17_sst_2004326_5day.gif

what exactly is it showing (in more detail than "a difference in temperature!)? They both seem to be taken over the same time frame (17-22Nov) so why the difference?


Look close at the images. One is temperature, the other is anomaly. Anomalies tell us more than temperature.

Some light reading on methodolgy. Have fun.
http://www.osdpd.noaa.gov/PSB/EPS/SST/methodology.html

Nice topic related page
http://www.whoi.edu/institutes/occi/viewArticle.do?id=9986

[This Guy]

Cool stuff!

You can really see how the temps in the UK could be affected by a long term stoppage of the Gulf Stream!

It's only been in the last few months that I realized the part the Gulf Stream plays in regulating temps, and it was just via Oh By The Way info while looking at some of the global warming information. Some of those animations really show it!


Thanks again robinson!! :)

[Soapy Sam]

Not just the UK.

Google "Younger Dryas"

This time around, there is no American ice sheet to melt via the St. Lawrence, but who knows what other surprises Nature has in store?

I was on a rig out west of the Shetlands in 95. We had oceanographers on board with a deep sensor array gathering data. One of them told me that they had records of cold water currents ascending the European continental slope at several knots, extending down thousands of feet and over hundreds of miles n-s, which would sometimes stop and reverse direction within half an hour.
Consider the inertial forces involved. Then ask how in the hell that's even possible?

[robinson]

I don't know, but I am trying to find out. This article from 98 seems on topic. And for those who live in Europe, perhaps a little alarming.

http://www.williamcalvin.com/1990s/1998AtlanticClimate.htm