Gulf Stream closedown: possible? effects?

Vortex · Post by **Vortex** » 08 Feb 2007, 19:02

Do we face a shutdown of the Gulf Stream?

If so, what would the effects be?

What would a 5 - 8 degree reduction in UK temperatures do to the country?

See also: http://en.wikipedia.org/wiki/Shutdown_o ... irculation

MacG · Post by **MacG** » 08 Feb 2007, 20:45

I hate to be the eternal killjoy. Or what you want to call it. It's not very certain that the Gulf Stream is that enormously responsible for the relative warmth here. There are some indications that air movements could be more important. On a positive sidenote, the air movements could of course also shut down and bring Siberian climate upon us. With the Gulf Stream intact. To lazy to find links right now.

biffvernon · Post by **biffvernon** » 08 Feb 2007, 20:46

The consensus amongst those who know about this stuff now seems that this one is pretty unlikely.

ianryder · Post by **ianryder** » 08 Feb 2007, 20:49

biffvernon wrote:The consensus amongst those who know about this stuff now seems that this one is pretty unlikely.

So was the view that Greenland would take centuries to melt in any significant way. Changed now. I thought the view on this one was a bit mixed.

MacG · Post by **MacG** » 08 Feb 2007, 21:12

ianryder wrote:
biffvernon wrote:The consensus amongst those who know about this stuff now seems that this one is pretty unlikely.
So was the view that Greenland would take centuries to melt in any significant way. Changed now. I thought the view on this one was a bit mixed.

Any idea why it's called "Greenland"? Could it be something about that it actually was green during the medieval warm period? There was a famous Norse settlement there for 400 years. They were running agriculture with cows and stuff between 900 and 1300.

mocara · Post by **mocara** » 08 Feb 2007, 22:14

I believe it was called Greenland in an attempt to persuade others to travel there. <-- checks wikipedia:

"It is said that Erik the Red was exiled from Iceland for murder. He, along with his extended family and thralls, set out in ships to find the land that was rumored to be to the northwest. After settling there, he named the land Gr?nland ("Greenland"), possibly in order to attract more people to settle there. "

There you go. I think we should rename Iraq to hugsland.

MacG · Post by **MacG** » 08 Feb 2007, 22:35

mocara wrote:I believe it was called Greenland in an attempt to persuade others to travel there. <-- checks wikipedia:

"It is said that Erik the Red was exiled from Iceland for murder. He, along with his extended family and thralls, set out in ships to find the land that was rumored to be to the northwest. After settling there, he named the land Gr?nland ("Greenland"), possibly in order to attract more people to settle there. "

There you go. I think we should rename Iraq to hugsland.

But, but... Impressions alone wont make hay grow? Hay needed to feed the cows during winter. They lasted there for about 400 years. Longer than the USA have existed. Then they died. Did they die because they suddenly realized that hay did not grow on Greenland? After 400 years of delusions? Feeding the cows imaginary hay for 400 years, then suddenly realizing it was a delusion?

Billhook · Post by **Billhook** » 08 Feb 2007, 23:39

Where is the evidence for hay being produced in Greenland in the period you state ?

While you're at it, you might further explain just why hay was not produced in Britain during this period.

MacG · Post by **MacG** » 09 Feb 2007, 07:54

Billhook wrote:Where is the evidence for hay being produced in Greenland in the period you state ?

While you're at it, you might further explain just why hay was not produced in Britain during this period.

There is very little evidence for anything in this world, so the archaeologists will have to do with what they find:

http://www.archaeology.org/online/features/greenland/

snow hope · Post by **snow hope** » 09 Feb 2007, 09:03

Very interesting link MacG.

Bilhook, from the article it refers to hay,

"Greenland's climate began to change as well; the summers grew shorter and progressively cooler, limiting the time cattle could be kept outdoors and increasing the need for winter fodder. During the worst years, when rains would have been heaviest, the hay crop would barely have been adequate to see the penned animals through the coldest days."

Blue Peter · Post by **Blue Peter** » 09 Feb 2007, 10:45

Billhook wrote:While you're at it, you might further explain just why hay was not produced in Britain during this period.

So what was the winter feed for animals in Britain during this period?

Peter.

Joe · Post by **Joe** » 09 Feb 2007, 11:42

MacG wrote:But, but... Impressions alone wont make hay grow? Hay needed to feed the cows during winter. They lasted there for about 400 years. Longer than the USA have existed. Then they died. Did they die because they suddenly realized that hay did not grow on Greenland? After 400 years of delusions? Feeding the cows imaginary hay for 400 years, then suddenly realizing it was a delusion?

Jared Diamond reckons that it was a combination of

1. The mini ice age:

a) Reducing the length of the growing season, making pastoralism more difficult due to lack of animal feed.
b) increasing the amount of sea ice in the north atlantic, making trade with the other norse nations much more difficult. At the same time, the crusades made african & asian elephant ivory available to European Norse which killed the market for the Greenland Norse's walrus tusk ivory. These 2 factors severely reduced the frequency of trading ships visiting from Iceland, the Faeroes, Shetland, Norway etc with supplies of the essential items that the Greenland Norse couldn't make/grow/mine themselves (iron was a particular problem, I think).

2. Arrogance/cultural inflexibility which stopped them from adopting inuit techniques for dealing with the increasingly intemparate climate.

Basically, he reckons that the climate changed and instead of adapting they clung to inappropriate survival strategies and gradually starved.

simonrichards912 · Post by **simonrichards912** » 09 Feb 2007, 13:25

If I remember the word from the IPCC is that the gulf stream will not stop, though it will probably slow down.
I also agree that the gulf stream does not directly affect our climate that much. The British Isles are heated primarily by solar radiation and geothermal energy. Secondly, the prevailing SW winds bring warm air from lower latitudes and thirdly, water vapour in clouds condensing and falling as rain (water vapour condensing emits heat).
The gulf stream for sure will affect the winds and the amount of water vapour in the clouds (warmer water means more evporation from the sea and hence more clouds and rain).