sexta-feira, 1 de junho de 2007

Global Warming = European New Ice Age?…


«The Gulf Stream, together with its northern extension towards Europe – the North Atlantic Drift – is a powerful, warm, and swift current that originates in the Gulf of Mexico, exits through the Strait of Florida, and follows the eastern coastlines of the USA and Canada before crossing the Atlantic. At about 30ºW-40ºN, it splits in two, with the northern stream crossing to northern Europe and the southern stream recirculating off West Africa.


It influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe. It is a western-intensified current, largely driven by wind stress. The North Atlantic Drift, in contrast, is largely thermohaline (temperature and salinity) circulation driven. By carrying warm water northeast across the Atlantic, it makes Western Europe warmer than it otherwise would be. However, the extent of its contribution to the actual temperature differential between North America and Europe is a matter of dispute.

The Gulf Stream transports about 1.4 petawatts of heat – equivalent to 100 times the world energy demand. It carries water at a rate of 30 million cubic meters/second (30 sverdrups) through the Strait of Florida. After it passes Cape Hatteras (North Carolina), this rate increases to 80 million cubic meters/second.

As it travels north, the warm water undergoes evaporative cooling and brine exclusion. The cooling is wind driven and causes evaporation, leaving a saltier brine. In this process, the water increases in salinity and density, and decreases in temperature. The second process involves the formation of sea ice, which likewise increases the salinity of the brine solution, thereby decreasing its freezing point. These two processes produce water that freezes at a lower temperature than 0ºC.

In the North Atlantic, the water becomes so cold and dense that it begins to sink down through warmer, less salty and less dense water. This downdraft of heavy, cold and dense water becomes a part of the North Atlantic Deep Water Current, a south going stream.

There is some speculation that global warming could decrease or (even) shutdown thermohaline circulation and therefore reduce the North Atlantic Drift. This could trigger localised cooling in the North Atlantic and lead to cooling (or lesser warming) in that region, particularly affecting areas such as Scandinavia and Great Britain. The chances of this occurring are unclear.

At present, most available data show that Gulf Stream flow was stable over the past 40 years. One report, based on a snapshot survey, suggested that the deep return flow has weakened by 30% since 1957, which would imply a weakening in the North Atlantic Deep Water production. However, this should have caused a temperature drop of several degrees in northwest Europe, which has not been observed. It was later discovered, using the first cross-Atlantic array of moored current meters, that variations within one year were just as large.


At least part of the apparent weakening of the Gulf Stream, if real, may be cyclical and connected to recent positive values of North Atlantic Oscillation. Recent research shows that Gulf Stream volume transport during the Little Ice Age was 10% weaker than today’s, implying that diminished oceanic heat transport may have contributed to the 16.th- to the mid-19.th-century cooling in the North Atlantic.»

"Gulf Stream", Wikipedia - edited & abridged

Man had no significant intervention in the Little Ice Age.
But what about now?
The Industrial Revolution only started by the end of the 18.th century, and up till now gazillions of tons of Carbon Dioxide (CO2) have been already thrown into the atmosphere, being the first cause of the greenhouse effect and of global warming.
For the very first time in the history of our planet – ± 4,500 million years – mankind may be altering life support conditions forever. From now on, environment and eco-worries will always be inseparable.
But what kind of signals do we get from economy and politics?
You think about that, dear blogger friend, and find it out…
Think meanwhile about Seychelles Islands, which are about to be submerged by the Indian Ocean… Or some of Solomon and Vanuatu islands threatened by the Pacific… Can this be sheer speculation?

RIC

16 comentários:

Catatau disse...

Olha, sabes o que me anda mesmo a preocupar? A subida progressiva do nível do mar e os fenómenos agudos de transgressão marinha que vejo um pouco por todo o litoral ocidental. Se soubesses no que se transformaram as fabulosas praias de entre-Cávado e Neiva e se visses o que está a acontecer às de entre-Ave e Cávado (com destaque para a Apúlia)!...

Ando a perder as paisagens dos meus olhos aos pedaços!

RIC disse...

Olá João M.!
Parece ser o que nos espera a todos... Na infância, quando ia à Costa da Caparica, lembro-me que me fartava de caminhar da povoação propriamente dita até à beira-mar... Nunca tinha visto um areal tão extenso; hoje, sai-se da povoação e o mar está logo ali, talvez nem a 50 metros...
E não tardará muito para que a maior parte das ilhas que são atóis fiquem submersas... Algumas já não podem ser habitadas...

Há sérias razões para nos preocuparmos...

Um bom fim-de-semana para ti, meu caro! :-)

Catatau disse...

Um bom fim-de-semana também para ti, rapaz! :)

RIC disse...

Muito obrigado! Diverte-te! :-)

Ricardo disse...

Acho que não existe nada mais em voga que o aquecimento global...

Mas não sei se essa movimentação toda vai adiantar, quando a solução envolve gastos exorbitantes.

As pessoas parecem mais dispostas a acabar com o planeta que a perder seus lucros...

E mesmo assim, um cientista disse que pra reverter o aquecimento, levaria mais de 2000 anos... será?

Beijão!

MrTBear disse...

Não te preocupes RIC, o americanos resolvem o problema.....quando ele realmente se apresentar irresolúvel.....
Viram como o Al Gore está gordinho???? é da preocupação...

Estou mais com o Catatau, isso sim é de preocupar....

P.S. por via das dúvidas, não faz mal nenhum aplicar a politica dos 3 R e evitar usar CFC's

BOM FIM DE SEMANA

T-Bird disse...

Good post. I’ll give up my ‘giving up talking’ campaign to make a rare comment and them clam up again.

I have known about this for a long time (among other types of nuts, I am a science and geology nut). Ironic that global warming could cool Europe.

The economist just had an article that there is a growing body of evidence that the earth’s magnetic pole is getting ready to shift in the next 1000. Patches of abnormal magnetism are growing now in the south Atlantic. Since that acts as an umbrella to shield us from deadly radiation that ten sun poops out, what will it mean when it shifts? Is it like – the shield is down for a second? A minute? 26 hours? Two weeks? Seven years?

Too many damned people resulting from waaaaaaaaay too much irresponsible breeding on the planet (people crapping out litters of kids like sows on grandpa’s farm) and too conspicuous consumption (and yes, I realize I am sitting in the epicenter of that).

The first thing I would do in the US tax code (after I cancel all tax breaks for the greedy rich and cancel all tax breaks for churches) would be to cancel any and all tax breaks for anything beyond one child.

T-Bird disse...

Had to read it a second time. Thank you for writing in English this morning (evening to you).

We live where there is a cold current heading south called the Japanese Current. Our ocean water is very chilled. There is a northern warm one coming up from the equator and the two meet with a third one traveling due west in Monterey bay (the latter wind driven). That is why this body of water in California is is rich in diversity.

T-Bird disse...

Cold ocean water is the richest in terms of life. Opposite of what most people think.

RIC disse...

Olá Ricardinho!
Bem, em voga ou na moda há muitas outras coisas... Esta, porém, pode acabar connosco de vez...
Se os dinheiros fossem devidamente aplicados talvez as soluções fossem mais transparentes... Parece que falar abertamente sobre o assunto é crime contra a santa economia...
Quanto aos danos causados, é bem provável que em alguns aspectos seja muito complicado reverter a situação...
Abração e beijão! :-)

RIC disse...

Olá Teddy Bear!
É isso mesmo! Os americanos e as soluções milagrosas!... Vê-se, não é? E se ficarmos à espera dos políticos, o melhor será tirar daí o sentido... A sacrossanta economia não tolera desvios à omnipresente ganância... E o resto são tretas!
Quanto ao que cada um de nós pode e deve fazer individualmente, estou completamente de acordo contigo! Porém, faltam mensagens mais insistentes para comprometer todos sem excepção!
Excelente fim-de-semana!
Abraço! :-)

RIC disse...

Hello Will!
This is still a rather complex subject, I agree, but if we people don't deal with it, we're bound to stick our heads in the sand...
It'e really unforgivable that right-wing politicians do absolutely nothing against this threat. I guess the main undelying idea is «we won't live to see the consequences, so let coming generations face the problem»...
Lots of scientific documentaries show quite clearly what's going on, mainly by «National Geographic» (I'm an attentive fan and supporter!)
Here in Portugal we benefit from the Gulf Stream too. Without it the peninsula would have winters as cold as say the Quebec... Lord!
Wish you a great weekend! :-)
(I post in English because I think it's important and also because I like it that way...)

dondon009 disse...

The present administration, dear friend.... is just beginning to wake up to global warming, and there are still many who doubt....

Nothing significant will be done until the current administration is out of office.

Is it too late? Much damage has already been done.... and I'm afraid will never be repaired.

Can we slow the process?

Possibly, but I'm not certain....

What I am certain of is that the prayers of the religious right will have no effect on the potential disasters awaiting this great planet.

The time to act is now....

BTW: I live on the Gulf of Mexico and it amazes me that the seemingly small body of water I gaze out at each day can have such a significant effect on the world's weather!

Have a wonderful week.....

DON~

RIC disse...

Hello dear Don!
Thank you so very much for your visit!
It's no doubt getting really late for the world to deal with this problem... All I can hope for right now is that Al Gore may become the next President. Or at least someone with his views and ideas concerning environment. Let's just hope!
When I first started to read and watch some documentaries about the Gulf Stream (passing by your door on its birth, I know!), I had in fact no idea how complex and vital it is for the whole planet!... And there's so much more besides the surface currents...
The time to act is now indeed, because yesterday is no longer possible...

Have a «fantabulous» week, dear Don! :-)

Gumby disse...

I fear the changes in our planet we will see during the next 10 to 20 years. And George Bush still keeps his head firmly buried deep in the sand. Or his ass.

RIC disse...

Hello dear Gumby!
I believe others should also be held responsible for the present situation, not Bush alone. Even if he's a poor ignorant asshole, I want to believe he has no dictator powers... yet...
Best wishes, dear friend! :-)