Le Gulf Stream a été en panne (ou en grève?) pendant 10 jours en novembre 2004

L’on vient d’apprendre que le Gulf Stream s’était arrêté pendant dix jours en novembre 2004. C’est la première fois qu’un tel événement est constaté. Il alimente bien entendu la thèse selon laquelle le réchauffement climatique aurait pour effet l’interruption du Gulf Stream et l’installation de l’Europe dans un climat beaucoup plus froid que celui qu’elle connaît actuellement — voire dans une nouvelle et brutale “ère glaciaire”.

Comme le rappelle le Guardian, qui annonce la nouvelle, la thèse est prise comme argument central du film The Day After Tomorrow. L’information sur le Gulf Stream vient accroître la tension, au Royaume-Uni, à propos de la crise climatique.

Quelques observations du Guardian :

«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.

»The nightmare scenario of a shutdown in the meridional ocean current which drives the Gulf stream was dramatically portrayed in The Day After Tomorrow. The climate disaster film had Europe and North America plunged into a new ice age practically overnight.

»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.

»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.

»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?”»

Mis en ligne le 27 octobre 2006 à 09H46