http://www.nature.com/news/2005/051128/full/051128-9.html

Normally I am not so worried about reports on increase of greenhouse gases, melting of icecaps and such. But the weakening of the atlantic currents as reported in this news report seems quite worrysome. These currents are supposed to keep Europe (and N-america if you care about that area) warm.

So far the weakening of the currents hasn't effected average temperatures yet. But will they?

Is the report weak, bogus? Should we be worried? Or is it another example of raising of fear unnecessarily?
What are your views on this matter?

The thing that really scares me, as I've said in other posts, is that when the Greenland icesheet collapses, the North Atlantic is going to be flooded with a surface layer of fresh water. The consequences of that will be a shut-down of the Gulf Stream, which is going to have some fairly dreadful results.

Spurious: Reference to this article was posted a few days ago at the start of the thread "Earths Magnetic Core and Polar flip. Possible big chill?" But perhaps it does deserve a seperate thread.

This conveyor belt circulation is called thermohaline circulation or meridional overturning circulation, which is responsible for the Gulf Stream heating the climate around Northwestern Europe. I do not see how Global Warming could NOT be responsible for a decrease in this circulation. Global Warming would prevent the northern currents from becoming colder, thus preventing them from sinking. Also, the decrease in ice caps at the Arctic would cause less fresh water to be taken out of the salt water to form the ice. This would prevent them from become more saline - a necessary condition for the water to become more dense in order for it to sink to the bottom to recirculate. If the water doesn't sink, then it creates a barrier to the southerly warm currents from coming up, thus slowing the circulation in the Atlantic.

The problem spurious is that the models and the evidence suggest the switch off could be very sudden, of the close order of one decade, with a subsequent drop in temperature in western Europe of 5 -10 degrees celsius. The switch on may not be as rapid and we don't know where the on 'switch' is located.
Contrary to valich's lack of imagination there are other possible causes for this. The mini-ice age in the 1400s onwards, when the Thames would freeze over, may have resulted from a partial switch off. And that in turn may have been promoted by almost zero sunspot activity and a lowering of overall solar output. J
Just too many variables to be sure as yet. I suggest investing in wool fabrics and fibre glass insulation just in case. I'm somewhat miffed as I have my house nicely positioned on the coast that will be in effect should the entire Antarctic ice sheet melt. I wasn't expecting a chill wind from the North.

I thought the north atlantic current was slowing down due to the north atlantic oscillation. Also, is it possible that the greenland as well as the antarctic ice caps melt and make them THICKER? Could that be the "switch" that you are discussing?

The reason why the Atlantic current circulates is due to the wind cycle at the ocean's surface which goes in a clockwise direction in the Atlantic, due to the Coriolis effect. This produces the Gulf Stream that warms Northwestern Europe from the warmer currents coming up from the tropics. When these warmer currents become less dense then they drop to the deep ocean where they recirculate back to the tropics, thus completing the cycle. This cycle of flow, is "technically known as the "Atlantic meridional overturning current." It also referred to as a "conveyor belt" or the "thermohaline circulation."

When the Greenland or Antarctic ice melts, it dilutes the salinity of the surrounding water making it less dense and less able to descend to the bottom, where it completes the circulation cycle. If it cannot descend to the bottom, then it becomes a barrier of resistance to the incoming surface flows of warm water from the tropics.

The so-called North Atlantic oscillations are due to variations of the westerly winds in the northern Atlantic Ocean. Although some contrbute these variations due to the glaciers melting in Greenland and Iceland. There is debate about this: some call it weak, others a strong variation. And the reasons behind it differ.