The 1 million "currency" question:

The one question everyone is currently worrying about in terms of global warming:

Could our release of greenhouse gases and the current increase in global mean temperatures lead to a shutdown of the THC and would this send the whole of Europe and North America into ice age like conditions?

 

(btw if you think this "freeze" is completely overexaturated.... check out the FUN FACT about Brinacles! ;) )

To investigate this question, we will take a paleoclimatic approach and look back in time to see whether the THC has shut down before, under which circumstances it does this, and what the consequences were for the North Atlantic region.

But then, where do we search? 1000 years ago? 100 000 years ago? 1 million? When the Earth was created??....

Let’s review what we know about the THC (see other posts):

-          It is sensitive to temperature and salt content (deep water production)

-          Heat is transported from south to north via currents

-          Currents may flow very fast

-          The mixing time for the whole world ocean is roughly 1000 years

-          We believe that changes called rapid climate changes are connected to ocean circulation

This gives us the hint that turning off the THC probably will happen on a rather short geological time scale. So luckily, we do not have to travel back to the Earth’s first birthday. However, 1000 years might be too short aswell, since one water drop needs this long to have gone through the whole conveyor belt system. So we expect to find something in the 100 000 year range!

Now we just need data! And if we look around the world, there are an uncountable number of archives that have recorded the last 100 000 years of climate! Especially important are ice cores! (for more information see SCIENCE FACT). Ice cores on Antarctica go back 800 000 years (Luthi et al.,2008)! Greenland ice does not reach back that far, but still enough to cover our period of interest (Svensson et al., 2008). The great thing about ice cores is that little bubbles of air have been trapped in the ice (Alley, 2000). With careful extraction, you can get an air sample from the 400 000 year old atmosphere! You gotta admit... that's pretty cool!

And this is what we are going to look at. Here you see "real" temperature values for the last 100 000 years:

(Ganopolski & Rahmstorf, 2001)

Let me know what you see/feel/think/notice!