True, but also, once the salinity (and hence density) of the water column changes to a point it is unsustainable, the balance will shift in the opposite direction and the reverse will occur.
Warm water is less dense - but this allows it to hold more dissolved salts and organics, and as such will actually be denser than cold water which can hold less dissolved salts etc. as the cold water is displaced by warm water, it will then start to move about and you can get drifting currents, but over the next how ever many millennia, the currents will shift again back to how they were 'when we were alive' and the oceans and currents will change again.....
As I say, we didn't start this cycle of change off, we may have sped it up, but we will never be abel to stop it - ever.....energy is a constant regardless of anything anyone does.
These events may cause man(and woman)kind to become extinct, thats life....look at the other populators of this little rock of ours, we may think we are smarter then them and that we can halt this natural cycle....but we can't. What we should do is try and get it back to its more normal frequency of oscillation - but we sure as hell can't stop it - and we have to except that in a few millions of years we will no longer be here and the next tenant of this planet will take over - maybe they will prefer it warmer - until that ends at the next ice age, and they will probably be trying to develop V8 powred space boards to generate greenhouse gases again to keep the planet warm....but they will fail also, and the Earth will carry on doing what it does.....she is a harsh mistress, but we cannot tame her swings in mood!
