[pete_inthehills (OP)]

Other than the obvious bit about the med eventually evaporating.

How would the global climate change?
How would the local climate to the med change?

Would there be other effects?

pete
inthehills

[JimBob]

You would make a dam. The Mediterranean would evaporate and become a salt-filled lake, as noted. Most weather that effects the Med. comes from the Northwest although during some times of the year the Levantine winds blow from the east so strongly that it at one time made sailing east in the Med. just about impossible in a square rigged ship.

Moisture is carried across the Sahara into the Med. basin. If the Levantine increased then thee would be less rain, and the reverse reaction would increase rain. I do not have a climate model program nor a Cray so I can't speculate further.

The Med. would retain the heat somewhat better and this would make local climate slightly hotter. The current that flows into the Med. under the warm water flowing out of the Pillars of Hercules would not happen so there would be increased heat in the area.

And the Med would become like the Black Sea, an oxygen-starved and largely dead basin.

[Sarah Elizabeth]

well obviously the supply of water to the mediterranean would be shut off and eventually the water evaporate to leave evaporites in the basin.the usual warm moist air wouldnt have a source pof moisture unless carried in from the atlantic for a distance and wouldnt supply the area with rain . thias would lead to hotter summers because a lack of rain means no evaporation of heat is occurring, and winters would be hot because warm air isnt picking up enough moisture to warm the land !  

[opus]

I think you may get arrested....

[frethack]

This has happened before, and recently (geologically speaking) during the Miocene, I believe.  Ill see what I can dig up about the paleoclimate of the time.

[frethack]

Heres some quick info.  Google it...theres LOTS more available.

Messinian Salinity Crisis

http://www.see.leeds.ac.uk/structure/tectonics/messinian/index.htm

[ScottLewis89]

This is actually going to happen, Africa is travelling north, albeit at a particularly slow pace, but after a few more million years it will close shut the straits of Gibraltar and we will have the Mediterranean Desert, Europes first.

[JimBob]

"The Mercian Geologist?" My lord, those Midland Brits are into everything. Like a bunch of beavers.

And the newbies are correct. The Tethys is closing for good one of these days. It has before in different areas but the end is near. For the compelete history of this sea-way see http://www-sst.unil.ch/research/plate_tecto/

[Exodus]

This has happened before, and recently (geologically speaking) during the Miocene, I believe.  Ill see what I can dig up about the paleoclimate of the time.

It has indeed happened before. I did some geology mapping in the South Western Alps and there are huge beds of gypsum, meters wide, which span across these Alpine areas (which have yet to suffer the extreme metamorphism of the central Alps). If you head down to Digne-les-Bains, these gypsum beds are clear to see as very little vegetation grown on them.

The gypsum beds are actually playing quite an important role in the movement of the Alps as due to the Northern movement of Africa, large areas of rock are actually sliding along gypsum planes, we know these as Nappes.

[JimBob]

Exodus, why not just say the gypsum acts as a décollement zone.

Oh yea, that would confuse Dr. Beaver and Paul.fr. Sorry 'bout that.

[paul.fr]

It takes a lot less more than that to confuse me...

[Exodus]

Exodus, why not just say the gypsum acts as a décollement zone.

Oh yea, that would confuse Dr. Beaver and Paul.fr. Sorry 'bout that.

lol, i was trying to keep things simple.

[that mad man]

It may have happened in the past but one thing I think important here is we now have the Suez canal.

I think the Med Sea would still keep to the normal sea levels because of the connection to the Gulf of Suez and then onto the Red Sea. IIRC there are no locks just a continuous waterway joined by some lakes on the way so nothing to imped the flow.

I would assume then that the Med would be more like a giant lake always at sea level and I think it doubtful in those circumstances for it to evaporate or become dead.

Hope that makes sense.

[JimBob]

There is only one problem with this. Blowing sand.

The canal company must constantly dredge to keep the waterway open. If not the sand blown in each year would fill the canal in a matter of years. It is a constant battle to keep it open.
 
Besides, when Africa completes closing the Med to make into a lake, it will also squeeze shut the eastern end of the Med as well. 

[that mad man]

I can understand the problem with the sand and that the channel has to be dredged to a depth of around 66 ft to keep shipping moving but so far in its history the Suez has remained open to the flow despite the sand. This means its fairly easily to keep it open although the financial incentive to do so would change from lack of shipping traffic.

What I cant understand is why the eastern end would close as all we are talking about here is sealing the straights of Gibraltar by man made means and wondering what would happen.

[JimBob]

Because all of Africa is moving north, not just the western end. It is the reason for the rift valley that is the Red Sea, the Gulf of Aquba and the valley of the Jourdan. That whole area west of the Jordan is moving north and will be crunched into mountains in the near future, geologically.

[JnA]

in the near future, geologically.

so a couple of million years?

[JimBob]

2-5, yes

[Exodus]

I am also uncertain that enough water would move through the suez canal in order to maintain water levels as they are now...