effect of ocean dynamics on climate and sealevel

[silverslith]

If I was to say I had a good understanding of this I would be a liar. Humanity as a whole can't make that claim. It needs a lot of research, observation and scenario modelling before we will begin to make accurate predictions.

Assuming people are interested in discussing this I'll start with a few diagrams and then explain some of the state of present knowledge as I see it.

 

ocean: thermal incline, macrolayering, and main circulation system.

 

The circulation diagram is wrong for the nth atlantic, as it should go clockwise.

[Martin]

this is a generous constructive initiative to take,

may contribute to keeping science discussion alive at the site.

 

I'd be interested to hear your take on the effects of ocean dynamics on climate.

I can't promise to discuss it intelligently because I don't know a lot in this area.

 

the technical papers I have seen do not all agree. so you may find that some of the conclusions in this area are controversial and people may argue with you

 

anyway if you want to launch a discussion of ocean dynamics/climate interaction that is really great! go to it! thx.

[silverslith]

this is a generous constructive initiative to take,

may contribute to keeping science discussion alive at the site.

 

I'd be interested to hear your take on the effects of ocean dynamics on climate.

I can't promise to discuss it intelligently because I don't know a lot in this area.

 

the technical papers I have seen do not all agree. so you may find that some of the conclusions in this area are controversial and people may argue with you

 

anyway if you want to launch a discussion of ocean dynamics/climate interaction that is really great! go to it! thx.

 

No-one seems to know a lot in this area. Its pretty recent discoveries that:

-bodies of water of different density mix very badly.

-the deep ocean zone has a very complex structure of different layers and intrusions of different salinity and temperature. (its not long been noticed that this can be resolved with geological sounding techniques).

 

no surprize that papers don't agree. I've seen some very credible looking ones that turn out to be funded by oil lobbies. If like those they assume constant rates of upwelling then its no surprize that they conclude a simular contribution to sea level rise from thermal exp as ice melt and century timescales for major change. The assumption of no major variation in circulation patterns and upwelling is very dangerous IMO.

what happens when all that cold low salinity icewater equalises temp with salty warmer layers above and below- major convection plumes and cyclone like mixing vortex's?

much argument on this topic is called for!

[silverslith]

Here's a chart of water density at different temps.

The increase in density of water up to 4degrC is a damn lucky phenomenon as its a great buffering system at present. from that graph of temp/depth you can see that at least half of the oceans volume is in that range. between this and 80% as the deep ocean water surfaces south or nth of 60degr. Polar water temps are rising faster than elsewhere recently though.

The gulf streams said to have slowed 30% and the atmosphere is likely to take up the heat distribution duties that are usually 80% gulf stream. This could expand the surface mixed zone -mixed by weather, and the pycnocline with transfer of water from the sub 4 degC to higher temps and altitude.

Density of Water.doc

[silverslith]

should we ignore the possibility that when the northern passage opens up the warm gulf stream may not be dammed, chilled and sunk in the north atlantic, but circle the north pole on the surface? Particularly after the ice cap breaks up.

The upwelling in the pacific and indian ocean would likely continue so this could expand the surface mixed zone and pycnocline like an emptying bathtub in reverse.

 

Or the current could stop altogether causing rapid freezing of the poles, glaciation in Europe and nth America, and much higher equatorial temperatures. The temperate zones would be hammered by constant storms as the atmosphere takes up the heat transfer duties between very extreme temp and humidity differentials This is said to have happened repeatedly 30000-5000 years ago.

[ecoli]

Or the current could stop altogether causing rapid freezing of the poles, glaciation in Europe and nth America, and much higher equatorial temperatures. The temperate zones would be hammered by constant storms as the atmosphere takes up the heat transfer duties between very extreme temp and humidity differentials This is said to have happened repeatedly 30000-5000 years ago.

 

This is the basis for the "day after tommorow" (as much as I hate to bring up that move). Although the movie greatly dramatized the time scale in which this could happen.

 

The deep ocean conveyor belt takes on the order or a thousand years to circulate, right? So I don't think the effects are going to be that fast. Anybody agree/disagree?

 

btw... silverslith, where did you get the pictures for post 1... I ask because they are the same exact pictures in my environmental/oceanography textbook.

[silverslith]

This is the basis for the "day after tommorow" (as much as I hate to bring up that move). Although the movie greatly dramatized the time scale in which this could happen.

 

The deep ocean conveyor belt takes on the order or a thousand years to circulate, right? So I don't think the effects are going to be that fast. Anybody agree/disagree?

 

btw... silverslith, where did you get the pictures for post 1... I ask because they are the same exact pictures in my environmental/oceanography textbook.

 

I've seen 200 years as residence time for the current in the deep ocean. I don't think we should assume stability in upwelling and subduction. I apologise if I've been concentrating on pessimistic scenario's, but they do need consideration. Frankly a few centuries is still unacceptably short for major potential sealevel unstability caused directly by humans. The facts that sealevels have definately risen in the last 100 years and the thermal forcing has only hit an accelerating trend in the last 2 decades mean that the risk of breaking the stable climate equilibrium that has allowed our "civilisation" to develop is high.

The climate would of course change very quickly if the ocean circulation system changes.

I googled up those pic's a couple of days ago for this thread. the circulation one was from microsoft, the other two from a Navy training resource.