Gulf Stream to Shut Down this Century

[so_whats_happening]

It is interesting to see the Florida Current is still as active as it has been with little if no slow down. Could it be simply this current just does not necessarily shut down (or takes a much longer time to occur than previously thought) versus Gulf Stream or region the North Atlantic drift region? I don't have nearly enough access to things as I did in school but has overall vertical properties changed drastically around Iceland? In my time of doing oceanography salinity, density, and temperature played a major role in how quickly currents moved in both the horizontal and the vertical, im sure none of that has changed. Are we seeing changes such as larger freshwater layers not necessarily at the surface but meters down impeding vertical transport or surface temperatures being just too warm to allow vertical transport to increase thus causing a pile up in a way of these warmer waters? This would ultimately create a positive feedback loop of warming and further slowing down if this were the case.

It is crazy to see little to no trace at least over the last 5 or so years of the Labrador current or hell even the Canary current. This is one of those chicken and egg situations i feel, was it the atmospheric pattern that helped create and enhance the NW Atlantic warming or was it a by-product of an already warming portion of the ocean (due to maybe a slowing northern process) that has shifted the jet configuration and has allowed to further enhance?

Have we seen vertical transport changes in the Southern Atlantic similar to what is occurring in the North Atlantic? I feel these two locations would be much more in sync with each other than the currents further south into the subtropics.

I know we probably do have quite some time and much warmer temps to experience before what is a collapse of the AMOC but these are just some of things I think about from time to time. Maybe one day in the next decade we flip the AMO and these things can be put to bed for a little...

[bluewave]

1 hour ago, so_whats_happening said:

It is interesting to see the Florida Current is still as active as it has been with little if no slow down. Could it be simply this current just does not necessarily shut down (or takes a much longer time to occur than previously thought) versus Gulf Stream or region the North Atlantic drift region? I don't have nearly enough access to things as I did in school but has overall vertical properties changed drastically around Iceland? In my time of doing oceanography salinity, density, and temperature played a major role in how quickly currents moved in both the horizontal and the vertical, im sure none of that has changed. Are we seeing changes such as larger freshwater layers not necessarily at the surface but meters down impeding vertical transport or surface temperatures being just too warm to allow vertical transport to increase thus causing a pile up in a way of these warmer waters? This would ultimately create a positive feedback loop of warming and further slowing down if this were the case.

It is crazy to see little to no trace at least over the last 5 or so years of the Labrador current or hell even the Canary current. This is one of those chicken and egg situations i feel, was it the atmospheric pattern that helped create and enhance the NW Atlantic warming or was it a by-product of an already warming portion of the ocean (due to maybe a slowing northern process) that has shifted the jet configuration and has allowed to further enhance?

Have we seen vertical transport changes in the Southern Atlantic similar to what is occurring in the North Atlantic? I feel these two locations would be much more in sync with each other than the currents further south into the subtropics.

I know we probably do have quite some time and much warmer temps to experience before what is a collapse of the AMOC but these are just some of things I think about from time to time. Maybe one day in the next decade we flip the AMO and these things can be put to bed for a little...

Yeah, the challenge is that many of these AMOC forecasts are based on models with proxies and not direct measurements. This recent study on the Florida current is actually measured and is maintaining its strength. Other studies on the cold blob in the North Atlantic suggest that it may be a function of more persistent +NAO patterns at times. They still don’t know if it’s caused by glacier melt with fresh water. It’s possible that it could be a function of both but how much each contributes is an unknown. When we look at some of the AMOC slowdown forecasts they resemble a +NAO pattern. Notice how the models show the record SSTs and warmth near the NW Atlantic and New England while the NAO area expands and cools. A more amplified version of what we have seen in recent years.

 

 

 

 

[Typhoon Tip]

ah,... it's (somewhat suppositional ) but I don't see the fl straight as much of a mystery    ...yet

the aspect to me, which is rather intuitive ... is geometric bottle-necking.   a lot of mass has to move through a small region down there.   the 80% still active amoc is still a huge mass quantity compared to what can geophysically squeeze through that region near florida.  

if the ~20% lowering of the total basin amoc exchange machinery is still above the critical mass continuity thresholds, then it's simply a matter of there still being enough mechanism in place to continue draw the sw atl basin waters out of that region - where mass-continuity keeps velocity/mass transport sufficiently high.   

most likely, it's gradual ... not yet begun.  fl straight starts to decline more gradually across a range of total basin amoc weakening, but doesn't likely begin registering change until the total basin weakening crosses some critical value, but it is > than the present 20% in this idea.

 

[jbenedet]

I agree.

Studies focused in/around the UK and Ireland makes a lot more sense at this stage, vs Florida...

 

[so_whats_happening]

15 hours ago, Typhoon Tip said:

ah,... it's (somewhat suppositional ) but I don't see the fl straight as much of a mystery    ...yet

the aspect to me, which is rather intuitive ... is geometric bottle-necking.   a lot of mass has to move through a small region down there.   the 80% still active amoc is still a huge mass quantity compared to what can geophysically squeeze through that region near florida.  

if the ~20% lowering of the total basin amoc exchange machinery is still above the critical mass continuity thresholds, then it's simply a matter of there still being enough mechanism in place to continue draw the sw atl basin waters out of that region - where mass-continuity keeps velocity/mass transport sufficiently high.   

most likely, it's gradual ... not yet begun.  fl straight starts to decline more gradually across a range of total basin amoc weakening, but doesn't likely begin registering change until the total basin weakening crosses some critical value, but it is > than the present 20% in this idea.

 

Flow can still happen continuously even with the overall lessening of the northern branch deep water formation zone. The water essentially just spreads out across the northern most Atlantic and into the Arctic ocean, makes sense sort of why we are seeing the issues with sea ice on the Atlantic front. Eventually the shock will come to the system with the slowing down down by Florida the estimated time of one loop is about 1000 years so if you have multiple shock locations working in tandem maybe it halves or quarters the time? (big question if that would be the cases) The biggest issue would be at the deep water formation zones basically how long does it take to push the issue through the system.

If we start to see Florida current slow down with respect to what we have seen thus far through measurements we can only assume this causes issues further downstream even more than we currently see. If I remember correctly one theory is the Gulf stream sort of takes on a more southerly look (gyre situation) versus branching into two paths west of the Azores.