AMOC and the Subpolar Gyre
The AMOC
Are we reaching a tipping point
See this informative video by Prof. Rhamstorf
Brief explanation of AMOC
cold dense water sinks to 2-3000m depth in sub polar and Norwegian sea area flowing down to South America and then transports heat north along the coast of the USA and eventually to the Western edge of Europe including the UK. This is not the same as gulf stream which is just part of the larger overturning motion in the Atlantic. Without AMOC tranfering this heat the range of temperature north south would be 20deg colder to 20deg warmer. Currently transfer is transfer is 10 to 20C to the north.
AMOC History
The last time AMOC changed was at the end of the ice age when abrupt warming occurred in greenland as measured in ice cores due to slip to north of the AMOC.
Global warming is NOW 20x stronger than at the end of the last ice age, so no similar warming has been known in earths history. Measurements taken indicate the AMOC is weaker than anytime after remaining stable for a 1000yrs.
Tipping Point
Measuring the actual tipping point where internal dynamics of the system make its transition to the next stable state un-stoppable are very difficult to calculate. Factors such as the salinity of the Atlantic in all three dimensions and the effects of precipitation and cloud cover compound the difficulty in creating accurate models.
However the salinity changes as measured indicate the lowest ever observed.
Tipping points in dynamic systems can be indicated by random variability regardless of the system being measured and paleoclimate data shows repeated instabilities past showing the affects on climate.
Model Predictions
As CO2 increases climate models all predict planet wide warming EXCEPT for Norwegian Sea which cools and these models all underestimate the amount of cooling when compared to the actual data is measured by satellite etc. How far away? again all the models underestimate as they do not included greenland ice sheet melt whereas the actual data show more slowing than models as measured by cold blob in the North Atlantic.
The Result
Increased heatwaves in Eastern Europe
For the UK models show feb temp cool by -40C <> 100 years. Let that sink inā¦ Temperature differentials creating a crazy stormy climate. Bear in mind C02 stays around for 100,000 years but we will know in few decades!