OK - maybe I have missed something. But I think this is panic mongering. . Last I heard:
1) Odds were nothing like even on the Gulf Stream failing this century. In fact the serious scenarios were of the Gulf Stream failing in the 22nd century.
2) In case of failure of the Gulf Stream due to global warming you don't end up with a new ice age - cause it only happens with the most extreme warming - in which case Gulf Stream failure mitigates what would others be an extremely overheated British Isles, Western Europe and North American. You do get one hell of a lot of draughts though. Yes, weakening of the Gulf Stream by 90% or so has caused local ice ages in the past - but that was not during the middle of a warming trend from other causes.
There are plenty of problems we know global warming leads to - droughts, floods, loss of coastland, spread of pests, diseases, and fungi, major drops in agricultural production. We don't need to make new ones up.
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