An underestimate of an important effect of climate change?

Oh my.  Until relatively recently, it seemed that there wasn't that much concern in the climate change science community about increased temperatures and glacial melt causing (at least any time soon) a major slowdown in the Atlantic overturning currents that help keep England and Northern Europe relatively warm.  But last year, it was noted that the current is already slowing down, which did raise some eyebrows as to whether it was part of a temporary cycle, or a sign of something worse.

Now, from Real Climate, looks like some detailed analysis shows the risk of a major shutdown has been underestimated.

What's not explained is how serious for parts of Europe the cooling (in winter?) may be.