Modelling suggests that increase of fresh water flows large enough to shut down the thermohaline circulation would be an order of magnitude greater than currently estimated to be occurring, and such increases are unlikely to become critical within the next hundred years; this is hard to reconcile with the Bryden measurements.
The Bryden results could be caused by natural variation, or "noise", that is, coincidence.
If the results are correct, perhaps thermohaline circulation reductions will not have the drastic effects that have been predicted on European cooling.
While previous shutdowns (e.g. the Younger Dryas) have caused cooling, the current overall climate is different; in particular sea-ice formation is less because of overall global warming.
However, a thermohaline circulation shutdown could have other major consequences apart from cooling of Europe, such as an increase in major floods and storms, a collapse of plankton stocks, warming or rainfall changes in the tropics or Alaska and Antarctica (including those from intensified El Niño effect), more frequent and intense El Niño events, or an oceanic anoxic event (oxygen (O2) below surface levels of the stagnant oceans becomes completely depleted - a probable cause of past mass extinction events).