Thanks again to RealClimate, a blog run by climate scientists, for giving us excellent if somewhat complex information about recent reports concerning the slowing of the Gulf Stream and the possible effect of that slowing on European climate. As the writer and subsequent commenters explain there are several things which contribute to the warming northern Europe including the shape of the jet stream and the movement of warm surface waters toward the region. The Gulf Stream is technically only part of a larger set of heat transporting currents and the one alluded to in the recent Times of London story is actually the North Atlantic Drift.
The RealClimate piece explains how the currents work and that they show significant variations in strength from decade to decade. While there is precedent in the geologic record for short-term dramatic slowdowns and even stoppages, that is not what is now being observed. It appears to be a gradual process that may take a long time, perhaps a century. Nevertheless, the author warns, the situation bears careful watching since the data available is difficult to gather in the icy climes of Greenland and its associated seas and conditions could change for unforeseen reasons.
The situation is a little less alarming than the reporting would make it seem. On the other hand, the slowing noticed so far is occurring sooner than expected. The trick will be to establish whether this is a normal variation or the beginning of a breakdown in the heat-transporting currents.
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