AESOP'S most famous fable is about a shepherd boy who cried “wolf” so often when no wolf was around that when one did appear nobody took any notice of his warning. Some environmentalists risk falling into the same trap. They are so convinced of the righteousness of their cause that they will cry “wolf” at any event that might plausibly be thought to support their view of the world.
That attitude makes it hard for responsible scientists studying important environmental issues to know when to raise the alarm. The climate is complex and no single piece of research is likely to prove the existence of a dangerous trend. It is a matter of judgment when enough bits of data have accumulated for action to be justified. So Harry Bryden and his colleagues at Southampton's National Oceanography Centre have been careful not to overstep the mark when commenting on their work on ocean circulation and its possible effects on parts of Europe, which has been published this week. Nevertheless, it is now possible to discern a dim howling in the distance.
A lot of heat moves around in the oceans. The currents that do the moving change from time to time, and both computer models and evidence from sediments and ice cores suggest such change can happen in a matter of decades. Dr Bryden's data indicate that what history and the models describe may actually be happening at the moment to currents in the North Atlantic. If true, it would mean a cooler future for north-west Europe—possibly a lot cooler. And that future would be close; the change could happen over the course of two or three decades. Moreover, the most plausible explanation for the shift is, paradoxically, global warming (see article).
Sceptics could, and should, point out the uncertainties—in particular, that the conclusion relies on a mere two individual years' worth of data. Though these indicate a shift in the past decade after four decades of stability, it is just possible they could be blips. Given the murky and statistically uncertain nature of climatology, however, Dr Bryden's result is about as robust as can be expected.
More important, it is the first in what will be a series of results, since oceanography's rise in the scientific pecking order means its practitioners can now afford the instruments and infrastructure to monitor parts of the ocean continuously. The truth will soon out and it is not, therefore, necessary to cry wolf quite yet, though it may behove those paid to think about such things to put more effort into looking at how governments should respond if north-west Europe does get significantly colder in the next few decades.
Dr Bryden's finding, though, also provides a reason to think more clearly about the whole issue of climate change. The Kyoto protocol, which is the subject of a big international meeting in Montreal this week and next, is costly and unlikely to achieve its stated aims. But the meeting is also supposed to begin the process of sketching out what the post-Kyoto world might look like. This result may focus minds, whether that focus is directed towards trying to stop global warming or, if it is decided that climate change is unstoppable, working out the best ways to live with it. And if the next few years do confirm Dr Bryden's result, it will be a triumph for the modellers who predicted it, and a reason to take their cries about other climatic wolves far more seriously.
I'll post an e-mail Britt sent, separately - a great overview (but not specific to yr ocean question).
Posted by: nlseaver | December 02, 2005 at 10:53 AM