Below is a nice map, courtesy of the BBC, showing the shift in the jet stream bringing unprecedented rain and flooding to the UK. As Kim Murphy put it for the Los Angeles Times today:
Few scientists are ready to immediately blame the quirky weather on
global warming. For one thing, current climate change trends predict
just the opposite in Britain: warmer, drier summers and wetter winters.
"One
thing to remember is that what seems to be indicated [with global
warming] is much more variability in the climate," [Jon Finch of Oxford U.] said. "So this
event, which basically looks like it’s a 1-in-200-year event, may with
a change in climate come down to a 1-in-50-year event. But that’s just
speculation."
The jet stream displacement is expected to right
itself in the coming weeks, and stay that way through the rest of
summer, said Jim Dale, a meteorologist with British Weather Services in
High Wycombe.
But note the caveats: "few scientists are ready to immediately blame…" Of course not! No scientist worth his salt is ready to attribute without causal evidence.
But those of us who watched the weather maps in Southern California during our record breaking floods of 2005 saw a similar phenomenon — an unexplained swing in the jetstream that surprised even the most experienced of climatologists. Usually the jetstream in the winter turns eastward over the West Coast far north of SoCal, but in December and January of 05, it swooped all the way down to Catalina Island…for weeks at a time, causing huge floods, vast damage, and killing quite a few people.
Now reputable climatologists (such as Kelly Redmond) say that swing was "not inconsistent with" global warming, in the murky double negative phrasing that scientists prefer.
Why not drop the "speculation" and say, as we can with assurance, that in the 21st century a warming ocean and atmosphere means increasing overall variability with a far greater chance of climate chaos?
Kit Stolz 
When scientists speculate they try to preface their statements with the caveat that they are in fact speculating. It’s OK to speculate, but without evidence it’s not backed by empirical science. Science is a rigorous mistress and many a good researcher has been mislead and embarrassed by empirical results based on flawed models and bad or misleading data.
As for the jet stream shift, if it is truly unprecedented and anomalous, and we are seeing a general increase of anomalous weather events, I’d tend to agree it’s portentous. But there are compound questions yet to be resolved – the effect of solar variability is still being disputed, soot is a new-found player in net heating, CO2’s effect cap is nearing its maximum… all the while we are still seeing yet more warming, regardless. The big unknown are aerosols – heretofore climatology ascribed a net cooling effect to the bulk of them, but soot was just found to have a net heating effect.
For instance, tropospheric and sea temperatures both closely follow the solar cycle while land-surface temperatures do not, suggesting endemic measurement issues in those land-based data.
In the interim we should indeed start cleaning up greenhouse emissions, but which ones? Soot mitigation might be a good, relatively inexpensive, place to start, considering its aggressive role in the Arctic melt-off & large role in the Pacific & Asia.
see: The Soot Files
http://www.scientificblogging.com/the_soot_files
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Thanks for the comments and the link, Mr. Leebert. I become impatient with equivocation on these topics, but you’re right to demand specificity, and maybe to begin with soot. I’m going to keep an eye on your site and try to learn more.
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