Will a warmer world mean fewer hurricanes hitting American soil? Nobody really knows. But a study just published in Geophysical Research Letters is bound to provide fodder for those who enjoy heralding every little morsel of evidence to support their contention that climate change is a communist plot.
"Global warming and United States landfalling hurricanes," by Chunzai Wang of NOAA's Atlantic Oceanographic and Meteorological Laboratory, connects the dots between wind shear patterns (the difference between high- and low-altitude wind speeds) and long-term trends in storms that hit the U.S. (doi:10.1029/2007GL032396).
He concludes that "global warming of the sea surface is associated with a secular increase of tropospheric vertical wind shear in the main development region (MDR) for Atlantic hurricanes. The increased wind shear coincides with a weak but robust downward trend in U.S. landfalling hurricanes."
This is what's being picked up by the media, for example, here and here.
But read beyond the abstract and few things pop up. First is the "weak but robust downward trend" in storms reaching the States. "Robust" here means that the trend seems to fit a variety of time series, both short and long. But Wang's trend "is statistically not significant (below 95% significance level)."
Second, there's still far too many unknowns to close the book on the subject, and Wang even writes that the opposite conclusion is quite possible (bold is mine). From the GRL study:
...the tropical oceans compete with one another for their impacts on the vertical wind shear over the MDR for Atlantic hurricanes.... Whether future global warming increases Atlantic hurricane activity will probably depend on the relative role induced by secular warmings over the tropical oceans. For example, if the effects of warmings in the tropical Pacific and Indian Oceans cannot overcome that of Atlantic warming, global warming may favor landfall incidence for the United States. Therefore, model projections of ocean warming patterns under future global warming scenarios may be crucial in predicting future Atlantic hurricane activity. Additionally, it should be recognized that anthropogenic global warming has a pervasive influence on both oceanic and atmospheric temperatures and circulation as well as water vapor, all of which affect tropical cyclones in complex and not yet fully understood ways. A better understanding of these factors and of the influence of natural climate variability on tropical cyclones is needed.
Coming on the heels of another study that casts doubt on the thesis that global warming will increase hurricanes, though, it would seems that we're in for a stormy year doing battle with the climate change pseudoskeptics.
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Coming on the heels of another study that casts doubt on the thesis that global warming will increase hurricanes, though, it would seems that we're in for a stormy year doing battle with the climate change pseudoskeptics.
Battling either one can be a rough job! Here's hoping we get a break on at least one front! Both would be good too! LOL!
Dave Briggs :~)
Speaking of climate change as a communist plot, there're a lot of deniers giving each other online high fives over this article:
http://www.americanthinker.com/2008/01/will_the_ice_caps_melt.html
A silly equation-ridden rant by a mechanical engineer which proves the sun can't melt a block of ice fast enough to cause the sea level rise that Al Gore predicted.
Even I, as a layman, know that the ice doesn't have to melt, it just has to slide into the ocean. But I haven't seen an online debunking from anyone with credentials yet.
Daniel,
The ice sheets are mostly located in depressions and hence cannot "slide into the ocean". Read the IPCC FAR statements on sea level rise and you'll see that outside of a few "outliers" (or is that out liars) like James Hansen, few scientists see any danger of a rapid meltdown of either the Greenland or Antarctic ice sheets in the next several hundred years.
The fact that you confidently stated it like it was fact shows that you need to do more investigation into the matter.
But hey, if you'd rather hang around alarmist blog sites chortling ignorantly don't let me spoil your fun.
I was greatly relieved to read an engineers analysis of ice melting. It's clear to me now that incidents like http://nsidc.org/iceshelves/larsenb2002/animation.html just can't happen.
I'm also relieved that the Antarctic plateau, an ice mass that caps out at about 10,000ft high is, in fact, in a local depression. I can only presume that my inability to see the giant mountain range holding in the ice mass around the perimeter of the continent is due to my wholesale acceptance of the hysteria. Thanks to Lance for setting me straight. Observations of ice melting and loss around the perimeter of Greenland have me scornfully chortling along with the sceptics now.
markg,
The Larsen B iceshelf was over water as can clearly be seen in the photo in your link and hense didn't raise sea level. Thanks for at least acknowledging that the Antarctic ice sheet is in a depression, and hense Dan's remarks about it "sliding into the ocean" are impossible.
Funny with all the talk of record low Arctic sea ice this past year you didn't hear much about the fact that Antarctic sea ice reached an historic high.
The truth is there is no long term temperature increase or long term melting trend observed in the Antarctic, but why let the facts get in the way of politically driven alarmism.
Daniel,
The American Thinker's rant is even worse than that. He only considers the amount of heat needed to raise the temperature of the air by 5K. The models don't warm the air by 5K unless they've also raised the temperature of the land and ocean surfaces by 5K, which takes a little bit more heat.
Not to mention his use of, essentially, 4 * 6 = 240.