Hurricane Severity Increasing Thanks To Water Temps - Science

[hatrack]

No!

A new study concludes that rising sea temperatures have been accompanied by a significant global increase in the most destructive hurricanes, adding fuel to an international debate over whether global warming contributed to the devastation wrought by Hurricane Katrina. The study, published today in the journal Science, is the second in six weeks to draw this conclusion, but other climatologists dispute the findings and argue that a recent spate of severe storms reflects nothing more than normal weather variability.

Katrina's destructiveness has given a sharp new edge to the ongoing debate over whether the United States should do more to curb greenhouse gas emissions linked to global warming. Domestic and European critics have pointed to Katrina as a reason to take action, while skeptics say climate activists are capitalizing on a national disaster to further their own agenda. According to data gathered by researchers at the School of Earth and Atmospheric Sciences at Georgia Tech and the National Center for Atmospheric Research, the number of major Category 4 and 5 hurricanes worldwide has nearly doubled over the past 35 years, even though the total number of hurricanes, including weaker ones, has dropped since the 1990s. Katrina was a Category 4 storm when it made landfall.

Using satellite data, the four researchers found that the average number of Category 4 and 5 hurricanes -- those with winds of 131 mph or higher -- rose from 10 a year in the 1970s to 18 a year since 1990. Average tropical sea surface temperatures have increased as much as 1 degree Fahrenheit during the same period, after remaining stable between 1900 and the mid-1960s.

Georgia Tech atmospheric scientist Judith A. Curry -- co-author of the study with colleagues Peter J. Webster and Hai-Ru Chang, and NCAR's Greg J. Holland -- said in an interview that their survey, coupled with computer models and scientists' understanding of how hurricanes work, has given the researchers a better sense of how rising sea temperatures are linked to more-intense storms. "There is increasing confidence, as the result of our study, that there's some level of greenhouse warming in what we're seeing," Curry said. "Is it the whole story? We don't know."

EDIT

http://www.washingtonpost.com/wp-dyn/content/article/2005/09/15/AR2005091502234.html

[acmavm]

1. Don't even bother to try to tell bush**. He's a science ingnoramus. By

choice or inclination I don't know. Probably both.

[whatever4]

2. I think it's about to get much worse

I just read this, thought I'd add it to the mix.

http://news.independent.co.uk/world/science_technology/article312997.ece

Global warming 'past the point of no return'
By Steve Connor, Science Editor
Published: 16 September 2005

A record loss of sea ice in the Arctic this summer has convinced scientists that the northern hemisphere may have crossed a critical threshold beyond which the climate may never recover. Scientists fear that the Arctic has now entered an irreversible phase of warming which will accelerate the loss of the polar sea ice that has helped to keep the climate stable for thousands of years.

skipped...

Experts believe that such a loss of Arctic sea ice in summer has not occurred in hundreds and possibly thousands of years. It is the fourth year in a row that the sea ice in August has fallen below the monthly downward trend - a clear sign that melting has accelerated.

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Such lows have normally been followed the next year by a rebound to more normal levels, but this did not occur in the summers of either 2003 or 2004. This summer has been even worse. The surface area covered by sea ice was at a record monthly minimum for each of the summer months - June, July and now August.

Scientists analysing the latest satellite data for September - the traditional minimum extent for each summer - are preparing to announce a significant shift in the stability of the Arctic sea ice, the northern hemisphere's major "heat sink" that moderates climatic extremes.

skipped...

Sea ice reflects up to 80 per cent of sunlight hitting it but this "albedo effect" is mostly lost when the sea is uncovered. "We've exposed all this dark ocean to the sun's heat so that the overall heat content increases," he explained.

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Sea ice keeps a cap on frigid water, keeping it cold and protecting it from heating up. Losing the sea ice of the Arctic is likely to have major repercussions for the climate, he said. "There could be dramatic changes to the climate of the northern region due to the creation of a vast expanse of open water where there was once effectively land,"

bad, bad stuff. They say that hurricanes are natures way of "blowing off steam", blowing off heat. That's what they said, on the weather channel we watched for hours and hours. Things heat up, and hurricanes are one result. Might be global warming, they say, maybe.

Please note I snipped, italicized and bolded some of the text.

[hatrack]

3. I saw that, too. I'd say I'm surprised, but I'm not

Depressed, sure, but far from surprised.

[Ksec]

4. Lets bump this on importance alone. nt

[NNadir]

5. Good idea.

[bloom]

6. "Gulf Stream slowdown" & "Chimneys"

When the Ice Melts – Everything Changes

"And now the news. The online edition of the Times of London reported in May that the Gulf Stream slowdown is no longer theoretical, but is already occurring. Peter Wadhams, a professor of ocean physics at Cambridge University, visited the Arctic ice cap on Royal Navy submarines and discovered “that one of the ‘engines’ driving the Gulf Stream – the sinking of supercooled water in the Greenland Sea – has weakened to less than a quarter of its former strength. The weakening, apparently caused by global warming, could herald big changes in the current over the next few years or decades. Paradoxically, it could lead to Britain and northwestern Europe undergoing a sharp drop in temperatures.”

Says Wadhams, “Until recently, we would find giant ‘chimneys’ in the sea where columns of cold, dense water were sinking from the surface to the seabed <1.8 miles> below, but now they have almost disappeared. As the water sank, it was replaced by warm water flowing in from the south, which kept the circulation going. If that mechanism is slowing, it will mean less heat reaching Europe.”

Dr. Gagosian says that a shutting down of the Gulf Stream would mean that “average winter temperatures could drop by five degrees Fahrenheit over much of the United States, and by ten degrees in the northeastern United States and in Europe. That’s enough to send mountain glaciers advancing down from the Alps; to freeze rivers and harbors and bind North Atlantic shipping lanes in ice; to disrupt the operation of ground and air transportation; to cause energy needs to soar exponentially; to force wholesale changes in agricultural practices and fisheries; to change the way we feed our populations. In short, the world, and the world economy, would be drastically different.

...Look at a couple of impacts. Most severe weather takes place when cold air and hot air meet. The tropics are getting warmer, Europe and the northeastern United States and Canada are getting colder. When air masses over the temperate and tropical zones meet, there will be more extreme weather. The water that has been locked into Arctic ice is now merging with the oceans. More water means sea levels rise. That doesn’t even begin to address the impact on the food we eat and where it is grown (and how it gets here), or the wood we use for construction. And then there are the increased costs of energy and transportation systems. So maybe we should start thinking about growing more of our food now, and importing less.”

http://caymannetnews.com/2005/08/907/ecocommentary.shtml

More on Chimneys (with graphics):

http://puddle.mit.edu/~helen/oodc.html