More hurricanes as result of global warming?

[Martin W]

Just published research suggests that numbers of Atlantic hurricanes are rising, and part of this rise is due to global warming. Been plenty of arguments re warming and hurricanes (major tropical cyclones; known as typhoons here in Hong Kong and other parts of Pacific/S China Sea). But, has always seemed likely: hurricanes form over warm seas, so as seas warm, can expect more – and more intense – tropical cyclones.

Yes, also seen Johnny Chan, HK researcher, who has found that over the Pacific, it's important ot also consider winds/air currents that can destroy these storms before they form: and these too may increase with warming, cancelling out effect of warming seas. (Plus, tropical Pacific warmer than Atlantic; temps generally well above those needed to form trop cyclones, while Atlantic more typically around the threshold level, so warming there can have more of an effect. [this guff partly from answer I asked Prof Chan at a global warming workshop, plus from his talk]) But interesting, too, to see that S America (east coast) lately had it's first tropical storm.

And, just a few weeks ago, Arabian Peninsula hit by strongest cyclone since record keeping began there in 1945. For the latter: http://www.sciencedaily.com/releases/2007/06/070613070547.htm Also, even been computer models suggesting hurricane force storms just might impact the Mediterranean should warming continue. Back to the hurricane research; info on Scientific American site includes:

Quote:

Using records dating back to 1855, hurricane researchers say they have uncovered an ongoing rise in the number of Atlantic hurricanes that tracks the increase in sea surface temperature related to climate change. Critics of such a link argue that this trend is merely because of better observations since the dawn of the satellite era in the 1970s. But the authors of the new study say the conclusion is hard to dodge.

"Even if we take the extreme of these error estimates, we are left with a significant trend since 1890 and a significant trend in major hurricanes starting anytime before 1920," say atmospheric scientists Greg Holland of the National Center for Atmospheric Research in Boulder, Colo., and Peter Webster of the Georgia Institute of Technology in Atlanta. … The experts agree that natural variability is largely to blame for the relative intensity of various hurricanes, but Holland and Webster note that the locations of such storms have changed. "As more storms form near the equator, they are experiencing much better conditions for intensification and they are experiencing these conditions for a much longer period," the pair note. And that means more numerous and stronger hurricanes in the foreseeable future, whether the forecast is from a computer model or a meteorologist's instincts.

Stronger Link Found between Hurricanes and Global Warming A century's worth of records suggests that hurricanes are on the rise and a warming Atlantic is to blame

[Martin W]

Good article by Chris Mooney, who has written book apparent link between hurricane/tropical cyclone intensity and global warming. Uses current Hurricane Dean as starting point, and includes:

Quote:

Dean now takes its rank among the top ten most intense Atlantic hurricanes. If you look at that list you’ll see that six of the strongest (Wilma, Rita, Katrina, Mitch, Dean, and Ivan) have been in the past ten years. That’s not the kind of statistic that’s easy to overlook. According to these data we are getting more super-strong storms in the Atlantic basin than we ever have before.

To be sure, there’s a counterargument here: Data wasn’t as good on hurricane intensity in previous eras as it is today, when our measuring equipment is better than ever. Stronger storms may well have existed in the past, but we were simply incapable of detecting their true strength.

This is a serious objection, although it’s hard to know precisely how serious. Nevertheless, the fact remains that if you look at the official records, Dean now fits in to a staggering hurricane decade. That’s highly suggestive, if not definitive. And this staggering decade has occurred in part because of anomalously warm ocean temperatures in the hurricane-prone regions. Many scientists question whether you can explain these warm anomalies without invoking global warming as at least part of the cause.
…
according to my ongoing “Storm Pundit” count of mega-hurricanes, Dean is the 10th Category 4 or 5 tropical cyclone observed globally this year. [Mooney lists the storms]
…
by my own count, there were 19 of these intense storms in 2006, 22 in 2005, and 23 in 2004. Hurricane specialist Jeff Masters says the long term average is 17 — in which case all of these years would be above it and we might indeed be looking at a trend.

Hurricane Dean: 1 Of 10 Most Intense Atlantic Hurricanes Ever Measured

[Martin W]

I’ve seen that numbers of west Pacific typhoons may decrease with global warming – as wind shear increases, so it’s harder for them to form. Now, first news I’ve noticed that maybe this will be true for Atlantic – albeit contentious. Must still wonder if warmer seas will lead to more strong storms (ie, powerful trop cyclones) – ie once they start forming, tend to become powerful, maybe fast.

Quote:

Global warming could reduce how many hurricanes hit the United States, according to a new federal study that clashes with other research. The new study is the latest in a contentious scientific debate over how man-made global warming may affect the intensity and number of hurricanes. In it, researchers link warming waters, especially in the Indian and Pacific oceans, to increased vertical wind shear in the Atlantic Ocean near the United States. Wind shear — a change in wind speed or direction — makes it hard for hurricanes to form, strengthen and stay alive. So that means "global warming may decrease the likelihood of hurricanes making landfall in the United States," according to researchers at the National Oceanic and Atmospheric Administration’s Miami Lab and the University of Miami. … Critics say Wang’s study is based on poor data that was rejected by scientists on the Nobel Prize-winning Intergovernmental Panel on Climate Change. They said that at times only one in 10 North Atlantic hurricanes hit the U.S. coast and the data reflect only a small percentage of storms around the globe.

Study: Warming May Cut US Hurricane Hits

[Dr Martin Williams [account from Drupal site]]

From BBC News:

Quote:

The strongest tropical storms are becoming even stronger as the world’s oceans warm, scientists have confirmed.

Analysis of satellite data shows that in the last 25 years, strong cyclones, hurricanes and typhoons have become more frequent in most of the tropics.

Writing in the journal Nature, they say the number of weaker storms has not noticeably altered.

…

James Elsner from Florida State University in Tallahassee, US and colleagues believed the link might become clearer if they analysed data according to the strength of storms.

"We’re seeing a signal, and it’s telling us that the strongest effect (of rising ocean temperatures) is on the strongest storms," he told BBC News.

"At average or median wind speeds, about 40m/s, we don’t see a trend; but when we get up to 50 or 60m/s we do see a trend."

…

The increase in strong storms shows up most markedly in the North Atlantic and Indian oceans, and is absent in the South Pacific.

"We’re looking at different ocean basins, and some are already pretty warm," said Professor Elsner.

"So there, an increase in temperature isn’t going to produce as strong an increase as in basins where the the temperatures are only marginally supportive of cyclones."

Warming Boosts Strongest Storms

[Dr Martin Williams [account from Drupal site]]

From Christian Science Monitor:

Quote:

The number of hurricanes, typhoons, and tropical storms globally is likely to either fall or remain flat over the course of the 21st century. But an increasing proportion of the storms are likely to hit the highest levels of intensity because of the projected effects of global warming, an international team of scientists concludes.

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However, it's unclear whether past trends in the number and intensity of storms – which some research suggested may be due to global warming – fall outside the range of natural variation. This is particularly true of the Atlantic basin, the team writes.

Number of storms may drop, but more could be intense, study says

[Dr Martin Williams [account from Drupal site]]

Quote:

Global warming is raising the danger from typhoons, Taiwan experts warned Monday, saying the island may be hit in a year or two by a powerful storm like the one which killed more than 700 last August.

Typhoon Morakot dumped a record 3,000 millimetres (120 inches) of rainfall and caused massive mudslides in the south of the island, and the government should be prepared for similar disasters in the future, they said.

"A typhoon as powerful as Morakot is very likely to strike Taiwan in a year or two," said Wang Chung-ho, a research fellow at the Institute of the Earth Sciences at Taiwan's top academic body Academia Sinica.

Global warming raises Taiwan typhoon danger

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