Something to think about.

[wxcrazytwo]

MIAMI (Reuters) - If hurricanes again pound the United States this summer, their roar is likely to be accompanied by the din of another storm -- an angry debate among U.S. scientists over the impact of global warming.

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Last season's $45 billion devastation, when 15 tropical storms spawned nine hurricanes in the Atlantic and Caribbean, prompted climatologists to warn of a link to warming temperatures.

But hurricane experts say the unusual series of hurricanes, four of which slammed into Florida in a six-week period, was the result of a natural 15- to 40-year cycle in Atlantic cyclone activity.

After a lull between 1970 and the mid-1990s, the number of storms picked up dramatically from 1995 and higher-than-normal activity is expected for the next five to 30 years as a phenomenon known as the "Atlantic multidecadal mode" holds sway.

"Really, for the folks that are doing work on hurricanes, there isn't a debate (about global warming)," said Chris Landsea of the National Oceanic and Atmospheric Administration's hurricane research division in Miami.

Many climatologists disagree. They say the large, decades-long swings in hurricane activity may mask, but do not rule out, longer term climate change trends.

The warmer waters and increased air moisture that global warming is expected to produce are, after all, the primary fuels that hurricanes feed off during the June to November season.

"Global climate change is happening. The environment in which these hurricanes form is clearly changing," said Kevin Trenberth, a climatologist at the National Center for Atmospheric Research in Colorado. He is also a lead author of the next major U.N. report on climate change, due in 2007.

Landsea withdrew from the U.N. Intergovernmental Panel on Climate Change this year after accusing Trenberth of linking current heightened hurricane activity too closely to global warming.

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The public clash highlighted the sensitivity of the climate debate in the United States, which under President Bush dismayed environmentalists by rejecting the Kyoto pact on cutting greenhouse gas emissions.

Some government scientists, such as James Hansen of NASA's Goddard Institute for Space Studies, have complained they are forced to downplay evidence of climate change, which most scientists link to industrial pollution.

But hurricane experts say their dismissal of global warming in relation to hurricanes is based on science not politics.

According to meteorologist Thomas Knutson of NOAA's Geophysical Fluid Dynamics Laboratory, higher carbon dioxide levels have probably resulted in a 1/7th of a category increase in Atlantic cyclone intensity in the past century, and likely will raise a storm's potential by half a category in 80 years.

Hurricanes are graded under the Saffir-Simpson scale based on wind speeds, with a Category 5, marked by winds higher than 155 mph (249 kph), the strongest and most destructive.

Similarly, studies by Kerry Emanuel, a professor of meteorology at the Massachusetts Institute of Technology, indicate the 2 degree Celsius (3.6 degrees Fahrenheit) increase in sea surface temperatures predicted by the IPCC would raise the upper limit on a storm's intensity by 10 percent.

Landsea said those changes were largely imperceptible given the overall ferocity of hurricanes.

He added that other factors, like the El Nino weather event in the Pacific, and the differences between lower level and upper level winds, called wind shear, play as critical a role as water temperatures in determining whether hurricanes form.

"The folks in the field are unanimous in saying that global warming doesn't have an appreciable impact on hurricanes today and that changes in the future look to be really tiny," Landsea said.

Climatologists take another view, arguing that a 10 percent increase in wind speeds leads to a 20 percent increase in destructive force. They also point out that many researchers are revising upward their original estimates of how much greenhouse gas emissions are affecting world climate.

"We are so far along, this is happening so much faster than we thought it would happen," said Paul Epstein of the Center for Health and the Global Environment at Harvard Medical School.

"I think this summer will portend some really strange weather."



http://news.yahoo.com/s/nm/20050530/sc_nm/weather_hurricanes_globalwarming_dc

[HurricaneBill]

Hmm.....looking back in time, it seems that there have always been one year in each decade (even the 1970s) where several hurricanes made landfall on the U.S.

Let's look at the U.S. landfalls of each decade:

1950s: 19 landfalls

1950: 3 (Baker, Easy, King)
1951: 0
1952: 1 (Able)
1953: 3 (Barbara, Carol, Florence)
1954: 3 (Carol, Edna, Hazel)
1955: 3 (Connie, Diane, Ione)
1956: 1 (Flossy)
1957: 1 (Audrey)
1958: 1* (Helene) (Helene passed close enough to bring Cat 3 conditions to Outer Banks)
1959: 3 (Cindy, Debra, Gracie)

1960s: 15 landfalls

1960: 2 (Donna, Ethel)
1961: 1 (Carla)
1962: 0
1963: 1 (Cindy)
1964: 4 (Cleo, Dora, Hilda, Isbell)
1965: 1 (Betsy)
1966: 2 (Alma, Inez)
1967: 1 (Beulah)
1968: 1 (Gladys)
1969: 2 (Camille, Gerda)

1970s: 12 landfalls

1970: 1 (Celia)
1971: 3 (Edith, Fern, Ginger)
1972: 1 (Agnes)
1973: 0
1974: 1 (Carmen)
1975: 1 (Eloise)
1976: 1 (Belle)
1977: 1 (Babe)
1978: 0
1979: 3 (Bob, David, Frederic)

1980s: 16 landfalls

1980: 1 (Allen)
1981: 0
1982: 0
1983: 1 (Alicia)
1984: 1 (Diana)
1985: 6 (Bob, Danny, Elena, Gloria, Juan, Kate)
1986: 2 (Bonnie, Charley)
1987: 1 (Floyd)
1988: 1 (Florence)
1989: 3 (Chantal, Hugo, Jerry)

1990s: 14 landfalls

1990: 0
1991: 1 (Bob)
1992: 1 (Andrew)
1993: 1 (Emily)
1994: 0
1995: 2 (Erin, Opal)
1996: 2 (Bertha, Fran)
1997: 1 (Danny)
1998: 3 (Bonnie, Earl, Georges)
1999: 3 (Bret, Floyd, Irene)

2000s: 9 landfalls (so far....)

2000: 0
2001: 0
2002: 1 (Lili)
2003: 2 (Claudette, Isabel)
2004: 6* (Alex, Charley, Frances, Gaston, Ivan, Jeanne) (Alex caused Category 1 conditions on the Outer Banks)

[SouthernWx]

I have to agree with Dr Landsea...we don't have enough evidence to say the increase in Atlantic hurricanes since 1995 is anything out of the ordinary (at least on a historical normal).

I wonder what the enviromentalists and global warming folks would have thought in 1957 when 140 mph monster Audrey smashed Louisiana in June....or in 1954 when three major hurricanes slammed the U.S.east coast.....in 1938 when a monster 130 mph hurricane roared across Long Island into New England.....or in 1935 when the ungodly ferocious Labor Day hurricane obliterated the Florida Keys (much more intense than hurricane Andrew).

If global warming had been an issue just before 1900, there would have been an outcry when Georgia was slammed by THREE major hurricanes in a five year period (and NONE since...not in 107 years!). I'm sure the year 1886 would have caused an uproar when 7 hurricanes slammed the U.S...including three 110 mph landfalling hurricanes before mid-July (all into northwest Florida).

The only difference I honesty see between 2004 and decades such as the 1950's, 1930's, or wild years such as 1886? INFORMATION....we can see, track, examine, discuss, and speculate 24 hours a day. We also have a much better handle on the intensity of hurricanes far at sea than in the days before IR satellite (mid 1970's); there's no telling how many Atlantic hurricanes were MISSED (never counted) in years before World War II.

Who knows how warm the Atlantic was in 1954, 1933, or 1886? SST's could have been warmer then than now for all we know.

I know the four hurricanes to slam Florida last season have really caused an uproar....but similar events have happened before. In 1848, two powerful hurricanes slammed the Tampa Bay area only weeks apart....in 1950, two major hurricanes slammed the Florida peninsula (and another near cat-3 hit Pensacola). In 1954, two major hurricanes struck southern New England ONLY 11 days apart....and look at the Western Pacific basin where islands such as Guam, Taiwan, Okinawa, and the Philippines are sometimes slammed over and over again during the same season by powerful typhoons.

The biggest reason Florida was hit so often in 2004? IMO it was simply nature's way of "catching up"; balancing the scales. Since hurricane Betsy slammed south Florida in 1965, only one major hurricane (Andrew) had hit the peninsula in 38 years between 1965 and 2003; an area historically struck by a major hurricane once every 4 years -- in all honesty, 2004 wasn't as unusual as some make it to be. I always figured when the unprecidated lull in Florida major hurricanes ended, it would be with a "bang"....and it did.

If I begin seeing things happen in the Atlantic basin which are totally incredible (a 240 mph hurricane, or a cat-4 hurricane on New Years Day), then I'll begin wondering about global warming, but until then....no way.

PW

FYI....even with landfalling intense hurricanes Charley, Ivan, and Jeanne in 2004, the decade (so far) is running near the long term average for major U.S. hits

1930-34...4 major U.S. canes
1940-44...4 major U.S. canes
1950-54...5 major U.S. canes
1960-64...3 major U.S. canes
1970-74...2 major U.S. canes
1980-84...2 major U.S. canes
1990-94...2 major U.S. canes
2000-04...3 major U.S. canes

total: 25/ 8 decades = 3.1

[cyclonaut]

This decade is already on pace to blow the other ones away.(Pun intended)

[MomH]

HurricaneBill --

I looked at your figures in a different way. The averages for the same years in each decade, 1953, 1963, 1973, etc. thru the 90's. Didn't use 2000's since they are not complete.

Those years ending in "3" had the least landfalls - .06 on average. Those ending in 5's and 9's had the most - 2.6 and 2.8 respectively. Other years were between 1 and 1.6. Hope we just jumped the gun last year.