Tuesday, September 04, 2007

Warnings From a Warming World: Hurricane Felix Makes Landfall as Second Category 5 Hurricane in Two Weeks

Making landfall today as a devastating Category 5 storm, Hurricane Felix is the second Cat 5 Atlantic hurricane to make landfall in as many weeks, carving a path of destruction across Central America.

As Chris Mooney points out at the Daily Green, "Nature isn't messing around this year in the Atlantic hurricane basin."

So far, we've already seen six named storms and two hurricanes, both making landfall as devastating Category 5 storms, shattering records and making landfall within two weeks of each other. And there's still a long way to go until the 2007 hurricane season has subsided.

Like Hurricane Dean, which ripped across Mexico's Yucatan Penninsula on August 21st (see previous post), Hurricane Felix hit the coast of Nicaragua with Category 5 strength (Hurricane Katrina was made landfall near New Orleans as a Category 4 storm, for comparison), shattering several records. Also like Hurricane Dean, the appearance of a second, record-breaking storm in as many weeks must give us pause to not only acknowledge the destruction it has wrought as it cuts a swathe across Nicaragua, Honduras, El Salvador and Guatemala, but also to worry about what else this year's hurricane season might have in store as we ponder the connection between global warming and a disturbing trend of intensifying hurricanes.


2007 Hurricane Season Just Heating Up

Offical estimates call for an "above-normal" Atlantic hurricane season and predict 13-16 named storms (Felix is just the sixth so far this season). The peak months of the Atlantic hurricane season are August through October, so the season has just begun in earnest.

Chris Mooney worries that "we might be seeing intense hurricane clustering in the Carribean. Sometimes the winds and water just set up in such a way that a particular stretch of ocean gest repeated Category 4 and 5 storms," Mooney explains. "The phenomenon occurence in the Cook Islands in 2005, with four intense hurricanes in just over a month, and similarly off the coast of the Phillipeans in 2006." Could a similar phenomenon be occurring in the Caribbean this year? Only time will tell.

Additionally, if a storm enters the Gulf of Mexico this year, there is a disturbing arrow of hot sea surface temperatures currently pointing directly at Louisiana. Hurricane intensity is fueled by warm water temps and the current map of sea surface temps means that if winds and other conditions line up, sea temps could fuel another intense storm making landfall on the Gulf Coast.

[Image source: NOAA]


Hurricane Felix Sets Records

Like Hurricane Dean, Hurricane Felix has set, or led to the adjustment, of several records, some of them very disturbing. Chris Mooney has a list:

1. Fastest intensification from a tropical depression to a Category 5 hurricane — around 51 hours. (This is apparently an Atlantic record only.) [Note: storms normally take weeks to intensify from a tropical depression to a Category 1 hurricane]

2. Second-fastest pressure fall in 12 hours (50 millibars), third-fastest in 24 hours (63 millibars). Again, apparently this is an Atlantic-only record.

3. 13th full Category 5 hurricane landfall in the Atlantic region. Others include 1935’s “Labor Day” storm, 1969’s Camille, 1992’s Andrew, and 2007’s Dean.

4. Felix makes 2007 only the fourth known Atlantic hurricane season to have more than one Category 5 hurricane. The others are 1960, 1961, and 2005.

5. Felix makes 2007 the only known Atlantic hurricane season to have two full Category 5 landfalls.

6. Felix makes 2007 the only known Atlantic hurricane season in which the first two storms to reach hurricane status (Dean, Felix) have also reached Category 5 status and gone on to Category 5 landfalls.

Making the Global Warming Connection

As with Hurricane Dean, we cannot blame global warming for Hurricane Felix, nor for any single extreme weather event. However, hurricane intensity is fueled by warm ocean temperatures, and the recent up-tick in intense Category 4 and 5 storms is consistent with scientific predictions based on basic thermodynamics and higher ocean temperatures due to global warming.

In his typical cautious fashion, Chris Mooney points out that "No single storm tells us anything, but on the other hand, both of these storms fit a troubling pattern. To be more specific:
  • After not having one since Andrew in 1992, we are now expected to see two Category 5 Atlantic basin hurricane landfalls in the space of 2 weeks.
  • There have now been eight Category 5 Atlantic hurricanes in the past five years (Isabel, Ivan, Emily, Katrina, Rita, Wilma, Dean, Felix)
  • There have been two Atlantic Category 5s so far this year; only three other seasons have had more than one (1960, 1961, 2005)
  • There have been eight Category 5 Atlantic hurricanes so far in the 2000s; no other decade has had so many. The closest runner up is the 1960s with six (Donna, Ethel, Carla, Hattie, Beulah, Camille).
  • Mooney goes on to caution that it is likely that we failed to record at least a few Category 5 storms in earlier decades due to poorer instrumentation and observation systems. However, even with that caveat, we've got to recognize that this decade has been clearly anomalous when compared to previous decades (and it's far from over yet).

    Is it fair for us to point the finger at global warming for this disturbing trend? Well, it will take more time to demonstrate that this trend of intensifying storms holds true, and a lot more work to show conclusively that this trend is due to global warming.

    However, climate scientists clearly predict global warming will bring higher sea surface temperatures and the resulting intensification of hurricanes and tropical storms, and the recent monster storms we've seen in the Atlantic and around the world have fit predictions to a T.

    As Chris Mooney writes, "at some point, it seems to me that people will simply have to throw up their hands and say: We are in a new place now."


    Interested in learning more about what we can and can't say about extreme weather events and global warming? Pick up Chris Mooney's new book, Storm World: Hurricanes, Politics, and the Battle Over Global Warming.

    [Image source: top right - Weather Underground; second right - Wikipedia]

    1 comment:

    Steven said...

    Christian Aid a UK INGO working in Latin America has just put out three podcast episodes looking at how Hurricane Dean affected the regions poorest people.

    The podcasts can be found on iTunes or feedburner at http://feeds.feedburner.com/christianaidpodcasts

    Worth a listen and lots of climate change episodes in there.