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Global Warming and Hurricanes

ivan-sm.jpgHurricane season is now underway (and if you live in a hurricane-prone area, or simply want to follow the season in detail, don't forget about the National Hurricane Center's RSS alert feeds), and a great deal of attention will be focused on whether this year's storms will match the ferocity of last year's. Climatologists were quick to deny any explicit causal connection between global warming and the multiple big hurricanes last year, only going so far as to say "this is what we could expect to see." If this year is a repeat of the last, however, expect some climate scientists to become a bit more assertive with their claims.

One who is already ahead of the trend is Kevin Trenberth of the National Center for Atmospheric Research. In a piece written for the current issue of Science, Trenberth argues that --

"Trends in human-influenced environmental changes are now evident in hurricane regions," says Trenberth. "These changes are expected to affect hurricane intensity and rainfall, but the effect on hurricane numbers remains unclear. The key scientific question is how hurricanes are changing." [...]

The strongest links between hurricane intensity and climate change, according to Trenberth, are a long-term rise in ocean temperatures and an increase in atmospheric water vapor. Both processes are already under way and expected to continue, he says. The additional water vapor will tend to produce heavier rains within hurricanes and an increased risk of flooding at landfall, Trenberth notes. [...]

"Computer models also suggest a shift in hurricane intensities toward extreme hurricanes," says Trenberth.

Because the climate is a complex system, transient interactions can lead to unexpected local weather. It is entirely within the realm of possibility that this year's hurricane season will be far milder than last year's. But if that happens, we should be guard against seeing it as a sign that global warming's effect on hurricanes isn't so bad. Instead, we should look to a mild season as an opportunity to build up our disaster warning, response and relief systems up -- particularly in the Caribbean nations -- before things do turn ugly.

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» Foresight in the Age of the Storm from Earth Share of Washington News
By Jamais Cascio of Worldchanging.com In the age of climate disruption, clear-eyed foresight is a necessity — but hurricane Katrina was a reminder that foresight means more than imagining the worst and preparing for it. Katrina came as a surprise... [Read More]

Comments (7)

I don't understand: I have read that the number of hurricanes per year hasn't significantly changed over the last few centuries.

I'm looking at a table of hurricane counts stretching from 1968-1989, and I'm not noticing any significant deviation- it looks like roughly 45 hurricanes a year. There is a little up and down, but I don't see any upward trend. But maybe I'm just looking at the data wrong.

Is this true?

Data found via links from Wikipedia:Hurricane.

Aleeya:

During the hurricane season last year, I remember watching a segment on the weather channel about hurricanes.

From what I remember about the studies, it seems every 50 years or so you have a period of HYPO active period of a hurricane patterns and then the next 50 years or so you have a HYPER actrive period of hurricane patterns. This segment had mentioned we have just finished up with the hypo-activity and are now beginning the hyper pattern of hurricanes.

This pattern had been traced back a few centries I believe and not just decades. From 1968-1989 would have fallen in the hypo state of activity.

Also, I am not sure if this affects the Number of Hurricanes or the Category of Intensity of the hurricanes.

I wish I could find more about the studies I had watched on the Weather Channel.

"Lion Kimbro," if you look again at the excerpt I included in the post, you'll see that Trenberth says "the effect on hurricane numbers remains unclear." That is, signs point to increased hurricane intensity (i.e., higher category storms), but not necessarily to increased hurricane numbers.

Aleeya, I seem to recall a similar argument. There are definitely big system effects at work, and I would not be surprised if there's a hurricane cycle. That said, last year was particularly bad -- more Category 4 and 5 storms than nearly any other year on record, if I recall correctly. Even if this is equally bad, that doesn't mean that every subsequent year will also be bad, of course, just as a mild year doesn't mean that we're not in danger.

Everything we know about how hurricanes form tells us that certain atmospheric and oceanic characteristics -- heat, water vapor, etc. -- correlate with storm strength. We've done (and continue to do) things to the atmosphere that happens to increase those characteristics. We should be concerned.

wintermane:

Its simple math realy. The more warm air and water a storm gets the more power it gets. Global warming while not realy warming the entire globe all that much does in fact warm certain portions of it a fair bit.. one portion being the very same one all these lovely hurricanes feed off of.

BUT a second question is will the weather patterns change too and if so does that mean the storms will hit the us more often or will they hit someone else more often or will they just hit the same places harder. We dont realy know.

wintermane:

Its simple math realy. The more warm air and water a storm gets the more power it gets. Global warming while not realy warming the entire globe all that much does in fact warm certain portions of it a fair bit.. one portion being the very same one all these lovely hurricanes feed off of.

BUT a second question is will the weather patterns change too and if so does that mean the storms will hit the us more often or will they hit someone else more often or will they just hit the same places harder. We dont realy know.

aleeya:

Here is a good link I found on the cycle... I only skimmed it, but I beleive it is related to the documentary and studies I have read and seen

http://www.climate.org/topics/climate/hurricanes2004.shtml

An ill wind blows - a Greener alert
Hurricane season is indeed once again on our charts according to World Changing, but perhaps the greater threat to homeowners this year will be their insurance providers. This week Allstate announced to Florida policy holders that they intend to raise premiums by 28% to help offset the losses they incurred during last season's unprecedented destruction.

Florida officials, the insurance commission and Governor Bush, immediately challenged the proposal and promised to block the 'requested' increase - unfortunately those same officials had previously set a rule which allows insurance providers to collect the increased fee while it is under consideration by the commission. The theory is that if a provider asks for an increase from the commission it is entitled to collect that increase until the fee hike is approved. If not approved why then the company simply refunds the monies as a credit to policy holders and everyone is forgiven.
The timing is unfortunate as Allstate earlier this month issued a very sunny quarterly report showing a considerable profit taking from the most recent period which was well received, as may be expected, by its shareholders.

Homeowners in Florida should check with My Florida regarding their insurance 'right to' options and the Deconstruction Institute if they want to protect their homes and the environment.

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