Does Global Warming Cause Hurricanes??

Recently I was listening to Democracy Now as they interviewed a scientist that was saying hurricane frequency and intensity is increasing due to global warming. I have been following Hurricane Katrina and her aftermath intently on both CNN and FOX and both news organizations have also spouted this doctrine.

Since I had never heard of this before, I decided to do some research. If it is true, we Americans hold a large share of the blame and, regardless of blame, need to fix it.

First, we must realize that this holds political ramifications because Bush rejected the Kyoto Protocol.

The Protocol calls for reductions of up to 70% current CO2 emissions. Bush nixed it because it would be too costly for American businesses. Coincidentally, some environmental groups say the accord is actually bad, whereas we should increase reforestation to use the CO2.

Regardless, the current debate is about hurricane intensity and frequency. The Geophysical fluid dynamics laboratory, part of the US Dept. of Commerce, says that

the hurricanes that do occur near the end of the 21st century are expected to be stronger and have significantly more intense rainfall than under present day climate conditions.

This is based on a recent study by Thomas R. Knutson and Robert E. Tuleya at the laboratory.

According to this latest study, an 80 year build-up of atmospheric CO2 at 1%/yr (compounded) leads to roughly a one-half category increase in potential hurricane intensity on the Saffir-Simpson scale and an 18% increase in precipitation near the hurricane core.

Scientists have been saying this before, however.

Commondreams.org reports that Dr. James McCarthy from Harvard warns that

"As the world warms, we expect more and more intense tropical hurricanes and cyclones," said James McCarthy, a professor of biological oceanography at Harvard University.

Large parts of the world's oceans are approaching 27 degrees C or warmer during the summer, greatly increasing the odds of major storms, McCarthy told IPS.

When water reaches such temperatures, more of it evaporates, priming hurricane or cyclone formation. Once born, a hurricane needs only warm water to build and maintain its strength and intensity.

Over the past 100 years, the average ocean temperature has risen 0.6 C and sea levels have risen 3.1 cm.

Time reports that

More-frequent hurricanes are part of most global warming models, and as mean temperatures rise worldwide, it’s hard not to make a connection between the two. But hurricane-scale storms occur all over the world, and in some places—including the North Indian ocean and the region near Australia—the number has actually fallen. Even in the U.S., the period from 1991 to 1994 was a time of record hurricane quietude, with the dramatic exception of Andrew.

It also reports that hurricane speeds have increased about 50% in the past 50 years.


Kerry Emanuel at MIT has a recent model that the half degree increase in ocean temperatures have doubled the number of destructive North Atlantic storms and increased North Pacific storms by 75% although past models should have increased destructive power only 10%.

However, not everyone agrees. Chris Landsea at the National Oceanic and Atmospheric Administration's Hurricane Research Division, has questions.

Storm winds are virtually impossible to measure directly, and techniques for estimating them indirectly have changed over the years. To adjust for those changes, Emanuel reduced wind estimates in the 1950s and 1960s.

But Landsea says the unadjusted figures show no overall trend, raising doubts over whether Emanuel's model is making the right corrections. Although winds from that period looked too low in the past, Landsea says that wind estimates may actually have been too low in the 1970s through to the early 1990s.

The Cooler Heads Coalition wrote in 1998 that according to Dr. William Gray of Colorado State University,

hurricane activity follows a natural 20 to 40 year cycle that is correlated to changes in ocean currents. The 1940s and 1950s, for example saw many land-falling tropical storms. From 1947-1960 there were 14 land-falling storms, but from 1960-1988 there were only 2. We are now in a period of heightened hurricane activity.

The mechanism that controls the Earth’s most important and largest ocean current, known as the thermohaline circulation, is salinity...

When salt content is high the ocean current is strong, pushing the salt particles through the system rapidly, preventing the build up of salt. This weakens the ocean current leading to greater salinity which in turn strengthens the current again.

Dr. Gray also points out the problems with statistical modeling (those of us who have taken statistics should already know never to trust any statistics).

As models predict farther into the future,

small modeling errors either in the measurements or in the physics grow over time becoming nonlinear and the whole thing "blows up on you."

The greatest problem with the models, however, is the failure to correctly model water vapor feedback, Gray said. Water vapor feedback accounts for 85-90 percent of the warming in the models, according to Dr. Gray...Dr. Gray believes that as carbon dioxide in the atmosphere increases there is a slight reduction in water vapor to balance the carbon dioxide pick up.

Junkscience.com reported last year that hurricane trends aren't that alarming when you take them in context. It shows this graph that puts the number of hurricanes in context by decade and strength since 1900.



So maybe the incidence of hurricanes has increased recently, but the number of landfalling hurricanes is given in this chart, and it shows a different trend.



It reports that

According to The Most Intense Hurricanes in the United States 1900-2000 only 28 of the listed 65 events occurred since 1950. The Deadliest, Costliest, And Most Intense United States Hurricanes From 1900 To 2000 (And Other Frequently Requested Hurricane Facts) indicates that fully half the years when no hurricanes struck mainland U.S. are after 1950 (10 of 19). The most hurricanes to strike in one year were six in 1916 and 1985. There were five in 1933, and four in 1906, 1909, and 1964. Three hurricanes struck the U.S. in one year a total of sixteen times. Ten of these sixteen times occurred during the sixteen years from 1944 to 1959.

What does this all mean?

Well, it means that global warming may increase the intensity of a storm, but models predicting this increase may also be founded on large assumptions. That would make their predictions about as good as a guess. It also casts doubt on the long range predictions that are causing all the stir. The armageddon predictions. Hurricane models just aren't that reliable when you start predicting far into the future.

It also means that we should take the accusations of increased incidence with a grain of salt also. Yes, we are seeing more, but we also have increased detection methods. Landfalling hurricanes (I would say the ones that really matter) show quite a different trend.

Should we be worried about global warming?? Yes, and no. I'm much more worried about the toxic effects of fumes than the warming effects. Reforestation seems like a good idea to me. I love the outdoors. Lord knows the mountains near Provo need more trees. They're bald.

Should we blame Bush for Katrina?? Heck no. Regardless of whether he signed the Kyoto Accord or not, global warming may have played into her ferocity. Signing the treaty would not have reduced emissions enough to have changed that outcome. We can yell at him for not signing it at all, because it's not very considerate of the environment, and definite pandering to big oil and coal, but not link him to Katrina. We've all done this, and it's a long time in the making.

I feel for the residents of the south, and those still suffering. New Orleans is a war zone. The federal government must take some blame in the poor rescue efforts. I place it on Congress (and it is a Republican congress) who have created this new Dept. of Homeland Security and allocated $5 billion to beefing up airport security (which we all hate) while cutting the budget for first-responders (the paramedics, ambulance drivers, firemen, etc. that respond first to a terror attack or natural disaster). More first-responders would have changed this outcome. Some of that blame also falls on Bush for making the budget, but Congress must approve it. They had they're chance to nix him.

Ultimately I pray we learn our lesson, and I pray the people of New Orleans get out alive.