Tornadoes Rip The South (again)

In one of those ironic moments bordering on cognitive dissonance, last Friday night, as thunder, lightning and hailstones were crashing down outside my house and my cats were hiding beneath the living-room sofa, the television newscasters on the local news channels were warning the residents of certain North Georgia towns that they had less than one minute to seek shelter before a new wave of tornadoes tore through their communities, while on HBO's Real Time with Bill Maher, automobile icon Bob Lutz was denying global warming and any increase in hurricane activity over the last 10 years.

According to the news reports, Friday night's storms touched down in at least a dozen states, killing 19 people in Kentucky, 14 in Indiana, three in Ohio, and one each in Alabama and here in Georgia.  The National Weather Service said the four twisters to hit Kentucky with wind speeds up to 160 mph were the worst in the region in 24 years.  In Indiana, an EF-4 tornado, the second-highest category on the Fujita scale that measures tornadic force, stayed on the ground for more than 50 miles.

My deepest condolences go out to those who lost loved ones in the storms.

But this does raise the question: were these tornadoes, which occurred so unusually early in the year, a result, at least in part, of climate change?

The scientific jury is apparently still out. As temperatures warm, air holds more water vapor, which adds fuel to the storm, so to speak. Last spring, when the Southeast was struck by multiple deadly outbreaks, the Gulf of Mexico was warmer than average and the same situation is occurring today. This is important because it means there is more moisture flowing northward from the Gulf, and a humid environment is necessary for severe thunderstorms to form. According to a sobering article in the Proceedings of the National Academy of Sciences, increases in atmospheric water vapor suggest a future increase of 100% or more in severe thunderstorm activity at locations in proximity to the Gulf of Mexico and in Atlantic coastal regions, such as Atlanta and New York.

On the other hand, although recent research has yielded insight into the connections between climate change and tornadoes and severe thunderstorms, these relationships remain mostly unexplored, largely because of the challenges in observing and modeling tornadoes.   As explained in an excellent article on the Climate Central blog, while hurricanes can be hundreds of miles wide, tornadoes are often less than a mile in diameter, which requires much more computing power in order to accurately model their behavior.  Although scientists are currently working to overcome that challenge, rather than simulating tornadoes themselves, they have made more progress in studying the conditions that give rise to the formation of severe thunderstorms (the Buddha taught that all things arise from conditions). 

The other necessary ingredient for tornado formation, in addition to increased water vapor, is wind shear, which was present in abundance during this week's tornado outbreak.  However, wind shear is projected to decrease as the climate warms. This would suggest that tornadoes will become less frequent in the future. Which factor wins out in the end - the increase in water vapor and heat energy, or the decrease in wind shear - may determine how tornadoes fare in a warming world.

Now back to Bob Lutz for a moment (warning: here come the maps and graphs).  He seems to be a good man and this isn't an attack on him but rather on the widespread assumption, which he expressed, that 2011 didn't produce many hurricanes.  The fact of the matter is 2011 was tied with 2010 for the third most active hurricane season on record.  This may not be readily apparent, as most of the tropical storms and hurricanes fortunately never made landfall on U.S. soil.

But just because we were lucky enough to not have the hurricanes make landfall doesn't mean that they didn't exist.  Climate change predicts there will be more tropical storm and hurricane activity, but not necessarily more tropical storm and hurricane activity where you live.   The active 2011 hurricane season was completely consistent with climate change predictions.

Mr. Lutz also scoffed at other predictions made by climate change scientists, and challenged the rest of the panel on the show to name just one prediction that the IPCC got right.  His skepticism was probably bouyed by a recent Wall Street Journal op-ed, which presented this graph:

It looks pretty bad, doesn't it?  The dotted lines are purported to be the prediction global average temperatures of the IPCC models of different years, while the red line is the actual recorded average.  Clearly, the 1990 model was way off, and while subsequent models performed a little better, they can't explain an apparent decrease in temperatures from 2005 through 2009, and from 2010 to the present.

Prof. Barry Bickmore of Brigham Young University, an active Mormon and an active Republican (he was a County Delegate for the Republican Party from 2008 through 2010), in his most impressive blog, Anti-Climate Change Extremism in Utah, explains, "But let’s look at the graph. They have a temperature plot, which wiggles all over the place, and then they have 4 straight lines that are supposed to represent the model predictions. . . What the authors don’t tell you is that the lines they plot are really just the average long-term slopes of a bunch of different models.  The individual models actually predict that the temperature will go up and down for a few years at a time, but the long-term slope (30 years or more) will be about what those straight lines say.  Given that these lines are supposed to be average, long-term slopes, take a look at the temperature data and try to estimate whether the overall slope of the data is similar to the slopes of those three lines (from the 1995, 2001, and 2007 IPCC reports). If you were to calculate the slope of the data WITH error bars, the model predictions would very likely be in that range."

Here are the individual model predictions along with the error bars (margin of error), depicted as the grey envelope around the individual lines:

Tellingly, the Wall Street Journal editorial did not provide error bars of any kind.  If it did, it would clearly show that the global mean temperature has wiggled around inside the margin of error for the models, just as predicted.

"So before I go on," Prof. Bickford writes, "let me be blunt about these guys. They know about error bars. They know that it’s meaningless, in a 'noisy' system like global climate, to compare projected long-term trends to just a few years of data. And yet, they did. Why? I’ll let you decide."

The truth of the matter is that global average temperatures have responded precisely as the climate models predicted due to man-made increases in atmospheric carbon dioxide, and yet a deliberate misinformation campaign, as most recently promulgated in the Wall Street Journal, is trying to convince the public of just the  opposite.  And as a result, a well meaning but misinformed Bob Lutz appears on television convinced that the IPCC predictions missed the mark, and further spreads confusion and doubt to the American public, even as they seek shelter from severe thunderstorm and tornado activity.

Why?  I'll let you decide.