Opinion

The folly of linking tornado outbreaks to climate change

In times of tragedy, there are always hucksters trying to use that tragedy to sell a position, a product, or a belief. In ancient times, tragedy was the impetus used to appease the gods and to embrace religion. In light of yesterday’s op-ed on The Center for American Progress’s Think Progress blog that essentially blames Republicans for last week’s devastating tornadoes, it seems some opportunists just can’t break the pattern of huckster behavior in the face of disaster.

The Think Progress piece cites Kevin Trenberth, a senior scientist at The National Center for Atmospheric Research in Boulder, Colorado:

“Given that global warming is unequivocal,” climate scientist Kevin Trenberth cautioned the American Meteorological Society in January of this year, “the null hypothesis should be that all weather events are affected by global warming rather than the inane statements along the lines of ‘of course we cannot attribute any particular weather event to global warming.’”

It should be noted that during that AMS conference in January, Dr. Trenberth called people who disagreed with that view “deniers” in front of hundreds of scientists. Even after being called out on the issue, he left the hateful term intact in his speech. Clearly, he is a man with a bias. From my perspective, these articles citing Trenberth are opportunistic political hucksterism at its finest. Unfortunately, there are many people like Trenberth who don’t bother to cite some inconvenient facts.

First, let’s look at the claim that tornadoes are on the increase, in parallel with the climate change that is claimed. In a previous article, I cited this graph from the National Climatic Data Center:

Obviously, when NCDC tallies the number of F3-F5 tornadoes from this recent outbreak and gets around to updating that graph, there will be an uptick at the end in 2011 that is on par or even higher than the famous 1974 tornado outbreak. The point though is that despite the 1974 uptick, the trend was down.

As The New York Times notes:

The population of the South grew by 14.3 percent over the last decade, according to the Census Bureau, compared with 9.7 percent for the nation as a whole. Of those states hardest hit by tornadoes this year, some were among the fastest growing, notably Texas and North Carolina.

This graph illustrates the relationship between population and tornado-related deaths (source: NOAA’s U.S. Severe Weather Blog, SPC, Norman, Oklahoma):

Let’s look at other figures. Yesterday, Dr. Roger Pielke Junior got an updated graph from NOAA to bring it to 2010:

That graph is a testament to the improved lead times, accuracy, and dissemination of severe weather warnings by the National Weather Service, whose members did an outstanding job during this severe weather event. Mike Smith, in his book Warnings: The True Story of How Science Tamed the Weather, discusses the vast improvements we’ve witnessed since the early days of severe weather forecasting. He writes of the recent outbreak:

There is no question that the current storm warning program, a collaborative effort of the National Weather Service, private sector weather companies like AccuWeather, broadcast meteorologists, and local emergency managers have saved hundreds of lives during these recent storms through excellent forecasts and warnings. This image shows the tornado warning (red hatched area) for Birmingham that was issued more than 20 minutes before the tornado arrived.

Can the warning program be improved? Certainly. The National Weather Service’s new dual-polarization radar will improve flash flood warnings and will incrementally improve warnings of tornadoes that occur after dark.

But in the immediate aftermath of these tragic storms we seem to have learned two things: People need to respond to today’s highly accurate warnings. For some reason, the media (see examples here and here seems determined to downplay the quality of the warnings which may have the effect of driving down response rates.

Second, they must have a place to take shelter. Most mobile home parks and many homes in the South do not have underground shelters or safe rooms. Mobile home parks and housing developments should look to constructing these in the future.

Because of the 30 minutes of advance warning in this case, and many other advance warnings during this outbreak, plus the super-saturation of live television coverage, plus the fact that weeks in advance my colleague, Joe D’Aleo, co-founder of the Weather Channel and now at Weatherbell LLC, discussed the likelihood of a super-outbreak of severe weather occurring due to the juxtaposition of cold air from snowpack in the Northern plains with warm moist air in the South, people knew the storms were coming; they just had few options for shelters that would survive at F3-F5 category tornado intensity. The death toll issue seems to be shelter, not lack of forecasts, warnings, or awareness.

The attempts at linking the tornado outbreak to “global warming” have been roundly criticized in the meteorological community. Thursday there was a denouncement of the tornadoes-to-global-warming link in this story from Physorg.com.

“If you look at the past 60 years of data, the number of tornadoes is increasing significantly, but it’s agreed upon by the tornado community that it’s not a real increase,” said Grady Dixon, assistant professor of meteorology and climatology at Mississippi State University.

“It’s having to do with better (weather tracking) technology, more population, the fact that the population is better educated and more aware. So we’re seeing them more often,” Dixon said.

But he said it would be “a terrible mistake” to relate the up-tick to climate change.

Anticipating this sort of nonsense in the current political climate that seeks to blame humans for the weather, last month The National Weather Association, representing thousands of operational meteorologists, forecasters, and television-radio meteorologists in the United States, adopted their first-ever position statement on climate change and severe weather events. They state:

Any given weather event, or series of events, should not be construed as evidence of climate change.

The NWA emphasizes that no single weather event or series of events should be construed as evidence of a climate trend. Daily weather is subject to extreme events due to its natural variability. It is only the occurrence of these events over decades that determines a climate trend.

No clearer statement could be rendered. It mirrors what a NOAA scientist at the Storm Prediction Center said yesterday to Fox News:

Greg Carbin, the warning coordination meteorologist at NOAA’s Storm Prediction Center in Norman, Oklahoma, said warming trends do create more of the fuel that tornadoes require, such as moisture, but that they also deprive tornadoes of another essential ingredient: wind shear.

“We know we have a warming going on,” Carbin told Fox News in an interview Thursday, but added: “There really is no scientific consensus or connection [between global warming and tornadic activity]…Jumping from a large-scale event like global warming to relatively small-scale events like tornadoes is a huge leap across a variety of scales.”

Asked if climate change should be “acquitted” in a jury trial where it stood charged with responsibility for tornadoes, Carbin replied: “I would say that is the right verdict, yes.” Because there is no direct connection as yet established between the two? “That’s correct,” Carbin replied.

Historically, there have been many tornado outbreaks that occurred well before climate change was on anyone’s radar. Here’s a few:

1908 Southeast tornado outbreak 324 fatalities, ≥1,720 injuries

1920 Palm Sunday tornado outbreak ≥380 fatalities, ≥1,215 injuries

1925 Tri-State tornado ≥747 fatalities, ≥2,298 injuries

1932 Deep South tornado outbreak ≥330 fatalities, 2,145 injuries

1952 Arkansas-Tennessee tornado outbreak 208 fatalities

1965 Palm Sunday tornado outbreak 256 fatalities

April 3-4 1974 Super Outbreak 315 fatalities

All of these occurred before “climate change” was even on the political radar. What caused those if “global warming” is not to blame? The real cause is La Niña, and as NOAAwatch.gov indicates on their page with the helpful meter, we are in a La Niña cycle of ocean temperature in the Pacific.

Here’s what it looks like on satellite measurements. Notice the cool blue:

The U.S. Climate Prediction Center explains the reason for such outbreaks in relation to ocean temperature cycles:

Since a strong jet stream is an important ingredient for severe weather, the position of the jet stream helps to determine the regions more likely to experience tornadoes. Contrasting El Niño and La Niña winters, the jet stream over the United States is considerably different. During El Niño, the jet stream is oriented from west to east across the southern portion of the United States. Thus, this region becomes more susceptible to severe weather outbreaks. During La Niña, the jet stream and severe weather is likely to be farther north.

Note the collision zone in the U.S. Southeast during La Niña patterns.

Finally, let’s examine the claims of global warming being linked to the tornado outbreak. If this were true, we’d expect the globe to be warmer, right?

Thunderstorms (and all weather for that matter) form in the troposphere, that layer of the atmosphere that is closest to the surface, and extends up to the stratosphere.

Dr. Roy Spencer, climate scientist from the University of Alabama, Huntsville, tracks the temperature of the troposphere. The university system that he tracks the temperature daily with is inoperable, due to the storms. People who have been watching it prior to this event know the current global tropospheric temperature is lower in April than the norm, but we can’t show it today. The last global value he plotted showed this:

The global temperature anomaly of the troposphere today is about the same as it was in 1979. If there’s any global warming in the troposphere, it must be a figment of an overactive imagination on the part of people who seek to link it to the recent tornado tragedy.

Dr. Roy Spencer sums it up pretty well on his blog:

It is well known that strong to violent tornado activity in the U.S. has decreased markedly since statistics began in the 1950s, which has also been a period of average warming. So, if anything, global warming causes FEWER tornado outbreaks…not more. In other words, more violent tornadoes would, if anything, be a sign of “global cooling,” not “global warming.”

Anyone who claims more tornadoes are caused by global warming is either misinformed, pandering, or delusional.

The people who seek to link this tragedy to the political movement of climate change should be ashamed of themselves. The only “deniers” here are the ones who deny all the long-established counterevidence of their bogus claims for political gain.

Anthony Watts operates the most visited blog on climate science in the world, www.wattsupwiththat.com.