The Science of Tornadoes

The recent wave of storms that have hit portions of the United States have been unusually deadly. In the two states in which I lived in my first nineteen years, Tennessee and Alabama, 276 people have died. In Joplin, Missouri, one town is estimated to have lost 142 people in one May storm. This got me to thinking about the science of storms. And it also made me wonder if the frequency and strength of these storms could have any relationship to global warming?

Before I proceed we need a simple definition of science. Science (from Latin: scientia meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the world. Science observes facts, organizes them and offers a response to what we see and know in the world. Good science never conflicts with religious faith and vice versa.

Researchers have been to places like Tuscaloosa, where I lived in 1967-69, to study the storm's impact. Now they've been to Joplin as well. Their goal is to study the unprecedented number of twisters that have destroyed towns and killed people. Here are some of the questions they've posed and responded to in recent writing I've given time to digesting about this subject.

1. Was there any direct connection between the storms in the Southeast and the one in Joplin?

“No” says a meteorologist for the National Oceanic and Atmospheric Administration’s Storm Prediction Center in Norman, Oklahoma. Because they were separated by three weeks they were “completely different weather systems.”

2. What caused these storms?

Warm, moist air from the Gulf of Mexico moved north until it encountered cold air from different altitudes. When these come together they produce wind shear and circular air motions. The air from the south was unusually warm for this time of year, about 2 degrees warmer than normal. In April the jet stream stalled and allowed a repeated series of storms to develop.

3. How severe was the Joplin storm and some of the others?

Many of these storms, and Joplin was certainly among them, were E5 storms. (The rating is called an Enhanced Fujita scale!) This scale measures intensity and this E5 means it had speeds of more than 200 mph. What is interesting is that you cannot measure the wind inside the storm. You can only determine this by the damage surveyed on the ground after the storm.

4. How common are such storms?

Between 1950 and 1994 only 1% of U.S. tornadoes were E4 or E5 in intensity. During that same period 67% of all deaths came in such storms. Deaths have increased in recent years. Experts believe this is primarily because of urban sprawl, which means a tornado has a greater likelihood of striking a more heavily populated area.

5. Is this an unusual year for tornadoes?

Over the last few decades 1,200 storms a year is the average. We were already at 1,076 before Joplin.  The real question we long to understand is why. In weather terms it is because the jet stream is moving farther south and bringing it in contact with excess moisture and triggering larger storms.

6. Does global warming have anything to do with this pattern?

Most agree that we do not know. It is, simply put, impossible to link specific storms to climate change in general. But one climate change model (note the word “model” I use here) suggests that we will see more intense storms as average global temperatures climb. This “appears” to be happening according to many scientists.

Nothing triggers more emotional reaction than to link any weather events to global warming. I confess that I do not understand this at all. I am well aware of the problems of global warming models but I also believe we have evidence (without clear and conclusive reasons for why) that such a phenomenon is taking place. The patterns are not simple and universal but there is something to be seen and studied that goes beyond what we saw decades ago. Why do we find it impossible to discuss this without it turning into a battle over theories of explanation that demonize the other side in the debate?

There are two conclusions I draw about the science in this instance. One, there is a lot we do not know and we should continue to do real science and be open to what it teaches us. When Christians have been at the top of their game, as it were, they have welcomed scientific research and study. Two, Christians should be much more interested in the planet than they often are. We are not known for loving creation and a deep desire to protect it. Why not?