global warming and tornadoes

Are tornadoes becoming more frequent and more violent because of climate change?

A powerful tornado as much As 3 kilometres wide devastated the Oklahoma City suburb of Moore on May 20. The tornado reportedly boasted winds above 300 kilometres per hour as it ripped through homes and schools, leaving a huge path of destruction and fifty one of people, including twenty children. People have started to ask the questions about what causes these shattering tornadoes, and a lot of people have started to ask if we are to play for these severe tornadoes because of human induced climate change.

Trying to establish whether tornado activity will change as the climate changes is complicated for a few reasons. Firstly scientists don’t have a good quality, complete data set on tornadoes that have already occurred. Without a reliable record, scientist can’t accurately look to see how tornadoes have changed since temperatures started rising. Secondly, computer simulated models can’t tell scientists much about tornadoes either. Because these models work on large scales, simulating changes in the ocean and the atmosphere on a global scale. In contrast, tornadoes are minor weather events. As Dr Suzanne Gray, a meteorologist from Reading University explains:

"Tornadoes are too small-scale for current climate models to simulate, so it is not possible to say very much about how strength and occurrence might alter under climate change."

Research published in the journal Climate Dynamics shows that tornadoes are occurring on fewer days per year than they have before, but they are forming at a greater density and strength. This indicates that on the days when tornadoes do form, there tends to be more of the tornadoes forming and they’re often more powerful.

Tornadoes are narrow, spinning columns of air reaching from the base of a thunderstorm down to the ground. They actually only account for a fraction of the energy released in a thunderstorm, but that energy is concentrated on a small area.

Also, climate change is likely to influence the two critical conditions for tornado formation – atmospheric moisture and wind shear – in conflicting ways. The atmosphere is expected to hold more moisture as temperatures rise, making tornadoes more likely. But wind shear will probably decrease, having the opposite effect. Scientists can’t say whether on force will override the other.

Although there is a marked increase of the amount of tornadoes over the past decade, some scientists believe the reason people are beginning to there are more tornadoes is simply because they are being more documented. With the new storm chaser craze, mixed in with social media, where people can share photos and videos of the tornado in seconds sharing these photos to millions of people in minutes. Before it took days even weeks to get information that a tornado had occurred, even then the tornado had to have caused a considerable amount of damage to homes. Now even the smallest of tornadoes is broadcasted all over social media.

In the future it is possible that climate change could extend the “tornado season” (generally early spring in the US South and late spring to summer in the Midwest) may shift a bit earlier, and the secondary autumn season could extend later. This could result in more tornadoes and those tornadoes being more powerful and more dangerous. It's also possible, according to recent research, that warming will reduce the frequency with which the required conditions for powerful tornadoes will co-exist. While the atmosphere is generally getting warmer and moister, which can boost the instability that fuels storms; it's also possible that the wind shear that organises tornadic storms will decrease. This could tip the balance away from tornadoes and towards other thunderstorm extremes, such as heavy rain. Worldwide scientists are continually reaching tornadoes to gain better understanding of how they work and to find out how their frequency and intensity might change in the future. As time goes on, the record of past tornadoes will grow too- this will provide a bigger set of data to spot trends in the behaviour of the tornados. It seems logical that climate change will have some effect on the manner of how the tornadoes form, but with limited data it is very hard to say what that effect will be.

Referencing

http://www.carbonbrief.org/blog/2013/05/tornadoes-and-climate-change-what-does-the-science-say/

http://www.carbonbrief.org/blog/2013/05/tornadoes-and-climate-change-what-does-the-science-say/

http://scienceblogs.com/gregladen/2013/05/21/are-there-more-tornadoes-because-of-global-warming/

http://www.debate.org/opinions/twin-tornadoes-in-nebraska-are-tornadoes-getting-worse-because-of-global-warming