Are The Number of Violent Tornadoes Increasing?

With news coverage about violent storms on the rise, many people also assume that there has been an increase in the number or severity of these storms. Homeowners have certainly seen an increase in hail damage or other property damage from storms. Insurance companies frequently try to avoid paying claims for storm damage, especially because one large storm may result in claims from thousands of customers, and a property damage attorney can help protect the rights of homeowner’s.

Because scientists are debating about whether climate changes have created more destructive hurricanes, let us focus on tornadoes and heavy thunderstorms, which often occur together. There is clear evidence that climate changes from global warming have created an increase in very heavy rains, which are responsible for heavy flooding. However, there is no evidence to indicate that global warming has increased the number or severity of tornadoes or severe thunderstorms.

In the United States, which has the highest number of tornadoes and severe thunderstorms in the world, it may appear that the frequency of tornadoes has increased in the past few decades, with nearly four times as many tornadoes in 2005 as in 1950. However, this is primarily due to changes in reporting, rather than changes in frequency.

For example, the country’s increased population means more tornadoes are spotted and reported.

Advances in weather tracking radar also provide higher detection rates for tornadoes. Also, in the past, multiple tornadoes in the same damage path would have been classified as a single tornado, while current technology allows researchers to correctly identify them as separate tornadoes.

Another question might be whether “violent” tornadoes are on the rise, which would be those classified as EF4 or EF5 on the currently used Enhanced Fujita Scale (F4 or F5 on the older Fujita Scale). Although violent tornadoes are rare, these are the storms that cause the majority of deaths and extreme property damage. Due to their size and destructive nature, they are unlikely to go uncounted. Therefore, studying the frequency of these storms might provide clues about how climate changes might affect severe weather patterns.

The problem is that we cannot measure a tornado’s wind speeds directly, except in extremely rare cases when scientists have been on-site with the proper research equipment. Tornadoes are therefore categorized on the EF (Enhanced Fujita) scale, which is categorized by the tornado’s damage. This means that if a large tornado touches down in empty fields and does not destroy structures, it will not be categorized as a violent tornado, while a smaller tornado that strikes a more populated area will be rated as more destructive. With the increase in population, there should be an increase in the number of storms rated as “destructive” because there are now more buildings that could be hit by tornadoes.

However, there has not been the expected increase in the number of violent storms in the past 50 years. In fact, there has been only one EF5 tornado in the past eight years, as opposed to six F5 tornadoes in the previous eight-year period. (Although the rating scale has changed from E5 to EF5, direct comparisons between the two measurements are still valid.) It appears that climate change has not created an increase in the number of violent storms.

We do not currently know how the number of tornadoes or severe thunderstorms might change due to global warming. Preliminary studies with climate change models indicate that there might be an increased number of severe storms later this century, including severe thunderstorms and tornadoes. However, the research is still in its preliminary stages, and more study will be necessary to confirm or disprove these findings.