It turns out that measuring tornadoes power is not easy.
To start with it is very rare that a tornado's wind speed gets recorded directly. Instead, experts estimate the power based on clues afterwards. Some of the people tasked with estimating tornado winds are much better at this than others. The best clues come from damaged buildings if the tornado happens to hit any. But for many tornadoes, especially in the past, guesstimates were made by a variety of people using photos or news accounts.
In addition the official tornado measuring scale has changed twice in recent decades and the interpretation of tornado strength has shifted at least two more times for political and economic reasons. For example a tornado today is given a significantly less powerful rating than it would have been given in the past.
The result is a database that experts say is unfit for determining climate trends either way:
"There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lighting, and dust storms."
-- UN IPCC 2007 Climate Report
" Unfortunately, even if a miracle occurs and a practical solution to the problems of tornado occurrence data is found and implemented in the near future, the relative rarity of tornadoes means that it would take many decades to accumulate enough accurate data even to begin to have a decent sample size. Thus, I see no near-term solution to the problem of detecting detailed spatial and temporal trends in the occurrence of tornadoes by using the observed data in its current form or in any form likely to evolve in the near future."
-- Doswell " Small Sample Size and Data Quality Issues Illustrated Using Tornado Occurrence Data" (2007):
"We don't have a good enough database to determine how tornadoes may have changed in recent decades, and our computer models are currently not able to tell us if tornadoes are more likely to increase or decrease in a future warmer climate."
-- Dr. Masters
We don't know and we are not likely to know for a long time. Unfortunately, many news articles and opinion pieces mistake this lack of knowledge as meaning that climate change isn't causing changes to tornadoes. For example I've read many times in the last couple weeks that climate change isn't to blame for the recent Moore tornado. This is not accurate.
The science says that we don't know either way. Maybe climate change made the Moore tornado worse and maybe it didn't. Nobody knows.
To me flying blind into high risk is not a very comfortable position. I'm the kind of person that would rather be safe than sorry when it comes to potentially over-energizing and destabilizing our weather system. I'm strongly in favour of reducing the amount of fossil fuels that are extracted and burned each year.
So far, however, the majority of humanity seems content to press our collective foot ever harder on the fossil fuel accelerator. Each year we release even more fossil fuel pollution than the year before. And decade by decade our weather system grows ever more energetic as a result.
Will increasing tornadoes become another climate legacy we leave to our kids, along extreme rainfall, flooding, heat waves, droughts, dying coral reefs, collapsing forests, more powerful hurricanes, arctic death-spiral, and ever-rising and over-acidified oceans?