Carpe Diem

An inconvenient fact: The frequency of violent tornadoes like the ones in the Midwest has been declining, not increasing


tornadoesFollowing a series of tornadoes in 2011, including an especially violent one (category EF5) that hit Joplin, Missouri and killed 158 people, many climate alarmists quickly drew a connection between the string of tornadoes and global warming climate change (or to their keep their options open, some in the green movement now prefer the term “violent weather“). For example, see this Washington Post op-ed by Bill McKibben (founder of the global climate campaign and a distinguished scholar at Middlebury College) from May 23, 2011 (“A link between climate change and Joplin tornadoes? Never!“) that generated more than 1,000 comments. Earlier this year, after tornadoes killed more than 20 people in Oklahoma, climate alarmists were again quick to blame global warming climate change violent weather, see articles here at The Huffington Post and here at Fox News, which quoted Senator Barbara Boxer from the floor of the Senate connecting the Oklahoma tornado to climate change:

This is climate change. We were warned about extreme weather, not just hot weather but extreme weather. … When I had my hearings … scientists all agreed that what we’d start to see was extreme weather.  … It’s going to get hot. But you’re also going to see snow in the summer in some places. You’re going have terrible storms. You’re going to have tornadoes.

Now the climate alarmists, like former United Nations adviser and economist Jeffrey Sachs (now director of the Earth Institute at Columbia University) are at it again, linking the recent tornadoes and thunderstorms in the Midwest to global warming. Via The Daily Caller:

Former United Nations adviser and economist Jeffrey Sachs sent out tweets Sunday night that the severe storms that hit Illinois on Sunday were the result of human-induced global warming, for example:

Tweet 1. Weather tragedy in Illinois. Research shows human-induced warming is likely to lead to more severe thunderstorms.

Tweet 2. Today’s tornadoes in Illinois were very uncommon in number and severity for the month of November. Not unprecedented, but very uncommon.

Tweet 3. Climate liars like Rupert Murdoch and Koch Brothers have more and more blood on their hands as climate disasters claim lives across world.

MP: As I reported earlier this year, there’s just one small, very inconvenient problem with making a connection between global warming climate change and an increasing frequency of violent, deadly tornadoes – it’s a link that doesn’t actually exist. Here are some inconvenient weather facts based on publicly-available data from the National Oceanic and Atmospheric Administration’s (NOAA) National Climatic Data Center.

The top chart above displays the annual number of “strong to violent tornadoes” (F3 to F5 on the Fujita Scale) in the US from 1954 to 2012, with these highlights:

1. Between 1954 (earliest year available) and 2012, there has been a downward trend in the frequency of strong to violent tornadoes in the US, and that declining trend is statistically significant at the 1% level (see red line in chart, based on a linear regression model). On average, there has been a decline of 0.44 violent tornadoes every year since 1954, or a decline of 4.4 violent tornadoes every decade since the 1950s.

2. Although there was a significant number (84) of violent tornadoes in 2011 (which generated responses like Bill McKibben’s op-ed in the Washington Post that linked tornadoes like the one that hit Joplin, Missouri to climate change), there were actually more violent tornadoes in the years 1957 (99), 1965 (98), 1973 (86) and 1974 (131).

3. In the first half of the sample period from 1954 to 1983, there were ten years when there were more than 60 violent tornadoes, and the average was 55.4 tornadoes annually during that 30-year period. In contrast, during the second half of the sample from 1984 to 2012, during a period when global warming was supposed to be increasing, there were only two years when there were more than 60 violent tornadoes (1999 and 2011), and the annual average was only 37.2 during that 30-year period.

4. The bottom chart above displays the ten deadliest tornadoes in US history, according to the NOAA (measured by number of weather-related deaths), and only one (the Missouri tornado in 2011) has occurred in the last 50 years; the other nine deadliest tornadoes in the US took place between 1840 and 1953. And the five deadliest tornadoes in US history that combined killed almost 1,500 people, all took place in 1936 or before.

Bottom Line: The statistical evidence on violent tornadoes, although frequently ignored by the media, politicians, and others claiming a link between violent weather and climate change, clearly shows that the frequency of violent tornadoes like the recent ones in the Midwest, has actually been declining over time, and not increasing. Further, of the ten most deadly tornadoes in US history, nine took place in 1953 or before, and only one has occurred in the last sixty years. But climate alarmists always prefer “green hysteria” over evidence, hard facts and data, and we can expect more Sachs-like tweets and McKibben-like op-eds in the days to come, with false claims linking the Midwest tornadoes to global warming and climate change.

13 thoughts on “An inconvenient fact: The frequency of violent tornadoes like the ones in the Midwest has been declining, not increasing

  1. This does show that humans have a great ability in predicting the past and the present, but not the future in any great detail.

    My own idea as to climate change (climate warming, in particular) is that it is, in fact, occurring. However, it is likely to occur over centuries and not dramatically over decades as some are saying. Worst case scenarios seem to be sprouting everywhere. I don’t think so. Yes, low lying areas can be hard hit. People will die and others will benefit.

    I think it best to relax, be aware of the possibilities – and prepare gradually. Panic decisions leave a lot of room for major errors in judgment – and human-caused disasters.

    But to deny climate change (and warming) has very little to support such a conclusion. The evidence is there – in the air, in the ocean, in the ground. My studies of geology, the way the earth works, oceanography, etc. does indicate that over the longer term, humans will have to adapt.

    The only thing that can kill off the human race would likely be an ice age, which could happen very quickly if a volcano such as Yellowstone were ever to explode.

    Earth warming seems to be a mixed blessing in contrast.

    Just saying.

    • I agree. For example, we can all see that all the glaciers are melting and decreasing in size everywhere. It is a directly measurable phenomenon. This warming may be just an oscillation, but Global WARMING, not just climate change, is happening, no doubt about it.

      The question is now at what rate is it happening worldwide on average, and if it is indeed an oscillation, and (barring a natural catastrophe like an massive eruption) then will it naturally reverse itself and when? Nobody knows yet.

    • That’s interesting a lot of glaciers are getting bigger. The more I did into this the more it is becoming a third or fourth order effect, if any. AGW is a religion and as such it is futile to argue with a true believers.

  2. The truth is trailer parks attract tornadoes. As living standards have improved in the Midwest, there not so many trailer parks. Some regions banned them. Ergo, fewer tornadoes. BTW. There used to be a boss car named the Toronado.

  3. The decrease in reports of strong and violent tornadoes over the years is mostly, if not entirely, due to changes in reporting and damage estimation practices. This has been discussed in the scientific literature for at least 25 years.

  4. “The decrease in reports of strong and violent tornadoes over the years is mostly, if not entirely, due to changes in reporting and damage estimation practices. This has been discussed in the scientific literature for at least 25 years.”

    So does that mean we basically don’t know how many F3+ tornadoes happened in the 1960′s, or that we do know but have to make an adjustment to the numbers?

    (I would not be surprised if before doppler radar we had little idea of the true numbers of F3+ tornadoes that happened in non-populated areas – even today, doppler radar doesn’t cover the country).

    • “So does that mean we basically don’t know how many F3+ tornadoes happened in the 1960′s, or that we do know but have to make an adjustment to the numbers?”

      It means we don’t really know. From looking at the environments the tornadoes occurred in, there are a lot of tornadoes rated F2 and higher in the era prior to ~1975 that occurred in environments that F2+ tornadoes were very rarely observed in after 1975 and that the distribution of environmental conditions for F2 tornadoes prior to ’75 looks like a combination of the distribution for F1 and F2 in ’75-’99.

      The pre-’75 tornadoes weren’t rated when the occurred. The F-scale was adopted in the mid-70s and the earlier tornadoes were retrospectively rated based off of the text description of damage by undergraduates hired for the summer. There are a number of threads of evidence that suggest they overrated the tornadoes by ~1/2 F-scale (environments, path length, width, etc.) Tom Grazulis did a project for the NRC where he collected information on F2+ tornadoes through 1995. His numbers are much lower for F3+ prior to ’75 and show no trend.

      The second big change in rating occurred ~2000-2001. Input from the engineering community and some policy changes led to another apparent decrease in the ratings. Doppler radar has nothing to do with it. Radar data has influenced probably 5-10 ratings over the course of the database.

  5. While, it’s true that one cannot link individual events to climate change, and that trends are important, we still have a very short record of reliable information about significant/violent tornadoes in the U.S. Here’s an “inconvenient fact” that the author doesn’t know: meteorologically speaking, periods of increased tornadic activity are believed to occur in cycles. For the Chicago area, this is believed to occur in ~45 year cycles, based on information from the late 1800s-now. Data from the earlier time periods is not presented in the graphic provided in this article. You can reference the first link I provided for local information in Northeastern Illinois going back to 1880. The second link I provided admits that the connection between tornadoes and climate change is not yet clear. This is fact however: the U.S. will always experience tornadoes, including violent tornadoes. As the population increases, more damage will occur to places that were previously open land. This is the increase in risk that the U.S. is facing. Everyone in states affected by significant tornadoes should know how to react when a tornado warning is issued.

    - a meteorologist

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>