Global Warming Reduces Tornadoes

In a recent story on global warming, ABC claimed that tornado frequency this year is running nearly twice that of last year and that this can be linked to global warming.   (HT Maggies Farm) Now, I would have tended to argue that year-over-year variations are probably not related to multi-decadal climate trends, but if ABC wants to so argue, I will go with it.

The only problem is that the first five months of 2008 have been the coolest since 1993 and has run well below the average temperature for the period from 1978-1990.   This while 2007 was one of the warmer Jan-May periods in recent memory.  In fact, average US temperatures were about a degree Celsius cooler in 2008 than in 2007:

UAH MSU temperature for USA (average anomaly)

Jan-May 2007:  .668 C

Jan-Apr 2008:  -.228 C

Difference:  .896 C

So, if one wants to posit that tornado variation in 2008 is a result of a long-term climate trend rather than natural variability, then one must assume that global cooling causes tornadoes to increase, and that in fact global warming would benefit mankind by decreasing tornado frequency.

The whole history of the global warming causes tornadoes claim is one of grossly bad science, most famously including Al Gore’s claim in that movie of his.  I debunked that claim here, demonstrating that the increase in measured tornadoes is a function solely of better measurement, not more tornadoes, something the NOAA has been careful to state as well.

  • jep, Kansas USA

    Everybody knows global warming causes every meteorological or climate related anomaly that deviates in any way from the “norm”. If it’s not average, then global warming is to blame.

    Global warming made OJ do it. Global warming created Hurricane Katrina. Global warming made the last two hurricane seasons weaker than predicted. Global warming killed Anna Nichole Smith. I’m pretty sure global warming causes global cooling, too.

  • Mike
    Joe D’Aleo expands on this over at Ice Cap. More Tornadoes corresponds to La Nina.

  • Tornadoes originate where warm and cold air collide. It is a relative difference of temperatures and moisture content that feeds the beast. A uniformly warm climate would have fewer tornadoes, just like a uniformly cool climate.

    The smarter warmers have adopted “climate change” as the new banner of CAGW. That way, anything the least bit out of the ordinary qualifies as climate change–caused by greedy corporatists and their political lackeys–empowered by everyone except correct thinking radicals of the environmental left.

  • coveman

    By claiming that any given meteorological trend or event is evidence of human-induced “climate change,” the Warmists have rendered their theory “unfalsifiable.”

    In other words, they have morphed their own theory from the realm of science to the realm of pseudo-science.

  • The tornado research community and the storm chase community (which intersect significantly) have long looked for ways to predict “good chase seasons.” As far as I know, and I read the debates, nobody has found any decent predictor.

    Note that tornado fatality rates ( are not good indicators because:
    (1) The change in population distribution over the period of interest
    (2) The change in forecasting and warning capabilities
    (3) Fatalities primarily occur in the southeast (except this year). This is because the tornadoes are more likely to happen during night-time hours in that area. It may also be due to a lower quality of housing. However, most tornadoes do not happen in the SE – they happen in “tornado alley” which is farther west and north.

    However, I like the forecast of more tornadoes yet this year, since I haven’t yet gone on my annual chase. Also, it is true that La Nina and El Nino have significant weather influence. They just don’t correlate well with tornado frequency.

  • Mike

    Everything that happens in weather tells a story of what is, and what is coming. In the case of tornadoes, they usually occur along cold fronts – the leading edge of cold air that is nosing into warm air. The jet stream has been in a winter-like pattern this spring, favoring the movement of cold air masses to move southeastward across the lower 48 states, just as we could normally expect to happen in January. These cold air masses are meeting warm air and lifting it to cause lots of convection, the life source of supercell thunderstorms that spawn destructive tornadoes. Therefore, what kind of meteorological story do tornadoes tell? The warm air IS, and the cold air is COMING. Cold air is repeatedly plowing into pre-existing warm air. It doesn’t really matter where the warm air came from, because it’s not the “What is coming” part of the story. The cold air is. One might ask why, then, do tornadoes most often occur in May, when the nation is warming up for the summer? Simple. The warm air of springtime is putting itself in the path of winter’s cold fronts which haven’t stopped coming yet. Those cold fronts are stronger in the spring because the cold air masses behind them have been chilling in the dark arctic all winter long. Once those cold air masses start to moderate during the summertime, they don’t create the same level of fireworks along their fronts when they make southward moves.

    Therefore tornadoes are not only a sign of cold air coming (immediate short term) but in the longer term (months) I think the current trend of abnormally severe weather shows that this spring’s cold fronts are stronger and more chilled than we’ve seen in a while. This hypothesis is supported by the snows that continue in the Rocky Mountains this May, where some ski areas continue to have mid-winter conditions even this month. For many ski mountains, this season’s close only came as a result of the loss of skiers to spring activities elsewhere.