by Judith Curry
Politics versus data and the science of communication.
On December 10 and 11, a catastrophic tornado hit the Mississippi Valley, particularly in Kentucky. A tornado storm traveled more than 200 miles, and more than 100 people may have died. A great overview of hurricanes written by Bob Henson [link]. Preliminary analysis indicates that the maximum tornado intensity was EF4, with winds estimated as high as 190 mph.
Tornadoes and global warming
The link between tornadoes and climate change is more nuanced than phenomena like heat waves or extreme rainfall.
Fortunately, there is no indication that the number or intensity of the most intense tornadoes (EF3+) is increasing. However, tornadoes are becoming tighter in outbreaks, and there are longer intervals between flares, leading to more variation from quiet to intense and vice versa. again. Before Friday, the US tornado death toll for 2021 was just 14, the third-lowest in data from 1875. (The lowest on record is 10, set in 2018).
There is also a marked multi-decadal trend as recent outbreaks have moved into and east of the Mississippi Valley, particularly through the South Central, in contrast to the more traditional territory of the southern and central Great Plains. heart.
For seasonal times, it’s never impossible to have a violent tornado in December, even as far north as Illinois. At least two Tornado F5/EF5 are in the record books for December: one in Vicksburg, Mississippi on December 5, 1953, killing 38 people (deadliest December tornado on record so far this year) and one on December 18 1957, which hit Sunfield, Illinois, was part of the state’s most severe outbreak recorded late this year.
This December has been mild over most of the United States, and warm, moist surface air poured into Friday’s tornadoes, invigorating them. It’s not hard to imagine the second spring and fall peak of tornado season moving closer to winter as greenhouse gases continue to warm our climate globally, nationally and regionally. Such a tornado time change has hard to confirm so far, though.
What does IPCC AR6 have to say about tornadoes and global warming?
“Typonic trends … associated with severe convection storms are not clearly detected”
“The distribution of certain types of extreme weather (e.g. tornadoes) is beyond current modeling and theoretical capabilities”
“How will tornadoes … change is an open question”
President Joe Biden made these statements in an interview:
Mr. President, does this tell you anything about climate change? Here – or do you conclude that these storms and their intensity are related to climate change?
PRESENT: Well, all I know is that widespread weather intensity has some impact due to planetary warming and climate change.
The specific impact on these specific storms, at this point, I can’t say. I will ask the EPA and others to look into that. But the reality is we all know things get more intense as the climate warms – everything. And, obviously, it has some impact here, but I can’t give you – a quantitative read on that.
Here’s what Michael Mann had to say [link]:
Penn State meteorologist Michael Mann told USA Today: “The latest science shows that we can expect much more than these massive outbreaks (cyclonic) caused by human-caused climate change. out”.
In another interview [link]:
We talk to climate scientist Michael Mann about climate change’s role in hurricanes and climate denialism among Republican leaders. “There’s no mistake that we’ve seen an increase in these large tornadoes that could be attributed to warming of the Earth,” said Mann, director of the Center for Earth System Science at Penn State University. planet”.
And first, it’s this tweet – data ‘disavow’ at its ‘best’:
Chris Martz, an undergraduate meteorology student at Millersville University, provides the following charts of NOAA’s tornado record
Here are the plots of December tornadoes from NOAA data:
US FEMA administrator says December tornadoes are ‘new normal’ [link]. It appears that 1963 was the only year on record without a tornado in the United States during December.
Regarding the normal US damage from tornadoes, Roger Pielke Jr provides this chart [link]:
Analysis by Greg Goodman
Historical data on tornado events in the United States is often dismissed as unreliable because changes in observation techniques affect the reliability and consistency of reporting. IPCC SREX states: “There is low confidence in observed trends in small-scale phenomena such as tornadoes and hail due to heterogeneous data and inadequacies in the monitoring system.”
One of the major factors that led to that heterogeneity was the development and deployment of Doppler RADAR beginning in the mid-1980s, although implementation has been an ongoing process over the decades since. Other factors are the spread of urbanized areas into rural areas and the reporting base of the non-technical people due to handheld devices and access to global communications. . RADAR observations capture many smaller events that have never been seen or recorded before. Historically, many events are required by insurance to record as they affect property or crops, and this means many minor events go unreported unless they cause significant injury or damage. tell. However, the big, powerful events will be hard to miss.
Tornadoes are classified on the Advanced Fujita Scale (EF Scale). An examination of the data available from 1950 to the end of 2019 shows that the more robust events (classified EF2 or higher) show consistent progress over time, and are only to a lesser extent EF0 and EF1 reported. enhanced in recent years by better, more comprehensive reporting.
The archive of individual tornado events lists each event by date and provides some data such as location, force ratings, and fatalities. The number of events for each force classifier in each calendar year is calculated, then each time series is normalized (minus the mean and divided by standard deviation) to see the relative progress of each type over time.
After the strongest record year, 1975, tornado activity dropped markedly in all categories. Except for some lower peaks, activity has remained below average since then. The EF2, EF3 and EF4 categories all show very similar evolution over time in both individual operating years and long-term trends. It is very unlikely that large tornadoes go unnoticed and unreported, so the similarity in the time course of each category suggests that reporting for EF2 is consistent over time. The data is consistent and consistent across categories, which gives confidence that there are no major reporting biases causing the current.
The period from 1950 to 1975 showed a steady increase in activity that peaked in 1975. It was followed by a sharp and sudden decline with no sign of increasing since. All three categories were remarkably similar, which showed no trend in the proportion of stronger or less powerful storms during this period.
The period after 1975 marked the beginning of the late 20th century warming that the IPCC attributed largely to anthropogenic (AGW). If it were necessary to hypothesize a link between “global warming” and the frequency or intensity of tornadoes in the United States, there would be fewer events in all categories. main item in this warming period. There was no significant change in storm severity distribution as temperatures rose, and recent warmer decades have shown significantly less activity than during the pre-World War II cooling period. before.
Marshall Shepherd wrote a good article in Forbes titled How climate messaging spirals out of control during tornado outbreaks.
The good news is that climate change is being discussed more intensely. The bad news is that some of that discussion is worthwhile. Recent tornado outbreaks have sparked an overwhelming wave of links to climate change. In my view, some messages are out of control.
I contacted Professor Allen for his thoughts on texting in the aftermath of the December tornadoes. The Central Michigan University scholar told me, “There’s a philosophical point that I think we have to be careful to know. limit their expertise and capacity when agreeing to an interview.” I am a scientist who frequently receives inquiries from the media. Today, there is a lot of media that says the content is high level and “heads talk”. Relative to the audience, I can talk about a variety of weather, climate and Earth science topics. Even though my degree is in meteorology, I get asked about wildfires, tsunamis, meteors, and other fundamental topics, and that’s usually fine.
However, we all have limits. Allen went on to say, “Although we can talk about other fields at a basic level, for most of the sciences (especially climate change), Ioften the nuance that defines what we can say – and familiarity with the latest developments in the field tends to be where this gets the most exposure. Such nuances can be even more difficult for a speaking “expert” without a strong background in meteorology or climate science.
Expert saturation is another matter. Amid events like the December tornado outbreak, journalists are seeking input from experts. Many professionals become overwhelmed by the requests. It is a double-edged sword. Scholars like Trapp, Brooks, Gensini, and Allen have achieved a certain degree of credibility and become “go to” sources. However, when the pool of experts is “saturated,” there may be a tendency to turn to other options. Usually, those choices are mostly good. However, some choices end up being confusing. Professor Victor Gensini, an expert at Northern Illinois, told me saturation is real. He’s done over 50 interviews in the past week and recommended 30 others. He wrote, “Honestly, I feel the same way as you…. I think the real problem arises when ‘edge field’ experts come in and try to apply their perspectives and research to the question of the day.”
At the end of the day, there are a lot of messengers and messengers out there. This will not change. How can we deal with conflicting stories in real time, poor scientific background by some talking head, or saturation problem. I’m not sure.