Until the April 26/27th 2011 tornado outbreak, The April 3rd 1974 was the biggest outbreak of tornadoes in US history. Last year, the usual suspects railed about how the outbreak was a clear consequence of global warming> climate change> climate disruption, even going so far as saying such linkage was “required by ethics” (insert facepalm here). I called them all “Hucksters“. The wailing was sort of like when 1934 was the warmest year in the USA until James Hansen came along and “adjusted” 1998 to be warmer.
I and many others said it connecting AGW to the 2011 outbreak was rubbish- there’s no connection in the data, and that it was what you expect to get when you have La Niña conditions like we did in the spring 0f 2011. WeatherBell’s Joe D’Aleo even predicted the likelihood of severe weather ahead of time based on La Niña conditions and snow cover. (Update: Here’s two reports from him before the outbreaks:)
During El Niño the jet stream is oriented from west to east across the southern portion of the United States. Thus, this region becomes more susceptible to severe weather outbreaks. During La Niña the jet stream and severe weather is likely to be farther north.
Note the collision zone in the US southeast during La Niña patterns. 1974 was a La Niña year too.
Then the wailing shifted to monetary damage claims, about how much more damage there was than in 1974 in terms of cost, not just in tornadoes, but well, everything weather related. While I can’t comment on everything, I can say with certainty the tornado claims are rubbish thanks to a new paper just published by Kevin Simmons, Daniel Sutter and Dr. Roger Pielke Jr..
Simmons, K., D. Sutter, R.A. Pielke, Jr. (2012), Blown away: monetary and human impacts of the 2011 U.S. tornadoes. Extreme events and insurance: 2011 annus horribilis (Edited by C. Courbage and W.R. Stahel) The Geneva Reports: Risk and Insurance Research , Published March 2012.
Pielke Jr. writes on his blog:
1. When using our dataset, it is best to use the damage numbers as tabulated by the US NWS as they are consistent over time
2. That said, 2011 damage is qualitatively indistinguishable from 1974 and
19541953 at >;$20B
3. That would give a simple baseline expectation of 1 in 20 for 2011, but half or twice that would not be implausible given the uncertainties, so between 1 in 10 and 1 in 40
4. For 2012 and looking ahead there are two big question marks, one more certain than the other. Urbanization is increasing, which means that the chance of large losses increases (somewhat at the expense of smaller and medium losses of course). And there has been a notable and significant decline in the incidence of strong tornadoes in recent decades
Here’s the summary from the report:
As 2011 began, the big news in the American sports world was the showdown between
Auburn and Oregon for the national championship in college football. The big political
story was the Tea Party, which had just helped Republicans regain control of the U.S.
House of Representatives. In Hollywood, speculation was rife on who would win an
Oscar. In other words, 2011 began as most years do. No one foresaw that the first five
months of the year would reset the expectations of meteorologists, insurance companies,
and the public regarding the toll tornadoes can impose on the U.S. today.
The decades leading up to 2011 convinced many that the tornado threat had been reduced to the point that 100 fatality tornadoes and 500 fatality years were in the past. After all, neither figure had been exceeded in the U.S. in over 50 years. The National Weather Service implemented a nationwide network of Doppler weather radars in the 1990s. Warning lead time doubled, and then almost doubled again, providing sufficient time for families to receive a warning and take shelter. Television stations used sophisticated graphics to cover tornadoes with ever-increasing accuracy. Street level tracking software allowed TV viewers to know the exact location of a tornado and how close it might get to their home.
In this environment, a tornado that killed 10 or more people was national
news and could grab the attention of the public for days and perhaps weeks. In 1999 one
of the most powerful tornadoes ever documented struck a metropolitan area and resulted in 36 deaths, which while tragic, was only a fraction of the toll that might have been expected from a tornado like this at the start of the 20th century. The benchmark for what constituted a major tornado event was much different than 1974, when the 3-4 April “Super Outbreak” killed over 300 people. Things were different now, or so many people thought.
We begin by summarising the damages and fatalities from U.S. tornadoes in 2011. Next,
we examine the tornado outbreak as it relates to the historical record. The next section
looks at the role that extreme weather played, followed by a discussion of some of the
vulnerabilities that are known to increase fatalities from tornadoes. We then consider
what can be done to limit damages and fatalities from future tornado outbreaks. Finally,
we discuss whether or not this was an event that can be expected to occur again and then
Three previous seasons—1953, 1965 and 1974—now rival damage in 2011. Normalised
damage exceeded US$20 billion in 1953 and 1965 and exceeded US$10 billion in
1974. The 1953 season provides perhaps the best historical comparison with 2011, as much of the damage in 1965 and 1974 occurred in just one outbreak. Damage in 1965
is attributable to the Palm Sunday outbreak, while damage in 1974 occurred in the 2-3
April “Super Outbreak”. 1953 had multiple damaging outbreaks in different parts of the
country. One of the worst tornadoes of 1953 occurred in Worcester, MA, and ranked first
in normalised damage until the Joplin tornado of 2011.
(Note: I think Pielke Jr. meant to say 1953 and not 1954 in his point #2 above, I’ve asked for clarification. UPDATE: Pielke Jr. verifies 1953, corrected here and at his blog – Anthony)
This echoes what I have been saying, from The folly of linking tornado outbreaks to “climate change”:
Historically, there have been many tornado outbreaks that occurred well before climate change was on anyone’s radar. Here’s a few:
1908 Southeast tornado outbreak 324 fatalities, ≥1,720 injuries
1920 Palm Sunday tornado outbreak ≥380 fatalities, ≥1215 injuries
1925 Tri-State tornado ≥747 fatalities, ≥2298 injuries
1932 Deep South tornado outbreak ≥330 fatalities, 2145 injuries
1952 Arkansas-Tennessee tornado outbreak 208 fatalities
1965 Palm Sunday tornado outbreak 256 fatalities
April 3-4 1974 Super Outbreak 315 fatalities
All of these occurred before “climate change” was even on the political radar. What caused those if “global warming” is to blame? The real cause is La Niña, and as NOAAwatch.gov indicates on their page with the helpful meter, we are in a La Niña cycle of ocean temperature in the Pacific.
I recommend reading my essay: Why it seems that severe weather is “getting worse” when the data shows otherwise – a historical perspective