Quad-state tornado: a new devastating record?

The tornado on the night of Friday, December 10, 2021, that devastated parts of Arkansas, Tennessee, Missouri and Kentucky was part of an unseasonal outbreak, fueled by very mild surface temperatures. The peak season for tornadoes in this area is usually in March and April. If confirmed to be indeed a single tornado track of over 250 miles (400km) with a lifespan of over four hours, it would set a new record for tornado distance and duration. Beyond this single tornado, further twisters affected other towns in Kentucky, Kansas, and Illinois, including an Amazon warehouse. While casualties are still being recovered and damage assessed, it is likely the deadliest and costliest tornado outbreak in decades.

Did climate change play a role in this unusual tornado outbreak?

Tornado outbreaks are the type of extreme event that scientists have the least confidence in attributing to climate change, unlike heatwaves or floods. This is in part because of the short-lived nature and limited geographical extent of these events but also because of the complex interplay of meteorological conditions that are required for tornadoes to form.

Early December 2021 saw some of the mildest weather ever experienced in the affected southern states, breaking multiple local temperature records for that time of the year. These are linked to the exceptionally warm Gulf of Mexico and the on-going La Niña phenomenon, which ultimately stems from a temperature imbalance of the Pacific Ocean but has global seasonal weather impacts. The combination of warm, moist air near the surface combined with cold, dry air at higher altitudes due to the onset of winter in the United States are the perfect mix for potent thunderstorms. As the moisture rises the thunderstorms swell to so-called supercells, like the one travelling from Arkansas across Kentucky, which spawn and fuel tornadoes.

Thus, a warming climate will likely lead to atmospheric conditions favorable of winter tornadoes as was observed over the weekend. However, other factors such as decreasing wind shear in a warming world could inhibit tornado formation. To date climate models cannot capture the small-scale meteorological dynamics that control tornadoes, making future projections highly uncertain.

Bastian Manz Senior Atmospheric Risk and Climate Risk Analyst at Allianz Re
Bastian Manz Senior Atmospheric Risk and Climate Risk Analyst at Allianz Re

How has the damage caused by tornadoes evolved over time?

To date, there have been no definitive trends in terms of tornado numbers across the United States in recent decades. However, increased losses can be attributed to two drivers. On the one hand, there has been some evidence that while the total number of strong tornadoes has remained stable, tornadoes are clustered over fewer days, so the damage of individual events becomes more widespread. On the other hand, the concentration of human population and assets continues to increase, which drives losses if these areas are impacted by a tornado, even if tornado strength and frequency were to remain unchanged.

What are the implications for the insurance industry?

In terms of quantifying losses, accurate location information and the use of geo information systems (GIS) is crucial, as tornados completely destroy structures in their paths while those close by remain unaffected. Insurers will look closely at the Quad-state tornado to better understand the damage dynamics of this specific event. This is particularly relevant if tornadoes continue to move from the traditional U.S. Tornado Alley into the southeastern states that generally have weaker constructed buildings and homes. Tornadoes are also a relevant peril outside the United States, as the extensive damage in the Czech Republic showed this summer.

Insured losses from so-called secondary perils have been increasing globally over the last two decades and exceeded those of traditional primary perils (wind, earthquake) in 2020. Amongst these secondary perils, tornadoes, straight-line winds (“derechos”) and hail (collectively termed severe convective storms) constitute the biggest loss drivers worldwide, despite their localized geographical footprint.

The Allianz Group is one of the world's leading insurers and asset managers with 126 million* private and corporate customers in more than 70 countries. Allianz customers benefit from a broad range of personal and corporate insurance services, ranging from property, life and health insurance to assistance services to credit insurance and global business insurance. Allianz is one of the world’s largest investors, managing around 767 billion euros on behalf of its insurance customers. Furthermore, our asset managers PIMCO and Allianz Global Investors manage nearly 1.9 trillion euros of third-party assets. Thanks to our systematic integration of ecological and social criteria in our business processes and investment decisions, we are among the leaders in the insurance  industry in the Dow Jones Sustainability Index. In 2021, over 155,000 employees achieved total revenues of 148.5 billion euros and an operating profit of 13.4 billion euros for the group.

These assessments are, as always, subject to the disclaimer provided below.

*Including non-consolidated entities with Allianz customers.

Press contact

Elizabeth Goetze
Allianz SE Reinsurance
As with all content published on this site, these statements are subject to our cautionary note regarding forward-looking statements:

Further information

Allianz reinforces its commitment to net-zero strategy

Allianz Group is accelerating the deployment of its climate strategy and has announced new ambitious commitments in both its core business and operations. The company will limit the greenhouse gas emissions (GHG) deriving from Allianz’s sites and activities in over 70 markets to net-zero by 2030, instead of 2050 as originally planned.

Capital markets fight against climate change

The dummy UN-Convened Net-Zero Asset Owner Alliance (AOA) released the second edition of its Target Setting Protocol (TSP) in January 2022. The TSP guides members in setting climate targets aligned with keeping global warming below 1.5°C. Allianz SE board member Günther Thallinger is Chair of the Asset Owner Alliance (AOA). 

Fighting for a future free from plastic pollution

Plastic is a threat to our oceans and seas. All life on earth depends on these important ecosystems. Action is urgently needed by governments, the business community and consumers to reduce to harm to our planet.