The deadly tornado outbreak that ripped through communities from Arkansas to Illinois on the night of Dec. 10-11, 2021, was so unusual in terms of duration and strength, especially for December, that many people, including the president of the United States, are wondering if climate change played a role – and whether tornadoes will become more common in a warming world.
Both questions are simpler to pose than to answer, but recent research is revealing fresh information. I am an atmospheric scientist that researches violent convective storms like tornadoes as well as climate change’s effects. So far, scientific investigation has shown the following.
Scientists employ complicated computer models to characterize the whole Earth system, from the Sun’s energy flowing into how the soil responds, and everything in between, year after year and season after season, to comprehend how rising global temperatures will influence the climate in the future.
On a worldwide scale, these models answer millions of equations. Each computation accumulates, necessitating significantly more processing power than a desktop computer can provide. We presently have to use a large scale to forecast how the Earth’s climate will change by the end of the century. Consider it similar to the zoom feature on a camera used to photograph a faraway peak.
The forest is visible, but individual trees are difficult to distinguish, and a pinecone in one of those trees is too small to discern even when the image is blown up. The smaller the item in a climate model, the more difficult it is to notice it.
Tornadoes and the violent storms that produce them occur on a far smaller scale than climate models can forecast. Instead, we may look at the large-scale factors that contribute to the formation of tornadoes.
Energy generated by warm, moist air generating powerful updrafts, and variable wind speed and direction, known as wind shear, which permits storms to become bigger and longer-lived, are two critical factors for severe storms. A third element, which is more difficult to identify, is a storm-forming trigger, such as a particularly hot day or a cold front.
Even if not every favorable setting leads to severe storms or tornadoes without this element, the first two criteria make severe storms more likely. Climate models can tell us something about the shifting risk by utilizing these elements to describe the chance of severe storms and tornadoes developing.
Climate model estimates for the United States imply that towards the end of the century, the overall chance of favorable ingredients for severe storms will grow. The fundamental reason for this is that rising temperature combined with increased moisture in the atmosphere enhance the likelihood of severe updrafts. Rising global temperatures are causing dramatic changes in seasons that were previously thought to produce severe weather very seldom.
Stronger increases in warm humid air in the autumn, winter, and early spring imply more days with suitable severe thunderstorm conditions — and these storms have the potential to be more intense when they do occur.