Is the rise in tornadoes tied to climate change? Scientists aren’t sure — yet

Tornadoes are moving eastward. A man gathers his belongings from his damaged home in Trotwood, Ohio, on May 28 after powerful tornadoes ripped through the Dayton area.

This spring has seen outbreaks of tornadoes and storms throughout much of the country that are almost unheard of.

The sheer number of tornadoes is mind-boggling, and the growing area affected by the twisters is even worse. Since mid-May, there have been 225 confirmed tornadoes in 12 days, with 400 individual tornado reports also logged by the National Weather Service. The matter that climate scientists are now studying is whether the increase in tornadoes is related to the human-made climate crisis. Yes, there is evidence that moist, warm air can exacerbate conditions that spawn tornadoes. But the very nature of tornadoes means that the scientific jury is still out.

Many of us who didn’t live in areas where tornadoes are prevalent grew up thinking of tornadoes as something from The Wizard of Oz. As we grew older, we realized that every spring, tornadoes were common across what is known as Tornado Alley, the area of the Great Plains and Midwest that contains the states of Texas, Oklahoma, Kansas, Nebraska, eastern Colorado, and South Dakota. Also affected are Arkansas, Louisiana, Mississippi, Iowa, Illinois, Tennessee, Kentucky, Wisconsin, and Minnesota.

Now, however, climate scientists and meteorologists are more frequently using a different term: Dixie Alley. These are the states in the Southeast that have seen an increased number of deadly tornadoes in recent years. There is some overlap in the two “alleys,” as the states that make up Dixie Alley are eastern Texas, Arkansas, Louisiana, Mississippi, Tennessee, Alabama, Georgia, upstate South Carolina, and western North Carolina.

It’s not that states in Dixie Alley never had tornadoes before. It’s just that the whole onslaught of tornadoes is spreading east and south, growing more frequent, and getting worse.

It should be a no-brainer, right? Higher temperatures and warmer air, all tied to global warming, should be the reason for more tornadoes when warmer air and cooler air collide. But here’s why those who are experts in climate science say that more study is needed. This is from a PBS News Hour story:

“Whether this is climate change or not, what all the studies have shown is that this particular part of the U.S. has been having more tornado activity and more tornado outbreaks than it has had in decades before,” said Mike Tippett, a Columbia University applied mathematician who studies the climate.

Tippett is among a group of scientists trying to dissect why the South has become a hotbed for tornadoes and severe thunderstorms.

Some signs point to human-made climate change, but those conclusions are mixed at best. Weather and climate scientists have confidence, for instance, in the parallels between tornadoes creeping east and global warming — but are less convinced that climate change is increasing the number of tornadoes overall.

Most of all, their research highlights the barriers in forecasting that keep us from predicting where and when tornadoes might strike. …

Given that these tornado trends coincided with those of warming oceans, there might be a link to climate change — except no one knows for sure.

There’s no such uncertainty for other weather catastrophes. We know definitively that hurricanes are exacerbated by the climate crisis. Warmer ocean temperatures and higher sea levels intensify the effects and the size of hurricanes. Besides the hurricane that devastated Galveston, Texas, in 1900, which remains the deadliest storm in U.S. history, the worst hurricanes have occurred more recently: Hurricane Katrina in 2005, Hurricane Harvey in 2017, Hurricane Maria in 2017, and Hurricane Michael in 2018. It doesn’t take a scientist to see how those storms caused the most deaths and property damage — we need only to look at the pictures and read the reports.

But tornadoes? That’s a different story that’s still developing. Records on tornadoes have been kept only since about 1950, and there are few records of tornadoes in unpopulated areas. Also, compared with hurricanes, tornadoes are tiny, even when they’re a mile wide.

“They happen in small areas, and they don’t last that long,” Tippett said. “It’s hard for us to use our scientific tools — whether they are physics models or other statistical tools — to have a good, clear idea of what’s going to happen.”

This limited resolution explains why weather forecasts cannot typically predict where a tornado will strike until 13 minutes before it hits — and that hampers climate change predictions, too.

Scientists expect climate change to increase America’s propensity for warm moist air, which should mean more thunderstorms and tornadoes. As far as anyone knows, wind speeds should stay the same.

But tornado patterns are too small to explore deeply in the global computer models meant to simulate huge sections of the planet.

The Center for Climate and Energy Solutions also says whether a link exists between tornadoes and climate change is currently unclear.

Researchers are working to better understand how the building blocks for tornadoes — atmospheric instability and wind shear — will respond to global warming. It is likely that a warmer, moister world would allow for more frequent instability. However, it is also likely that a warmer world would lessen chances for wind shear. Climate change also could shift the timing of tornadoes or the regions that are most likely to be hit, with less of an impact on the total number of tornadoes.

A bigger problem is that, as more and more tornadoes develop and move southward and eastward, they hit areas that are more populated, causing more property damages and killing more people. “We get caught up on the climate aspect, but the real issue going forward with tornadoes — and hail storms and hurricanes and insert your favorite natural disaster — is the fact that we have more human exposure,” Victor Gensini, lead author of a study on tornado frequency that appeared in Nature, told Pacific Standard in March.

We all believe that we should listen to scientists when it comes to interpreting the climate crisis and resulting weather patterns. We know that there’s a 97 percent consensus of scientists that global warming is caused by human action. Even when scientists say it’s likely that the number of tornadoes is growing because of climate change, they know that more study needs to be done.

Unfortunately, more study is what the Trump administration doesn’t want. The administration and many in the GOP are taking the exact wrong track: Denying that climate change is man-made or that it exists at all. Rolling back environmental regulations and vehicle emission standards. Dropping out of the Paris Climate Agreement. Appointing a former coal lobbyist as head of the Environmental Protection Administration. Pushing fossil fuel energy and putting up roadblocks to renewable energy. Expanding drilling in federal lands and waters.

Now, the administration seeks to undermine the very science needed to develop policy on climate change. According to a story in The New York Times:

Parts of the federal government will no longer fulfill what scientists say is one of the most urgent jobs of climate science studies: reporting on the future effects of a rapidly warming planet and presenting a picture of what the earth could look like by the end of the century if the global economy continues to emit heat-trapping carbon dioxide pollution from burning fossil fuels.

The attack on science is underway throughout the government. In the most recent example, the White House-appointed director of the United States Geological Survey, James Reilly, a former astronaut and petroleum geologist, has ordered that scientific assessments produced by that office use only computer-generated climate models that project the impact of climate change through 2040, rather than through the end of the century, as had been done previously. …

The administration’s prime target has been the National Climate Assessment, produced by an interagency task force roughly every four years since 2000. Government scientists used computer-generated models in their most recent report to project that if fossil fuel emissions continue unchecked, the earth’s atmosphere could warm by as much as eight degrees Fahrenheit by the end of the century. That would lead to drastically higher sea levels, more devastating storms and droughts, crop failures, food losses and severe health consequences.

Work on the next report, which is expected to be released in 2021 or 2022, has already begun. But from now on, officials said, such worst-case scenario projections will not automatically be included in the National Climate Assessment or in some other scientific reports produced by the government.

A Democratic administration can change all that in January 2021.

Originally posted on Daily Kos on June 2, 2019.

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