It’s Not Yet Clear Why Extreme Tornado Outbreaks Are On The Rise

tornadoPhoto Credits: Timmy27. Downtown Miami. (CC 3.0)

The increase in large-scale tornado outbreaks in the US doesn’t appear to be clearly linked to climate change, a new study suggests.

The new findings tie the growth in frequency to trends in the vertical wind shear found in certain supercells—a change not so far associated with a warmer climate.

“What’s pushing this rise in extreme outbreaks, during which the vast majority of tornado-related fatalities occur, is far from obvious in the present state of climate science,” says Joel E. Cohen, a professor at Rockefeller University and Columbia University, who conducted the research as a visiting scholar at the University of Chicago.

Tornado outbreaks are large-scale weather events that last one to three days, featuring several thunderstorms and six or more tornadoes in close succession. In the study, published in Science, Cohen and colleagues used new statistical tools, including extreme value analysis—a branch of statistics dealing with deviations—to analyze observation-based meteorological estimates associated with tornado outbreaks together with National Oceanic and Atmospheric Administration datasets.

Data on thousands of tornadoes

They estimated that the number of tornadoes in the most extreme outbreak in a five-year interval doubled over the last half-century. This means that in 1965 the worst outbreak expected over five years would have had about 40 tornadoes, while in 2015 the worst outbreak expected over five years would have had about 80 tornadoes.

“Viewing the data on thousands of tornadoes that have been reliably recorded in the United States over the past half-century as a population has permitted us to ask new questions and discover new, important changes in outbreaks of these tornadoes,” Cohen says.

To understand the increased frequency in tornado outbreaks, the researchers looked at two factors: convective available potential energy, or CAPE, and storm relative helicity, which is a measure of vertical wind shear.

Earlier studies had projected a warming climate would increase CAPE, creating conditions favorable to a rise in severe thunderstorms—and potentially tornado outbreaks. But Cohen and his colleagues found the increases in outbreaks were driven instead by storm relative helicity, which has not been projected to increase under a warming climate.

“Our study raises new questions about what climate change will do to severe thunderstorms and what is responsible for recent trends,” says coauthor Michael K. Tippett, an associate professor at Columbia University’s Fu Foundation School of Engineering and Applied Science.

“The fact that we didn’t see the presently understood meteorological signature of global warming in changing outbreak statistics for tornadoes leaves two possibilities: Either the recent increases are not due to a warming climate, or a warming climate has implications for tornado activity that we don’t understand,” says Tippett.

Columbia University Research Initiatives for Science and Engineering; Office of Naval Research; NOAA’s Climate Program Office’s Modeling, Analysis, Predictions and Projections; Willis Research Network; and the National Science Foundation funded the work.

Source: University of Chicago

Related Books:

enafarzh-CNzh-TWnltlfrdehiiditjakomsfaptruesswsvthtrurvi

LATEST VIDEOS

Blue Ocean Event : Game Over?
by Just Have a Think
A Blue Ocean Event, or Ice-Free Arctic, is the source of almost fever pitch speculation in the climate science world.…
Climate Change - The Facts by Sir David Attenborough
by David Attenborough, BBC
After one of the hottest years on record, Sir David Attenborough looks at the science of climate change and potential…
Why it’s time to think about human extinction
by Kerwin Rae
After listening to this ep with Dr David Suzuki, you’ll never be the same again. The environmentalist, activist,…
Record Temperatures 20-25C Above Norm in far North
by Paul Beckwith
The Northwest Territories of Canada had March temperatures above 20C for the first time (hit 21.6C or 71F); breaking…
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
by Chris Hawes
According to a recent major UN report, if we are to limit temperature rise to 1.5 °C and prevent the most catastrophic…
Why Climate Change Will Dull Autumn Leaf Displays
Why Climate Change Will Dull Autumn Leaf Displays
by Matthew Brookhouse
Every autumn we are treated to one of nature’s finest seasonal annual transitions: leaf colour change and fall.
Climate denial isn’t stopping climate action.
by David Wallace-Wells
Climate change denial draws headlines. But is it actually an obstacle to climate action? A great majority of Americans…
Energy Storage: How to store renewable energy?
by Total
Under your bed, in the attic even on your mobile phone, it seems there's never enough storage. It turns out it's also…

LATEST ARTICLES

Misreading The Story Of Climate Change And The Maya
Misreading The Story Of Climate Change And The Maya
by Kenneth Seligson
Carbon dioxide concentrations in Earth’s atmosphere have reached 415 parts per million – a level that last occurred…
File 20180122 182968 19hqzwv.jpg?ixlib=rb 1.1
Why Climate Change Is Worsening Public Health Problems
by Espinosa Chelsey Kivland and Anne Sosin, Dartmouth College
Around the world, the health care debate often revolves around access. Dr. Tedros Adhanom Ghebreyesus, head of the…
Crops at risk from changing climate
Crops at risk from changing climate
by Tim Radford
Global warming could bring yet more challenges to a hungry world. New studies have identified precise ways in which a…
Seeing The Planet Break Down In Climate Crisis Is Depressing – How To Turn Your Pain Into Action
Seeing The Planet In Climate Crisis Is Depressing – Turn Your Pain Into Action
by Cameron Brick
Environmentalism can feel like a drag. People trying to reduce their environmental impact often feel stressed and…
Global Inequality Is 25% Higher Than It Would Have Been In A Climate-stable World
by Nicholas Beuret
Those least responsible for global warming will suffer the most. Poorer countries – those that have contributed far…
Jason Kenney's Victory Means We'll All Pay The Price For Fossil Fuel Emissions
Jason Kenney's Victory In Alberta Means We'll All Pay The Price For Fossil Fuel Emissions
by D.T. Cochrane
Jason Kenney has led the United Conservative Party to victory in Alberta. There were manyobjectionablecomponents to the…
How Can Trees Really Cool Our Cities Down?
How Can Trees Really Cool Our Cities Down?
by Roland Ennos, University of Hull
In cities around the world, trees are often planted to help control temperatures and mitigate the effects of the “urban…
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
by Global Warming & Climate Change
But Varshini Prakash, executive director of the Sunrise Movement, a youth-led activist group that has advocated for the…