Will global warming cause more tornadoes?
To read more from scientists on global warming, go to the Earth & Sky homepage.
Guest post by Roger Edwards, a meteorologist at the Storm Prediction Center of the National Weather Center in Norman, Oklahoma.
Will we have more, fewer or as many tornadoes 100 years from now? As an atmospheric scientist specializing in tornadoes, my short answer is: We simply don’t know.
As of this writing, no scientific studies solidly relate climatic global temperature trends to tornadoes. I don’t expect any such results in the near future either, because tornadoes are too small, short–lived, hard to measure and count, and too dependent on day to day, even minute to minute weather conditions.
Is it possible that any given shift in global temperature patterns may eventually change long–term tornado risk probability? Maybe, just maybe…if we make assumptions built on assumptions built on assumptions, about subtleties of regional warming (or cooling) by a few degrees, and how it might change the distribution of the four basic ingredients for tornado producing storms (below). Do we have anything that can stand up to scientific tests? Not even close, not yet. Here’s the trouble:
First, we still don’t understand exactly how and why tornadoes form, because it is so hard to understand what we can’t measure well. Tornadoes develop on such fast and small scales — both at the surface and up inside the storm where vehicles can’t drive — that even with probes and mobile radars, we have tremendous trouble sampling even a tiny fraction of all the tornadoes that do occur every year. We still don’t understand well enough why some thunderstorms produce tornadoes and others don’t, even on the same day and in the same region. We do know that the most deadly and damaging class of tornado producing thunderstorm — the supercell — needs four basic ingredients to develop and survive: moisture, instability, lift and vertical wind shear. Numerous scientific papers over the last 20–30 years show that these four ingredients can vary greatly from day to night, one day to the next, and even one minute to the next. Even with all four of these ingredients coming together in the local atmosphere, most supercells still don’t produce tornadoes. Even if we eventually can justify speculation on whether there will be more middle latitude storm systems or hurricanes (which sometimes produce supercells and tornadoes), having more of those storm systems still doesn’t necessarily mean having more tornadoes. Too many other little forces are at play…
Second, a gigantic problem relating global average temperature shifts and tornadoes is in the huge differences in size, time scale and physics between them. Even more so than with hurricanes, a very delicate balance of numerous dominoes must fall to get a supercell, even more still for a tornado, and these tiny little dominoes simply aren’t visible to global climate models. Local–scale tornado weather still depends on too many things to happen which are independent of small shifts in the climate. Global climate models, by contrast, focus on gradual shifts of some measurable part of long–term weather (average temperature, for example) covering broad swaths of the plant over periods of years, decades and more.
Third, tornado counts aren’t what they seem! It’s much easier to measure and compare rain, temperature or everyday wind than a tornado. We really don’t know how many tornadoes really have happened in the past, whether in the U.S. or around the world. The U.S. has the most detailed tornado reporting system in existence, and several recently published scientific studies have shown that even our roughly half–century of “good” tornado data still can be very deeply flawed. Tornado reports don’t mean actual tornadoes, and actual tornadoes go unreported an unknown amount of the time. Changes in storm spotting, media awareness and verifying warnings have combined to raise tornado reports hugely, but mainly on the weak end where it was harder to sample in decades past. Some heavy and complicated statistical hammering has to be done to U.S. tornado data to smooth out its many warts, and we don’t know how valid those hammered stats are over time periods longer than the shaky data we’ve got. Elsewhere in the world, tornado records are so spotty and inconsistent that they’re next to useless for this purpose. Most countries don’t even count their tornadoes in a way that will stand up to the test of science. Finally, especially on the weak and marginal ends, we severe weather meteorologists still don’t agree completely on what is a tornado, and why!
Our challenge, then, is made even harder: To predict future worldwide changes in something we haven’t sharply defined, can’t even count or measure very well, and that we often can’t predict an hour from now, all based on a model that doesn’t know it exists. That “something” is a most elusive, quick and stealthy quarry: the tornado. We might meet this challenge someday, but right now we’re a long, long way from that place in science.
Disclaimer: These are my opinions, and not necessarily those of my agency.
Roger Edwards
Meteorologist
Storm Prediction Center
National Weather Center
Norman, OK
i know that smoke and the ozonelayer is causing globalwarming
but what can people do to stop it i am so into this i mean i
want to learn more about it and i want to go on a trip to see it i really dont know why im so upssesed about it i ask every one
about it but they never know so i want to ask a person who do
knows thankyou.by the way im ten years old.
Hello Kayla,
Please don’t be upset about global warming. People have always faced challenges on Earth. That’s part of being alive on this planet! We just have to work together toward solutions.
I’m glad you are looking for information about global warming. That’s a good start. Here are some good websites for kids about global warming.
Global warming for kids study buddy
Time magazine’s global warming for kids
Global warming: kids page from the Pew Center for Climate Change
If you have questions, you can ask me here. I don’t know all the answers, but I’ll try to answer as best I can, or point you in the right direction.
All the best,
Deborah