May 24th, 2011 by Zachary Shahan
This is a question that has definitely popped into my mind. And, if you are at all familiar with the fact that climate change is not just about sea levels or heat but is also causing (and going to cause more) much more extreme weather or “global weirding” as some put it, you are probably curious as well.
Well, it is clear that the number of recorded tornadoes have increased significantly in recent years, but it is still hard to determine if that is linked to global climate change or simply due to better weather-tracking technology.
As Alok Jha of the Guardian puts it: “As the city of Joplin deals with the devastation from Sunday’s tornado, some people might wonder whether these extreme weather events are getting more common because of climate change. The answer is that no one really knows.”
Of course, it is difficult (or impossible) to scientifically link any single extreme weather event to global warming. However, linking increases in weather events (like hurricanes) can be done. Unlike hurricanes, though, there isn’t the depth of scientific research on tornadoes needed to evaluate a potential link.
Recorded Tornadoes Increasing, but Is that Linked to Global Warming?
“If you look at the past 60 years of data, the number of tornadoes is increasing significantly, but it’s agreed upon by the tornado community that it’s not a real increase,” Grady Dixon, assistant professor of meteorology and climatology at Mississippi State University, told AFP. “It’s having to do with better (weather tracking) technology, more population, the fact that the population is better educated and more aware. So we’re seeing them more often.”
Now, I won’t doubt that this is all part of the issue. But whether or not it is the whole issue seems up for debate (or, rather, unknown).
Global Warming Factors that May Cause More Tornadoes
“Another broader factor that may be aiding and abetting the destructive weather is a very warm Gulf of Mexico, where sea surface temperatures have been between 1 and 2.5°C above average for this time of year,” Andrew Freedman of Climate Central wrote at the end of April. “This is important because it means there is more moisture flowing northward off the Gulf, and a humid environment is necessary for severe thunderstorms to form.”
Furthermore, global warming results in more storms, and especially stronger storms. We know that. With more and stronger storms come more tornadoes. Simple.
Nonetheless, there is still scientific uncertainty about the link between tornadoes and global warming. So, hold off on any claims that the tornadoes are related to global warming until the science confirms it….
Here’s more from Freedman to wrap-up/summarize (emphasis mine):
As for global warming, this is an active area of scientific research, with some conflicting projections so far about whether a warming atmosphere will make it more or less likely that tornadoes will form. Since more moisture gets added to the atmosphere as the climate warms, additional water vapor may help severe thunderstorms and tornadoes to form. On the other hand, wind shear is expected to decline due to climate change, which would argue against an increase in tornado numbers.
According to some studies, though, by the end of the present century, the added water vapor will be enough to overcome the lower wind shear, and create more opportunities for severe thunderstorms to form.
Tornadoes are a bigger wild card for climate scientists than other types of extreme weather and climate events, such as heat waves and flooding. (Studies have consistently found that both of these hazards will occur more frequently and severely as the world warms.)
Photo via el clinto
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