Global warming = worse storms?
The frequency and severity of thunderstorms and tornadoes will both likely increase with changes in climate and warming temperatures, whether natural or man-made, a new study shows.
That opens the door to more potential weather damage, most notably in the eastern part of the U.S., as overall global temperatures rise as little as 2 degrees (something that's been uncertain in prior research on the topic). These findings are in an article by a Purdue University researcher and two climate scientists from Stanford University published recently in the Proceedings of the National Academy of Sciences (PNAS) of the United States of America.
"Severe thunderstorms are one of the primary causes of catastrophic loss in the U.S. However, the response of such storms to elevated greenhouse forcing has remained highly uncertain," according to the article compiled by Stanford environmental earth system science researchers Noah Diffenbaugh and Martin Scherer, and Purdue earth and atmospheric sciences researcher Robert Trapp. "We use an ensemble of global climate model experiments to probe the severe thunderstorm response. We find that this ensemble exhibits robust increases in the occurrence of severe thunderstorm environments over the eastern U.S."
It's been difficult in the past to forecast the most severe thunderstorms -- and tornadoes -- for numerous reasons, the researchers say. They're unpredictable and there's little long-term climate data showing correlations between severe storms and other weather trends. But, a new implicit approach to the research has combined data in a way that shows correlations between factors like wind shear and days when conditions are rife for severe weather. The end result is a trend that shows as temperatures rise, so too does wind shear, or abrupt and potentially damaging differences in wind speed and direction over short distances in the atmosphere, as well as the number of days when severe thunderstorms and tornadoes are more likely.
"The simulated changes in the atmospheric environment indicate an increase in the number of days supportive of the spectrum of convective hazards, with the suggestion of a possible increase in the number of days supportive of tornadic storms. Given current vulnerabilities, such increases imply increasing risk of thunderstorm-related damage if global warming continues," according to the PNAS article. "Our results indicate that continued global warming might cause substantial increases in the occurrence of the atmospheric environments associated with severe thunderstorms, because the implied reduction in vertical wind shear may not be as important as previously thought. These increases include regions where severe thunderstorms currently are most common, and regions where severe thunderstorms currently are less common but where substantial assets are exposed."
Research of this type, though based in sound science, still leaves a lot of questions unanswered, making its premises tough ones on which to base farm-level management decisions, says Kyle Tapley, senior ag meteorologist with MDA Weather Services. That's partly because of the variables in play and how difficult they can be to pinpoint with much accuracy in a more farm-specific framework. In other words, it's good research, and it points to long-term trends that could influence ag weather. But it falls short of something that should be weighed too seriously when making farm-level management decisions, Tapley says.
"There are just too many unknowns to draw any kind of grand conclusion," he says. "That's not to say that this research is wrong or faulty, I just wouldn't be making any long-term decisions on the potential that climate change could lead to more thunderstorms and tornadoes."