On Friday evening, a tornado hit the Ottawa-Gatineau area with winds of up to 200 kilometres per hour damaging homes, changing lives, uprooting trees, and knocking out electricity for about 261,000 people in the area.
At a time like this, given we are already worried about changing weather patterns, one might ask, what is the relationship between tornadoes and climate change?
Climate change has been linked to heat waves, heavy rains and flooding, hurricanes, and wild fires, but there are questions with respect to tornadoes.
The Royal Society says, "Some conditions favourable for strong thunderstorms that spawn tornadoes are expected to increase with warming, but uncertainty exists in other factors that affect tornado formation, such as changes in the vertical and horizontal variations of winds."
National Geographic explains that energy (warm, moist, unstable air) and wind shear ("a measure of how much the wind changes speed and direction between the ground and higher levels of the atmosphere") are needed to make a tornado.
Some news reports note that while climate change is increasing the energy in the atmosphere, it may not necessarily affect wind shear.
Adding to this question, while the total number of individual tornadoes and outbreaks (storms with multiple tornadoes) do not appear to be increasing, a study has found that the number of tornadoes within outbreaks is increasing.
Columbia University professor Michael Tippett says, "The fact that we don’t see the presently understood meteorological signature of global warming in changing outbreak statistics 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."
A Columbia University blog adds, "Tippett noted that more studies are needed to attribute the observed changes to either global warming or another component of climate variability."
The Weather Network reports, "On average, Canada gets 62 verified tornadoes per year. Saskatchewan has the highest per province with about 18 tornadoes, followed by Alberta with an average of 15 tornadoes then Ontario with an average of 12-13 tornadoes each year."
Environment Canada says, "The majority of Canadian tornadoes have maximum wind speeds under 180 km/h, but a small percentage can be considerably stronger with devastating impacts."
The deadliest tornado in Canadian history happened in Regina in June 1912. That tornado -- with wind speeds over 300 kph -- claimed the lives of 28 people.
The U.S. National Weather Service says there have been more than 200 tornado-related deaths in that country over the last five years.
Tornado Alley is a term referring to where tornadoes are most common in the U.S., including Texas, Oklahoma, Kansas and Nebraska. LiveScience has reported that over the past decade this area has averaged 298 tornadoes in the month of May alone.
Dr. Joshua Wurman of the Center for Severe Weather Research says, "The area of tornado alley might move north into Canada, but we don’t know."
Overall, the Union of Concerned Scientists notes, "Scientists don’t have robust enough data to determine whether and how climate change may be affecting tornado frequency, intensity, or the geographic range where tornadoes are most likely to form."
Image: Wikimedia Commons
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