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Terms describing severe weather patterns like “El Niño” and “polar vortex” get bandied about on the nightly news without much context or definition. Understanding climates and how extreme weather and climate variability manifest and affect life on Earth helps put rising temperatures and mild winters in perspective. 

“We are seeing fewer really extreme cold days,” says Scott Sheridan, PhD, professor and chair of the Department of Geography, who published a in the Journal of Geophysical Research in 2019. “Winter weather has gotten more irregular across the hemisphere but even in a warmed world, that doesn’t mean cold weather is going away.”  

Although the term polar vortex was popularized in recent years, the winter weather condition is nothing new. In stable polar vortex conditions, the cold air forms a dome that circulates in the Arctic. When changes in the jet stream disrupt the polar vortex, it forces unusually cold weather south from the pole. As the Arctic continues to warm, it leads to more chaos in the atmosphere and more wild weather. 

The extreme cold wave that swept through Texas in February 2021 brought record-low temperatures, overloading the power grid and bursting pipes. The temperatures were severe, but cold weather in winter is expected. What interests Sheridan are the weather events that are unusual relative to the season. 

“We’re going to have to prepare for challenges to the way we live if it’s weather dependent.”

Scott Sheridan, PhD, professor of geography

“In the spring of 2012, we had the warmest outbreak in the history of the Eastern United States for the month of March,” he says. “We think nothing of highs in the 80s in summer, but a week of highs in the 80s in March is unusual. This false spring caused trees to bloom early. When normal weather returned a few weeks later, the frost killed all the tree buds.” 

This kind of mismatch, where the weather pattern doesn’t align with the season, can lead to widespread losses, particularly for tree fruits. Less fruit to harvest results in higher prices at the grocery store. Unusual weather can also trigger birds and insects to migrate before food sources are sufficient in their destinations. 

“There are a lot of ways in which our lives can be impacted by weather,” Sheridan says. “You only need to look at places like California or the Southwest United States to see what happens to water resources when you have anomalous conditions year after year. There’s a potential for a lot of the systems that we’ve relied on for so long to suddenly not work the way that they had before. We’re going to have to prepare for challenges to the way we live if it’s weather dependent.”

A larger, global push to reduce greenhouse gas emissions is the most critical step necessary to slow the warming of the planet. But even if greenhouse gas emissions were reduced tomorrow, the climate system wouldn’t return to normal immediately. Regions that rely on precarious water sources will need to figure out how to adapt in the coming decades regardless. 

“The thing to focus on is what sort of society do we want to have?” Sheridan says. “Realizing that if the climate system is going to get more chaotic, there will be a lot of negative impacts. We still have a role to play in trying to minimize them and help make the environment and our natural systems more resilient as best we can.” 

Other climate-related work from ����ɫ��ҹ geographers includes:

Weather Whiplash: , assistant professor in the Department of Geography, received research funding from the National Oceanic and Atmospheric Administration Climate Program office to explore long-term changes in shorter-term climate variability. He in the International Journal of Climatology in 2021 examining trends in rapid temperature changes—sometimes within 24 hours—and how they relate to the warming climate. 

Ecosystem Disturbances: , also an assistant professor in the Department of Geography, studies the effects of disturbance (e.g., drought, fire and insects) on forest and shrubland ecosystems, typically by measuring the rate and pattern of environmental change. Of his most recent collaborative project, funded by the Northwest Climate Adaption Science Center, he says, “Our primary goal is to provide sound science to both resource managers and policy makers to help shape ecosystem management and conservation as we move into an uncertain future.” 

Learn more about the Department of Geography.

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