Extreme weather

Summer 2023 was the hottest on record by a huge margin. Hundreds of millions of people suffered as heat waves cooked Europe, Japan, Texas and the Southwestern U.S. Phoenix hit 110 degrees Fahrenheit (43 degrees Celsius) for a record 54 days, including a 31-day streak in July. Large parts of Canada were on fire. Lahaina, Hawaii, burned to the ground. As an atmospheric scientist, I get asked at least once a week if the wild weather we’ve been having is “caused” by climate change. This question reflects a misunderstanding of the difference between weather and climate. Consider this analogy from the world of sports: Suppose a baseball player is having a great season, and his batting average is twice what it was last year. If he hits a ball out of the park on Tuesday, we don’t ask whether he got that hit because his batting average has risen. His average has gone up because of the hits, not the other way around. Perhaps the Tuesday homer resulted from a fat...

Tropical Storm Hilary made landfall on Mexico’s Baja peninsula, and its damaging wind and heavy rainfall moved into Southern California on Aug. 20, 2023. For the first time ever, the National Hurricane Center had issued a tropical storm watch for large parts of Southern California. Forecasters warned of a “potentially historic amount of rainfall,” and the governors of California and Nevada declared states of emergency. Hurricane scientist Nick Grondin explained ahead of landfall why the storm, with help from El Niño and a heat dome over much of the country, could bring flash flooding, wind damage and mudslides to the region. How rare are tropical storms in the Southwest? California had only one confirmed tropical storm landfall in the past. It was in September 1939 and called the Long Beach Tropical Storm. It caused about US$2 million dollars in damage in the Los Angeles area – that would be about $44 million today. A hurricane in 1858 came close bu...

Scorching temperatures have put millions of Americans in danger during recent heat waves, with heat extremes hitting states from coast to coast. Phoenix hit 110 degrees Fahrenheit (43.3 Celsius) or higher every day for over three weeks in July 2023. Other major cities, from Las Vegas to Miami, experienced relentless high temperatures, which residents described as “hell on earth.” While the evening news runs footage of miserable sunbathers and joggers dousing themselves with water, these images conceal a growing hidden crisis: the millions of older adults who are suffering behind closed doors. As researchers who study older adults’ health and climate change, we have found that two societal trends point to a potentially dire future: The population is getting older, and temperatures are rising. During the July 2023 heat wave, people gathered at the Justa Center, a day cooling center in downtown Phoenix for people age 55...

Heavy rainfall generated widespread flooding. in the Upper Midwest in late June 2024, putting at least one aging dam at risk. In southern Minnesota, the Blue Earth River cut a path around the Rapidan Dam in Rapidan Township, about 15 miles south of Mankato, on June 24, putting the structure at imminent risk of failing. Officials warned local residents that if the dam burst, the river could rise by 2 feet, but said that evacuations were not needed. This event comes a year after flooding in Vermont collapsed at least one dam and threatened others. Hiba Baroud, associate professor and associate chair in the department of civil and environmental engineering at Vanderbilt University, explains how flooding stresses dams in a changing climate. How serious is the risk when water flows over or around a dam? These conditions can result in erosion, which subsequently could lead to a dam breach or failure and a sudden, uncontrolled release of impounded water. The risk reflects the combin...

As rising global temperatures make extreme storms more common, the nation’s dams and reservoirs – crucial to keeping communities dry – are being tested. Storms in the U.S. Northeast stretched the region’s flood control systems nearly to the breaking point in July 2023. California and states along the Mississippi River faced similar flood control challenges in 2023. Managing these flood control systems is a careful balancing act. Do managers release water to make room for the storm’s runoff, increasing the risk of flooding downstream, or hold as much as possible to protect downstream farms and communities, which could increase the chance of larger floods if another storm comes through? The earlier decisions can be made, the better the chance of avoiding downstream damage. But forecasts aren’t always reliable, and waiting for the rain to fall may mean acting too late. Satellite water vapor imagery from July 9-11, 20...