Texas is making national headlines for its climate-change-related extreme weather again — this time for a so-called heat dome that’s trapping warm temperatures over the area. More than a year after its infamous deep freeze triggered massive blackouts, the Lone Star State is sweltering through a severe summer heat wave.
On Sunday, over a dozen municipalities in Texas set record-high temperatures, with some reaching 113 degrees. The National Weather Service labeled the conditions “oppressive and dangerous” and experts warned of potential disruptions to electricity distribution. The extreme heat has lasted for several days, with San Antonio expecting to reach 104 degrees and Houston hitting a high of 98 degrees on Wednesday.
News accounts typically described the occurrence as a heat dome that settles over the state for days. The same term was used last June, in reference to the record-breaking weeklong heat wave that caused hundreds of deaths in the Pacific Northwest.
Unlike other extreme weather events such as hurricanes, heat domes are a phenomenon that most Americans have become aware of only recently. But because of climate change, they will likely be an increasingly common feature of weather reports.
While extreme heat waves have become more prevalent in recent years, a heat dome is a particular type of heat wave. The National Oceanic and Atmospheric Administration explains that a heat dome “happens when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets trapped under the high-pressure ‘dome.’”
A team of scientists funded by the NOAA Modeling, Analysis, Predictions and Projections program studied the cause of heat domes and found that the primary factor was “a strong change (or gradient) in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter.”
Basically, global warming is causing warm air to rise over the western Pacific. “As prevailing winds move the hot air east, the northern shifts of the jet stream trap the air and move it toward land, where it sinks, resulting in heat waves,” the NOAA study states.
Much like the severe winter weather that the South has also increasingly experienced lately, the heat dome is related to the jet stream, a band of air flowing in a westerly direction.
“When the jet stream swings far to the north, air piles up and sinks,” wrote William Gallus, a professor of atmospheric science at Iowa State University, in a recent column for the Conversation. “The air warms as it sinks, and the sinking air also keeps skies clear since it lowers humidity. That allows the sun to create hotter and hotter conditions near the ground.
“If the air near the ground passes over mountains and descends, it can warm even more. This downslope warming played a large role in the extremely hot temperatures in the Pacific Northwest during a heat dome event in 2021, when Washington set a state record with 120 degrees Fahrenheit.”
Because the poles are warming faster than the Equator, and the difference in temperature between those regions drives the jet stream, climate change has made the jet stream wavier and more likely to move towards the North Pole in the Northern Hemisphere. As a result, heat domes are going to be a more regular occurrence, especially if the greenhouse gas emissions causing climate change are not curbed.