Is Climate Change Making Heat Domes More Likely?

A heat dome is building over the U.S. and Canada this week, bringing triple-digit temperatures to millions of people. The extreme heat comes as forecasts predict that most of the U.S. will face a hotter than average summer this year.  Extreme heat is only becoming more common. In the United States, heat waves now occur three times as often as they did in the 1960s, and one study, published in 2022 in the journal Copernicus, found that climate change is making heat domes 150 times more likely. Is climate change going to make heat domes worse? The answer, experts say, is a resounding yes.  “I think that’s one of the easier things to answer,” says Bill Gallus, professor of meteorology at Iowa State University. “There’s so many things that are complicated and we can’t say for sure what climate change is going to do, such as how many hurricanes or tornadoes we get, but, it is likely that we will have more heat domes, and probably hotter temperatures in the heat domes.”  What is a heat dome?  A heat dome occurs when a high pressure system stalls, trapping hot air in place.  Heat domes and heat waves occur simultaneously, however when a heat wave passes through, it tends to only last for a few days. A heat dome, in comparison, tends to stick around—anywhere from a few days to a few weeks. “[With heat waves] you can at least look forward to, within a pretty short period of time, the weather’s going to change. You get cooler,” says Gallus. “When you get a heat dome, it can stay put for a longer period of time.”  Read More: What to Know About Heat Domes—and How Long They Last How is climate changing impacting heat domes? As our climate warms, we are likely to experience heat domes more often. “Heat domes are a common weather phenomena that we’ve seen for a long time, but we are seeing now, with the warming of the climate, that the number of heat domes is probably slightly increasing, but [also] the intensity of them, the heat in itself within them, is increasing,” says Gordon McBean, professor emeritus at Western University.  There are two reasons for that. Greenhouse gases are warming the planet by trapping heat in the atmosphere—which contributes to the areas of high pressure that make up heat domes. Secondly, Arctic regions are warming faster than the areas closer to the equator. This difference is weakening the jet stream that helps influence temperatures we feel on the ground—slowing it down and leading to more lingering, high pressure systems, and high temperatures. “We believe that when the jet stream is weaker, it’s more likely to take this roller coaster-like pattern across the planet,” says Gallus. (The changing jet stream is also impacting our winters, setting the stage for severe weather storms and polar vortexes.) Can anything be done to prevent worsening heat domes?  Many regions around the world have begun to adopt heat-mitigating strategies to adapt to high temperatures—whether it be planting trees for shade or painting homes with heat-reflective paint. But to really address the cause of heat domes and ever-rising temperatures, experts emphasize that countries need to be lowering emissions around the world.  “The atmosphere is going to be warming, and we have to start reducing our greenhouse gas emissions,” says McBean.  Still, if we flipped a switch tomorrow and stopped all emissions, the atmosphere would still take decades to recover, says Gallus. “Even if we suddenly stopped burning fossil fuels and we weren’t adding any more greenhouse gasses, we’ve really warmed the atmosphere, so we’re going to have to pay the consequences.”