While the states in the Midwest and Northeast of the USA struggled with heat waves throughout June, the US National Aeronautics and Space Administration (NASA) announced that the main reason for this situation was the weather phenomenon called “Heat Dome”.
This weather event, relatively less well known than a heat wave, occurs when a high pressure system traps heat over a specific area and can last for days or even weeks.
The formation of heat domes is generally caused by narrow-band strong winds called “jet winds” that blow in the subtropical regions of the Southern and Northern Hemispheres and in the high troposphere level of the mid-latitudes. As jet winds turn north, they move more slowly and collapse. This reduces the humidity in the region, but the resulting conditions allow the sun's rays to heat the ground more.
The impact of global warming on these winds is being studied by scientists.
US National Center for Atmospheric Research (NCAR) researcher Dr. Osamu Miyawaki found that with global warming, the polar regions are getting warmer and this is reducing the temperature difference between the polar regions and the mid-latitudes, which affects the nature of the jet winds.
Miyawaki said, “Increasing warming in the Arctic is predicted to reduce the speed of east-west winds in the Northern Hemisphere. On the other hand, the connection between the jet stream and extreme weather events such as heat domes is still a subject of research,” he said.
Impact on forest fires
According to the European Union's Copernicus Climate Change Service, heat domes also played a role in the extreme heat that hit Europe last year. Heat domes, which were effective in Greece, eastern Spain and southern Italy with temperatures reaching 45 degrees, caused heat waves to last longer in the region.
Last year, these countries experienced high temperatures, leading to forest fires that could not be controlled for days.
A paper published in April in the journal Nature showed that heat domes also have an impact on wildfires. The study, conducted in Canada, examined the wildfires that occurred in North America in 2021 and the heat dome in effect in the northwest Pacific this year.
The study found that extreme heat was in effect in the Canadian province of British Columbia and the US states of Washington and Oregon, with thermometers reaching 49.6 degrees Celsius in some regions and that the resulting heat dome was creating suitable conditions for forest fires due to higher temperatures and inadequate humidity.
As a result of their analysis of wildfire data and the periods during which the heat dome was in effect, the researchers found that 21 percent of the total area burned in North America in 2021 was observed during the heat dome and in regions where the heat dome was in effect.
The study that found that human-caused climate change could be behind heat domes found that the duration of wildfires was 59 percent longer and the area affected by fires was 34 percent larger during periods when this weather event was in effect.
“Avoiding human error has become more important”
Abatzoglou, one of the scientists involved in the study, said that heat domes are a type of “more permanent heat wave” because due to this weather phenomenon, temperatures reach extreme extremes during the summer months and this causes the air on Earth’s surfaces to dry quickly.
Abatzoglou explained that her study showed the link between heat domes and wildfires in effect in the United States and Canada: “In 2021, the heat wave played a facilitating role in the spread of wildfires between late June and early August.” This also occurred in July 2021: “It caused wildfires that destroyed the largest area in both countries in the last 20 years,” he said.
Abatzoglou said of the impacts of climate change on heat domes and wildfires:
“We expect that the heat dome has become much longer, larger and stronger due to climate change. In other words, climate change may play a role in the formation of such severe fires. Climate change increases the temperature, which increases the likelihood of more persistent heat events such as the heat dome. “We expect that as the planet warms, heat waves will increase. Wildfires will occur more easily.”
Abatzoglou stressed that it has become more important to prevent human errors that could lead to the outbreak of fires, as heat domes create the necessary conditions for fires, adding that appliances should not be operated near dry vegetation, cigarette butts should be properly disposed of and fires lit for recreational purposes should be avoided.
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