By: Youheng Zhong
Almost 60 million people are under extreme heat alerts in the US effective this Monday as the recent heat wave in the US continues. Except for about five million, all of those under the alert are in the southern central part of the US.
Last week the heat wave hit the US, especially taking a toll in the northeastern states. After a 7-day heatwave and several new all-time high recorded temperatures, the East Coast is finally getting a break from scorching temperatures. However, that doesn’t hold true for all of the US.
As the heat wave continues this week, it is shifting its attention to the Central and Southern Plains and the Deep South. Houston, Dallas, Little Rock, Oklahoma City, Kansas City, and Omaha all will have heat indexes— what it feels like outside— as high as 105. This heat will continue through the week.
While the South is suffering though, the Mid-Atlantic states will get a break from the heat, thanks to a cold front pushing off from the East Coast. However, this respite won’t last long, as on Wednesday, there might be widespread mid-90s to around 100 due to a resurge in temperature, which will mainly affect the Ohio Valley, Lower Lakes, and Mid-Atlantic regions.
These high temperatures mean new highest temperature records are being broken left and right in major US cities. According to the National Oceanic and Atmospheric Administration
(NOAA), over 297 US daily records were broken in the past seven days. In the same seven days, 19 all-time highest-recorded temperatures for specific months and one all-time high record were broken.
Another effect of this heat wave is a spike in heat-related illnesses, such as rising internal temperature, heat stroke and heat exhaustion. C.D.C. data shows that last week in parts of New England, the Midwest, the Mid-Atlantic States, and the Rockies there was “extremely high” rates of heat-related illness visits to the emergency room. For example, on a scale of per 100,000 visits to the ER, the number of visits related to heat-illnesses in the Mid-Atlantic climbed from 290 on Monday to 1150 on Saturday. That was the highest rate anywhere in the country all week. On top of that, several temperature records were broken in Baltimore, Philadelphia, and Washington on Saturday and Sunday.
Other than making you hot and tired, heat can also take a toll on organ health. When the air temperature is hotter than skin temperature, usually around 90 degrees, the body gains more heat than it can release. This isn’t really a problem in dry climates, as sweat evaporation can continue to cool the body at high temperatures. But in humid conditions, sweat doesn’t evaporate, it just drips off the skin without cooling it, leaving you feeling sticky and hot.
As the body works harder to stay cool, there is a need for increased circulation to your skin (so you can sweat) causing your heart rate to go up and your blood pressure to drop. And while sweating, the body becomes dehydrated and blood volume decreases – even lowering blood pressure. Low blood pressure can lead to fainting, but in extreme situations internal organs can be deprived of blood and oxygen. High temperature can also cause cell death, leading to organ failure.
So why are there so many heat related injuries and heat waves happening recently? Well, heat waves can sometimes be caused by heat domes. Heat domes are created when a high-pressure system forms in the upper atmosphere and causes the air below it to sink and compress, raising temperatures in the lower atmosphere. Then, because hot air expands, it creates a bulging dome, thus the name heat dome.
While heat domes may seem like a rare phenomenon, it has been happening more and more often. Heat domes are becoming longer, hotter and more frequent due to climate change. A 2021 study found that human-caused climate change intensified heat domes and are 34% larger and last 60 % longer than if global warming were absent. The 2021 heat dome was also associated with up to a third of the area burned in North America. The heat dome also caused heat waves, and several cities had new temperature records. Piyush Jain, a research scientist at Natural Resources Canada that was living in Edmonton at the time, said he was blown away. “I’d never experienced those temperatures anywhere I’d lived.” he said, regarding that day when the temperature topped 100 degrees.
Sources:
https://www.nytimes.com/live/2024/06/23/us/heat-wave-news#heat-wave
https://www.nytimes.com/interactive/2023/08/10/well/live/heat-body-dehydration-health.html?region=BELOW_MAIN_CONTENT&block=storyline_flex_guide_recirc&name=styln-extreme-heat&variant=show&pgtype=LegacyCollection
https://www.ncdc.noaa.gov/cdo-web/datatools/records
https://www.washingtonpost.com/weather/2024/06/24/heat-forecast-plains-south/
Heart problems and the heat: What to know and do – Harvard Health
Climate change supercharged a heat dome, intensifying 2021 fire season, study finds (phys.org)
What is a heat dome and are they getting worse with climate change? | New Scientist