Heat-related deaths surge by 117% since 1999, exceeding 20,000 fatalities

A new report reveals that extreme heat claimed 2,325 lives in the U.S. last year, the highest on record, marking a 117 percent increase since 1999.

In an alarming testament to the escalating climate crisis, a staggering 2,325 Americans succumbed to extreme heat last year, marking the highest annual toll on record, according to the American Medical Association journal JAMA.

This sobering statistic underscores a 117 percent surge in heat-related deaths since 1999, with over 20,000 lives claimed by blistering temperatures over the past two decades.

As climate change relentlessly drives up global temperatures, experts warn that the true extent of these fatalities may be severely underestimated, casting a grim shadow over the future.

"Heat sometimes doesn't get the attention that other types of severe weather do because you don't have the compelling video of homes or businesses being destroyed by a hurricane or a tornado or by a blizzard, but it's even more dangerous because people can be caught off guard," Chief AccuWeather Meteorologist Jon Porter said, adding that the number of deaths being reported is likely underestimating the actual impact because heat-related illness and deaths are categorized as another medical issue.

"So many times, we've seen heat-related illnesses and deaths categorized as another medical issue because the heat can aggravate underlying medical conditions such as heart diseases, COPD (Chronic obstructive pulmonary disease) and asthma, just to name a few. So, many times, the toll of extreme heat is not captured."

The amount of land area in the United States impacted by extremely hot days and very warm nights has significantly increased over the past 30 years, according to the Environmental Protection Agency (EPA). As a result, many more people are now being exposed to potentially dangerously hot weather during the summer and even portions of the spring and fall.

Last year was the warmest year on record globally, according to NOAA, and the fifth warmest on record for the contiguous U.S. Based on observed surface temperature data so far this year, it is highly likely that 2024 will end up even warmer than 2023 in terms of global surface temperature, as climate change continues to be the primary driver of all this record heat.

And it's not just the overall temperature that is rising; the types of temperature records being set are also changing. During the 1960s and 1970s, the number of new record-low temperatures outweighed the number of record-high temperatures by almost a 2 to 1 margin. Since 2000, there has been a major reversal within this category, with the number of new daily record high temperatures outweighing record low temperatures by an average ratio of about 3 to 1, with some years reaching above 5 to 1. This means for every record low set, there are up to five new record highs.

Certain characteristics of heat waves have also been changing for the worse in recent decades. The frequency and duration of heat waves in the U.S. have been trending upward since the 1960s, with the most notable uptick during the two most recent decades.

Climate change has also significantly lengthened the heat wave season. In the 1960s, the average heat wave season in this country lasted about 24 days. So far this decade, it has increased to 72 days.

Heat waves and human health

Being exposed to extended periods of extreme heat takes a toll on the body and can be especially dangerous for those in poor health, older adults and young children.

"Extreme heat is the silent killer and can catch people off guard, unlike large storms and other severe weather, which typically get most of the headlines and video coverage", said Porter.

In parts of the world, such as the Middle East and India, there are normally several days during the year when the heat is so intense (in excess of 120 degrees) that it reaches the threshold of human survivability. Most people in these regions have learned to adapt and survive when there is extreme heat for days or a week or two, but when these periods of dangerous heat extend to multiple weeks to over a month, there will likely be many people who may not be able to survive, according to Dr. Joel N. Myers, AccuWeather's Founder and Executive Chairman.

"The temperature and other indices do not tell the whole story of how weather conditions make us feel. Other weather variables in addition to temperature such as sunlight, humidity, wind, precipitation and a multitude of other factors can impact our comfort or discomfort outside and may even cause harm or illness," Myers said.

The way a temperature actually feels to a person can be more important than a specific temperature number because the experience of extreme heat over number values can be life-threatening in a matter of minutes. This is why AccuWeather created The AccuWeather RealFeel® Temperature. "It's an exclusive tool that helps you optimize health, safety and comfort," said Porter. It is a great way to help the user understand the impact of a particular temperature and how best to prepare for that, especially during periods of extreme heat or cold.