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Report: 'Killer' Heat Days In Florida, U.S. Could Increase Exponentially

Jul 16, 2019

A report released Tuesday says that the nation will face extremely hot days - along with deaths from killer heat waves - in the near future if carbon emissions aren't reduced. And perhaps not surprisingly, Florida may experience some of its hottest days on record.

The report is called Killer Heat in the United States - and its authors aren't kidding about the title. The Union of Concerned Scientists, a nonprofit science advocacy group, said we can expect an exponential number of heat-related deaths if we don't cut back on the amount of carbon that's released. Juan Declet-Baretto is one of the authors.

"That is one of the most compelling findings that we have found in our study," he said. "That if we do not take drastic action to reduce carbon emissions that are warming the planet, relative humidity conditions and temperature in Florida will expose millions of people to killer heat by the mid century and the late century."

And he said we can expect more extreme heat - days defined as those with a “feels-like” temperature of at least 105 degrees.

"Florida is facing 58 additional days per year over 105 ‘feels-like’ temperature. That is a profound change in a state that has experienced only four days," Declet-Baretto said. 

He says Tampa Bay area cities now average about four of these extreme heat days. If nothing is done to slow global warming, by the end of the century we could see 127 days of extreme heat over 105 degrees.

"One hundred and five is where everybody - not just people who work outside or people who are more vulnerable physiologically - like children, or the elderly, or people with pre-existing conditions - we're talking about everybody is at risk of severe illness or dealth due to extreme heat," he said.

And Declet-Baretto says this could disproportionally affect low-income and the elderly. He noted the 1995 heat wave that killed more than 700 people in Chicago affected mostly elderly, African-American women who lived on their own and didn't have air conditioning.

"We're talking about people living with low incomes, people without the ability to purchase or operate an air conditioning unit because of the costs, and we know cities have higher energy costs than other places," he said. "In addition, many low-income people don't have access to preventative health care, which may imply that certain pre-existing conditions they have could become aggravated under extreme heat episodes."

The heat won't just affect people. It could increase the number of fish kills, algae outbreaks and forest fires and even strain the nation's electrical grid as more people plug in their air conditioners.

Here's an excerpt from the report:

Florida

  • Historically, there have been 125 days per year on average with a heat index above 90 degrees Fahrenheit, the worker safety threshold. This would increase to 166 days per year on average by midcentury and 186 by the century’s end.
  • Historically, there have been 25 days per year on average with a heat index above 100 degrees Fahrenheit. This would increase to 105 days per year on average by midcentury and 141 by the century’s end. Of the cities with a population of 50,000 or more in the state, Bonita Springs, Cape Coral and North Port-Port Charlotte would experience the highest frequency of these days. Limiting warming to 2 degrees Celsius above pre-industrial levels would cap the frequency of such days at an average of 87 per year.
  • By the end of the century, an estimated 17.6 million people would be exposed to a heat index above 100 degrees Fahrenheit for the equivalent of two months or more per year. By limiting warming to 2 degrees Celsius, about 570,000 of those residents would avoid such days of extreme conditions. 
  • Historically, there has been an average of four days per year with a heat index above 105 degrees Fahrenheit. This would increase to 63 days per year on average by midcentury and 111 by the century’s end. Limiting warming to 2 degrees Celsius above pre-industrial levels would cap the frequency of such days at an average of 41 per year.
  • By the end of the century, an estimated 17.6 million people would be exposed to a heat index above 105 degrees Fahrenheit for the equivalent of a month or more per year. By limiting warming to 2 degrees Celsius, roughly 5.1 million of those residents would avoid such days of extreme conditions.
  • Historically, the state as a whole has experienced zero “off-the-charts” heat days in an average year. This would increase to two days per year on average by midcentury and 15 by the end of the century. Limiting warming to 2 degrees Celsius would cap the frequency of such days at an average of zero per year. 
  • By the end of the century, an estimated 13 million people would endure “off-the-charts” heat days for the equivalent of a week or more per year. Historically, fewer than 2,000 people nationwide have experienced such conditions in an average year. By limiting warming to 2 degrees Celsius, all residents would avoid such days of extreme conditions.

Temperatures around the world have been increasing for decades in response to rising heat-trapping emissions from human activities, primarily the burning of fossil fuels. These rising temperatures are causing more days of dangerous—even deadly—heat locally. This Union of Concerned Scientists (UCS) analysis shows that if we stay on our current global emissions path, extreme heat days are poised to rise steeply in frequency and severity in just the next few decades. This heat would cause large areas of the United States to become dangerously hot and would threaten the health, lives, and livelihoods of millions of people. Such heat could also make droughts and wildfires more severe, harm ecosystems, cause crops to fail, and reduce the reliability of the infrastructure we depend on.

Climate change and its consequences are already manifesting in the form of deadlier storms, rising sea levels, droughts, wildfires, and floods. Yet the heat extremes forecast in this analysis are so frequent and widespread that it is possible they will affect daily life for the average US resident more than any other facet of climate change. But this analysis also finds that the intensity of the coming heat depends heavily on our nearterm choices.

By cutting emissions quickly and deeply, we can slow global warming and limit the increase in the number of extremely hot days. Every 10th of a degree we avoid in increased temperatures will matter to our overheating world.

If we wish to spare people in the United States and around the world the mortal dangers of extreme and relentless heat, there is little time to do so and little room for half measures. We need to employ our most ambitious actions to prevent the rise of extreme heat—to save lives and safeguard the quality of life for today’s children, who will live out their days in the future we’re currently creating.

Credit Union of Concerned Scientists