Miami Could Have 200 "Deadly Heat" Days Every Year by 2100

Miami Could Have 200 "Deadly Heat" Days Every Year by 2100
Photo by joiseyshowaa / Flickr
Photo by joiseyshowaa / Flickr
Some of Miami's business and political elite have argued that because it might be impossible to stop the effects of climate change, we should let the city flood, capitalize on it, and perhaps become a 21st-century Venice. The idea seems sort of quaint: Instead of attracting tourists to our beaches, people would visit to experience a modern Atlantis, a city of canals at the southern tip of America. Vanity Fair has reported that some Miami high-rises are now being built with "washout floors" designed to take consistent flooding.

What those projections miss, however, is the fact that the city will also get really, awfully, extremely hot by the end of this century. So hot, in fact, that a University of Hawaii study published this week in the peer-reviewed journal Nature Climate Change warns that the southern tip of Florida could face 100 to 200 "deadly heat" days per year by 2100. Miami is already an inhospitably hot and humid place May through August, and in less than 100 years, summers in the Magic City might begin to feel like the balmy, breezy surface of Venus.

"An increasing threat to human life from excess heat now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced," the study says.

The researchers confirmed a previous report published last year by the website Climate Central, which warned of virtually the same problem arising. That study noted Miami faces the highest increase in extrahot days when compared to any other city in the nation and ranked third-worst when it came to the highest expected increase in dangerous heat-index days, behind two other Florida cities. At the time, the Miami Herald noted that heat kills more people than any other weather event, including floods.

The study warns that days hotter than 37 degrees Celsius — 98.6 degrees Fahrenheit, the optimum human body temperature — can begin to cause a body to overheat. But there's a reason cities such as Miami will likely be worse off than desert communities like Phoenix: On high-humidity days, the study says, sweating becomes less effective and doesn't cool the body as fast because of the amount of water already in the air. As such, "deadly heat" conditions can arise even if the outside temperature is lower than 37 degrees Celsius.

"These properties help to explain why the boundary at which temperature becomes deadly decreases with increasing relative humidity  and why in our results some heat mortality events occurred at relatively low temperature," the study says.

The study then provides a breakdown of which areas will begin to get cooked by 2100. Miami fares the worst of any area in the nation. The charts compare the world's historical number of "deadly heat" days with a low, medium, and high estimate for the number of sweltering days by the 22nd Century. The worst-case scenario shows South Florida lit a burnt shade of orange, which means the area could face up to 200 deadly-heat days — almost two-thirds of the year.
Nature Climate Change
The study also suggests that some of the world's poorest countries are also about to get cooked: Some sections of Latin America, South America, Central Africa, and South Asia could exist under deadly-heat conditions year-round by the end of the century.

In April, a study also published in Nature warned that at least 2.5 million Miamians could become refugees, forced to move to other parts of the United States thanks solely to climate-change-related flooding. The new study shows again that the 2.5 million figure might be a conservative estimate when heat is factored in as well.

"Our study underscores the current and increasing threat to human life posed by climate conditions that exceed human thermoregulatory capacity," the researchers warn.
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Jerry Iannelli is a former staff writer for Miami New Times from 2015 to March 2020. He graduated with honors from Temple University. He then earned a master's degree in journalism from Columbia University.