We know that every year Florida grows hotter.
The National Oceanic and Atmospheric Administration reported that this May was the hottest May in Florida in more than a century.
While climatologists attributed the hotter conditions to a deep-layer, high-pressure system that sat over the state for more than two weeks, a detailed study of rising temperatures in the U.S. released today says that climate change will make the entire country much hotter in the decades to come.
The report from the Union of Concerned Scientists, Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days, says that in Florida specifically, there will be a dramatic increase in the days of the year averaging over 100 degrees Fahrenheit.
Historically there have been 25 days per year on average in Florida with a heat index above 100 degrees Fahrenheit. That would increase to 105 days per year on average by midcentury and 141 days by the end of the 21st century, the report says.
Of the cities with a population of 50,000 or more in the state, Bonita Springs, Cape Coral and North Port-Port Charlotte region would experience the highest frequency of these days. If governments worked to limit warming to 3.6 degrees pre-industrial levels, it could cut the number of 100-degree days to 87 a year, the report says.
And the scientists looked at even hotter days – the report says historically Florida has an average of four days a year with a heat index above 105 degrees. That would increase to 63 days per year on average by midcentury and 11 by the century’s end.
The authors of the study say the only way to stop this extreme heat from taking over the U.S. is “to take bold action now to dramatically reduce emissions and prevent the worst from becoming reality.”
“This includes transitioning our energy system to low-carbon energy sources; ramping up energy efficiency; electrifying as many energy systems as possible across the transportation, buildings, and industrial sectors; and investing in land use and forest management practices that help store carbon in soils, trees, and vegetation,” the report says.
The National Weather Service, which uses the heat index to warn the public about hot weather, generally issues a heat advisory when the index is expected to reach or exceed 100 degrees within the next 12 to 24 hours. A heat warning is issued when the metric is likely to be 105 degrees for more than 48 hours.
The report looked at three possible scenarios for the future – and all of them include the state getting hotter.
The “no action scenario” assumes carbon emissions continue to rise and the global average temperature increases about 8 degrees above pre-industrial levels by century’s end.
The “slow action scenario” assumes carbon emissions start declining at midcentury and the global average temperature rises 4.3 degrees by century’s end.
In the “rapid action scenario,” global average warming is limited to 3.6 degrees – in line with the Paris Agreement, a world-wide pact designed to reduce carbon emissions. The Trump administration has announced the U.S. will no longer abide by the Paris agreement.