Think it’s hot now? Michigan’s 90° days could quadruple in 20 years

All 83 counties in Michigan are getting hotter, and a report released Tuesday predicts it will only get worse, as the number of days with heat indexes over 90 degrees will quadruple in the next 20 years.

The report from the Union of Concerned Scientists, a Massachusetts-based nonprofit science advocacy group, predicts extreme temperatures will soar nationwide if nothing is done to curb climate change.

The impact could be devastating for Michigan: destroyed crops, an increase in disease-bearing insects, dangerous conditions for outdoor workers, and rising death rates, according to the report.

Related: Climate change could bring woe to Michigan’s lakes, farms, forests
Opinion: Climate change drives shifts between high, low Great Lakes water levels

Between 1971 and 2000, Michigan averaged eight days a year with heat indexes above 90 degrees Fahrenheit. By midcentury, that will rise to 34 days per year if no action is taken to stem greenhouse gases linked to climate change, the report claims.

Cities in southern Michigan –  Benton Harbor, Kalamazoo and Monroe –  would have the most days with 100 degree-plus heat indexes, a measure that factors humidity into temperature to gauge how weather feels. 

But even Mackinac County, in the eastern Upper Peninsula, would feel the heat, as the average number of days with heat indexes over 90 increases to 12 per year from none, while they jump to 27 from four in Roscommon County in northern Michigan.

“If it does get that warm, it is going to have an impact on health, and you might have to start working at different times of the day,” said Tom Miedema, president of a turf farming company in Ottawa County.

“You’re going to have to adjust for some of those things.”

The report joins a growing number of studies that predicts a host of problems, from infrastructure deterioration to lake algae blooms, in Michigan if temperatures increase an average 2 degrees over the next 40 years.

Jennifer Morse, the medical director for the Central Michigan District Health Department, oversees 12 counties including Roscommon. She worries that rising heat would hurt a variety of demographics.

Related: Surging Great Lakes water levels shrink beaches, flood docks in Michigan
Related: Michigan shrinks credits for rooftop solar, clouding industry’s future

“When we have high heat index days, a big population that really suffers is our elderly population,” said Morse. “They are just very susceptible to heat changes.”

The report warns that communities of color, such as Benton Harbor, are particularly vulnerable to extreme heat because of limited access to cooling or healthcare centers. 

The report parallels the Paris Agreement, a United Nations goal to limit the global temperature increase this century to well below 3.6 degrees Fahrenheit, and predicts scenarios if there is “slow” or “rapid” actions to limit emissions.

Without any effort to reduce global warming, the Union of Concerned Scientists predicts that 8.7 million people – nearly 90 percent of Michigan’s population – would experience a heat index of 100 degrees for a month or more per year by the end of the century.

The extreme heat would be avoided with rapid action, and limited with slow action: an average of six days a year in Michigan with an average heat index above 100 degrees and 26 days above 90 degrees by midcentury. 

Nationwide, one-third of the United States would experience “off-the-charts” heat by the late century if nothing is done. “Off-the-charts” conditions refer to when the temperature is so high that it exceeds the National Weather Service’s heat index calculations.

“For the nation, extreme heat is projected to increasingly put people at risk – that is going to be the case across the country,” said Rachel Licker, a senior climate scientist at the Union of Concerned Scientists and a co-author on the report. 

“This is something that is really going to change the daily life for many residents in the United States.”

Urban areas have a “unique vulnerability,” due to a phenomenon known as the heat island effect, said Licker. And in Michigan, a state with over 51,000 farms, agricultural workers are especially at risk.

“What we found was that the conditions that we could be seeing in the future are conditions that could be dangerous to outdoor workers,” said Licker. “Those people are uniquely vulnerable to extreme heat.”

A similar report by the Michigan Department of Health and Human Services and the University of Michigan predicts that extreme heat mortality in Michigan will increase from 33 to 240 deaths annually by midcentury, if nothing is done to combat climate change. The report includes any death prompted by extreme heat in the mortality rate, not just those from heatstroke.

“We were considering all natural cause mortalities, not just heat stroke in that estimate,” said Carina Gronlund, an environmental epidemiologist and author on the University of Michigan report. “It’s not necessarily emergency room visits with heat exhaustion or heatstroke on the [patient] record.”

Along with outdoor workers, children, the elderly, low-income communities and those with pre-existing health conditions, such as respiratory or cardiovascular illness, are at a greater risk for heat-related death.

This report also suggests that without climate change action, the number of emergency room visits related to heat health issues will increase from 1,200 to 7,800.

The projected cost as a result of rising mortality and ER visits is more than $290 million.

To curb the effects of the climbing heat rates, the global warming average would need to be limited to 3.6 degrees Fahrenheit, per the “rapid” action plan. If done so successfully, by late century about 115 million less people would experience over a week of “off-the-charts” heat.

“If we don’t take action to reduce global warming emissions now, we’re really setting ourselves up for a dramatically different future,” Licker said. “And it’s one that would have implications for health, for many economic sectors, and our day-to-day activities.”