It was just his second day on the job at the Modesto Junk Company in California’s Central Valley — but it was the region’s 34th consecutive day of 90-plus-degree weather.

Feeling dizzy, he asked for a break around 2 p.m. The 40-year-old never received one. Later, a co-worker found him unconscious and sprawled across the concrete.

The nameless man in the U.S. Department of Labor’s July 2021 accident report database is one of more than 275 linked to heat-related cardiovascular deaths, like heart attacks and strokes, between May 2018 and December 2022. A 2014 report found that nearly half of these deaths happen on a worker’s first day on the job.

Extreme heat takes a heavy toll on the heart, and Black people are particularly vulnerable.

A new report released this week reveals how much more deadly the effects of climate change may become in the United States. By 2053, 13 times as many Americans will be regularly exposed to extreme heat compared to 2022 rates. So the prevalence of these deadly events is only going to get worse, according to the new study.

Published in the American Heart Association’s scientific journal, the study found that even if the U.S. successfully implements all of its plans to curb climate change and rising temperatures, annual heat-related cardiovascular deaths in the U.S. will more than double between 2036 and 2065 compared to the last decade.

If we fail to implement all of our plans to lower greenhouse gasses, which are attributed to rising global temperatures, these deaths will triple.

In either scenario, the increase will be most acute among Black adults over 20 and for all adults over 65.

Is the government doing enough to protect us?

Black Americans have higher rates of negative underlying health factors and are more likely to live in underinvested neighborhoods that “have less access to air conditioning; less tree cover; and a higher degree of the ‘urban heat island effect,’” lead study author Sameed Khatana, assistant professor of medicine at the University of Pennsylvania, said in the report.

The projections raise the question of whether the U.S. government is doing enough to protect people from extreme heat through labor protections or infrastructure interventions, such as public cooling centers, increased shade cover in neighborhoods, and access to health care.

A report earlier this year found that federal heat protections for workers would prevent 50,000 injuries per year. In 2021, the Biden administration vowed to create federal protections, but the process has stalled. In the meantime, only seven states have some type of protection.

And although hundreds of U.S. cities have increased access to cooling centers, most sit empty because of communication gaps and how difficult it is for vulnerable people to find transportation to the centers.

Limiting air pollution can be seen as a positive medical intervention, said Robert Brook, a professor of Internal Medicine at Wayne State University in Detroit.

Lowering the time Black folks spend on highways is a perfect example of addressing both issues. It limits the country’s largest source of pollution — vehicles — and the documented stress effects that driving has on the body and mind.

Research dating back decades shows the connections between extreme heat and cardiovascular illness. To stop ourselves from baking in the sun, our hearts carry bigger burdens than usual. Not only is blood being pumped faster, straining our hearts, we produce more sweat. It makes it harder for us to regulate our body’s temperature until, in the worst cases, our hearts stop altogether.

The new analysis looked at all reported cardiovascular deaths in the U.S. between 2008 and 2019 and compared how deaths rose or declined on days of extreme heat. On average, extreme heat was associated with 1,651 excess cardiovascular deaths yearly.

Then, researchers used future socioeconomic and racial demographic estimates of the U.S. population and climate models, which estimate the country’s average temperature changes based on the trajectory of greenhouse gas pollution, and compared those models to the baseline temperatures between 2008 and 2019.

Ultimately, they predicted the number of deaths for each U.S. county if no extreme heat occurred versus if the projected number of heat days occurred.

Researchers estimate a 162% increase in heat-related cardiovascular deaths if the country can significantly lower greenhouse gas emissions. If the U.S. government falters on its goals, they predict a 233% increase. The steady increase, even in the best-case scenario, results from the already rooted increase in extreme heat and general negative trends in health amongst adults.

Black adults are expected to have as high as 4.6 times greater increase in cardiovascular death due to extreme heat compared with white adults, the study found. There were no statistically significant increases above the average for any other racial group.

Brook said while the study’s results are grave, they’re also an understatement because it only tracks deaths, not nonfatal heart attacks, strokes, and heart failure hospitalizations, which outnumber fatal events.

Adam Mahoney is the climate and environment reporter at Worldacad. Twitter @AdamLMahoney