(NewsNation) — Cardiovascular related deaths due to extreme heat are projected to increase between 2036-2065 in the United States, according to a new study.

The study, published in Circulation, says “non-Hispanic Black adults are projected to have a 4.6 times greater increase compared to non-Hispanic White adults” who will likely be disproportionately affected.

Currently, extreme heat accounts for less than 1% of cardiovascular-related deaths, according to the study.

Researchers predict this will change due to a projected rise in summer days that feel at least 90 degrees. Older adults and Black adults will be most vulnerable due to having underlying medical conditions or socioeconomic barriers that can influence their health, such as not having air conditioning or living in locations that can absorb and trap heat.

Researchers evaluated county-level data from the contiguous 48 states between May and September of 2008–2019. More than 12 million deaths related to cardiovascular disease occurred during that time. 

Using environmental modeling estimates, researchers also found the heat index rose to at least 90 degrees about 54 times each summer. They linked the extreme temperatures that occurred during each summer period to a national average of 1,651 cardiovascular deaths.

Areas in the South and Southwest were affected more than others, such as the Northwest and Northeast.

Using modeling analysts, researchers looked to 2036–2065 and estimated that each summer, about 71 to 80 days will feel 90 degrees or hotter. They predicted the number of annual heat-related cardiovascular deaths will increase 2.6 times for the general population — from 1,651 to 4,320.

The estimate is based on greenhouse gas emissions. The study found that if emissions rise, deaths could more than triple to 5,491.

Among adults ages 65 and older, deaths could increase from 1,340 to 3,842 if greenhouse gas emissions remain steady — or to 4,894 if they don’t. Among Black adults, deaths could increase from 325 to 1,512 or 2,063.