By the end of the century parts of the Persian Gulf will sometimes be just too hot for the human body to tolerate, a new study says.

WASHINGTON (AP) — If carbon dioxide emissions continue at their current pace, by the end of century parts of the Persian Gulf will sometimes be just too hot for the human body to tolerate, a new study says.

How hot? The heat index — which combines heat and humidity — may hit 165 to 170 degrees (74 to 77 Celsius) for at least six hours, according to numerous computer simulations in the new study. That’s so hot that the human body can’t get rid of heat. The elderly and ill are hurt most by current heat waves, but the future is expected to be so hot that healthy, fit people would be endangered, health experts say.

“You can go to a wet sauna and put the temperature up to 35 (Celsius or 95 degrees Fahrenheit) or so. You can bear it for a while, now think of that at an extended exposure” of six or more hours, said study co-author Elfatih Eltahir, an MIT environmental engineering professor.

While humans have been around, Earth has not seen that type of prolonged, oppressive combination of heat and humidity, Eltahir said. But with the unique geography and climate of the Persian Gulf and increased warming projected if heat-trapping gas emissions continue to rise at current rates, it will happen every decade or so by the end of the century, according to the study published Monday in the journal Nature Climate Change.