ISLAMABAD-Rising temperatures caused by climate change could see up to 1.2 billion people suffer from heat stress by 2100 if greenhouse gases are not curbed, a study found. Researcher from Rutgers University in New Jersey found that four times as many people could end up being impacted by heat stress than are today. Heat stress harms human and animal health, agriculture, the economy and the environment. Heat stress in humans is caused when the one is unable to cool down adequately by means of sweating — leading the body’s temperature to rise dangerously. Previous studies into projected future climates and heat stress have typically focused on heat extremes, but overlooked another key driver — humidity.