About 12,000 Americans die from heat-related deaths each year. Under a climate scenario in which heat-trapping gas emissions continue to rise, that number would increase by 97,000 deaths in the United States by the year 2100, according to a recent study. If only modest progress is made in constraining emissions, those deaths are projected to rise by 36,000. With aggressive emissions reductions, deaths would go up by 14,000.