150,000 Americans could be killed by extreme heat according to the NRDC:
"Climate change is literally killing us. According to NRDC's "Killer Summer Heat" report, more than 150,000 Americans could die by the end of this century due to the excessive heat caused by climate change. And that estimate only covers America's top 40 cities."
"Why will climate change cause so many casualties? Illnesses that are caused or made worse by extreme heat -- including heat exhaustion, heat stroke, cardiovascular disease, and kidney disease -- currently lead to hundreds of deaths each year."