Earth is heating faster than expected. Deadly heat in India, unheard-of heat in France and Alaska. The Arctic is thawing out. People have died and many more will be killed by heat in the future. But how does heat kill? and who? Three experts explain what we all need to know, in the second of my series on “Extreme Heat”: Elizabeth Hanna, Robert Kopp and Jonathan Patz from the best of Radio Ecoshock.