ieExplains: The 'silent killer' — what you need to know about heatwaves

Firefighting planes drop water while battling a blaze in the seaside area of Palaia Fokaia, south of Athens earlier this month during Greece's first summer heatwave. Picture: AP Photo/Giorgos Delveroudis

Heatwaves have grown hotter and stronger as the planet has warmed, making what doctors call a “silent killer” even more dangerous. How worried should we be about heat — and how can we stay safe as the climate changes?

How many people die from heat?