Results: Extreme heat is challenging human survival limits

While some people are more vulnerable to heat than others, including the very old and young, no one is immune — not even the world's top athletes. Many are expressing anxiety as temperatures are forecast to soar past 95 degrees this week in Paris, as the Olympic Games get underway. Do you think we will see any heat related injuries or illnesses during the Olympics?

Extreme heat rips through your body's defenses, quickly going from uncomfortable to deadly as the heavy feeling of a hot, sticky day turns into something more malevolent. It often starts with symptoms like nausea, headaches, muscle cramps, even fainting. These are all signs of heat exhaustion — your body is dehydrated and starting to lose the ability to cool itself. From there, things can spiral. Have you ever experienced heat exhaustion?

Billions of people will be exposed to a combination of temperature and humidity higher than their bodies can tolerate as global warming accelerates, according to a recent study. Today's searing-hot summers will likely seem cool by future standards, and the heat we experience is changing in ways that are not in our favor. Extreme, humid heat is persisting at night time, depriving the body of vital time to recuperate. In your lifetime, do you think you will see parts of the world become inhabitable due to climate change?