people traveling on trains as flames roared near the tracks. in france the fires forced at least 37,000 people to evacuate. in uk today was the hottest day ever. 104 degrees fahrenheit. the heat is triggering fires around london now as well. back here in the u.s. 60 million people will experience triple digit temperatures in the next week. there is no bigger story right now, no issue affecting more people, billions of people. the u.n. secretary-general says half of humanity is in the climate danger zone. and he had this warning. we have a choice, collective action or collective suicide. it is in our hands. we have team coverage all across the globe. let s start with nina. london fire officials are facing major strains. what are you seeing? reporter: yeah, that s right. we ve seen the specter of those wildfires that are raging across southern europe, ana, hit here on the fringes of the britishcal tal three miles away from where i am. there was a wildfire burning and ther