Climate in Crisis

Heavy, pungent smoke from Canadian wildfires darkened skies in the U.S. on Thursday from the Great Lakes to parts of the East Coast, reducing visibility for commuters and prompting warnings that air quality could make being outside dangerous.

As temperatures neared their midday peak, Hu Xiaosong was doing his regular patrol, at an altitude of more than 5,500 feet, to protect a 1,000-year-old pine tree that he says is like family to him.

In the next five years, the Earth is overwhelmingly likely to surge again and again past the international climate threshold set as safe and shatter its hottest-year record along the way, according to new United Nations climate projections