As an extreme year for hurricanes, wildfires and heat waves comes to an end, the head of the United Nations challenged world leaders to make 2021 the year that humanity ends its “war on nature” and commits to a future free of planet-warming carbon pollution. With new reports highlighting 2020’s record-breaking weather and growing fossil fuels extraction that triggers global warming, U.N. Secretary-General António Guterres delivered yet another urgent appeal to curb climate change. It was tinged with optimism but delivered dire warnings, as the UN gears up for a Dec. 12 virtual climate summit in France on the 5th...