Of the sheer peril of direct heat, Wallace-Wells writes that dangerous heat waves are 50 times more common today than in 1980. Going back 500 years, the five hottest summers in European history have all happened since 2002. By 2050, the city of Mecca, to which millions of Muslims make pilgrimages each year, could become uninhabitable.

On the question of politics, the author points to the 2016 Paris Accords, a pledge signed by 195 countries to keep global temperatures no greater than two degrees above pre-industrial levels. Though the pledge was celebrated by climate scientists and activists, only six of its signatories are in range of this commitment. Meanwhile, China—the nation with the world’s largest carbon footprint—saw emissions rise by four percent in the first three months of 2018, despite signing the Paris Accords and making a rhetorical commitment to curb climate change.

Wallace-Wells views the relationship between food production and climate change from two perspectives. The first pertains to the grim scientific research suggesting that yields from cereal crops like wheat will decline by an average of 10% for every one-degree hike in the global temperature. Already there are 800 million undernourished people around the globe, and that number only stands to increase as the planet continues to warm.