As the world warms, the link between heat and social disturbance is an increasingly important one and, this summer, an especially concerning one. Each upheaval has its own causes, but certain factors make disturbances more likely everywhere. Surging temperatures, rising food prices and cuts to public spending—three of the strongest predictors of turmoil—have driven estimates of the potential for unrest to unprecedented highs in recent months. These estimates will probably rise higher still this summer. Temperatures are unlikely to have peaked. Russia’s exit from the Black Sea Grain Initiative to export supplies from Ukraine and India’s recent ban on rice exports may raise the price of staples. Social unrest is already bubbling in Kenya, India, Israel and South Africa.