Climate change’s sweaty fingerprints are all over the July heat waves gripping much of the globe. A new study finds these intense and deadly hot spells in the American Southwest and Southern Europe could not have occurred without it. Tuesday’s study finds the increase in heat-trapping gases from the burning of fossil fuels has made a third simultaneous heat wave — one in China — 50 times more likely. An ever-warming world also made the European heat wave 4.5 degrees Fahrenheit hotter, the one in the United States and Mexico 3.6 degrees warmer and the Chinese one 1.8 degrees toastier.