This record summer heat was driven primarily by human-caused climate change, which not only has been raising average global temperatures but also has been fueling more lethal heat waves. A new study released on Wednesday finds that climate change likely tripled the number of heat-related deaths in European cities this summer. “Many of these [people] would not have died without climate change,” said study co-author Friederike Otto, a climate scientist at Imperial College London, during a press conference about the finding. They found that in 854 urban areas they examined, 68 percent of the 24,400 estimated heat deaths were attributable to climate change. “That’s what it boils down to.”And the proportion of heat deaths attributable to climate change is creeping up, Otto says.