The hotter it gets outside, the more we use air conditioning, and the more we use air conditioning, the hotter it gets. AC units and refrigeration combined adds up to 10 percent of global greenhouse gas emissions. But how can we solve this cooling paradox? Building on last episode’s conversation with the UN’s global chief heat officer, host Manjula Selvarajah meets the experts harnessing novel innovations to keep cities and people cool — from massive infrastructure projects using ice-cold lake water to microscopic solutions to get rid of that sticky, sweltering humidity.