Every four years, the world’s finest winter athletes gather for the top competition on snow and ice. But even as we celebrate competition and athleticism, global warming is undermining the climate conditions that make the Winter Olympics possible. Nine of the hottest years ever recorded on Earth have happened since 2000. Winter average temperatures across the contiguous United States have warmed more than 2 degrees Fahrenheit since 1970. The primary cause of this warming is human use of fossil fuels and we need to act now to prevent the worst from happening. Global warming is affecting Winter Olympic sports in multiple ways.