ice. >> reporter: climate scientists warn this scene will become the norm as global warming threatens the future of snow sports. a new report finds that viable venues for the winter games are dwindling. iconic winter olympic host sites like vancouver, norway, sochi, and the french alps are seeing temperatures warm and shorter and less reliable snow seasons. of the 21 cities that have hosted the winter olympics, only one is expected to have the necessary conditions to host them again safely at the end of the 21st century if green house gases are not drastically reduced. >> i worry that the mountains around me won't have snow for the next generation or maybe even in my lifetime with the path that we're on. >> reporter: two-time olympic snowboarder elena hight says climate change is impacting her sport in her hometown of lake tahoe. due to shorter winter seasons and a lk of snow, resorts have