Of the 21 cities to host the Winter Olympics, only Sapporo would be able to provide fair and safe conditions to stage them again by the end of the century if greenhouse gases are not dramatically reduced, a University of Waterloo study released on Tuesday said.

An international team of researchers, led by the University of Waterloo, reviewed historical climate data from the 1920s along with future climate change trends. They determined that winter playgrounds such as St. Moritz and Lillehammer could become Olympic relics by the mid to late century, with unreliable conditions ruling them out as Games hosts.

Research revealed that the average February daytime temperature of host cities has steadily increased — from 0.4 degrees Celsius at the Games held in the 1920s to the 1950s, to 3.1 C at the Games during the 1960s to 1990s, and 6.3 C in Games held in the 21st century, including next month's Beijing Games.