In 30 years' time, there may be only four places where the Winter Olympic Games can be held again.

If greenhouse gas emissions continue to accelerate, professional athletes will be forced to face more unsafe or unfair venues.

Hosting a Winter Olympic Games is not an easy thing, and the most difficult thing to control is the natural climate and geographical environment of the place where it is held. There are not many places to meet these requirements, but the list is still shrinking as climate change intensifies.

A recent study even pointed out that, given the demand for snow tracks of world-class snowboarders and snowboarders, there will be even fewer cities that can host such an ice and snow event if they want to get a reasonable taxiing speed and land safely by the end of the century.

The Summer or Winter Olympics, which take place every two years, arouse concerns among climate scientists. For example, in the Summer Olympic Games, the heat wave may pose a serious threat to the health of athletes. However, climate change has an even greater impact on the Winter Olympic Games than the Summer Olympic Games. On the one hand, the venue of the Summer Olympic Games is very flexible, and the holding time is often not in the middle of summer, when the weather is much cooler. But for the Winter Olympic Games, even ice skating, curling, hockey and other sports can be held indoors with refrigeration equipment. Even Miami in the United States has a hockey team. However, outdoor sports such as snowboarding and snowboarding are more dominated by local weather conditions.

Daniel Scott (Daniel Scott), a climate scientist at the University of Waterloo in Canada and co-author of the new study, believes that while there are already some studies on how global warming will affect snow and temperature distribution in Winter Olympic venues, they ignore more specific needs related to competitive athletes. In Ontario, Canada, he and his team conducted an anonymous online survey of 339 snowboarders, snowboarders and coaches in 20 countries. to find out which weather conditions they think will lead to unfair or unsafe competition. The survey shows that the favorite venue conditions for athletes and coaches are hard snow, no rain, and the temperature is-20-10 ℃.

Rain and high temperatures can lead to snow melting, and skiing in such weather is like "skiing on a pile of sand," according to Scott. This is what happened to athletes at the 2014 Winter Olympic Games in Sochi, Russia. Retired cross-country skier Simi Hamilton (not involved in the study), who competed in the 2010, 2014 and 2018 Winter Olympics, recalled that temperatures climbed to 15 degrees Celsius on several days during the Sochi Games, when the snow was "hard enough in the morning to provide enough speed." But for the rest of the day, the friction in the snow increases and the speed provided is not fast enough. Obviously, in some cases, it can lead to unfair competition. "

Temperature is very important for artificial snow. Since the 1980 Winter Olympic Games in Lake Placid, New York, artificial snow technology has been widely used in the Winter Olympic Games. In all the venues of the Beijing Winter Olympic Games, almost all the snow is artificial. "in the future, the question of whether the Winter Olympic Games can be successfully held is not whether there are conditions for natural snow, but whether the state of artificial snow can be maintained here." Scott said.

According to the simulation results, the researchers divided the host site into three categories: if all four factors appeared less than 7 days (< 25%) in February, they would be rated as "reliable"; if one or more factors appeared between 7 and 14 days (25% to 50%), they would be rated as "marginal". If one or more factors have been present for more than 14 days (> 50%), they are classified as "unreliable" (unreliable). In addition, taking into account the artificial snow technology, if the snow layer is too thin is the only high risk factor (> 50%), and the other three indicators are less than 25%, the area will be rated as "risky".

By the standards of the study, the four host sites-Chamoni in France, Sochi in Russia, Palisades in the US and Garmish Pattenkirchen in Germany-are now in a state of "untrustworthiness". The most influential factors in these areas are high temperatures and wet snow. Under the high-emission scenario (greenhouse gas emissions are almost unrestricted, still growing at the rate of the past 20 years), by the middle of this century, only four host sites (Lake Praxid in the United States, Sapporo in Japan, Lillehammer in Norway and Oslo) are still in a "trustworthy" state; by the end of the century, only Sapporo in Japan was left.

In a low-emission scenario (the government takes measures to control carbon emissions in accordance with the objectives of the Paris Agreement), nine host sites in the middle of the century are still "trustworthy"; even by the end of the century, there are still eight "trustworthy" host sites. "the good news is that the future is still in our hands." Scott said.

Thomas Painter, a climatologist who studies snow at the University of California, Los Angeles, who was not involved in the study, believes that the details considered by the study are a good complement to the field. "I very much appreciate the perspective of this article: they do not start with the simple dualism of 'whether the Olympic Games can still be held'." He added that the problems that are threatening the Winter Olympic Games are also threatening water resources in many parts of the world. In these places, locals rely on snow for water, which melts and fills rivers and lakes when the warm month comes.

Hamilton said the results of the study were consistent with "my personal experience of winter throughout my career" and stressed the speed at which these changes were taking place. Ten years ago, "I think [professional skiers] just assume that this will be a problem and will affect us in the future, but it's not that urgent. But now, I think it's happening so fast, and when you really see it, it's terrible. "