Could the world become too warm to hold Winter Olympics?

Without drastic reductions in greenhouse gas emissions, climate change threatens future Winter Olympic Games because their locations would be too warm to host the events, a new study has found.

If the world's high emissions continue on their trajectory, by the 2080s all but one of the 21 cities that previously hosted the Winter Games — Sapporo, Japan — would not be able to do so again.

Six cities would be considered "marginal," while 14 would be deemed "unreliable" — meaning the right conditions for snow and athlete safety cannot be met.

But that won't necessarily happen if the world takes drastic action and follows the 2015 Paris Climate Agreement, according to Daniel Scott, the lead researcher for the University of Waterloo's report. Under that deal, nearly 200 countries agreed to drastically cut their collective greenhouse emissions.

"Under a low-emissions future in the 2050s even the 2080s, we don't really see much change in terms of those climate reliable locations," Scott told NPR. "We pretty much keep all of what we have today."

The report comes just as the world prepares for the 2022 Winter Olympics in Beijing, starting Feb. 4.

Athletes and coaches surveyed by the researchers said they're already seeing the effect climate change has on their sports.

"Some of the coaches that did the survey have been coaches in the sport for 30 years," Scott said. "They've traveled the world, back to the same competitions, and they've seen that certain competitions don't happen as regularly or uninterrupted as they used to" because of warmer temperatures.

Rosie Brennan, a U.S. Olympic cross-country skier, said race organizers rely on technology to work around the climate impact — with varied results. Brennan participated in the 2018 Olympics and plans to compete in Beijing.

"I think the thing that we see now is with warmer weather, there's less snowfall, so we're much more reliant on man made snow," she told NPR. "And man-made snow doesn't act the same as natural snow. It tends to be much firmer, it gets icier faster and it's a faster surface."

That has resulted in devastating injuries to athletes — normally a rarity for Brennan's sport, she said.

"I think we have seen that in the last few years there's been a number of World Cup races where people have broken bones from crashing," she said.

The future of winter sports could be entirely indoors

The Summer Olympics are also feeling the effects of climate change.

This summer's Tokyo's Olympic and Paralympic Games are likely one of — if not the — hottest and most humid Games on record. Daily temperatures reached the high 80s with high humidity that could make it feel more like 100 degrees.

But winter sports seem acutely vulnerable to the impact of a warmer world.

During the 2014 Winter Olympics in Sochi, Russia, skiers were overheating in the same way a marathon runner would at nearly 90-degree weather, according to Scott.

There may come a point when outdoor games may have to move indoors or be held at a different time of year altogether in order to accommodate higher temperatures, he said.

Some countries with traditionally hot climates have already adopted indoor ski resorts.

Dubai opened the first indoor ski resort in the Middle East, which has been deemed the "world's best" — better than even what traditionally wintry conditions like Scotland or Germany can offer — six years in a row.

But Brennan said a major part of why she loves her sport is lost if this becomes the norm.

"The reason I am a skier is because I love being outside," she said. "I love being in the mountains, I love being in nature. I love being alone on the trail, hearing my own breathing. And none of that is possible when you're indoors."