We are used to seeing Holmenkollen's classic competitions in cross-country skiing and biathlon in March every year - but in the future they risk having to be moved if climate change continues at the same pace as today.
It shows figures that SVT Sport has produced together with SMHI.
And in Oslo, the organizer has begun to prepare for greener winters.
- There are no figures that surprise us.
It is something we have seen and that we live with, but it is clear that it creates concerns.
We must probably reckon with the fact that the races in Holmenkollen can not take place in March for all years to come.
We have to look at dates for when you can have races in Holmenkollen in the future, says Stefan Marx.
The season will be shorter
They have organized ski competitions in Holmenkollen for 130 years and want to do it for another 130 years.
But if global warming continues at the same rate as today, the ski season looks set to be clearly shorter.
According to SMHI, the number of days with snow on the ground per year will decrease by 15 percent by 2099.
In other words - at the turn of the century, Oslo seems to have lost 28 days of snow on the ground, one month of the winter season.
- It is clear that we are worried and worried.
But at the same time we are optimistic.
We hope that this can be stopped in a way that makes it possible to have winter events in Holmenkollen in 100 years, says Marx.
"As a sport, you have a responsibility"
Climate work has begun in Holmenkollen and has concrete goals.
- In 2025, everything that runs on a motor must be electric and it goes all the way down to the chainsaw and the smallest motor-driven tool.
As a sports and sports federation, you definitely have a responsibility that goes beyond the individual's responsibility.
It must be said.
You can not take responsibility for everything, but you can influence.
You have so much influence, says Marx.
The modern technology with artificial snow and stored snow means that you can practice winter sports even without a "real" winter - but the organizer at Holmenkollen prefers to avoid that.
- We have a summer event where you compete on roller skis, but it will not be quite the same.
It will not be the same when you see TV pictures where only white snow goes through a green forest.
Although it is possible in the future, winter sports should be during the winter.
Then we must be able to preserve the winter, says Marx.
REPORTAGE: Classic Holmenkollen goes towards a month shorter winter:
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Classic Holmenkollen is heading towards a month shorter winter