Is climbing K2 in Winter without oxygen even possible?

When Reinhold Messner and Peter Habeler first climbed Everest without oxygen in 1978, a mix of respected Doctors and Scientists doubted it was possible.

With atmospheric pressure only providing them 1/3 of the oxygen availability one has at sea level, the ability to acclimatize, stay warm, digest food and have the energy to actually move was beyond the limit of what many thought could be physically accomplished.

Or perhaps it could be done, but they would return with a serious loss of brain cells? None of that occurred, Messner and Habeler ascended from the South Col to the summit in a time that many can’t match even with oxygen today. And fortunately they were still speaking full sentences on their return.

Reinhold Messner, Everest, 8000 meter peaks
Messner at one of his Messner Mountain Museums, Firmian Castle, Italy. Photo: Robert Mads Anderson/Forbes Magazine,

Two years later, Messner went on to solo the North Face of Everest, again completing it without oxygen at the tail end of the monsoon, when there may have been marginally better conditions for oxygen availability.

While a number of climbers have gone on to climb both Everest and K2 without oxygen in the regular climbing seasons, it is generally reserved for the rare climber who is happy to push themself to their absolute limits – and the chance of failing and/or dying is much increased.

If you want to climb Everest without oxygen, be prepared to lose a few kilos in the process. Stephen Venables at Base Camp after becoming the first British Climber to Summit Everest without oxygen. Photo: Joseph Blackburn

There is only one single person who has climbed Everest in Winter without oxygen, Ang Rita Sherpa, who climbed with Korean climber, Young-Ho Heo, reaching the summit just a day into the official winter season on 22 December, 1987. Ang Rita was phenomenal at altitude, climbing Everest over 10 times without oxygen. And he lived to be 72, dying just last September.

This winter, a host of climbers on K2 have said they will be attempting the climb without oxygen, including Nims Purja, Mingma Gyale Sherpa along with teamates Dawa Tenzin Sherpa and Kili Pemba Sherpa, as well as John Snorri and the Father/Son Sadparas team. Alex Gavan and Tamara Lunger are also sans-oxyen.

Every one of these climbers has a depth of high mountain experience that should the weather and other factors all align, have a respectable chance of doing well.

However, there is another factor to consider, beyond motivation, a desire for a pure ascent and simply the added challenge.

Winter isn’t just about brutal conditions, it is also about how much oxygen is available for our use. And in winter conditions, it is mostly less as air pressure dictates oxygen and that varies with the weather.


At 8300 metres above Everest South Col after completing the new Kangshung Face route. No pack, no rope and no oxygen on the way to the South Summit of Everest. As opposed to climbing towards the summit, it felt more like a crawl for me. Photo: Ed Webster

Recent studies indicate that winter weather may affect pressure even more, as reported in a well researched article in IScience:

Winter pressures can also plunge lower than previously reported, highlighting the importance of air pressure forecasts for the safety of those trying to push the physiological frontier on Mt. Everest.

While the research is on Everest, with K2 being only a few 100 metres lower, still highly relevant.

If you like the deep data (which I admit I do), it seems that the hidden, single and perhaps biggest challenge with getting up K2 without oxygen is having a day when there is enough available to actually climb it. That is a very big variable.

The Everest data says not only was Ang Rita Sherpa incredibly good at climbing Everest without oxygen, he also ended up on a day where the pressure was much higher than normal for December.

The only winter climb without supplemental oxygen was also attained at a time when pressure was 330 hPa (in close agreement with the 329 hPa reported by West, 1993), which is higher than over 86% of all other December values, and close to the long-term mean (331 hPa). Although very rare, summit air pressures in all winter months (December–February) can rise above the long-term mean, even exceeding the mean pressure during oxygenless summits (0.1–0.8% of the time). IScience

You don’t need to be a scientist to work out the high degree of variability as recorded at the South Col in the chart below on Everest – just in case you like your data visually.

It may be all about picking the lucky day, with big spikes seen in the winter pressures. IScience

Even a day or two can make a big difference, as those spikes in January and February indicate. Even spending a night at Camp 4, with the pressure dipping, could put one at much higher risk without oxygen.

So while a few purists call from their couches for an oxygenless ascent, the reality is likely going to be the need for a combination of factors, many out of any individual climbers control.

Can it be done? Of course. Will it be done? Hmmm.