Climbing Everest Without Oxygen: Reinhold Messner

What Messner did on Everest

Messner climbed Everest twice without supplemental oxygen, first in 1978 with Habeler and second in 1980 alone. Both ascents were considered impossible by the medical and mountaineering establishment of the time.

The climber

Reinhold Messner is an Italian mountaineer born in 1944 in South Tyrol. By 1978 he was already considered one of the leading high altitude climbers in the world. He had climbed multiple eight thousand metre peaks and had pioneered fast alpine style ascents. He went on to become the first person to climb all 14 of the world peaks above 8000 metres.

The 1978 ascent

Messner and Habeler reached the summit of Everest at approximately 1:15 PM on 8 May 1978 via the South Col route. They climbed without supplemental oxygen, which had been used by every previous successful Everest summit team. The ascent took 12 hours from Camp 4 at the South Col.

The 1980 solo ascent

Two years after the first oxygen free climb Messner returned alone. He climbed the Tibetan side of Everest via the North Col and Norton Couloir in pure alpine style, carrying everything he needed, without oxygen, without fixed ropes and without other climbers in the high mountain. He summited on 20 August 1980 in poor weather.

The legacy

Messners climbs proved that humans could survive briefly at altitudes above 8500 metres without supplemental oxygen. By 2022 over 200 climbers had repeated oxygen free Everest ascents. The 1978 climb remains the reference point for the absolute upper limit of human altitude tolerance.

What happens to the body above 8000 metres

The death zone above 8000 metres represents an altitude at which the human body progressively deteriorates regardless of fitness or acclimatisation. Survival without supplemental oxygen requires specific physiological adaptations and remains time limited.

Atmospheric oxygen at altitude

At sea level atmospheric pressure is approximately 760 mmHg and oxygen partial pressure is around 160 mmHg. At the summit of Everest atmospheric pressure is around 250 mmHg and oxygen partial pressure is approximately 50 mmHg, about one third of sea level. This is the lowest oxygen environment in which humans regularly survive.

Acclimatisation responses

The body adapts to altitude over weeks. Red blood cell production increases driven by erythropoietin. Plasma volume initially decreases then partially recovers. Capillary density increases in tissues. Mitochondrial density adapts. These adaptations help but do not fully compensate for the oxygen deficit at extreme altitude.

The death zone

Above 8000 metres the body cannot acclimatise. Tissue oxygen delivery is insufficient to maintain physiological function indefinitely. Climbers in the death zone deteriorate progressively. Sleep is impaired, appetite is suppressed, mental function declines and physical performance drops by 50 to 70 percent of sea level capacity. Survival time is limited to hours or at most a few days.

Cognitive effects

Brain function suffers at extreme altitude. Decision making, judgement and motor coordination all decline. Climbers report visual and auditory hallucinations. Memory is impaired. Many high altitude accidents trace to cognitive failures rather than physical exhaustion. This is one of the most dangerous aspects of climbing without supplemental oxygen.

What oxygen free climbing costs

Climbing Everest without supplemental oxygen carries dramatically higher risk than climbing with oxygen. The Messner achievements were exceptional partly because the survival margins were so narrow.

High altitude cerebral oedema

HACE is a swelling of the brain caused by capillary leakage at extreme altitude. Symptoms include severe headache, confusion, loss of coordination and altered mental state. Untreated HACE progresses to coma and death. Descent is the only effective treatment. Climbers without oxygen are at higher risk because their tissue oxygenation is already compromised.

High altitude pulmonary oedema

HAPE is fluid accumulation in the lungs caused by pulmonary capillary leakage. Symptoms include severe breathlessness, cough and chest tightness. HAPE can develop quickly and is fatal if untreated. Climbers without oxygen face higher risk because their pulmonary system is already under maximum demand.

Frostbite and tissue damage

Reduced oxygen delivery at extreme altitude impairs peripheral circulation. Frostbite of fingers, toes and face is common on Everest summit attempts. Messner sustained frostbite damage on multiple expeditions. The cumulative tissue damage from repeated extreme altitude exposure is one of the long term costs of high altitude mountaineering.

Acute mortality risk

Death rates on Everest above 8000 metres are significant. Estimates suggest approximately 3 to 4 percent fatality rate for all summit attempts, with higher rates for oxygen free attempts. The Messner ascents were exceptional partly because of his experience and partly because both occurred in weather windows that prevented worse outcomes.

Lessons from the death zone

The Messner ascents proved that briefly tolerable conditions exist at altitudes once thought lethal. They also defined the limits of what acclimatisation and training can accomplish. The lessons inform modern high altitude medicine.

Acclimatisation has limits

Time at altitude produces measurable physiological adaptation but the adaptations cannot fully compensate for the oxygen deficit above 8000 metres. The death zone exists whether or not climbers acclimatise. The Messner climbs showed that brief exposure is survivable but did not demonstrate sustainable function at extreme altitude.

Individual variation is significant

Some climbers tolerate altitude better than others, partly through genetic factors and partly through trainable adaptations. Messner appears to be a genetic outlier in altitude tolerance. Other elite climbers including Nimsdai Purja and Edmund Hillary have shown similar but not identical responses. The genetic basis for altitude tolerance is still being studied.

Risk increases sharply without oxygen

Modern Everest expeditions almost always use supplemental oxygen. The risk reduction is significant. Oxygen free ascents are reserved for elite climbers and remain among the most dangerous undertakings in mountaineering. The Messner climbs proved the physiological possibility but did not make it routine.

Long term effects exist

Repeated exposure to extreme altitude causes cumulative neurological and physiological changes. Some elite climbers show subtle cognitive effects after decades of high altitude work. The long term cost of multiple oxygen free climbs is an ongoing area of medical research. The acute survival of a climb does not capture the cumulative load.

More from the limits library

For another extreme altitude climber, our Fourteen Eight Thousand Metre Peaks guide covers Nimsdai Purja. Training at Extreme Altitude covers high altitude physiology and adaptation. And Climbing Without Ropes covers Alex Honnold and a different climbing limit.