# How high a mountain can humans climb unassisted? **URL:** \ **Category:** Factual Questions\ **Created:** [April 24, 2018, 5:50pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054 "2018-04-24T17:50:40Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![blood63](https://avatars.discourse-cdn.com/v4/letter/b/97f17d/32.png) [@blood63](https://boards.straightdope.com/u/blood63)\ **Post date:** [April 24, 2018, 5:50pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/1 "2018-04-24T17:50:40Z")
Mount Everest is our highest mountain and it seems barely reachable on a human level. Even with oxygen assistance, many climbers have either perished or turned back. Apparently, about 200 climbers have accomplished the climb without additional oxygen. I wonder if anyone has ever considered an Earth with an unclimbable mountain. How high would it be? Have any existed on the Earth in the past? How much do oxygen levels decrease at an altitude beyond Everest? ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [April 24, 2018, 5:56pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/2 "2018-04-24T17:56:15Z")
> [@blood63](#): > > Mount Everest is our highest mountain and it seems barely reachable on a human level. Even with oxygen assistance, many climbers have either perished or turned back. Apparently, about 200 climbers have accomplished the climb without additional oxygen. I wonder if anyone has ever considered an Earth with an unclimbable mountain. How high would it be? Have any existed on the Earth in the past? > How much do oxygen levels decrease at an altitude beyond > Everest? If you can bring additional oxygen and a pressure suit, and other life support, the limit may be cosmic radiation beyond the van Allen belts… Able to shield from those too, well then you have the issue that humans only live so long. Including reproducing along the way, with appropriate medical care, no real upper limit because they will always be a bit higher the next day. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [April 24, 2018, 5:58pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/3 "2018-04-24T17:58:02Z")
> [@kanicbird](#): > > If you can bring additional oxygen and a pressure suit, and other life support, the limit may be cosmic radiation beyond the van Allen belts… Able to shield from those too, well then you have the issue that humans only live so long. Including reproducing along the way, with appropriate medical care, no real upper limit because they will always be a bit higher the next day. How is any of this relevant to **unassisted** mountain climbing? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 24, 2018, 5:58pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/4 "2018-04-24T17:58:05Z")
Your question seems to be mostly about human capacity, which I can’t say much about, but it’s worth mentioning that geologically, Everest is about as tall as it’s possible for a mountain to be on Earth. And a planet that was capable of supporting taller mountains would probably have a lower surface gravity, which would probably make them easier to climb to any given height. There’s also a question, not only of a mountain’s height, but of its shape. Some mountains can be “climbed” by simply hiking to the top, while others require scaling shear rock faces. ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [April 24, 2018, 6:03pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/5 "2018-04-24T18:03:01Z")
Without straying afield here, it sounds like your meaning of “unassisted” is “no oxygen tanks”. Google says this: > [@](#): > > Used to describe high danger altitude on the Mount Everest ascent, the “Death Zone” begins at about 8,000 meters or 26,246 feet. At this elevation, unassisted from compressed air or oxygen, severe altitude sickness sets in, debilitating the human body and eventually resulting in death.Aug 14, 2017 So, that would have to be it, yes? ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [April 24, 2018, 6:14pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/6 "2018-04-24T18:14:18Z")
> [@Wiki](#): > > At this elevation, unassisted from compressed air or oxygen, severe altitude sickness sets in … Note that compressed air would do nothing for you - unless breathed within some sort of compression chamber. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 24, 2018, 6:23pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/7 "2018-04-24T18:23:06Z")
> [@Jasmine](#): > > Without straying afield here, it sounds like your meaning of “unassisted” is “no oxygen tanks”. Google says this: > > So, that would have to be it, yes? Not sure what this means. The “death zone” of high-altitude mountaineering doesn’t mean “instant death.” People do linger there, albeit not indefinitely. Given that people have _just barely_ climbed Everest without supplemental O2, I would imagine that trying to climb much higher would increase the odds of death (either from illness, or from misadventure due to hypoxic mental faculties) to the point that no one would want to try it (sort of like free-diving to 1000 feet of depth). Camp 4 is right on the edge of the death zone, ~3000 feet below the summit. AIUI it’s an all-day affair to summit from Camp 4 and then get back down to Camp 4. I don’t imagine you could have a “Camp 5” any higher, since it’d be in the death zone and you’d be slowly dying while you try to rest there. So you’d be trying to summit a hypothetical higher-than-Everest peak from the same camp 4. Another 1000 feet of elevation increases your summit attempt time from that location by 33%. I’m not even sure that would be possible. ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [April 24, 2018, 6:28pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/8 "2018-04-24T18:28:57Z")
200 some people may have gotten to the top of Everest without supplemental oxygen, but the fact that they made it and returned doesn’t mean they weren’t at or very close to the very physical limits of human ability. Any altitude higher than 8000 m is incompatible with human life, period. Consider that the maximum limit of permanent human survivability is 5500 m. Also, like doing push-ups, you haven’t “climbed a mountain” until you’ve both gone up and come back down. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [April 24, 2018, 6:39pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/9 "2018-04-24T18:39:28Z")
There are also various mutations that make it easier to survive and climb at altitude. The Sherpa population in Nepal and Tibet have a variety of biochemical adaptations that make them capable of climbing higher and with fewer debilitating side effects. > **[Mutations may reveal how Tibetans can live on world's highest plateau](https://www.science.org/content/article/mutations-may-reveal-how-tibetans-can-live-world-s-highest-plateau)** > > Adaptations include those for increased BMI and folate production Some of the best western climbers like Reinhold Messner many have also had these genes which allowed them to operate at altitude much better than the average climber. Gradual acclimatization only goes so far, and at high altitude it’s just a race between building hemoglobin and your body eating itself. The Sherpa have better odds. And some climbers, especially the Sherpa, can actually operate fairly well at that altitude for a reasonable period of time. If there were higher peaks they could climb them. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 24, 2018, 7:16pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/10 "2018-04-24T19:16:50Z")
Plus, the people of the Andes also have adaptations to high altitude, but it’s a different set of adaptations than the Sherpa have. One can imagine a descendant of both populations lucking out and getting both sets of adaptations, and possibly surviving even higher than either. ---
**Author:** ![Penfeather](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/penfeather/32/384_2.png) [@Penfeather](https://boards.straightdope.com/u/Penfeather)\ **Post date:** [April 24, 2018, 11:40pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/11 "2018-04-24T23:40:09Z")
> [@kanicbird](#): > > If you can bring additional oxygen and a pressure suit, and other life support, the limit may be cosmic radiation beyond the van Allen belts… Able to shield from those too, well then you have the issue that humans only live so long. Including reproducing along the way, with appropriate medical care, no real upper limit because they will always be a bit higher the next day. Also take a gun, in case you meet the Buddha. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [April 25, 2018, 1:50am UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/12 "2018-04-25T01:50:25Z")
> [@Telemark](#): > > Some of the best western climbers like Reinhold Messner many have also had these genes which allowed them to operate at altitude much better than the average climber. I remember a National Geographic detailing how Messner climbed Everest _alone…without supplemental oxygen._ ---
**Author:** ![Delicious](https://avatars.discourse-cdn.com/v4/letter/d/dbc845/32.png) [@Delicious](https://boards.straightdope.com/u/Delicious)\ **Post date:** [April 25, 2018, 11:43am UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/13 "2018-04-25T11:43:39Z")
> [@Chronos](#): > > Plus, the people of the Andes also have adaptations to high altitude, but it’s a different set of adaptations than the Sherpa have. One can imagine a descendant of both populations lucking out and getting both sets of adaptations, and possibly surviving even higher than either. You could take one of these super-climbers and do that athletics doping thing where they remove some blood then get the red cells put back in later to give them more oxygen capacity in their blood. Are there any performance-enhancing drugs you could pump them full of that would help with climbing mega-Everest? ---
**Author:** ![pdhenry](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pdhenry/32/5561_2.png) [@pdhenry](https://boards.straightdope.com/u/pdhenry)\ **Post date:** [April 25, 2018, 12:24pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/14 "2018-04-25T12:24:22Z")
> [@Chronos](#): > > Your question seems to be mostly about human capacity, which I can’t say much about, but it’s worth mentioning that geologically, Everest is about as tall as it’s possible for a mountain to be on Earth. And a planet that was capable of supporting taller mountains would probably have a lower surface gravity, which would probably make them easier to climb to any given height. > … Seems to me that a planet with lower surface gravity would also have lower atmospheric pressure, making those taller mountains more inaccessible. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [April 25, 2018, 12:26pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/15 "2018-04-25T12:26:36Z")
> [@Delicious](#): > > Are there any performance-enhancing drugs you could pump them full of that would help with climbing mega-Everest? [Diamox](https://en.wikipedia.org/wiki/Acetazolamide)is the standard drug taken to help with high altitude acclimatization, but I’m not sure if it would be helpful to folks with the genetic adaptations. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [April 25, 2018, 12:29pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/16 "2018-04-25T12:29:04Z")
> [@pdhenry](#): > > Seems to me that a planet with lower surface gravity would also have lower atmospheric pressure, making those taller mountains more inaccessible. Yes, but the lifeforms that evolve on such a planet would be used to the lower atmospheric pressure, so it may cancel out. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 25, 2018, 12:47pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/17 "2018-04-25T12:47:51Z")
> [@Chronos](#): > > Everest is about as tall as it’s possible for a mountain to be on Earth. From base to summit, [Mauna Kea is a good bit taller](https://www.azula.com/mauna-kea-worlds-tallest-mountain-mostly-underwater-2476365635.html). ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 25, 2018, 12:51pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/18 "2018-04-25T12:51:20Z")
> [@pdhenry](#): > > Seems to me that a planet with lower surface gravity would also have lower atmospheric pressure, making those taller mountains more inaccessible. Surface gravity and atmospheric pressure aren’t rigidly locked together. For examples, see Earth and Venus. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 25, 2018, 1:19pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/19 "2018-04-25T13:19:16Z")
> [@Darren\_Garrison](#): > > Surface gravity and atmospheric pressure aren’t rigidly locked together. For examples, see Earth and Venus. For low gravity and high atmospheric pressure you need more atmospheric mass. Venus has that. If we’re talking about a hypothetical planet that has lower gravity than earth, but the same total atmospheric mass (i.e. 14.7 pounds of _mass_ above every square inch of the planet’s surface), I’m not certain what would happen to the atmospheric pressure profile. It would be lower at the surface, but that also means that the rate-of-decrease with altitude would be less; the atmosphere would be taller. To know what the new atmospheric pressure would be at any altitude other than sea level, I think you’d have to make a spreadsheet model of the atmosphere. If you’re not quite convinced of this, then imagine taking things far, far in the opposite direction. Imagine a planet with ten times earth gravity, but same atmospheric mass. Sea-level pressure would be 147 psi, and there wouldn’t be much air mass remaining at the summit of Everest; pressure there would certainly be lower. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 25, 2018, 1:29pm UTC](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054/20 "2018-04-25T13:29:14Z")
> [@Machine\_Elf](#): > > To know what the new atmospheric pressure would be at any altitude other than sea level, I think you’d have to make a spreadsheet model of the atmosphere. OK, I just modified my standard-atmosphere spreadsheet to allow for variable gravity. Here’s what I found. normal earth gravity: sea level pressure 14.7 psi, Everest summit pressure 4.58 psi. 75% of normal earth gravity: sea level pressure 11 psi, Everest summit pressure 6.13 psi 50% of normal earth gravity: sea level pressure 7.35 psi, Everest summit pressure 8.21 psi. And going in the opposite direction, 10 times normal earth gravity: sea level pressure 147 psi, Everest summit pressure 0.0001 psi. So, assuming you are able to reduce the gravity on the earth, you’d definitely have an easier time climbing Everest without supplemental O2. Not just less exertion, but more air. We should look into making this happen. 😃 [Next page](https://boards.straightdope.com/t/how-high-a-mountain-can-humans-climb-unassisted/813054.md?page=2)