By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM
In Thin Air: Climbing the Highest Peaks
Just as the 2014 climbing season got underway, an avalanche killed 16 climbers on Mt. Everest on April 18, four of whom were Sherpas. This tragic accident is just one of the dangers that can befall climbers attempting to set personal or world records by summiting the earth’s highest mountains.
To date, more than 30 alpinists have claimed to join the “8,000ers” club, an elite group of adventurers who have climbed the world’s 14 highest peaks—those more than 8,000 meters (26,247 ft) high.
All 14 of the world’s 8,000-meter peaks are located in the Himalaya or the Karakoram ranges in Asia. The crests of these mountains all share the same type of climate, called alpine climate, which is above the tree line. Extreme mountaineering occurs above the tree line and on snow and ice.
The tree line is that area beyond which trees cannot grow. For most plants, the growing season is about 180 days. In alpine climates, however, the night temperature is almost always below freezing (32 degrees Fahrenheit, 0 degrees C) and woody plants never experience a growing season long enough to establish themselves in the soil. Both elevation and latitude determine where the tree line exists on any given mountain.
Seasonal temperatures at extremely high elevations, however, are among the coldest on earth. Although cold temperatures, snow and wind may limit climbers somewhat, these conditions are particularly debilitating when combined with thin air and heavy exertion.
Changes in altitude affect atmospheric pressure and therefore oxygen levels, creating the condition known as thin air. At sea level, atmospheric pressure is greater, making it easier to breath than at higher elevations where the pressure gradually decreases as altitude increases.
Most of us have experienced the change in atmospheric pressure that occurs when driving through mountainous terrain. The result for us is ear discomfort. For mountain climbers, changes in atmospheric pressure have much more dramatic consequences.
Atmospheric pressure determines the amount of oxygen available for breathing at high altitude. For example, the concentration of oxygen throughout the troposphere is constant at 21 percent. As altitude increases, although the oxygen concentration remains at 21 percent, the atmospheric pressure decreases and the air becomes thinner. This means that the number of oxygen molecules per breath decreases. Therefore, at 12,000 feet (3,658 m) there are approximately 40 percent fewer oxygen molecules available per breath. The breathing rate of the human body, even at rest, has to increase to properly oxygenate the blood.
If a person climbing to a high elevation does not take the time to acclimatize slowly to the decrease in air pressure and oxygen, altitude sickness will result. Mountaineers generally rest for a day or two at intervals as they attempt to climb high mountains, giving their lungs a chance to acclimate. As their party assaults a particularly high peak, some climbers carry oxygen tanks sufficient for a couple of days just to be safe.
The symptoms of mild altitude sickness are headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. A severe case of altitude sickness called pulmonary edema, however, causes fluid to collect in the lungs. Life-threatening symptoms are confusion, coughing up blood and inability to walk or climb, usually requiring rapid hospitalization for recovery.
People who live their lives at elevations above 8,000 feet (2,400 m) have much greater lung capacities and ability to absorb oxygen than those who live nearer sea level. Examples are the Sherpas of the Himalayas and Bolivians of the high Altiplano in South America.
Mountain climbing carries a great many risks to both climbers and potential rescuers. Low temperatures coupled with thin air and heavy exertion can be deadly, not to speak of accidents involving falls and avalanches. Nonetheless, for some mountaineers, climbing the highest of the world’s mountains offers an ultimate challenge to both mind and body, despite the risk to themselves and their support and rescue personnel.
And that is Geography in the News.
Sources: GITN 1014, “In Thin Air: The Highest Peaks,” Maps.com, Nov. 6, 2019; The London Times, http://www.timesonline.co.uk/tol/news/world/article6861657.ece; and National Library of Medicine and National Institutes of Health, MedlinePlus, https://www.google.com/health/ref/Acute+mountain+sickness
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.