By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM and Maps.com
May is the month that high elevation climbers focus on Mt. Everest and other high mountains of the Himalaya. Many have been planning for years and will be journeying to Nepal shortly to adjust to the elevation and prepare base camps for assaults on some of the world’s highest mountains.
In 2009, a mountaineer from Australia joined 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) in elevation. Andrew Lock was only the 18th person in the world to have accomplished the feat. Others continue to reach that “plateau” of climbing.
Lock and his climbing partner reached the summit of Shisha Pangma in Tibet, which has an elevation of 26, 289 feet (8,013 m). Lock had been climbing the world’s highest peaks for the previous 16 years.
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. Nonetheless, for some mountaineers, climbing the highest of the world’s mountains offers an ultimate challenge to both mind and body.
And that is Geography in the NewsTM.
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.
Sources: The London Times, http://www.timesonline.co.uk/tol/news/world/article6861657.ece; National Library of Medicine and National Institutes of Health, MedlinePlus, https://www.google.com/health/ref/Acute+mountain+sickness; and http://www.ehow.com/how_17485_climb-mount-everest.html
This article is a revision of GITN 1014 In Thin Air: The Highest Peaks, posted on Nov. 6, 2007 by Maps.com. Nearly 900 of the 1200, full-length weekly Geography in the News articles (with Spanish translations) are available in the K-12 online education resource Maps101.com, including maps and other supporting materials and critical thinking questions.