the importance of acclimatization
In and of itself, Kilimanjaro is not a difficult trek. With the exception of Day 3, we only hiked 3-4 hours a day. We also did not experience significant net elevation gain after the second day, so the hiking was not exceptionally challenging as the route mostly skirted the mountain at a gradual incline. The final summit push is steeper, with the path reaching a 45 degree slope; even so, the route to the summit is non-technical and does not require any ice climbing, making Kilimanjaro one of the easiest high-altitude peaks to climb. Nevertheless, would-be climbers attempting Kili have only a 40-50% success rate of reaching the summit.
The cause of the discrepancy between the relative ease of the route and Kili’s low success rate is the high altitude. At around 3,000m (10,000ft) – below the elevation of our first camp – the amount of oxygen our lungs can extract from the air begins to rapidly diminish. Even before reaching that elevation, some people experience symptoms of high altitude sickness. Physical exertion for those who are not acclimatized leads to shortness of breath, rapid fatigue, lightheadedness, and headaches. The body loses water at a faster rate at high altitudes so dehydration frequently exacerbates these symptoms. As one gains altitude, the symptoms proliferate: loss of appetite, nausea, insomnia, nosebleeds, diarrhea, and a persistent sense of weakness are all common indicators of altitude sickness. At very high elevations, altitude sickness can lead to fever, retinal hemorrhage, and a gradual loss of consciousness – symptoms of pulmonary or cerebral edema, both of which are fatal if not immediately treated by a descent to a much lower elevation.
Both of us had experienced altitude sickness on previous climbs. D, for instance, mistakenly thought that living at high altitude in the Andes for a year (at 3,200m/10,500ft) would excuse him from having to train for his first mountain climb. He played on a soccer team and hiked multiple hours for work every day so he thought he’d be in great shape to climb; unfortunately, altitude sickness strikes irrespective of fitness level. During the last hour and a half of the ascent up Cotopaxi his body essentially felt as if it had turned to mush and he had to stop every dozen steps to catch his breath. He did make it to the summit but had nothing in the tank left for the descent; to get back to base camp, the guide advised D to sit down on the snow and slide down while the guide followed behind, arresting D’s momentum with the rope that bound them so that he wouldn’t accidentally tumble into a crevasse. S likewise had a rough time on El Misti in Peru as she spent most of the night before her summit bid crouching outside her tent. She too made it to the summit, but having to climb after a night when her roiling insides made sleep impossible was an experience she was not eager to repeat. As we climbed towards our goal, we carefully monitored our health to ensure that our bodies were ready for the extremely high altitudes that awaited us on summit day.