Death Zone Weather Extremes Mountaineers Have Experienced in Successful Ascents

Abstract

BackgroundFew data are available on mountaineers’ survival prospects in extreme weather above 8000 m (the Death Zone). We aimed to assess Death Zone weather extremes experienced in climbing-season ascents of Everest and K2, all winter ascents of 8000 m peaks (8K) in the Himalayas and Karakoram, environmental records of human survival, and weather extremes experienced with and without oxygen support.Materials and MethodsWe analyzed 528 ascents of 8K peaks: 423 non-winter ascents without supplemental oxygen (Everest–210, K2–213), 76 ascents in winter without oxygen, and 29 in winter with oxygen. We assessed environmental conditions using the ERA5 dataset (1978–2021): barometric pressure (BP), temperature (Temp), wind speed (Wind), wind chill equivalent temperature (WCT), and facial frostbite time (FFT).ResultsThe most extreme conditions that climbers have experienced with and without supplemental oxygen were: BP 320 hPa (winter Everest) vs. 329 hPa (non-winter Everest); Temp –41°C (winter Everest) vs. –45°C (winter Nanga Parbat); Wind 46 m⋅s–1 (winter Everest) vs. 48 m⋅s–1 (winter Kangchenjunga). The most extreme combined conditions of BP ≤ 333 hPa, Temp ≤ −30°C, Wind ≥ 25 m⋅s–1, WCT ≤ −54°C and FFT ≤ 3 min were encountered in 14 ascents of Everest, two without oxygen (late autumn and winter) and 12 oxygen-supported in winter. The average extreme conditions experienced in ascents with and without oxygen were: BP 326 ± 3 hPa (winter Everest) vs. 335 ± 2 hPa (non-winter Everest); Temp −40 ± 0°C (winter K2) vs. −38 ± 5°C (winter low Karakoram 8K peaks); Wind 36 ± 7 m⋅s–1 (winter Everest) vs. 41 ± 9 m⋅s–1 (winter high Himalayan 8K peaks).Conclusions1.The most extreme combined environmental BP, Temp and Wind were experienced in winter and off-season ascents of Everest.2.Mountaineers using supplemental oxygen endured more extreme conditions than climbers without oxygen.3.Climbing-season weather extremes in the Death Zone were more severe on Everest than on K2.4.Extreme wind speed characterized winter ascents of Himalayan peaks, but severely low temperatures marked winter climbs in Karakoram.

The Oxygen Transport Triad in High-Altitude Pulmonary Edema: A Perspective from the High Andes

“…The limiting factors for climbers to the summit of Mt. Everest include cold, fatigue, lack of sleep, and malnutrition [47]. As expected, all these factors bring forth a potentially temporary progressive physiological deterioration but, unfortunately, it is only attributed to hypoxia, an often blind and biased sea-level approach.…”

Prolonged Sojourn at Very High Altitude Decreases Sea-Level Anaerobic Performance, Anaerobic Threshold, and Fat Mass

“…Experiments performed in simulated conditions allow researchers to control many confounding variables and enable them to focus on the effects of hypoxia on the human organism ( Rose et al, 1988 ; Green at el., 1989 ; Westerterp-Plantenga et al, 1999 ). Mountaineering expeditions, however, experience many variables – such as low temperature, high wind, low humidity, high UV radiation, dietary restrictions, psychological stress, and great physical effort – apart from hypobaric hypoxia ( Szymczak et al, 2021a , b ). These confounding variables likely affect the results of these studies ( Ferretti et al, 1990b ; Hoppeler et al, 1990a ; Reynolds et al, 1999 ; Mizuno et al, 2008 ).…”

Heat Balance When Climbing Mount Everest

“…The most important research on how Himalayan climate affects human physiology involves barometric pressure, air temperature and wind speed, the meteorological parameters that most limit human performance and survival at high altitudes. These parameters are derived from direct assessments at high altitude ( West et al, 1983b ; West, 1999 ), radiosonde data ( West, 1996 ) and lately reanalysis data such as those from the US National Centers for Environmental Prediction (NCEP) ( Kalnay et al, 1996 ; Moore and Semple, 2011 ) and the ERA5 from the European Centre for Medium-Range Weather Forecasts ( Hersbach et al, 2020 ; Matthews et al, 2020a ; Szymczak et al, 2021a , b ). The state-of-the-art ERA5 data have a spatial resolution of 0.25° (about 28 km at the equator) at hourly intervals.…”

“…The levels and changes in barometric pressure and PiO 2 at different high-altitude locations has been explored extensively ( West et al, 1983b ; West, 1996 ; Matthews et al, 2020a , b ; Szymczak et al, 2021a , b ). Precise calculations of barometric pressure and PiO 2 at different altitudes have enabled analyses of how levels of hypobaric hypoxia affect humans in high-altitude expeditions ( Grocott et al, 2010 ; Milledge, 2010 ; West, 2010 ) and in simulated conditions ( Houston et al, 1987 ; Richalet et al, 1999 ).…”

“…Knowledge of the influence of hypobaric hypoxia on humans can be considered satisfactory, but hypothermic stress at high altitude has been studied only with simple parameters such as temperature, wind speed, wind chill temperature (WCT), and facial frostbite time (FFT) ( Moore and Semple, 2011 ; Szymczak et al, 2021a , b ). The standard equations for WCT ( Osczevski and Bluestein, 2005 ) and FFT ( Tikuisis and Osczevski, 2003 ) do not include variables that significantly determine high-altitude heat balance, such as solar radiation ( Pugh, 1962 ) and air density ( Huey et al, 2001 ).…”