1.00pm - By CHARLES ARTHUR
Eight climbers died near the summit of Mount Everest eight years ago because the sky fell below them, a scientist has claimed.
The calamity that befell two groups of climbers around the mountaintop in May 1996 was later immortalised by the writer Jon Krakauer, who was among them, in the book "Into Thin Air".
New Zealand guides Rob Hall and Andy Harris both died in the tragedy.
Now Kent Moore, a physicist at the University of Toronto in Canada, has dramatically discovered that the title is more accurate than anyone realised.
And he has suggested that in future, climbers attempting the highest peaks should avoid days with high winds, which will strip vital oxygen from the air.
Professor Moore told New Scientist magazine that he thinks the weather patterns that day led to the atmospheric pressure falling so dramatically that in effect the stratosphere dropped onto the summit of the 8,848-metre mountain. Normally the peak sits just below the atmospheric layer.
That would be the equivalent of raising the summit by 500m on a normal day - and would cut the available oxygen in the air, which on the summit is just one-third that at sea level, by 14 per cent.
Although most climbers at the summit use supplementary oxygen, they still rely on that in the air to help them breathe. But above 8,000m there is too little oxygen to sustain life, making it essential that people spend as little time as possible at such heights.
The events of the tragic day have been pieced together from survivors' accounts.
Led by American Scott Fischer, some of the group climbed through the night of 9 May and reached the summit in clear weather early in the afternoon of 10 May. Looking down they noticed storm clouds below them on the mountain, and decided to descend as fast as possible.
But as the team made their way down, Mr Fischer - who had previously climbed the mountain a number of times - began to "struggle", according to Neal Beidleman, one of two other highly experienced guides with the group.
By late afternoon, amidst 75mph winds, some of the group had to be abandoned, disoriented, on the upper reaches of the mountain. Mr Fischer and seven others eventually died.
Professor Moore's hypothesis also sheds new light on the heroism that day of one of the professional climbers on Mr Fischer's team, the Russian Anatoli Boukreev.
He was key in rescuing a number of the group who had become stranded on the mountain below the summit, climbing repeatedly up to the group and leading or even dragging them down to the safety of their camp below the 8,000m mark.
Most remarkably, he carried out his rescues for more than 12 hours with no bottled oxygen, in the teeth of the storm and at a time when the air would have been severely depleted.
Professor Moore explained that the "jet streak" winds travelling at more than 100mph up the sides of the mountain would have dragged a huge volume of air upwards, causing the air pressure to drop and leaving less oxygen available to the desperate climbers.
"At these altitudes climbers are already at the limits of endurance," he said. "The sudden drop in pressure could have driven some of these climbers into severe physiological distress."
The suggestion has been strengthened by results recorded by a temporary weather station that was placed on the summit in 1998 when a similar "jet streak" occurred.
That recorded a fall in pressure of 16 millibars, which would raise the summit by 500m. The height of Everest has always struck climbers as a convenient accident.
If it were 500 metres higher, some experts reckon it would be impossible to climb without oxygen: the distance from the start of the "death zone" to its summit and back would be too great for anyone to survive.
- INDEPENDENT
Everest climbers died because sky fell below them says scientist
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