Everest height balances on shaky scales
In 1954, an Indian surveyor BL Gulati had used an optical instrument to put Everest's height at 8848 metres. Doubts, however, were soon raised on the efficacy of the instrument.india Updated: May 28, 2003 12:26 IST
What is the height of Everest is not an obvious question to ask in the 50th year of the first ascent to the tallest mountain on the planet. But, since the 1998 American Everest Expedition (sponsored by Boston's Science Museum) put a Trimble 4800 GPS receiver on Bishop Ledge, a rocky feature below the summit, geophysicists across the world are debating whether the mountain is taller or shorter than its accepted height.
In 1954, an Indian surveyor BL Gulati had used an optical instrument called theodolite to put Everest's height at 8848 metres. Doubts, however, were soon raised on the efficacy of the instrument. Experts said that refraction of light in the upper reaches of the earth's atmosphere could affect theodolite results.
In 1999, the satellite-guided Global Positioning Systems (GPS) were used to measure the Everest again, and they put a new height to the mountain: 8850 metres. Later, the scale was again revised to 8830 metres, which is 18 metres less that the scale put out by Gulati.
The lacuna has prompted not only many in the scientific community but also the Government of Nepal to reject the new findings. "Our survey department has refused to accept the finding because the methodology of the experiment remains doubtful as also the efficacy of the findings," says Shyam Kuikil, an official in the mountaineering division of the Nepalese Ministry of Culture, Tourism and Civil Aviation.
The 1998 American Everest Expedition led by Wally Berg had planted a GPS receiver on the Bishop Ledge, which is at 8810 metres. The device recorded data for almost a week before climbers retrieved it.
"The priority was to occupy a benchmark on the Bishop Ledge. Running the receiver on the actual summit itself was not high on our list because the summit is made of snow and is therefore a moving target due to seasonal accumulation and ablation of the summit snow pack, " science manager for the expedition Charles Corfield said later on the choice of spot where the receiver was positioned
According to existing records, the Barry Bishop Ledge (or Barry Bishop Rock, as it was previously known), is a good 38 metres below the actual summit. However, according to Corfield's 'guess', it is only about 20 metres under. "Our best guess is that the summit lies no higher than 20 metres above the ledge - give or take changes in snow pack. Therefore, the contemporary height for the summit must be no more than 8,830 meters, which is a hair less than 29,000 feet, or about 30 feet lower than the current accepted height of Mount Everest," Corfield said.
(Vivek Mukherji is a freelance journalist, currently on an assignment to Kathmandu, Nepal, which is celebrating the 50th anniversary of the Everest conquest.)