Climate change makes Mt Everest less breathtaking

IN 25 years’ time, will climbing Mt Everest without oxygen still be impressive? Scientists think not.

Thanks to rising temperatures, the so-called death zone near the top of Everest, in which a lack of oxygen slowly kills climbers, is shrinking.

Now a study, authored by scientists who climbed almost to the top of Everest themselves, has quantified by just how much: with 2 degrees Celsius of warming, it is as if the summit were about 100 metres lower.

‘‘As the climate warms, the (air) pressure at the summit goes up,’’ said Dr Tom Matthews, from Loughborough University in England.

Thanks to glacier melt, the formidable Khumbu Icefall that so intimidated Sir Edmund Hillary and Tenzing Norgay on their first ascent in 1953 is slowly receding. Other parts of the mountain have become more dangerous – thaws can lead to rockfalls and loosened holds.

More than 4000 people have climbed Everest, but only 200 have done so without oxygen. The higher you get, the thinner the air, and around 8000m it is impossible for most climbers to continue without help. This is when the many tourist climbers use supplementary oxygen.

In 2019, Matthews climbed to 8400m, 400m below the summit, to install a weather station. The data from it told him that for climbers, even those who eventually used extra oxygen, the hidden effects of atmospheric pressure might have been the difference between success and failure.

Over a single year, the air pressure fluctuated hugely – so much so that the difference between the worst and best days was the equivalent of raising Everest’s summit by 750m.

Using the data, Matthews and his colleagues were able to reconstruct the weather on Everest in previous years. They found that of those climbers who reached the top without oxygen, about 80 per cent did so on days with above-average air pressure.

With a 2C rise in temperatures anticipated by the end of the century, the scientists calculated that the average oxygen intake of climbers would increase by 5 per cent – equivalent to lowering the summit by roughly 100m.

The research was published in the journal

Air pressure at Mt Everest’s summit is rising due to climate change – which means more climbers may be able to conquer the famous peak without using oxygen.