Despite being the highest point on Earth, Mount Everest still can’t escape the effects of climate change. The only place that punctures the stratosphere—Everest’s peak reaches 29,035 feet above sea level—has an atmosphere so thin that it leaves mountaineers gasping for breath and glaciers so big that they stretch for miles on end. But both of those elements are changing fast. According to two new studies published today in iScience and One Earth, the air pressure near Everest’s summit is rising, making more oxygen available to breathe, and glaciers are melting at unprecedented rates, leading to more meltwater. The changes will impact climbers scaling the peak and local people who live in the shadow of it.
When temperature rises, molecules move faster. And when these molecules start to collide with each other, pressure increases. More pressure means more molecules, making more oxygen available to breathe, says lead author Tom Matthews, a climate scientist at Loughborough University in the U.K.
To analyze the changes in the atmosphere, Matthews and his team collected data using those weather stations they installed on the Everest expedition in 2019. They coupled their newly collected data with analyses produced by the European Centre for Medium Range Weather Forecasting to reconstruct what the climate was like on Everest from 1979 to 2020.
The real surprise of this study, Matthews says, is learning how dramatically the atmospheric pressure on Everest can vary. From the 40 years of data, the team picked out the day with the lowest air pressure on record and compared it to the day with the highest. The difference was huge, Matthews says, with oxygen availability between the two days being equivalent to an elevation change of 2,460 feet.
And the climate can vary remarkably within a span of a few days, he says. On one day, the air at the summit can feel breathable without supplemental oxygen; a few days later, the pressure can plunge to thin, sharp, mid-winter-like air, making it unclimbable. This means that for climbers planning to forego supplemental oxygen and push their bodies to the absolute limits, they must pay close attention to oxygen forecasts. For example, if climbers leave basecamp on a day when an oxygenless summit would be physiologically possible and then arrive a week later when the pressure has bottomed out, it could be a “real horror show,” Matthews says.
The average temperature from 2000 to 2016 is about 1.8 degrees Fahrenheit warmer than the average between 1975 and 2000. Although rising temperatures are the primary drivers of glacier thinning, other big factors are at play, King says. As the glaciers retreat, they often leave behind rocky debris and expose cliffs and troughs on the mountainsides. The exposed rocks absorb more radiation from the sun, melting the adjacent ice. The melted water then seeps into the troughs created by the retreating glaciers, creating small ponds. The ponds melt the surrounding ice, and more water fills the ponds. Ultimately, clusters of ponds join up and form huge glacial lakes. As a result, more than 400 new lakes formed between 1990 and 2015, King says.
In addition to the 18 Indigenous communities residing in the Himalayas, nearly two billion people depend on the mountain range for a source of freshwater. As melting accelerates, it puts that once-steady source of water in jeopardy, threatening the lives and livelihoods of nearly a fifth of the world’s population.
At 8,430 meters above sea level, the high-altitude expedition team celebrates after setting up the world’s highest operating automated weather station during the National Geographic and Rolex Perpetual Planet Everest Expedition.
A member of the National Geographic and Rolex Perpetual Planet Everest Expedition team takes a sample from a rock outcrop next to the Khumbu Icefall above Everest Base Camp.
https://www.smithsonianmag.com/science-nature/thicker-air-and-thinner-ice-how-climate-change-affecting-mount-everest-180976360/