Solar power hits Everest
Data from a network of newly installed weather stations atop Mt Everest shows that the mountain experiences some of the most intense sunlight on the planet.
This epic lighting does more than give hikers nasty sunburns. In a warming world, it might be hastening ice melt atop the world’s highest mountains and affecting glaciers in ways scientists don’t fully understand.
Presented at the American Geophysical Union’s annual meeting in San Francisco yesterday, the new data is among the first scientific results to emerge from the National Geographic Society’s Perpetual Planet Extreme Expedition to Everest, a multidisciplinary effort to study climate change atop the world’s tallest mountain.
Earlier this year, researchers installed a network of five automatic weather stations at elevations of up to 8400 metres (27,600 feet), including the two highest weather stations on the planet. Previously, the highest station the researchers knew of sat atop nearby Mera Peak, at a comparably paltry altitude of about 6400m (21,000 feet).
‘‘There’s still a lot of ice in the Himalayas above that altitude,’’ said Tom Matthews, a climate scientist at England’s Loughborough University and the meteorology co-lead for the expedition. ‘‘It’s a monumental data gap.’’
All five stations are collecting data on air temperature, pressure, relative humidity and wind speed. Every station except for the highest one is outfitted with a net radiometer, an instrument that measures incoming and outgoing radiation.
One of the key motivations behind the network is to better understand the amount of energy available to melt snow and ice in high alpine environments.
Matthews said the highest Himalayan peaks were incredibly sunny, both because there’s less atmosphere to attenuate the light and because of their nearequatorial latitude. Everest hikers experience this viscerally, often becoming overheated when the air temperature is close to freezing.
However, solar radiation often wasn’t accounted for when scientists modelled ice loss, Matthews said. Without available data, scientists may assume ice melt is driven solely by the air temperature.
Early returns from the new weather station network suggest the Sun is a truly dazzling force atop Everest, and its ice-melting power needs to be considered.
In some cases, Matthews said, the stations had registered levels of solar radiation equal to or exceeding the solar constant – the amount of sunlight scientists expect to see at the outermost limits of Earth’s atmosphere.
The researchers suspect that this unearthly luminescence is the result of sunlight getting pingponged around by snow and ice as it falls on Everest’s frozen spires.
The new data hasn’t yet been published in a peer-reviewed journal. But if the findings hold up, Matthews said it could mean there was significant melt occurring hundreds of metres above the point where air temperatures drop below freezing.
At very high altitudes, much of the meltwater produced by the Sun is probably refreezing in place as it percolates into the snow. As it does, it releases heat energy and fills in air pockets, causing the surrounding snow and ice to become warmer and denser. This may be affecting the long-term evolution of alpine glaciers in ways that aren’t being captured by modelling.
Sorting out the various processes driving ice loss in the Himalayas has never been more urgent. Its glaciers, which provide the water nourishing lands home to more than a billion people, are receding fast as global temperatures rise.
A groundbreaking report published this year concluded that glaciers across the Hindu Kush Himalayan region could shrink in size by a third even if the ambitious global warming target of 1.5 degrees C is reached.