Why Chinese Scientists Are Covering A Glacier With White Sheets

The air was thin as a group of scientists trudged through snow near the peak of the Dagu Glacier in southwestern China on a gloomy June morning. It was quiet up there, 3 miles above sea level, except for the sound of running water - a constant reminder of the ice melting right beneath their feet.

As they trekked upwards, oxygen canisters tucked into their fleece jackets, porters walked alongside carrying thick rolls of white fabric. The researchers planned to spread those sheets across more than 4,300 square feet (400 square meters) of the mountain. The film was designed to reflect the sun's rays back into the atmosphere, effectively shielding the glacier from the heat and hopefully preserving some of its ice.

For decades, Dagu has supported the lives of tens of thousands of people who live around it. The glacier's meltwater provides drinking water and helps to generate hydropower, while the majestic views of the Tibetan Plateau can attract more than 200,000 tourists a year, fueling an industry that keeps over 2,000 people employed. Now all that is under threat as the planet warms.

The Chinese scientists were under no illusion that their project would save Dagu. The glacier has already lost more than 70% of its ice over the past half century. One researcher described such efforts to a local newspaper as akin to a doctor merely trying to extend the life of a terminally ill patient by a few years. The only real cure would be to drastically cut emissions of planet-warming carbon dioxide, of which China is the world's biggest source.

"All the human intervention methods that we're working on, even if they prove effective, are only going to slow down" the melting, said Zhu Bin, the 32-year-old Nanjing University associate professor leading the expedition. "If the Earth keeps getting warmer, in the end there is no way to protect the glaciers forever."

This was not the kind of field work that Zhu had set out to do.

A material scientist by training, he spent most of his time in laboratories in Nanjing and New York, including more than a year researching battery storage at Columbia University. The switch to glaciers puzzled some of his academic colleagues, who teased him about leaving the comfort of doing research in an air-conditioned room. His family worried about his safety, but, he says, ultimately came around because they saw preserving glaciers as "something that's difficult but right."

Covering glaciers with sheets of reflective material isn't a new idea. European ski resorts have been using white blankets to protect their snow for nearly two decades. But China has only just begun experimenting with the approach. Small trials conducted on a glacier in Xinjiang and Dagu beginning in 2020 appear to have slowed their retreat.

This time, Zhu's team was testing out a new material that their research suggests has the potential to reflect more than 93% of sunlight and help Dagu actively lose heat. The film is made out of cellulose acetate, a natural fiber made from plants, in order to minimize its environmental impact. The substance can also be used as small particles deposited by drones on less accessible glaciers.

The first day of the expedition didn't go well. The goal was to secure the white sheets to the glacier using steam drills, wooden frames and nail guns, but the crew suffered from headaches and dizziness in the high altitude. As they moved deeper into the glacier, the waist-high snow got so thick that it was too dangerous to proceed. They decided to turn back when the weather forecast showed a rainstorm arriving in the next hour.

Previous studies have shown that covering parts of glaciers with special materials can reduce the melting of snow and ice by between 50% and 70% compared with unprotected surfaces. But chemicals or plastic particles from the sheets could negatively impact local ecosystems and downstream water quality, according to Matthias Huss, a professor of glaciology at ETH Zurich. Covering large glacial areas may also have huge and unexpected consequences.

"It's a very good solution to locally combat the effect of climate change," said Huss, especially when there are specific economic benefits. However, the real answer is "very clear," he said: "It's to save the climate."

The sheets that Zhu and his team hauled up Dagu wouldn't be effective on larger glaciers anyway, because they are constantly moving, according to Johannes Oerlemans, a climatologist at Utrecht University. "For small glaciers that are kind of dying and don't move, you can cover them easily," he said. "But as soon as the glacier moves, the cover is destroyed."

Not only is the infrastructure needed to place the sheets on a large glacier impractical, dirt would likely accumulate over time, darkening the surface and reducing their ability to reflect sunlight, says Oerlemans. He instead advocates for depositing artificial snow. A project that Oerlemans worked on sought to spread snow made from meltwater - without the use of electricity - on a glacier in Switzerland.

On the fourth day of the Dagu expedition, Zhu's team finally managed to lay down the sun-reflecting sheets after the weather improved. They'll return in September to remove the shields and take measurements to evaluate how well they worked. The researchers also collected water samples to examine the environmental impact. The experiment is set to continue for three to five years, after which the scientists will decide whether to try using their materials on other glaciers in China, or even take them abroad.

The project is supported by the local tourism bureau and tech giant Tencent Holdings Ltd., which provided funds through a sustainability initiative. While there's economic incentive for saving Dagu, everyone involved repeats the same message: the most important thing is to cut carbon emissions that are causing it to melt in the first place.

It took tens of millions of years for the Tibetan Plateau to rise to its height today. The India and Asia tectonic plates collided, making the top cold enough to host the glaciers and snow that feed nearly all the major rivers in the region, including the Ganges, Mekong, and Yangtze. Together they are lifelines for billions of people across Asia. In comparison, the reverse is happening at warp speed - the plateau has lost over 15 % of its glaciers in just 50 years.

The vast majority of glaciers around the world are retreating rapidly, leading to rising sea levels and deadly floods. Covering parts of them with sunlight-reflecting blankets is like placing a band-aid on a gushing wound. Even if the world manages to keep global warming below 2C compared to pre-industrial times - the target most countries committed to when they signed the Paris Agreement in 2015 - less than half of the roughly 4,000 glaciers in the Alps today will remain by the end of the century.

Huang Shihai, deputy head of the Dagu Glacier Management Bureau, has seen firsthand what climate change has brought to Heishui County, which sits at the bottom of the glacier. Since moving there in 2006, he's watched as summers arrived earlier, winters got warmer, rivers grew dirtier and extreme weather events occurred more frequently.

Living near the icy mountain, Huang never had much use for short-sleeved shirts. Now he starts wearing them as early in the year as May. He worries constantly that Dagu might disappear forever, and about the impact that will have on the people who rely on it. "There is a sense of crisis," he said.