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The newly installed station will help Chile understand a historic drought with no signs of easing.

At 19,000 feet above sea level on the Chilean mountain of Tupungato, Baker Perry and his fellow climbers were clobbered in the early morning hours by an unforecasted blizzard that pinned them in their tents with punishing winds and swirling snow. Perry, a climate scientist at Appalachian State University, was philosophical as he recalled it.

“It’s part of the beauty of the mountains that it is so challenging. That’s one reason there’s not many stations up in some of these places,” says Perry. “We want to see it at its stormiest and at its most challenging as well. That’s part of the climate. We need to measure that.”

Perry is the co-leader of a team that in February braved a global pandemic and a two-week trek through dense snow to install a weather station just below the summit of Tupungato, a dormant volcano in the southern Andes, where Chile meets Argentina. Now the highest weather station in the Southern and Western hemispheres, the tool will help scientists understand how rapidly this region’s climate is changing. The expedition was organized by the National Geographic Society and supported by Rolex.

With data on temperature, wind speed, and snowfall, scientists can better understand how central Chile and the country’s capital of Santiago will fare as climate change exposes the region to more drought—like the historic one it’s in right now—while shrinking the mountain glaciers and snowpack that act as its water towers.

“The stakes are really high now,” says team member Tom Matthews, a climate scientist at Loughborough University in the United Kingdom. “There are millions of people living downstream of these water towers. They are part of this system we know very little about in terms of how it may respond as the climate warms.”

Tupungato is the third highest peak in Chile, and the tallest mountain in the Maipo river basin, the watershed that supplies the seven million people living in and around Santiago. With better data on how much precipitation is falling on mountaintops like Tupungato, government officials will know how much water they have to allocate in a given year.

“Since 1982 I’ve been studying glaciers. Within my lifetime we've seen tremendous changes in glaciers and snow cover,” says expedition co-leader Gino Casassa, a National Geographic Explorer and the head of the Chilean government’s glacier unit.

In a dry year, says Casassa, two-thirds of the water feeding the Maipo River at the end of the summer comes from glaciers that are shrinking.

Central Chile is a Mediterranean ecoregion, climatically similar to places like California. It lies just below the Atacama Desert, the driest desert on Earth, and is wedged between the Andes mountain range and the Pacific Ocean.

Historically, Chileans are used to periodically seeing dry years; 2010 was one such year. Then 2011 came, and 2012, and still there was little rainfall.

“Then came 2014,” which was also dry, “and that was suspicious,” says René Garreaud, a climatologist at the University of Chile, who was not involved with the expedition.

By 2015, Garreaud and his Chilean colleagues had determined that the region was experiencing what they called a mega-drought. It still hasn’t lifted after a decade of dry conditions. On average, since the drought began, there’s been a third less rainfall every year than in normal years. During the driest year so far, 2019, there was 90 percent less rainfall.

While Garreaud says there’s some natural variability that influences rainfall on decades-long timescales, there’s no doubt climate change is behind the mega-drought. In general it is expected to make dry regions drier and wet regions wetter.

That’s bad news for central Chile, which relies on the mountain water towers in the Maipo river basin for fresh water. According to a paper published in the journal Nature in 2019, water towers around the world, from the Andes to the Himalayas, are imperiled by climate change.

Two years ago, Perry and Matthews installed a weather station on Mount Everest, making it the world’s highest. The Chile trek was the latest of National Geographic Society’s Perpetual Planet Expeditions,  which fund exploration and research in ecosystems impacted by climate change.

It took the team about a week to summit Tupungato, at more than 20,000 feet, and another to descend it. In the months leading up to the trip, team members trained extensively. Perry, who’s based in North Carolina, spent hours climbing steep trails with a heavy backpack.

The weather station carried to the top of Tupungato is a relatively lightweight tripod made of aluminum, though it still weighs 120 pounds and is six feet tall. It’s engineered to be light enough to carry in a backpack, but still strong enough to withstand some of Earth’s strongest winds.

Securing it at the summit required approximately two hours of bolting and staking with guy wires to keep it stable. The station is powered by solar panels and has an antenna for satellite communication.

It has already clocked wind speeds of over 112 miles per hour, Perry says.

The scientists installed temperature sensors three feet deep in the permafrost at the summit to track changes in the temperature of the  permanently frozen soil. The station will also measure radiation, snow depth, and albedo, or reflectivity. As less snow falls and the ice melts, exposing dark rocks, the ground will reflect less and absorb more solar energy, potentially accelerating the melt.

“As the climate warms, glaciers will retreat quite quickly,” says Matthews. “How quickly? We don’t know. Most observations have been made on the mountain at quite low elevations, so we lack information about what’s going on in the upper third.”

Figuring out just how much fresh water Chile has locked in its mountains and when it might reach critically low levels is a complex prediction to make, he says. In the short term, warming temperatures lead to more water that can cause floods. However, as the melting accelerates, the glaciers eventually “get so small that even though they’re melting quite quickly, there’s less to melt,” says Matthews.

Scientists refer to that transition point as “peak water,” when the short-term rush of water turns into a longer-term shortage.

As the U.S. and other countries around the world, including Chile, commit to reducing the emissions that fuel climate change, central Chile must still prepare for worst-case scenarios.

Garreaud is cautious about saying Santiago might hit a “day zero” for running out of water, as residents of Cape Town, South Africa feared might happen there in 2018. He’s optimistic the region can adapt, using water more efficiently and reducing consumption. The city is also constructing its first desalination plant.

Only three other high-altitude weather stations are in the Maipo River Basin, and Casassa hopes the station will become one of many. He and his team plan to install more throughout Chile.

Read this article in Spanish or Portuguese.

The Tupungato Volcano Expedition was organized by National Geographic Society and supported by Rolex as part of its Perpetual Planet initiative.

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