In a warming world, glacier scientists have to keep going higher
From the summit of Huascarán, the highest mountain in the tropics, the valleys of the Western Andes seem placid and peaceful, even calm. The signs of climate change - the melting of glaciers in the Andes, changes in the water supply to local villages - are not immediately obvious.
But the scientific team at the top of the mountain knows that these changes are there.
That's partly why they traveled so far, from the United States, Mexico, Italy, Peru, France and Russia, and undertook this heartbreaking ascent to over 22,000 feet: to visit the glaciers at the top and drill ice columns to send them back to Ohio State University for analysis. The ice contains many clues about what has happened in the Earth's atmosphere and climate in the region over the past 20,000 years. And if the Earth continues to warm up, the glacier may not be here much longer.
Lonnie Thompson climbs Huascaran, the highest peak in the tropics, in Peru in the summer of 2019.
"I have been working in Peru for 44 years and have visited some ice fields 25 times," said Lonnie Thompson, a distinguished university professor at the School of Earth Sciences and senior research scientist at the Byrd Polar and Climate Research Center. "And I was able to document the increase in temperature and melting that is occurring on the peaks of several of these glaciers."
Huascarán is a peak in the White Cordillera in northern Peru. Thompson was here in 1980, 1992, 1993, 2016, and in the summer of 2019, he led a group of scientists to see how the glacier had changed and to collect new ice samples.
Due to its altitude, Huascarán is one of the most difficult and dangerous peaks Thompson and his crew have ever trained on. But this altitude also protects the ice. Currently, the low-lying glaciers, where it is warmer, are melting rapidly and the Huascarán glacier will eventually melt, but for now it is probably one of the few remaining intact tropical glaciers in the world.
"We believe this mountain is the only one in Peru that still has a largely unaltered trace of ice, both in the pass (the flat glacial zone between the northern and southern peaks) and on the upper southern peak," Thompson said. "And this makes it ideal for some types of gas measurements that have never been made in low latitudes before - if there is a tropical place on Earth where you can measure gases like methane, it will be him."
Although they encountered local political tensions during the expedition, the drilling process went smoothly - more easily, Thompson said, than any of the 80 similar trips he has made over the past 80 years.
Extracting ice from glaciers in the tropics can be difficult. Climbing is often dangerous - in the case of Huascarán, avalanches have forced the team's mountaineers to create a brand new route to the summit (mountaineers are known for naming their routes; they have named it the "Lonnie Thompson Route" in Thompson's honour). The air becomes scarcer as you climb up to the heights; altitude sickness is a real threat. Symptoms, which include shortness of breath, can also go unnoticed or begin at altitudes as low as 8,000 feet. At 22,000 feet, the air is so thin that the science team has moved with emergency oxygen tanks and a Gamow bag, a portable hyperbaric chamber that can be pressurized to sea level. Fortunately, neither of them had to be used.
"It's this high altitude that keeps the record in the ice cores - if you hadn't had these cold temperatures, you wouldn't have had the record," says Thompson. "We have made dozens and dozens of expeditions, and the result of climate change is that we must continue to go higher on the glaciers. And it becomes a problem, because - well, I'm getting old, for example. And we are strict about acclimatization - we hike four or five thousand metres, then go down and sleep at lower altitudes. But it can wear out on the body."
And Thompson, who celebrated his 71st birthday in Peru at the beginning of this summer's expedition, had a heart transplant in 2012.
But the work is necessary, Thompson and other scientists believe: Through their work on ice cores, climate scientists around the world now know that climate change could have devastating effects on vulnerable populations in the Andean Cordillera and Tibetan plateau region. Their research has shown that glaciers in both parts of the world are melting faster than at any other time in the past 6,000 years, with potentially serious impacts on water supplies in parts of Peru, Pakistan, China, India and Nepal.
On this last trip, they drilled more than 471 metres of ice cores - long columns of ice that had been frozen since the last ice age. Analysis work is already underway - Thompson calls it "some of the best cores we have ever drilled".
They hope to start publishing their results from the carrots soon. The cores will be analyzed to detect mineral dust to detect droughts; isotopes that indicate temperature changes; black carbon and trace elements to determine if fires such as those burning in the Amazon this year are part of historical records; greenhouse gases to see how their concentrations in the atmosphere have changed over time; pollen to track changes in vegetation and microbes to determine their evolution over the last 20,000 years.
In the meantime, Thompson and the team are planning their next trip. There are glaciers in Peru and Tibet that they would like to review, and there are other analyses to be done on the ice that they have already collected in other parts of the world. He wants to ensure that he helps the next generation of scientists understand how to do this kind of field work.
"These are difficult expeditions - there is the risk of avalanches; there is always the risk of injuries, inflections and various problems at high altitude," he says. "But if you overcome them, you realize the potential you are capable of. Some of our younger members use it like a duck in the water. But the only way to get this experience is to go out in the field, first on low-lying glaciers, then on higher and more difficult glaciers like those in Huascarán."
