tropical permafrost – A team studying Peru’s Nevado Coropuna says a frozen ground layer—15 to 20 meters thick—sits near the surface under the volcano’s upper flanks. As nearby glaciers retreat, that hidden permafrost could become a crucial regional water source, though its full ext
Up on Nevado Coropuna, at roughly 5,000 meters above sea level, researchers expected to find some frozen ground—just not how much.
On the volcano’s upper slopes. geographer Ramón Pellitero and colleagues report a layer of frozen ground 15 to 20 meters thick. sitting two to four meters below the surface. The paper. published May 26 in *Permafrost and Periglacial Processes*. describes the find as part of one of the world’s largest tropical permafrost areas. The scientists have not mapped its full extent yet, but they suspect similar conditions extend across the wider area.
For Pellitero, the surprise wasn’t simply that the permafrost exists. It was the thickness. “How thick it was was surprising,” he says. “So, the volume is going to be very, very big.”
That matters because the Peruvian Andes are losing their traditional safety net. Much of the region’s water now comes from glaciers that are rapidly shrinking. The team argues that permafrost could provide something different—a hidden water reservoir that may become more important as glaciers retreat.
“Such resources could be a lifesaver for local communities in this arid region,” the researchers write, and Pellitero puts the point directly: “But you have permafrost underneath, and the water resources from permafrost are becoming more and more important.”
The researchers also stress that the Coropuna deposit is not comparable in size to the massive permafrost found in colder regions such as Canada and Russia. Still, even without matching those extremes, the authors say this cache could matter on a local scale.
Other scientists are watching closely because tropical permafrost in mountains has been under-studied. Stephan Gruber. a geographer at Carleton University in Ottawa. Canada. says the combination of permafrost and high terrain is full of knock-on effects. “The combination of permafrost and mountains is under-researched,” he says. “And there are a lot of important connections with hazards and with water and with ecosystems. So I think it’s great that they do research there.”.
The findings rest on difficult fieldwork. To look for evidence of frozen ground underground. the team hiked across harsh terrain on Coropuna’s upper slopes and relied on ground-penetrating radar. along with vertical electrical sounding. That second method uses electrodes placed in the ground to measure electrical resistance: high resistance signals the presence of ice. But the work came with an immediate practical constraint.
“Because the method needs water to work well and there’s none to be had in the area. the team had to carry it up the mountain themselves. ” the researchers write. Another challenge was simply reaching the site and working there repeatedly. Pellitero says fieldwork has been rare for a reason: “One of the reasons that nobody has been doing this fieldwork is because the area is quite far away from everything and we always work at over 5. 000 meters.”.
Tropical permafrost is known in other places too—Pellitero points to Tanzania’s Kilimanjaro and Hawaii’s Mauna Kea volcano. He notes that one patch on Mauna Kea shrank from about 600 square meters in the 1970s to roughly 200 by the mid-2010s and continues to melt. But he says none are as large as the tropical permafrost area suspected beneath the Peruvian Andes.
The team is now continuing their work in Peru. They plan to use electric resistivity tomography—subterranean imaging technology—to map the permafrost more precisely around Coropuna, where they suspect similar frozen layers extend.
Pellitero’s confidence is cautious but pointed. “If you have permafrost at this [5,000-meter] elevation, we can assume that there will be permafrost over there as well,” he says. “But we don’t know yet.”
Behind the science is a clear real-world question: as glaciers retreat, will this buried ice be enough—and for how long? The team’s current estimate focuses on a specific frozen layer near Coropuna’s surface, but their main conclusion depends on what their mapping will reveal next.
tropical permafrost Peru Nevado Coropuna glaciers water resources ground-penetrating radar electric resistivity tomography climate change arid region