A massive experiment in Taiwan aims to reveal landslides’ surprising effect on the climate
By Katherine Kornei
Taroko National Park, famous for a precipitous marble gorge that cuts through it, is in a futile fight with gravity. Rockfalls litter the park's serpentine main highway. The scars of at least a dozen landslides punctuate the view in all directions. Maintenance crews are perpetually spraying concrete on slopes in a last-ditch effort to stabilize them. The park gives out safety helmets for free, and strongly encourages visitors to wear them.
For [Niels Hovius, geomorphologist at GFZ German Research Centre for Geosciences], all this moving rock and soil makes for a perfect laboratory. For the past 3 years, he and his colleagues have scrambled and rappelled across the park, installing dozens of instruments in what will end up being Taiwan's most comprehensive landscape dynamics observatory. One goal is to monitor landslides and understand their triggers. A bigger aim is to investigate their hidden impact on the climate: As massive chemical reactors, landslides draw carbon dioxide (CO2) out of the sky and sometimes belch it out, too. Understanding their role as both carbon source and sink could help researchers better model the carbon cycle that ultimately controls our planet's climate and habitability.
Many of the instruments will work as sensitive landslide detectors. Seismometers will pick up ground shaking from tumbling rocks, and cameras will record fresh landslide deposits and scars. The continuous monitoring is a step up from patchy satellite observations and sporadic reports from tourists and park rangers, Hovius says. He and Turowski plan to share their data with Taroko officials, who can use the near–real-time detections to decide whether to close trails or roads—or search for stranded hikers.
The team will also tackle a deeper mystery: the invisible influence of landslides on the atmosphere. The exchange of carbon between the atmosphere, the surface, and the oceans ultimately regulates Earth's habitability. For now, humanity—through industrial and agricultural emissions—is a dominant force in the carbon cycle. But over geologic time, the interaction of water with rocks freshly exposed by erosion—so-called chemical weathering—is another powerful player. And landslides are catalysts that speed up chemical weathering. They exhume fresh rock and grind it down into smaller pieces, creating more surface area for reactions. They also carve depressions in slopes that funnel rainwater into the rock.