New ways to study permafrost and climate change

Susan Hubbard - radar
Susan Hubbard collecting ground-penetrating radar data

What does pulling a radar-equipped sled across the Arctic tundra have to do with improving our understanding of climate change? It’s part of a new way to explore the little-known world of permafrost soils, which store almost as much carbon as the rest of the world’s soils and about twice as much as is in the atmosphere.

The new approach combines several remote-sensing tools to study the Arctic landscape—above and below ground—in high resolution and over large spatial scales. It was developed by a group of researchers that includes scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).

They use ground-penetrating radar, electrical resistance tomography, electromagnetic data, and LiDAR airborne measurements. Together, these tools allow the scientists to see the different layers of the terrestrial ecosystem, including the surface topography, the active layer that seasonally freezes and thaws, and the deeper permafrost layer.

The goal is to help scientists determine what will happen to permafrost-trapped carbon as the climate changes. Will it stay put? Or will it enter the atmosphere and accelerate climate change..?

The scientists tested their system on a plot of land near Barrow, Alaska, that measures about 500 meters long and 40 meters wide. Hubbard and her team conducted their first field campaign at the site last fall when the system was freezing up. They’ve since returned several times to conduct more research…

The scientists use data from airborne Lidar, surface geophysical measurements, and point measurements to explore the complex relationships between different layers of permafrost soil.

The scientists also used three tools to explore the hidden world below the surface. Ground-penetrating radar was pulled from one end of the plot to the other. They set up a string of electrodes at different locations to conduct electrical resistance tomography measurements. Electromagnetic data was collected along more than a dozen lines that spanned the length of the plot. The scientists also collected point measurements of temperature, moisture, and other properties at several locations to verify the data from the remote-sensing tools.

These geophysical measurements, coupled with the point measurements, allowed the scientists to see how the different layers of the permafrost system vary spatially, including the topography, the active layer, and the deeper permafrost. They could also see how these layers relate to each other…

“Overall, this combination of methods helps us understand the spatial and temporal interactions between surface microtopography, the active layer that controls soil respiration and generation of greenhouse gasses, and the deeper permafrost layer, which controls the formation of the polygonal features,” says Susan Hubbard. “This approach also allows us to sample over large spatial regions with minimal disturbance to the ecosystem—two important criteria when it comes to studying the vast and delicate Arctic landscape.”

Bravo! And yet more information worth reading in detail if you care to be well-informed on all aspects of questions dealing with climate change.

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