Ice Stories: Dispatches From Polar Scientists » soil http://icestories.exploratorium.edu/dispatches Mon, 15 Nov 2010 20:40:36 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 Digging Soil Pits http://icestories.exploratorium.edu/dispatches/digging-soil-pits/ http://icestories.exploratorium.edu/dispatches/digging-soil-pits/#comments Fri, 08 Aug 2008 19:06:46 +0000 Amy Breen http://icestories.exploratorium.edu/dispatches/?p=581 TOOLIK FIELD STATION, ALASKA– The northern foothills of the Brooks Range, including Toolik Lake, received nearly 15 cm of rain over the past several months. In Fairbanks, the rivers are at levels not observed since 1967. The tundra is fully saturated with the recent precipitation. Because of the underlying permafrost, these waters don’t penetrate deep into soils. Instead, the water sits stagnant. This phenomenon affects our efforts to sample the tundra soils adjacent to our vegetation plots.

Often, soon after we dig a soil pit, it fills with water from the surrounding saturated tundra.

Watch this video, to see how we remedied the problem on a recent snowy and blustery day.



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Tundra and Permafrost http://icestories.exploratorium.edu/dispatches/big-ideas/tundra-and-permafrost/ http://icestories.exploratorium.edu/dispatches/big-ideas/tundra-and-permafrost/#comments Tue, 13 May 2008 00:44:21 +0000 Exploratorium http://icestories.exploratorium.edu/dispatches-new/?page_id=12 The Arctic tundra
The Arctic tundra.
Digging in permafrost. Photo by Nick Bonzey.
A jackhammer is needed to dig deeper into the permafrost.
The summer tundra
The summer tundra.
Courtesy of Shishmaref Erosion and Relocation Commission
In Shishmaref, Alaska, melting permafrost has contributed to major erosion, forcing residents to consider moving the entire village to a new location.
Melting permafrost from above
Melting permafrost from above.

If you want to dig a ditch in the Arctic, you’d better bring more than a shovel. Even at the height of summer, you may only be able to dig down a foot or two before you hit solid, frozen soil known as permafrost. Permafrost is found in places where the average annual temperature is below about 23°F (- 5° C), including most of the Arctic and all of Antarctica.

Land with underlying permafrost is called tundra. The arctic tundra is stark and treeless. Roots can’t penetrate the frozen soil, so only moss, lichen, and low shrubs can grow there. In summer, the topmost layer of the permafrost melts, leaving behind soggy ground, marshes, bogs, and lakes.

Buildings constructed on permafrost have a notorious tendency to sink, crumble, or tilt like the Leaning Tower of Pisa. That’s because heat and pressure from overlying structures can cause the permafrost just under the structure to melt, turning formerly firm soil into mush.

In recent years, however, permafrost has been melting en masse, thanks to increases in global average temperatures. The zones where permafrost can be found year-round are creeping northward, and permafrost coverage, currently 20 percent of the earth’s land surface, is predicted to shrink drastically in coming years.

A mass-melting of permafrost would contribute significantly to rising sea levels. It might also accelerate global warming by releasing greenhouse gases into the air. Rich in organic material, the soil in the Arctic tundra will begin to decay if it thaws. As it breaks down, it will release large amounts of methane and carbon dioxide—two greenhouse gases—into the atmosphere. Thawing permafrost could thereby result in a positive feedback loop in which thawing causes faster warming, resulting in more thawing.

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