Tuesday, November 23, 2010

Module IX - Not-So-Permanent Permafrost










ENGAGE

Permafrost--A Sleeping Giant Problem.
Glaciers are easy to observe and monitor. They are right out in the open. But an enormous quantity of solid water is found just underground over much of the surface of North America.

Because these icy soils remain frozen year-round, we call them permafrost. However, a new question arises in light of present warming trends; Just how permanent is permafrost? And, is permafrost a sleeping giant problem?

Pesky Positive Feedback Loop
Remember sea-ice's pesky positive feedback mechanism--albedo vs. absorption? Permafrost has its own interesting pesky positive feedback potential problem; Methane. CH4. And lots of it.

Every year, the shallow surface, or active layer, in permafrost zones thaws in the summer allowing a brief window for plants to grow, die and partly decompose. But because freezing inhibits microbial decomposition of ancient plant matter, decomposition is very slow work in cold climates.

The non-decomposed material left over each year accumulates in an every-growing massive biomass store of frozen Carbon. This is good if you want to take Carbon out of the atmosphere--and it stays frozen.

The pesky problem arises when this massive carbon biomass sink starts to thaw at an accelerated rate; As it warms, this giant compost heap produces decomposition gases, methane and carbon dioxide, which are released in correspondingly massive quantities. And here is the problem--methane and carbon dioxide are greenhouse gases that exacerbate the situation. Particularly methane.

It's like this: more thawing ... more decomposition ... more green house gases ... more atmospheric heating ... more thawing ... more decomposition ... more greenhouse gases ... more atmospheric heating ... more thawing ...... you get the picture....like a snowball rolling downhill.


How Firm a Foundation?
Ice can be very structural, as long as it remains solid. But, when sub-surface ice melts, man-made structures and natural systems are disrupted and altered. Undulating waves of surface soils and odd soggy polygonal patterns are indicators of localized changes in hydrology and the depth of permafrost.

Pingo, polygon ice wedges, thermokarst, and solifluction not yet in your daily vernacular? Permafrost science has its own fun language and heroes. Ever seen Tunnel Man? It's time to explore the weird world of permafrost.
EXPLORE

Teachers' Domain
Melting Permafrost









YouTube
Here's another of Alaska's permafrost heroes--TUNNEL MAN! Watch one or all.
Tunnel Man Episode 1
Tunnel Man Episode 2
Tunnel Man Episode 3








NOAA's Ark of Arctic Information
One of Alaska's permafrost ice science heroes is Vladimir E. Romanovsky, Associate Professor Geophysical Institute University of Alaska, Fairbanks. NOAA hosts his research and photos on their Arctic Theme Page.

Read this overview of Alaska ice science issues: How rapidly is permafrost changing and what are the impacts of these changes? Then go on to the excellent permafrost photo gallery showing the various features and effects associated with permafrost.


  • Helpful Hint: Spend some extra time at NOAA's Arctic Theme Page. Check out their near-real time Arctic indicators and even the 2009 North Pole web-cam!
  • Helpful Hint: Included in the Alaskool collection is this primer on permafrost, including a great treatment of some of the vocabulary unique to ground ice science. While you're reading about these landscape features and processes associated with permafrost, try referring back to NOAA's Romanovsky's permafrost photo gallery
EXPLAIN
  • How does melting permafrost change local hydrology?
  • How does permafrost changes affect human structures?
  • What positive feedback systems accompany melting permafrost?
EXTEND
  • Consider making and posting your own video regarding the affects of climate change in your area.

EVALUATE
  • How valuable are these digital media for helping students understand permafrost processes?



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