Hi! My name is Ms. Harsh. Please join me as I travel to Churchill Canada to study climate change.

Saturday, September 12, 2009

Permafrost



Today we collected more samples- we did our peat pits,seedling samples but today we also did a permafrost core sample. I have learned alot about permafrost on this little adventure. Before I thought that permafrost was always the top layer of soil- but I have learned that the layer of permafrost can be just a few centimeters to several meters below the surface. Today we dug down to the permafrost layer- it was so hard that you couldn't break it with the shovel. We had to dig down 50 cm in one are and only 30 cm in another are. Of course we took soil samples and surveyed for seedlings. The upper layer that thaws in the summer is called the active layer. The thicker the active layer the larger the trees - the soil is thicker and warmer and more nutrients are available.


What is permafrost? (answer in your journal) What is the difference between continuous and discontinuous permafrost?


The thickness of permafrost can be altered by changes in the climate or disturbance of the surface. Permafrost thins and the active layer thickens when ground temperatures increase. Some 24 percent of land area in the Northern Hemisphere is underlain by perennially frozen ground. Another 57 percent -- extending down into much of the United States and Europe -- freezes seasonally. But the permafrost in some areas is declining and this is affecting the structures on the surface. Sometimes ponds will form when the ice melts and the soil above it collapses, roads have been damaged to name a couple. The effect is not just in the far north. Some 80 percent of U.S. soil freezes every winter. Change to the cycle will affect crops, native plants and even how much carbon is exchanged between Earth's surface and atmosphere. This is why research like Dr. Kershaw's is so important.




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