Supplementary reading L2


University finals GEOG3004 (2 Drivers & Contrasts) Note on Supplementary reading L2, created by samflint93 on 07/10/2013.
Note by samflint93, updated more than 1 year ago
Created by samflint93 almost 11 years ago

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Paraglacial land form assemblages at High Alt(Tibet): In transitional paraglacial landscapes it is mostly moraine material that is responsible for mass movement. Paraglacial landscapes in high altitudes (alpine) that have undergone glacial processes are generally sediment rich in comparison, and so the sediment landform's are described as polygentic.

As the US looks to diversify its energy supply Karion et al. have found that leaks are between 6.2-11.7% and that this contradicts any short term climate benefits as well as representing economic loss and pollution hazard.

Warming will result in: surface temp increase of 4 - 10 deg for northern canada, with the greatest increases occuring near the sea due to changing sea ice patterns. These changes will affect the soil  Higher Autumn precipitation can be expected leading to more snow cover and insulation for the permafrost, hindering the cooling of it. An increase in the speed of the spring warmth will cause snow melt, however as the ground is still frozen this could cause flooding as all the snow becomes run off. Higher summer air temp and increased evaporation will result in greater wildfire frequency removing the organic later insulating the ground. This will cause the active layer to deep/thicken => melting permafrost. In discontinuous permafrost it could disappear completely. Smith 1988 stated a critical temperature of -3 for permafrost in order to halt/reverse melting. If permafrost melts yet still exists discontinuously, then the area of cryosols(permafrost no more that 2 meters beneath the surface) is drastically reduced. Degradation of cryosols leads to the formation of brunisols/gleysols. Their respective carbon balances are very different to cryosols as they store carbon for a much shorter time, so wildfires would reduce more carbon into the atmosphere that if it were cryosol. Increased wildfire extent and frequency also leads to the removal of organic soils and trees, and can cause deep carbon to be exposed initiating decomposition. 48% of carbon stored in cryosol stated as severe or very severe risk and it is likely that substantial amounts of carbon will be released. To summarise a lot of deep stored carbon would not be released if permafrost did not melt so much.

Permafrost is a powerful indicator of climate change, and relict landforms can be used to infer the previous extent of permafrost where sufficiently preserved. The active layer appears to directly respond to climate change, in terms of vegetation cover, snow cover and actual temperature. Barsh 1993 suggested that the polar permafrost boundary could shift 250-350km northwards. Colorado front range Permafrost is covered by rock glaciers and exhibits a lag in response to temperature change due to the protection from insolation and cooled by ventilation. Permafrost generally reacts at a slower rate than glaciers to warming. At the Front Range, relict rock glaciers indicate a previous MAAT 3-4 degrees cooler in the pleistocene and permafrost 600-700m deeper than present day. This has resulted in a continually increasing active layer. Melting permafrost could result in increased debris flows, rockfalls and associated catastrophic events.

At higher altitudes in Western Europe (Alps) permafrost exists and is generally just below 0 degrees meaning the system in extremely vulnerable to temperature change as predicted by GCMs. Thawing permafrost can affect the terrain by thawing soil thereby increased soil pore pressure, thawing can also result in increased groundwater flow contributing to the pore pressure. Therefore it is predicted that permafrost degradation will lead to increased scale and frequency of slope failure. PACE permafrost assessment is not concerned with mapping the past rather predicting the future. Thawing permafrost introduces problems to preexisting structures and destabilizing foundations. PACE is split into 3 phases all leading to an accurate mapping of the permafrost in the region and defined instances of soilufluction and other mass movement processes. Phase 1 = GIS Phase 2 = ground investigation Phase 3 = Permafrost monitoring usually if boreholes are using during investigation, it is advisable to install monitoring technology.

Kneisel (2010): A combination of geophyis and near surface measurements are suitable to interpret the state of the frozen ground. Surface measurements showed little variability, perhaps due to snow cover. Higher snow depth leads to less surface cooling of permafrost.

Iturrizaga (2008)

Karion et al. (2013)

Tarnocai (1999)

Janke (2005)

Harris et al. (2001)

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French Ch. 5
6 - Ice Wedges
8 -  Thermokarst
11 - Frost Shattering
9 - Arctic rivers
Lecture 3 extra
13 - debris transfer
Lecture 1 - Introduction
Lecture 4 core
Frost heaving/hillslope processes
7a - additional reading