Thursday, 5 April 2012

Degradation of Frozen Earth Layers and Release of Green House Gases on the Tibetan Plateau

The presence or absence of the permafrost layer necessitates major variations in the soil’s physical structure mainly its moisture and nutrient content. The permafrost covers approximately 1.3 to 1.6 million sq. km. These covers have thickness ranging from 1 to 130 m, depending on such local characteristics as slope and exposure, altitude, geological structure, soils, and soil water content.

The permafrost and ground ice in Tibet. Image copyright EDD (CTA)

The alpine permafrost on the Tibetan Plateau stores about 12,300 million tons of Carbon. Significant amount of methane gas are also trapped in the permafrost, preventing its release into the atmosphere. The alpine permafrost on the Plateau are characterized by warm permafrost and rich ground ice, as a result they are sensitive to climate change and are particularly vulnerable to rising temperature.

Tibet serves as a major carbon sink with around 37% (12,300 million tons of Carbon) of the its grassland Soil Organic Carbon (SOC) stored in the alpine permafrost of the Tibetan Plateau. Their degradation would lead to a huge amount of carbon entering the atmosphere, intensifying global warming. Recent studies have shown that glacial melting and thawing of permafrost on the Plateau will lead to a large-scale release of green-house gases into the atmosphere and could bring further changes in the already warming global climate.

With a significant measured increase in the mean cold season average temperature, the permafrost layers and seasonally frozen grounds are slowly degrading leading to increased microbial decomposition of previously frozen organic carbons. The degradation of permafrost, besides disturbing the carbon balance over the plateau, will also lead to the lowering of the water table, loss of soil moisture content, drying of wetland, extinction of native plant species and desertification.

If the current trend of melting permafrost and loss of wetlands continue then the carbon deposits and methane would be released in the air and it can speed up the Global Climate Change. The loss of carbon deposits will also degrade the grasslands directly hurting the biodiversity on the Tibetan Plateau.

In addition, since the wetlands and permafrost work as sponges controlling the amount of water running into the rivers, there could be flash floods and ultimately water crisis in the most populous regions of the world.

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