Permafrost
Permafrost: P.K.Ghatak,MD No.67 When the ground remains frozen at or below 0°C (32°F) for at least two consecutive years; the Geologists designate it as Permafrost. Types of Permafrost. 1, Continuous .The entire ground remains frozen. 2, Discontinuous. Less than 100 % of the ground but more than 50% remains frozen. 3, Sporadic. Less than 50% but more than 5% remains frozen. 4, Isolated. Small patches of land here and there remain frozen. In the arctic region, the oldest permafrost has remained frozen for 700,000 years. 25% of land in the Northern Hemisphere is covered by permafrost and is located in Alaska, Canada, Siberia. Tibetan Plateau and Greenland. Much less landmass in the Southern Hemisphere is covered by permafrost and mainly found in the High Andes, Patagonia, New Zealand and Antarctica. Depth of Permafrost. It varies from less than one meter to over 1,500 meters deep. Beneficial Effects of Permafrost. Permafrost acts as a massive Carbon Dioxide sink and it holds twice...