________________
Shri Ashtapad Maha Tirth - II
On the contrary, in the eastern margin of Asia including Taiwan, Central Japan, Hokkaido and probably Mount Changbai, maritime type glaciers were more extensive. The simple reason for this was the higher monsoonal precipitation, especially heavy snowfall in northwest Japan owing to the rich moisture content of the winter monsoon over the Japan Sea. The millennial scale monsoon intensity and glacial cycle in the Tibetan Plateau are strongly affected by the precession cycle and the orbit-inclination cycle (cf. Figure 6) which dominates the solar irradiance variation in low latitudes, as the high radiation and strong monsoon caused the warmer and wetter climate during 40–30 thousand years before present. The low radiation produced a weak monsoon and large depression of temperature and precipitation around 21 thousand years before today. This climatic pattern differs from that in the high latitudes where the eccentricity cycle is prominent. The temperature during the last glacial maximum (LGM) was 6-90 C lower than today on the Tibetan Plateau. Also the equilibrium line altitude was depressed by about 1000m in the southeast part, and in the east, south and west margins of the Plateau where precipitation was high. On the other hand, the equilibrium line altitude depression was 500–300m in the inner and especially in the west part of the Plateau. This variation in equilibrium lines might be caused by the combined effect of the decrease in precipitation, the expansion of extreme continental glaciers and the active uplift of glaciated mountains. The estimation of a glaciated area of about 350,000 km2 in the Tibetan Plateau and roughly 500,000 km2 in High Asia is based on the observations of prominent features of LGM glacier extension. However, these estimations may be the direct evidence that shows there was no Quaternary unified ice sheet developed in the Tibetan Plateau. The actual extent of the glaciated area during LGM in the Tibetan Plateau was calculated from the Quaternary glacial distribution map of Qinghai-Xizang (Tibet) Plateau at a scale of 1:3,000,000 (Li et al., 1991). Considering that this small-scale map cannot exclude mid-latitude westerlies. However, shortly after 19000 years before present, drought was exacerbated, pollen content decreased and was dominated by Chenopodiaceae, and the lake water turned brackish. Around 17000 years before present the lake shrank and separated into some small lakes, resembling the present state (Li., 1998). Thus under the severe cold and arid conditions of the LGM, vegetation seriously degraded and forest retreated to the south and east margin of the Tibetan Plateau (Tang et al., 1998). In summary, five shorter cold and warm stadial and inter-stadial cycles occurred during the last glacial and interglacial cycle in the low-latitude regions due to the tremendous influence of precessional and obliquity variables. According to the Guliya ice core records and the data from lacustrine deposits, and pollen records from the major part of the Tibetan Plateau, the summer monsoon was stronger, air temperature was higher and precipitation was abundant in the interstadial times. On the contrary, the winter monsoon was stronger, air temperature was low and precipitation was less in the past glacial stadials. Thus current human civilization appears to be of less than 22 thousand years from present if we consider similar catastrophe occurred during last LGM. The greenhouse gas (CO) emission (green color in Figure 8) also reveals similar results. The records also reveal that the period from 850 to 630 Million year B. P. was most severe Ice Age in the Earth's history. The greenhouse gas CO, emission is a consequence of large volcano eruptions after the LGM.
New Techniques to discover Ashtapad
