|
China's northwest arid area located in Central Asia, is an important part of the arid Central Asia. Reconstruction of the history of climate change in northwest arid area in China over the past 2000 years, to help conduct a more in-depth study of the arid Central Asia in the past global change. Bosten Lake is the largest freshwater lake in the arid region of northwest China. This article analyzed multiple sedimentary cores pollen and grain size, carbonate content, and other indicators of Bosten Lake, AMS C-14 dating based on the reconstruction of the evolution of climate change in the arid region of northwest China over the past 2000 and the following conclusions and preliminary understanding: 110AD-300AD (1840 ~~ 1650 cal yr BP), A / C ratio of the average of 0.96, the cattail pollen percentage content of an average high of 12.8 percent, sharply lower to 0.61 and 2.73 in the late %; carbonate content of up to 36.8% of the average content of late quickly dropped to 27.64%. During this period, the Arid Region of Northwest climate mountain warm moist into cold and dry, the first expansion of the lake area after contraction. 300AD-850AD (1650 to 1100cal yr BP), the A / C ratio of cattail percentage content after several ups and downs, but generally are first increased and then decreased slightly lower; carbonate content is a rapid increase in first. During this period, the Arid Region of Northwest experienced many cold - warm wet - dry alternating process. On the whole, during this period, the northwest arid zone climate gradually warming dries. 850AD-1300AD (1100-650cal yr BP), the Medieval Warm Period in China's northwest arid area, A / C ratio and cattail percentage content fluctuations at a low level, with an average of 0.76 and 3.01%, respectively; the Pediastrum quality concentration average 842 / g, up to 6216 / g; carbonate content of up to 43.3% of the average content. During this period, China's northwest arid zone climate mainly warm and dry, which 950AD-1060AD climate change wet event as a whole. 1300AD-1810AD (650 ~ 140 cal yr BP), the Little Ice Age of the arid zone of northwest China, fluctuations up and down the A / C ratio and the the cattail percentage content, average values ??of 0.81 and 2.89% and the highest value of 1.18 and 6.49%; carbonate content decreases rapidly, but the middle of a period of increased period. During this period, China's northwest arid zone climate mainly wet cold on the whole, 1430AD-1700AD once the climate warmed up event. 1810AD so far (since modern global warming, the A / C ratio and cattail percentage content in fluctuations rise, carbonate content increased rapidly to a maximum value of 48.48% since 140cal yr BP). During this period, the rebound in China's northwest arid zone temperature region effective humidity increased, becomes warm and humid climate.
|