Study on Climate Change in Pollen Records in Barrow, Arctic,and Compared with the Tibetan Plateau since 13~(th) Century

Barrow is located in the northeast of Alaskan coastal plain (71°20′ N, 156°40′ W), which is encircled by the Chukchi Sea in the west and the Beaufort Sea in the north. Barrow is a quite cold area with the mean annual temperature of \{-12.4\} ℃, the mean temperature of \{-29 ℃\} in winter and 20℃ in summer. Mean annual precipitation is less than 250 mm.\;For understanding the climatic and environmental changes in Barrow, 9 lake cores, 100～350 cm in depth, were taken by piston corer in this area. Based upon the analyses and measurements of \{\} 210 Pb, \{\} 137 Cs, TOC, TN, organic materials, CaCO 3 , grain size and pollen of Core 98-4B, climatic and environmental records since 13 th century in Barrow were reconstructed.\;It is found that in the past 700 a, there were four main warm periods in 1240\_1425, 1535\_1600, 1720\_1730 and 1880\_1992, and three cold periods in 1440\_1520, 1605\_1650 and 1750\_1850. \;Comparative study shows that the Barrow lake core record is compatible with three main cold-warm conditions since the Little Ice Age deduced from the Guliya and Dunde ice cores and the tree ring record in the Qilian Mountains, although there exist some differences in high frequent climatic change.