Study On Climate Change Of Stalagmite Records In Chongqing Area During MIS11

In recent years, with the development of the industrial revolution, human beings released greenhouse gases into the atmosphere constantly such as CO2, CH4, causing climate warming, greenhouse, which produced some climate disasters, making some places drought, desertification,others sea level rise due to the melting of the polar ice caps and produce floods,resulting in part of the island sank into the sea and the coastal city has the danger of being submerged Therefore, climate change affects human’s life and humans want to know the direction of future climate change urgently. To forecast the direction of future climate change become a very urgent task.Since the last IMa 100ka, The history of climate change is dominated by the glacial interglacial cycles, the quaternary glacial interglacial cycles feature is obviously. The two recent interglacial have duration about 10ka, but the current warm interglacial (Holocene), which human living is started from the 11.5ka BP, now has lasted for more than 10ka. The Holocene is in exceed of the shortest interglacial stage in the past, only in terms of the length of the interglacial, we are now facing the threat of interglacial end, obviously. MIS 11 is very similar to Holocene in track configuration, which is considered to be the best reference of Holocene climate change.Study on the process and characteristics of climate change in MIS11, which will contribute to a better understanding of the current climate and environment status and the prediction of the future climate change trend. MIS 11 is the warmest and the longest interglacial for 500ka, paleoclimate records have strong reflection in marine and terrestrial.Because MIS 11 is about 400ka before present, the ancient climatic proxies available is very limited, stalagmite has the characteristics of dating precision, high resolution,to preserve climate information integratly,which is often used as a proxy of paleoclimate reconstruction. This paper selects the Chongqing Jinfo cave of Asian monsoon region as the study region, The Jinfo Cave Stalagmite J33 recorded paleoclimate information since 430ka BP. Using J33 stalagmite oxygen isotope and U/Th data of age reconstructed the paleoclimate information of 430-390ka BP. Discussed the start and end time of MIS 11 and its internal climate fluctuations, and analyzed the climatic driving mechanism, draw the following conclusion:The Jinfo Cave Stalagmite records show that:Jinfo Cave Stalagmite J33δ18O recorded Termination V occurred around 423 ka BP, stalagmite J33 S18O curve began to rapidly turn lighter at about 423 ka BP. The summer monsoon is increasing rapidly, the climate changing to warm and humid rapidly.The climate from MIS 12 enter MIS11 interglacial stage. The MIS11 interglacial from 423 ka BP to 356 ka BP, stalagmite J33δI8O values showed lighter trend overall, its internal have sub stages. Stalagmite J33 recorded 356 ka BP-343 ka BP is MIS10 stage. The summer monsoon weakened until Termination IV about 343 ka BP. Stalagmite J33δ18O curve recorded the beginning of MIS11 is around 423 ka BP in Chongqing area. The end time is around 356 ka BP, lasted 67 ka.Stalagmite J33 recorded MIS11 duration is longer compared to other records, may be due to Stalagmite J33 is in East Asian monsoon region, the monsoon has its uniqueness.(2) Different scholars have different partition on MIS11 internal climate.Chongqing Jinfo Cave J33δ18O records is more close to the Sanbao Cave Stalagmite record of the whole process of climate change during MIS 11. The process of its climate change can be divided into the following stages. The Jinfo Cave Stalagmite J33δ18O recorded MIS 11 in the whole process of climate change expericed the MIS11a(423 MIS11a ka BP-418 ka BP) the monsoon stable stage, MIS11b (418 ka BP-412 ka BP) weak monsoon period, the climate is cold and dry, MIS11c (412 ka BP-400 ka BP) the monsoon peak stage, MIS11d (400 ka BP～390 ka BP) climate transition to cold and dry, weak monsoon stage,MIS11e (390 ka BP～356 ka BP) to warm and humid transition stage five stages.(3) The orbit configuration and curve comparison show that the MIS11c is fit to be the climate reference system of Holocene. greenhouse gas concentrations, simulation of the amount of ice also support this view.This paper uses frequency spectrum analysis Jinfo Cave J33δ18O nearby MIS11c, in order to understand its climate driven mechanism, the results show that The external driven is mainly solar radiation, Also affected by the other internal driving factors,such as the instability of the Ice sheet, ocean circulation, atmospheric dust and greenhouse gases and so on. The formation of the earth’s climate is the interior factors coupling between the solar radiation.The comparison of Jinfo Cave stalagmite J33δ18O curve with the solar radiation curve during MIS11 also illustrates the climate is mainly controlled by solar radiation. In this paper, compared Jinfo Cave J33δ18O nearby MIS11 to Dongge Cave D4δ18O during Holocene, The strong monsoon period has passed, the general trend of Holocene development is likely to enter the weak monsoon stage.