NOAA/WDS Paleoclimatology - Arabian Sea 20KYr Carbonate and Stable Isotope Data

Previously published results suggest that the strength of the SW Indian Monsoon can vary significantly on century- to millennium time scales, an observation that has important implications for assessments of future climate and hydrologic change over densely populated portions of Asia. We present new, well-dated, multi-proxy records of past monsoon variation from three separate Arabian Sea sediment cores that span the last glacial maximum to late-Holocene. To a large extent, these records confirm earlier published suggestions that the monsoon strengthened in a series of abrupt events over the last deglaciation. However, our data provide a somewhat refined picture of when these events took place, and suggest the primacy of two abrupt increases in monsoon intensity, one between 13 and 12.5 ka, and the other between 10 and 9.5 ka. This conclusion is supported by the comparisons between our new marine data and published paleoclimatic records throughout the African-Asian monsoon region. The comparison of data sets further supports the assertion that maximum monsoon intensity lagged peak insolation forcing by about 3000 years, and extended from about 9.5 to 5.5 ka. The episodes of rapid monsoon intensification coincided with major shifts in North Atlantic-European surface temperatures and ice-sheet extent. This coincidence, coupled with new climate model experiments, suggests that the large land-sea thermal gradient needed to drive strong monsoons developed only after glacial conditions upstream of, and on, the Tibetan Plateau receded (cold North Atlantic sea-surface temperatures, European ice-sheets, and extensive Asian snow cover). It is likely that abrupt changes in seasonal soil hydrology were as important to past monsoon forcing as were abrupt snow-related changes in regional albedo. Our analysis suggests that the monsoon responded more linearly to insolation forcing after the disappearance of glacial boundary conditions, decreasing gradually after about 6 ka. Our data also support the possibility that significant century-scale decreases in monsoon intensity took place during the early to mid-Holocene period of enhanced monsoon strength, further highlighting the need to understand paleomonsoon dynamics before accurate assessments of future monsoon strength can be made.

本存档古气候学（Paleoclimatology）研究数据集可从美国国家海洋和大气管理局（NOAA）国家环境信息中心（NCEI）获取，隶属于古气候学世界数据服务（WDS）。该NCEI研究的类型为古海洋学（Paleoceanography）。数据集包含古海洋学相关参数，研究区域为印度洋。时间覆盖范围为距今27320至2530个日历年（BP，即Before Present）。如需了解参数与研究地点的详细信息，请查阅元数据。使用本数据集时，请引用该研究。