Collaborative Research: P2C2--Reconstructing Deglacial and Holocene Climate Variability in Southeast Asia Using Speleothems and Isotope-Enabled Model Simulations

亚洲季风系统是全球气候系统的重要组成部分，在从热带向高纬度输送热量和水汽方面发挥着重要作用。即使季节性降雨的强度和/或时间上的微小变化也可能对生活在亚洲季风区内的数十亿人产生重大影响，但气候模型对未来季风变化的预测仍然不确定。虽然古气候记录极大地促进了我们对一些地区夏季风变化的了解，但我们对东南亚季风变化的范围和机制仍然知之甚少。这项研究是加州大学欧文分校和新泽西州威廉·帕特森学院的科学家合作完成的，将生成过去2万年来老挝过去水文气候变化的高分辨率洞穴方解石沉积记录，老挝是印度和东亚季风系统交界处的关键地点。新的氧同位素记录将记录东南亚季风强度在亚十年至轨道时间尺度上的变化，填补热带古气候记录中的一个关键时空空白。通过整合古气候代理数据、仪器气候数据和气候模式分析，该项目将解决三个主要问题：(1)东南亚季风强度在过去20,000年中如何变化，以响应轨道强迫、千年尺度的突然气候事件和年际至数十年气候模式？(2)老挝年际到轨道时间尺度上控制降水和喷发氧同位素的机制是什么？(3)老挝洞穴记录与热带印度洋-太平洋、亚洲季风区和高纬度地区过去气候变化的更广泛的时空模式有何联系？除科学成果外，该项目还将为研究生和本科生提供研究机会，并将纳入旨在改善未被充分代表群体参与地球科学的外联工作中。例如，将为每年夏天在加州大学欧文分校举行的美国国家科学基金会资助的美洲印第安人地球系统科学夏季研究所开展关于古气候、气候变化和土著文化的实地和实验室练习。

The Asian Monsoon system is an important component of the global climate system that plays a major role in the transport of heat and moisture from the tropics to higher latitudes. Even small variations in the strength and/or timing of seasonal rainfall can have significant impacts on the billions of people living within the Asian monsoon domain, yet climate model projections of future monsoon changes still remain uncertain. While paleoclimate records have significantly advanced our understanding of summer monsoon variability in some regions, we still know very little about the range and mechanisms of monsoon variability in Southeast Asia. This research, a collaborative effort between scientists from the University of California, Irvine and William Patterson College of New Jersey, will generate high-resolution speleothem (cave calcite deposit) records of past hydroclimate variability over the last 20,000 years from Laos, a key site at the interface between the Indian and East Asian monsoon systems. The new oxygen isotope records will document changes in Southeast Asian monsoon strength on sub-decadal to orbital timescales, filling in a key spatial and temporal gap in the paleoclimate record of the tropics. Through integrating paleoclimate proxy data, instrumental climate data, and climate model analyses, the project will address three main questions: (1) How has Southeast Asian monsoon intensity varied over the past 20,000 years in response to orbital forcing, millennial-scale abrupt climate events, and interannual to multi-decadal climate modes?; (2) What are the mechanisms that control precipitation and speleothem oxygen isotopes on interannual to orbital timescales in Laos?; and (3) How do the Laos speleothem records relate to broader spatial and temporal patterns of past climate variability in the tropical Indo-Pacific, the Asian monsoon region, and high latitudes? In addition to the scientific outcomes, this project will provide research opportunities for graduate and undergraduate students and will be incorporated in outreach efforts aimed at improving the participation of underrepresented groups in the geosciences. For instance, a hands-on field and laboratory exercise on paleoclimate, climate change, and native culture will be developed for the NSF funded American Indian Summer Institute in Earth System Science held at the University of California, Irvine each summer.