Drought in the Australian Outback: Milankovitch and Anthropogenic Forcing of the Australian Monsoon

Am-9709806 Miller，Gifford H.University of Colorado，Boulder ATM-9714893 Fogel，Marilyn L.Carnegie Institute of Washington of the Australian Outback：Milankovitch and人为Forcing of the Australian季风湖Eyre盆地是一个受季风控制的内陆盆地，覆盖了澳大利亚大陆的六分之一。该盆地观测到的大部分干湿循环是由澳大利亚季风的米兰科维奇强迫所解释的。尽管受到太阳辐射和海平面的强烈强迫，爱尔湖在全新世早期仍未能填满，这被认为是最早的人类移民系统燃烧的结果。过去50ka，澳大利亚各地植被密度和组成的减少，可能导致季风向内陆渗透的显著减弱，并有加剧干旱的长期趋势。为了进一步验证这一假设，该奖项支持现场、分析和建模研究：1)使用其他脊椎动物扁平蛋壳和骨骼/牙齿中新记录的稳定同位素信号，评估澳大利亚北部过去70,000年来降水和植被组成的变化；2)开发格雷戈里湖的干湿循环年表，格雷戈里湖是一个完全位于季风灌水区的较小盆地；3)完善艾尔湖盆地通货紧缩事件的年表，以更严格地评估与米兰科维奇控制的相关性，4)开发新的古植被重建指标；5)利用大气环流模式评估植被变化对季风降水进入艾尔湖盆地的影响。

Abstract ATM-9709806 Miller, Gifford H. University of Colorado, Boulder ATM-9714893 Fogel, Marilyn L. Carnegie Institute of Washington Drought in the Australian Outback: Milankovitch and Anthropogenic Forcing of the Australian Monsoon Lake Eyre Basin is a monsoon-controlled interior basin covering one-sixth of the Australian continent. A majority of the observed wet and dry cycles of this basin are explained by Milankovitch forcing of the Australian monsoon. The failure of Lake Eyre to fill in the early Holocene despite strong forcing by solar radiation and sea level is hypothesized to be a consequence of systematic burning by the earliest human immigrants. A reduction in the density and composition of vegetation across Australia in the past 50 ka, may have resulted in a significant weakening of monsoon penetration into the interior with a long-term trend towards increased aridity. To test this hypothesis further, this award supports field, analytical, and modeling studies 1) to use newly documented stable-isotope signals in ratite eggshell and bone/teeth of other vertebrates to evaluate changes in precipitation and vegetation composition over the past 70,000 years across northern Australia, 2) to develop a chronology for wet and dry cycles in Lake Gregory, a smaller basin wholly within the monsoon-watered region, 3) to refine the chronology of deflationary events in the Lake Eyre Basin to more rigorously evaluate the correlation to Milankovitch controls, 4) to develop new proxies for paleovegetational reconstructions and 5) complete sensitivity tests evaluating the role of vegetation change on the penetration of monsoon precipitation into the Lake Eyre Basin using General Circulation Models.