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

澳大利亚内陆干旱：Milankovitch和澳大利亚季风的人为强迫。艾尔湖盆地是一个由季风控制的内陆盆地，面积占澳大利亚大陆的六分之一。观测到的该盆地的大部分干湿循环可以用澳大利亚季风的米兰科维奇强迫来解释。全新世早期，尽管受到太阳辐射和海平面的强烈影响，Eyre湖仍未能填满，这被认为是最早的人类移民系统燃烧的结果。在过去的50年里，整个澳大利亚的植被密度和组成的减少，可能导致季风渗透到内陆的显著减弱，长期趋势是干旱加剧。为了进一步验证这一假设，该奖项支持实地、分析和建模研究：1)利用新记录的稳定同位素信号，在其他脊椎动物的蛋壳和骨头/牙齿中，评估过去7万年整个澳大利亚北部的降水和植被组成的变化；2)开发格雷戈里湖（一个完全位于季风灌溉地区的较小盆地）的干湿循环年表；3)完善艾尔湖流域通货紧缩事件的年代学，以更严格地评价其与Milankovitch控制的相关性；4)开发新的古植被重建代用物；5)利用环流模式完成植被变化对季风降水渗透作用的敏感性试验。

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.