Paleoclimate and paleoecology of Tasmania, Australia

地球的气候在时间和空间上变化很大。我们知道，在数千年到数万年的范围内，地球经历了从冰河时代到温暖的间冰期(冰河时代之间)的气候重大变化。地球是如何从一个切换到另一个的是人们非常感兴趣的。直到最近，人们还认为北半球(NH)是气候变化的主要参与者，但现在看来，南半球(SH)引领着NH走出冰河时代。对NH是驱动气候变化的重要半球的偏见现在已经倾斜，导致在SH的研究增加。发生在SH的气候事件与NH的气候事件相比如何？事件是否同步？它们的持续时间和强度是相同的吗？这项研究的一个主要重点是解决与过去两个半球之间的气候联系有关的问题。再往前追溯，以前的间冰期(大约125,000-135,000年前)与今天的间冰期相比有多热？为了解决这些问题，我们将分析塔斯马尼亚的湖泊沉积物岩心，塔斯马尼亚位于咆哮40年代(高西风)的重要气候边界附近。我们将研究的湖泊之一L.Selina是SH罕见的，它拥有超过一个完整的冰川/间冰期周期(超过135,000年)的连续沉积记录。我们将应用一个数学模型，从蚊虫(摇蚊)的种类和丰度来估计夏季的温暖，并将其应用于远在135,000年前的沉积物中的化石蚊子，以获得对数千年前夏季温度的定量估计。然后，我们产生的温度曲线可以与世界各地的其他温度曲线进行比较。此外，我们将研究化石花粉，以确定过去的植被可能如何受到夏季温暖变化的影响。最后，众所周知火是对目前植被的主要影响，所以我们将研究保存在湖泊沉积物中的木炭，以及花粉和蚊虫，以全面了解这些因素是如何作用于过去的植被结构的。

Earth's climate varies enormously in time and space. We know that, on the scale of thousands to tens of thousands of years, the Earth has gone through major changes in climate from Ice Ages to warm interglacial periods (between Ice Ages). How the Earth switches from one to the other is of great interest. Until recently, it was thought that the Northern Hemisphere (NH) is the main player in climate change during this transition, but it now seems that the Southern Hemisphere (SH) leads the NH out of an Ice Age. The bias to the NH being the important hemisphere in driving climate change has now tipped, resulting in increased research in the SH. How do climate events that occur in the SH compare with those in the NH? Are events synchronous or not? Are they of the same duration and magnitude? A major focus of this research is to address questions relating to climate linkages between the hemispheres in the past. And, going further back in time, how warm was the previous interglacial period (about 125,000-135,000 years ago) compared to today's interglacial? To address these questions, we will analyze cores of lake sediment from Tasmania, which is located near the important climate boundary of the Roaring Forties (high westerly winds). One of the lakes we will work on, L. Selina, is a rarity for the SH in having a continuous sediment record for more than one complete glacial/interglacial cycle (more than 135,000 years). We will apply a mathematical model, which estimates summer warmth from the kinds and abundances of midge flies (chironomids), to fossil midges from sediments that date as far back as 135,000+ years ago, in order to obtain quantitative estimates of summer temperatures thousands of years ago. The temperature curves that we produce can then be compared with others throughout the world. In addition, we will examine fossil pollen to determine how past vegetation may have been affected by changes in summer warmth. Finally, fire is known to be a major influence on present vegetation, so we will examine charcoal preserved in lake sediments, along with the pollen and midges, to gain a comprehensive picture of how these factors have interacted to structure past vegetation.