Paleoclimate and paleoecology of Tasmania, Australia

澳大利亚塔斯马尼亚的古气候和古生态

• 批准号: 39785-2010
• 负责人: Cwynar, Les
• 金额: $ 1.46万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=521529
• 关键词: Paleoclimate; paleoecology; Tasmania; Australia

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.

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尺度上，地球经历了从冰河时代到温暖的间冰期（冰河时代之间）的重大气候变化。地球如何从一个转换到另一个是非常有趣的。直到最近，人们还认为北方半球（NH）是这一转变过程中气候变化的主要参与者，但现在看来，南半球（SH）带领NH走出了冰河时代。对北半球是推动气候变化的重要半球的偏见现在已经倾斜，导致在南半球的研究增加。发生在SH的气候事件与发生在NH的气候事件相比如何？事件是否同步？它们的持续时间和规模是否相同？这项研究的一个主要重点是解决与过去两半球之间的气候联系有关的问题。再往前追溯，与今天的间冰期相比，前一个间冰期（大约125000 - 135000年前）有多温暖？为了解决这些问题，我们将分析塔斯马尼亚湖沉积物的核心，塔斯马尼亚位于咆哮四十年代（高西风）的重要气候边界附近。其中一个湖，我们将工作，L。Selina是SH的罕见之处，它拥有超过一个完整的冰期/间冰期循环（超过135，000年）的连续沉积物记录。我们将应用一个数学模型，从摇蚊（摇蚊）的种类和丰度来估计夏季的温暖，从沉积物中的化石摇蚊可以追溯到135，000多年前，以获得数千年前夏季温度的定量估计。我们制作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受到夏季温暖变化的影响。最后，众所周知，火是对现在植被的主要影响，所以我们将研究保存在湖泊沉积物中的木炭，沿着花粉和蠓，以全面了解这些因素如何相互作用，以构建过去的植被。