Reconstructing Australian hydro-climate and temperature for the Pliocene warm period: a near future climate analog

全球气候变化是当今人类面临的主要挑战之一。上新世时期（520万至260万年前）是最近的全球变暖时期，大气中二氧化碳浓度相似。因此，它被广泛认为是21世纪末我们未来气候的模拟。因此，这一时期的气候重建是必不可少的。然而，上新世陆地气候重建的数量非常少。主要的限制是测年，它通常不能提供上新世气候记录所需的精度，更不用说重建上新世的气候变化了。UoM拥有世界领先的洞穴化石U-Pb测年研究所。用这种方法，400万年的洞穴化石的年代可以精确到1%。UoM收集了大量来自南澳大利亚纳拉伯平原的上新世洞穴化石，需要进行U-Pb测年。我想熟悉这种方法，把它应用到这些上新世的洞穴中，用它们来重建上新世的气候。可以说，没有比UoM更好的地方了。洞穴氧同位素记录是最有价值的气候变化记录之一，可能代表（除其他外）降雨量、温度、湿源条件和大气环流模式的变化。然而，它们很少在同位素平衡中沉淀。结合岩浆岩流体包裹体同位素分析和团块同位素分析，可以估计岩浆岩的不平衡程度。在过去的两年里，我分析了许多洞穴样品的流体包裹体同位素，但我还没有团块同位素的经验。UoM有一个很好的团块同位素设施，我想深入了解，这样我回到德国后就可以建立这个方法。今天的纳拉伯平原是一片沙漠，但最近对纳拉伯洞穴遗址的花粉研究表明，上新世比今天湿润得多。然而，目前尚不清楚原因，以及哪种大气环流模式占主导地位。我的目标是将团块同位素与流体包裹体氧同位素分析相结合，生成上新世氧同位素记录，并从温度和大气环流模式方面提供解释。这个项目的结果将提供对我们未来气候的详细观察，并可用于验证上新世气候模式的模拟。

Global climate change represents one of the major challenges confronting humankind today. The Pliocene time period (5.2 to 2.6 million years ago) is the most recent global warming episode with similar atmospheric CO2 concentrations. It is thus widely regarded as an analog to our future climate at the end of the 21st century. Climate reconstructions from this time period are thus essential. However, the number of Pliocene terrestrial climate reconstructions is extremely small. The major limitation is dating, which can often not provide the precision required to assign a climate record to the Pliocene, let alone reconstruct climate variability within the Pliocene.UoM hosts the world-leading institute in U-Pb dating of speleothems. With this method, speleothems with an age of four million years can be dated down to 1% precision. UoM has a large collection of Pliocene speleothems from the Nullarbor Plain in South Australia that require U-Pb dating. I would like to become acquainted with this method by applying it to these Pliocene speleothems and use them to reconstruct Pliocene climate. Arguably, there is no better place for this than UoM.Speleothem oxygen isotope records are among the most valuable records of climate change and may represent (among others) changes in rainfall amount, temperature, moisture source conditions and atmospheric circulation patterns. However, they rarely precipitate in isotope equilibrium. The degree of disequilibrium can be estimated by combining speleothem fluid inclusion isotope analysis and clumped isotopes. For the last two years, I analysed many speleothem samples for fluid inclusion isotopes, but I have no experience with clumped isotopes yet. UoM has an excellent clumped isotope facility, and I want to acquire in-depth knowledge such that I can establish this method when I return to Germany.Today the Nullarbor Plain is a desert, but a recent pollen study from Nullarbor speleothems has shown that the Pliocene was much wetter than today. However, it is unclear why, and which atmospheric circulation patterns dominated. I aim to combine clumped isotopes with fluid inclusion oxygen isotope analysis, generate a Pliocene oxygen isotope record and provide an interpretation in terms of temperature and atmospheric circulation patterns. The results of this project will provide a detailed look into our future climate and can be used to verify Pliocene climate model simulations.