Geological Testing of Global Warming Models on Venus

在地球上，越来越多的人认识到，被称为大火成岩省（lip）的巨大火山事件（高达数百万立方公里）是快速气候变化的主要驱动因素，有时会导致大规模物种灭绝（高达90%的生命被消灭）。在金星上，大约7亿年前发生了一次唇状火山活动，释放了大量的二氧化碳。这导致了极端的温室效应，目前火星表面温度达到450摄氏度（是你家烤箱温度的两倍），大气密度是地球的90倍，由96%的二氧化碳组成。因此，金星表面没有液态水，因此没有明显的水侵蚀。然而，最近有人提出，在这次超级变暖事件之前，金星的条件更像地球，甚至包括海洋和河流的存在，以及生命的可能性。我建议，金星的这种戏剧性的气候变化模型可以通过地质测绘（使用麦哲伦航天器的雷达数据）来评估两种类型的单元：一种是更古老的单元，称为tesserae，可以代表像加拿大盾一样的岩石，另一种是更年轻的广泛分布的玄武岩熔岩流（类似于夏威夷），覆盖了金星的90%。Tesserae应该是在全球变暖之前被安置的，当时金星上可能有水侵蚀。我们还假设，金星上最早的玄武岩熔岩流也是在较冷的（类地）条件下形成的，而后来的玄武岩流则是在更热的电流条件下形成的。我们的团队最近在tesserae中发现了水侵蚀的证据，与模型一致。这一发现表明，tesserae的地质历史可能比之前认为的要长得多，甚至可能延伸到40亿年前，就像地球上最早的岩石一样。我建议开展一项系统测绘活动（包括它们的侵蚀历史、线性结构和叠合熔岩池），以帮助解开它们漫长的地质历史。我还建议对最古老的火山平原进行系统的详细测绘，以便通过识别显示侵蚀的单元被没有侵蚀的单元所切割，来确定气候从类地到不适宜居住的转变。我的研究将为金星上失控的温室气候变化提供地质约束，这将为地球上现代全球变暖的风险提供见解。我的研究将把金星的火山历史与地球的火山历史进行比较。考虑到金星早期类似地球的历史，一个显而易见的问题是，为什么金星走的道路与地球不同。一个可能的答案是金星经历了多次火山活动，使温度超过了临界点。如果是这样，也许金星提供了一个展望地球未来的视角。本研究将培养3名硕士和2名博士研究生。

Geological Testing of Global Warming Models on Venus On Earth, there is growing recognition that huge volcanic events (up to millions of km3) known as Large Igneous Provinces (LIPs) are major drivers of rapid climate change sometimes leading to mass extinctions (where up to 90% of life was obliterated). On Venus, a major pulse of LIP-style volcanism occurred ~700 million years ago and released a massive volume of carbon dioxide CO2. This caused extreme greenhouse warming to a current surface temperature of 450oC (twice as hot as your oven), and an atmosphere 90 times as dense as that of the Earth and composed of composed of 96% CO2. As a consequence, there is no liquid water on the surface of Venus and therefore no significant water erosion. However, it has recently been proposed that prior to this hyper-warming event Venus had conditions that were more Earth-like, even including the presence of oceans and rivers, and the potential for life. I propose that this dramatic climate change model for Venus can be evaluated through geological mapping (using Magellan spacecraft radar data) of two types of units: older units called tesserae which could represent rocks like those of the Canadian shield, and younger widespread basaltic lava flows (similar to Hawaii) that cover 90% of Venus. Tesserae would have been emplaced prior to global warming at a time when there could have been water erosion on Venus. Our hypothesis is also that the earliest basaltic lava flows on Venus were also emplaced during cooler (Earth-like) conditions, while the later basaltic flows would have been emplaced under the much hotter current conditions. Our team has recently discovered evidence for water erosion in tesserae, consistent with the modelling. This discovery indicates that tesserae could have a much longer geological history than previously believed, maybe even extending back 4 billion years, like the earliest rocks on Earth. I propose a campaign of systematic mapping of tesserae (of their erosional history, linear structures and superimposed lava ponds) to help unravel their protracted geological history. I also propose a systematic detailed mapping of the oldest volcanic plains in order to identify the transition in climate from Earth-like to inhospitable, by identifying units exhibiting erosion being cut by units exhibiting no erosion. My research will provide geological constraints on this runaway greenhouse climate change on Venus that will provide insights into the risks of modern global warming on Earth. My research will allow comparison of the volcanic history of Venus with that of Earth. Given an early Earth-like history for Venus, the obvious question is why Venus took a different path than Earth. One possible answer is that Venus experienced multiple pulse of volcanism that increased temperature beyond a tipping point. If so perhaps Venus offers a perspective into Earth's future. This research will train three MSc and two PhD students.