The Evolution of Climate and Biosphere During the Past 20 Million Years

美国威斯康星州大学约翰·E·库茨巴赫的ATM-9806918报告题目：过去2000万年来气候和生物圈的演变对地球历史的研究表明，过去巨大的气候变化与生物圈、深海、巨大的大陆冰盖和地球的碳循环都有同样大的变化。该奖项支持使用大气、陆地表面、陆地生态系统、海洋、冰盖和碳循环组成部分的数值模型来研究过去的大型气候变化。过去，大规模的气候变化是由陆地-海洋分布的构造相关变化、山脉的起伏和地球轨道参数的变化引发的。通过规定这些“外部”气候压力的变化，就有可能使用模型来模拟气候的直接反应，并研究可能涉及生物圈或冰冻圈的可能的反馈机制，这些反馈机制可能会放大或抑制直接反应。利用过去作为研究气候变化的“试验场”的最大好处是，可以将陆地和海洋环境的地质记录与模拟结果进行比较，以评估模型的准确性。这项研究选择的特定试验场是大约2000万年前开始的最近一次大冰川。大气中二氧化碳浓度的较大变化可能在这种情况下发挥了作用，并将是该项目的一个重要重点。这项工作的结果将有助于更好地理解过去这种大规模气候变化所涉及的机制，并将有助于评估正在开发的模型的准确性，以估计未来可能发生的气候变化。

Abstract ATM-9806918 Kutzbach, John E. University of Wisconsin Title: The Evolution of Climate and Biosphere During the Past 20 Million Years Studies of the Earth's history show that the large climate changes of the past have been associated with equally large changes in the biosphere, the deep ocean, the large continental ice sheets, and the earth's carbon cycle. This award supports a study of large climate changes of the past using numerical models of the atmosphere, the land surface, terrestrial ecosystems, oceans, ice- sheets, and components of the carbon cycle. In the past, large climate changes were initiated by tectonically-related changes in land-ocean distribution, by the rise and fall of mountains, and by changes in earth's orbital parameters. By prescribing changes in these "external" forcings of climate, it is possible to use models to simulate the climate's direct response , and to study possible feedback mechanisms involving the biosphere, or the cryosphere that might amplify or dampen the direct response. The great advantage of using the past as a "testing ground" for studies of climate change is that geological records from terrestrial and marine environments can be compared with the results of the simulations to evaluate the accuracy of the models. The specific testing ground chosen for this study is the most recent major glaciation that began about 20 million years ago. Large changes in the atmospheric concentration of CO2 probably played a role in situation and will be an important focus of the project. The results of this work will lead to improved understanding of the mechanisms involved in this large climate changes of the past and will help assess the accuracy of models being developed to estimate possible climate changes of the future.