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

题目：过去2000万年气候和生物圈的演变对地球历史的研究表明，过去的大气候变化与生物圈、深海、大大陆冰盖和地球碳循环的大变化有关。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对过去大规模气候变化的研究。在过去，大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起的。通过规定这些“外部”气候强迫的变化，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，这些机制可能会放大或抑制直接反应。利用过去作为气候变化研究的“试验场”的巨大优势在于，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。为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期。大气中二氧化碳浓度的巨大变化可能在这种情况下发挥了作用，这将是该项目的一个重要焦点。这项工作的结果将使人们更好地了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用于估计未来可能的气候变化的模式的准确性。

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.