应用MPM-2模式新元古代气候初步研究

CLIMATE OF LATE PROTEROZOIC:A SIMULATION STUDY BY MODEL MPM-2

新元古代(650MaB.P.)是地球演化历史上最重大的转折时期之一,这一时期地球气候的模拟研究,对于了解气候变迁、现代气候的形成、自然地理环境的演变有重要意义;在地质学上,对于地层划分和对比,地壳演化研究以及矿产资源成因和探测都有重要意义。本文在借鉴国内外已有研究的基础上,应用MPM-2——一个中等复杂程度的地球系统模式(EMIC),通过太阳常数和大气二氧化碳浓度的敏感性试验,对新元古代地球气候进行了模拟研究,结果表明在650Ma前,地球全球平均温度一直低于零度,即地球一直是"雪球",直到650Ma前,全球半均温度大于零,"雪球"消融,雪球时代才结束。

The Late Proterozoic is one of the most important periods in the history of the Earth evolution. The events such as the breakup of the supercontinent,the low-latitude glacier,the abrupt change of climate,the Ediacaran fauna and the Precambrian life explosion had close relations to the Earth environment of this period. Therefore, the Late Proterozoic environmental change was paid more attention by geoscientists in recent years. The simulations of the Earth climate of the Neoproterozoic play an important role in understanding of the change of climate, the formation of the present climate, the evolution of the natural geographical environment so as to help the stratigraphic classification and correlation and the detection of resources. In order to simulate a snowball Earth during the Late Proterozoic,we conducted simulations using an Earth system model with intermediate complexity -MPM-2,whose solar forcing and CO2 concentration can be reducted with time. In this study, A land-sea geometry of 650Ma was used. Through analyzing relationships between the land-sea distributions and corresponding climates,we found that the ocean heat transport had great changes under different land-sea geometries, which might impact the global average temperature. The MPM-2 simulations of the Earth climate evolution show that the global average temperature would be below zero until 650Ma and about 5℃ in 650Ma. The Earth would be a snowball before 650Ma. The snowball period started ending from 650Ma on.