Evolution of Cenozoic surface environments is a process of transition from greenhouse world to icehouse world. Review of studies on developments of continental ice sheets, associated sea level change, deep water circulation, and atmospheric circulation revealed close association among them. The transition occurred through steps of significant and abrupt changes, between such steps the surface environmnent was more or less stable. Timing of such steps is correlatable to tectonic events in many cases. Examination of their close correlation may give a clue to solve the operation mechanism of the surface environment system.
The history of global climate on the earth during these 600 million years is presented based on the oxygen isotope data of fossil shells. The paleoclimatic curves clearly show the cyclic changes with different frequencies, such as, glacial-interglacial cycle of 0.1 Ma and Fischer-Arthur cycle of 32 Ma, and Greenhouse-icehouse cycle of 300 Ma. Today is located in the interglacial period of icehouse state. There are essential differences of the environmental systems and conditions between the greenhouse and icehouse states. The greenhouse state characterized by no continental ice sheets, simple climatic zones, more carbon dioxide in atmosphere, small annual temperature range, warmish and humid poles, high sea level, wide continental shelves, low latitudinal and vertical gradients of seawater temperature, warm oceans, slow circulation of bottom currents, anoxic oceans, abundant marine organisms, black shale deposition of oil raw material, sulfide deposits on oceanic ridges, manganese deposits on continental shelves, active magmatism, first spreading, magnetic quiet and active orogeny. A modern greenhouse warming was also compared with the warming after the “Younger Dryas Event” in the postglacial age.
Snow-ice cores obtained from ice sheets and glaciers are formed from deposited snow and other materials of marine, terrestrial, cosmic and artificial origin. The depositional mode of these materials is presumed to be a good signal of climatic and environmental changes during the past several hundred thousand years. In this report, formation processes of these deposits are investigated mainly on the basis of knowledge of regional characteristics of deposition processes obtained from a comprehensive Japanese glaciological study during 19671989 on the Antarctic Ice Sheet.
World ocean circulation has been playing an important role on the transport of heat energy and material on the surface of the earth and have had an intimate relation with climate. In order to discuss its evolution, four representative regimes of ocean circulations are summarized : (1) world ocean circulation in a superocean, Panthalassa during the early Mesozoic, (2) anoxic event in the young Atlantic during the late Mesozoic, (3) the evolution of Antarctic Ocean and the formation of Circum-Antarctic Current during Tertiary, and (4) ocean circulations during glacial and inter-glacial times. World ocean circulation and climate have been ultimately constrained by the land and sea distribution and botton topography. It is suggested that only a small environmental change should be amplified by the joint system of Atmosphere-Ocean-Biosphere. Fluctuations of temperature around 0°C in the high latitude would be important to those of ocean circulation and climate.