Abstract
On the geological scale, earth history yields vital information concerning past environments and climates. This highlights the urgency for increased collaborative international response and research into solutions of problems posed by current climatic changes, whether natural or induced by the activities of man. Climatic changes occur on variety of timescales, ranging from catastrophic volcanic eruptions (minutes or days), through gradual changes in Earth's orbital parameters (104-106 years) to tectonically driven changes (106-108 years). It seems likely that the long-term fluctuations of climates (less than the time-scale of planetary evolution), which give rise to glacial epochs, are largely determined by continental plate distributions and movement, whilst the shorter-term fluctuations which produce glacial and inter-glacial periods in glacial epochs reflect variations in coming solar radiation.
Attention is focussed on the possible existence of an anoxygenic, primeval atmosphere and on the history of atmospheric CO2. Five great biologic revolutions have occurred through earth history that have fundamentally shaped the modern geochemical picture. It is significant that organisms have controlled their own environment. Organic CO2 and calcium budget have played critical roles.
