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The author reviews the work done by himself and by Bezrukova-and Rubashev at the Pulkovo Observatory in relating fluctuations in the characteristics of the general circulation of the earth's atmosphere over the Northern Hemisphere to fluctuations in solar activity, on the one hand, and to climatic fluctuations, on the other. The general circulation of the atmosphere is thus found to meet the requirements of an intermediate link in the research system: sun—climatic change. This paper was read at the New York conference on solar variations, climatic change and related geophysical problems in January 1961.

This paper reviews some of the major findings, conclusions, and recommendations of the Study of Man's Impact on Climate (SMIC). This study was conducted in Stockholm during the summer of 1971 under the sponsorship of the Massachusetts Institute of Technology and was hosted by the Royal Swedish Academy of Sciences and the Royal Swedish Academy of Engineering Sciences. Thirty scientists from fourteen countries devoted 3 weeks of concentrated effort to develop a consensus concerning the present and future scale of man's activities that may affect the global temperature and heat balance and to determine whether such effects may become large enough to cause climate changes for the whole earth or for large regions. The principal conclusions of the study was that man may indeed be affecting local, regional, and global climate through a large number of varied activities. The gaps in present knowledge were identified and recommendations on how to fill these gaps were developed.

The existence of Quaternary climatic fluctuations in Southern Africa has been difficult to prove conclusively since, unlike countries of the northern hemisphere, glacial evidence is non-existent Nevertheless, it is generally agreed that periods both wetter and drier than now experienced have occurred in the past. Evidence is controversial and widely scattered and as yet no single chronology is accepted nor has the contemporaneity of events in the northern and southern hemisphere been accepted. Recent studies of karst landforms developed on the Transvaal Proterozoic Dolomite Series have shown that karst environments may preserve valuable evidence of alternating wet and dry periods. In this paper the types of evidence are discussed and possible conclusions are demonstrated. Since evidence may exist on the surface and underground and be derived from either the morphology of the landforms themselves or from depositional sequences, a number of corroborative, contemporaneous sequences are often availab...