by Rudolf BALANDIN, geologist
Climate is a statistically generalized description of weather conditions. It used to be considered stable within the life span of one single generation. In these past fifty years, however, the situation has changed, what with weather vagaries everywhere and the ongoing global warming, according to many competent experts. What is the cause of this warming? Its possible consequences? Some of the clues are offered in a capital study off the press here in this country (Climate in the Ages of Major Biospheric Reconstructions; M., Nauka Publishers, 2004; 299 pp.).
The geologic history of our planet is characterized by predominantly warm periods alternating with cold spells now and then. That has led to cardinal structural changes of natural zones and landscapes and to the appearance of ice sheets (caps) spreading from circumpolar regions down to lower latitudes.*
Now what caused such changes, and how did they proceed? The book under review furnishes a wealth of information to this effect and is illustrated by a picture of paleoclimatic succession of events, maps, charts, and so forth. The authors seek to explain the peculiarities of climate dynamics as an important factor of biological life.
The book is in four parts, each dealing with changes that occurred in the natural environment at the turning-points of geologic epochs. Looking through paleographical maps you kind of travel back into the distant past to see the changeability of the face of the earth: its continents moving here and there, its climatic belts, land-and-sea balance changing out of recognition. You just wonder: there is another planet before you, poles apart from what we are having today-its surface, land and ocean contours, and many other things are so much different.
The first part of the book (author, Mikhail Akhmeyev) considers the period of transition from the warm biosphere to a colder one during the Paleogene (65 - 23 mn years ago). The second, much more extensive ... Read more