Climatic Changes of the Past and Present

摘要: Inhabitants of the so-called temperate zone are quite familiar with both unusual weather and rapidly changing conditions. Lately, however, even climate?that is, composite con ditions over a period years?has seemed somewhat "reality" climatic conditions has become not only apparent, but newsworthy. Some people may be old enough to have recol lections "good days" when climate was different: winters at least been much colder snows deeper than they today. Although reliable meteorological records do go back very far, seem show that major changes rather minor fluctuations taking place. Present warmer were in latter half 19th century. In terms remote geologic past, today's is ac tually unusually cold. fact, we still living "glacial age" com pared 35 40 million years ago. An examination Figure 1 will that, since beginning Cambrian Period, 500 ago, earth's considerably present about two-thirds time. The evidence indicates from this "non-glacial" "glacial" occurred several times during history. world today one these glacial episodes, which few thousand ago frigid support an ice sheet most Canada as far south northern United States. Furthermore, it noted (Fig. 1) cooling trend culminated recent episode really started Oligocene Epoch not, some believe, Late Pliocene. paper three topics discussed : (1) past 50 12,000 Eocene end Pleistocene "Ice Age"; (2) im mediate Age" present; (3) prediction possible near future next years.