Document Type : Research Paper

Author

• Puran Tahuni

Ph.D. of Natural Geography (Geomorphology)

Abstract

The Earth's climate is not constant; the range of changes is vast and includes from warm and humid periods to the glacial. Rocks and sediments carry many signs of the past climatic changes with them. Salt deposits, red soils, kaolin, lime sediments and corals are evidences of hot climes, and glacial sediments and deposits and river terraces are evidences of cold climates. The dating of such evidence suggests that some of these changes have occurred in long-term and some others in short-term. Mesozoic heat lasted for millions of years, while glacial and interglacial periods of the Pleistocene have lasted only thousands of years.
 Why and how do such vast changes occur? With a systematic approach to the Earth, it would be easier to answer this question. Earth is a system in which a set of interconnected processes act on a large spatial and temporal scale, so there is not a single cause, and necessarily a set of causes are effective.
 In general, climatic conditions are the result of a mutual and complex interaction of two important sources of energy, namely solar energy and the Earth’s energy. Radiation from the Sun is the first source of the Earth’s energy that drives the Earth's fluids (water and atmosphere). The internal energy of the Earth is the cause of movement of plates; this movement causes continental displacement, formation of volcanoes, rise of mountains, and large changes on the scale of the sea level. So far, several views have been laid down in explaining the causes of climate change, but none of them has definitely answered the questions; each has described a part of the phenomenon. With the emergence of the theory of tectonic plate, this theory found a special place in explaining the causes of long-term climate changes.

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