The evolution of the earth’s environment

The evolution of the earth's environment

Since the birth of the earth, the earth’s environment has already undergone vicissitudes of life. When the earth was formed about 4.5 billion years ago, it was a huge hot ball of fire, without the differentiation of the sphere of the environment. The earth is surrounded by a primitive atmosphere, which is mainly composed of H2, CH4, CO2, NH3 and water vapor without O2. It is a reducing atmosphere. The various sphere environments of the earth like today were formed after hundreds of millions of years of evolution and evolution.

The origin of life was about 3.8 billion years ago. It may be that under the action of some mechanism, such as the torrential rain, water appeared on the earth and produced rivers, lakes and oceans. The circulation of water reduces the temperature of the earth’s surface and creates the most basic conditions for the emergence of life. In this way, life appeared on the earth. The appearance of water is an important condition in the history of the earth’s development. Nowadays, more than 70% of the earth’s surface is covered with water, and the water content in most organisms is also more than 70%. The water content in humans and birds is 65%, and the water content in fish is 80%. The physiological saline used in medicine is a 0.9% NaCl solution, which is consistent with the original seawater. This seems to indicate that the blood flowing in the body of modern people is extremely similar to ocean water billions of years ago. In natural plants, the water content is higher, many vegetables are about 80%, and some are even as high as 95%. All this fully shows that the production and evolution of life on earth cannot be separated from water, which is the source of life. Although people have different views on the mechanism of the origin of life, it is generally believed that life originated in the ocean. At that time, the reductive atmosphere could not provide the necessary protection to the earth to protect life from the strong ultraviolet rays radiated by the sun. Primitive life can survive this kind of damage only if it is under the protection of the ocean water layer.

Early bacteria obtained energy through fermentation and released CO2 in the course of life, gradually changing the composition of the original atmosphere. Two billion years ago, the concentration of CO2 in the atmosphere was very high, about 10 times the concentration of CO2 today. By about 2 billion years ago, prokaryotes evolved into single-celled algae capable of photosynthesis. It is the chlorophyll in this plant that receives sunlight for photosynthesis, converts solar energy into organic matter, stores it and releases O2, and O2 appears for the first time in the earth’s environment. After about 400 million years of accumulation, the original reducing atmosphere has gradually transformed into an oxidizing atmosphere containing CO2, H2O, and O3. By 1.6 billion years ago, the concentration of CO2 in the atmosphere had gradually dropped to today’s level. An oxygen-containing atmosphere finally formed. Moreover, the accumulation of O3 at high altitudes has gradually formed the ozone layer that protects the earth, creating conditions for the evolution of higher marine organisms and the landing of life.

Due to the emergence of organisms, a large amount of CO2 in the atmosphere is transferred to the lithosphere, forming a huge amount of carbonate rocks. On the one hand, it changes the composition of the lithosphere. On the other hand, due to the interaction between organisms and rock weathering, Soil gradually formed on the surface. Therefore, the development of the various layers of the earth and the evolution of the earth’s environment are the result of the interaction between the biological world and the earth over a long period of time.

The circulation and conversion of material and energy on the earth’s surface are realized by living activities. If there is no life to capture, transfer and store solar energy, there would be no today’s earth environment. Life activities play a huge role beyond people’s imagination in the capture and storage of solar energy and the migration and transformation of the earth’s surface material. According to rough estimates, the cumulative total mass of all organisms in geological history is more than 1,000 times the mass of the earth; if no organisms absorb CO2 in the atmosphere, the CO2 in the atmosphere today will increase by 1,000 times, and the earth’s environment will become poor. It is suitable for the survival of human beings and all other creatures. The earth’s modern environment is the result of life’s participation in the evolution process of various geological periods in history for hundreds of millions of years.

The earth’s environment has been constantly evolving and evolving. During the Quaternary Period, the earth experienced an alternation of glacial and interglacial periods. In the more recent period of 1450~1880, the earth passed a small ice age. The average temperature of the earth is also in the process of change. The earth today is actually in a relatively hot interglacial period. Life on earth is constantly evolving, and species are constantly being produced and extinct. Dinosaurs once flourished on the earth 65 million years ago and their subsequent extinction is a good example.