Ecology is a very popular word today. But what does it mean? Ecology is a since which studies the relationship between all forms of life on our planet and the environment. This word came from Greek “oikos” which means home. The idea of home includes our whole planet, its population, Nature, animals, birds, fish, insets and all other living beings and even the atmosphere around our planet.
Since ancient times Nature has served Man giving everything he needs: air to breathe, food to eat, water to drink, wood for building and fuel for heating his home. For thousands of years people lived in harmony with the environment and it seemed to them that the resources of nature had no end or limit. With the industrial revolution our negative influence on Nature began to increase. Large cities with thousands of steaming, polluting plants and factories can be found nowadays all over the world. The by-products of their activity pollute the air we breathe the water we drink the fields where our crops are grown. That’s why those who live in cities prefer spending their days off and their holidays far from the noise of the city, to be closer to nature. Perhaps they like to breathe fresh air or to swim in clear water because the ecology is not so poor as in the cities.
So, pollution is one of the most burning problems of nowadays. Now millions of chimneys, cars, buses, trucks all over the world exhaust fumes and harmful substances into the atmosphere. These poisoned substances pollute everything: air, land, water, birds and animals. So, it is usually hard to breathe in the large cities where there are lots plants. Everything there is covered with soot and dirt. All these affect harmfully. Every year the atmosphere is polluted by about 1000 tons of industrial dust and other harmful substances. Big cities suffer from smog. Cars with their engine have become the main source of pollution in industrial countries. Vast forests are being cut down for the need of industries in Europe and USA. The loss of the forests upsets the the oxygen balance of the new wastelands. As the result some species of animals, birds, fish and plants have disappeared and keep disappearing.
Water pollution is very serious, too. Ugly rivers of dirty water polluted with factory waste, poisoned fish are all-round us. And polluted air and poisoned water lead to the end of the civilization. So, nowadays a lot of dead lands and lifeless areas have appeared. Because our actions and dealings can turn the land to a desert.
What is the greenhouse effect, and is it affecting our climate?
The greenhouse effect is unquestionably real, and is essential for life on Earth. It is the result of heat absorption by certain gases in the atmosphere (called greenhouse gases because they trap heat) and re-radiation downward of a part of that heat. Water vapor is the most important greenhouse gas, followed by carbon dioxide and other trace gases. Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C). However, the concern is not with the fact that we have a greenhouse effect, but it is with the question regarding whether human activities are leading to an enhancement of the greenhouse effect.
Are greenhouse gases increasing?
Human activity has been increasing the concentration of greenhouse gases in the atmosphere (mostly carbon dioxide from combustion of coal, oil, and gas; plus a few other trace gases). There is no scientific debate on this point. Pre-industrial levels of carbon dioxide (prior to the start of the Industrial Revolution) were about 280 parts per million by volume (ppmv), and current levels are about 370 ppmv. According to the IPCC "business as usual" scenario of carbon dioxide increase (IS92a) in the 21st century, we would expect to see a doubling of carbon dioxide over pre-industrial levels around the year 2065.
Is the climate warming?
Global surface temperatures have increased about 0.6°C (plus or minus 0.2°C) since the late-19th century, and about one half degree F (0.2 to 0.3°C) over the past 25 years (the period with the most credible data).
The warming has not been globally uniform.
Some areas (including parts of the southeastern U.S.) have cooled. The recent warmth has been greatest over N. America and Eurasia between 40 and 70°N. Warming, assisted by the record El Niсo of 1997-1998, has continued right up to the present.
Linear trends can vary greatly depending on the period over which they are computed. Temperature trends in the lower troposphere (between about 2,500 and 18,000 ft.) from 1979 to the present, the period for which Satellite Microwave Sounding Unit data exist, are small and may be unrepresentative of longer term trends and trends closer to the surface. Furthermore, there are small unresolved differences between radiosonde and satellite observations of tropospheric temperatures, though both data sources show slight warming trends. If one calculates trends beginning with the commencement of radiosonde data in the 1950s, there is a slight greater warming in the record due to increases in the 1970s. There are statistical and physical reasons (e.g., short record lengths, the transient differential effects of volcanic activity and El Niсo, and boundary layer effects) for expecting differences between recent trends in surface and lower tropospheric temperatures, but the exact causes for the differences are still under investigation (see National Research Council report "Reconciling Observations of Global Temperature Change").
Реферат опубликован: 5/06/2006