The cause

A greenhouse is a glass-built building for growing plants. With illumination from the sun, heat enters the house with little of it escaped as the glass traps it. The temperature inside the house ismuch higher than that of air outside. Plants grow there can have more warmth and healthier.

Our atmosphere is like a huge greenhouse. Greenhouse gases, like carbon dioxide, acts like the glass of a greenhouse. The changes in climate of the Earth and the subsequent effects are called greenhouse effect.

What are greenhouse gases?

Source: Global Ecology Handbook

How the problem intensifies

1. The burning of coal and oil in cars, power stations and factories gives out huge amounts of carbon dioxide and nitrogen oxides into the atmosphere.
2. The rapid growth of population needs more food. More cattles, sheep, etc., are reared. More people breathe out more carbon dioxide, and the waste of animals generates methane.
3. Forrests are cleared or burnt for development. Fewer plants can contribute for the absorption of carbon dioxide that maintains the balance of oxygen and carbon dioxide in the atmosphere. The level of carbon dioxide increases.

Carbon dioxide and greenhouse effect

Much carbon dioxide is absorbed into oceans or used by plants for photosynthesis. Nevertheless, the production rate is higher..

Chemists have monitored atmospheric carbon dioxide concentration since 1958. Analysis of air trapped in ice cores from the polar regions permits us to know the past carbon dioxide levels from about 160,000 years ago. The level is fairly constant since the past ice ages some 10,000 years ago. Until the industrial revolution some 300 years ago, the concentration of carbon dioxide has increased by about 25%.

The accumulation or the gas has caused absorption of radiant heat. The climate changes.

The impact

Greenhouse effect may be beneficial. When the Earth is warmer, there may be an increase in agricultural production. But the problem is that the amount of greenhouse gases increases dramatically. It grew 3 times in the past 100 years. Such rising may induce harmful effects to the environment:

1. Rise of sea-level
   Climates do change naturally over long periods of time. However, the Earth becomes warmer in the recent decades. It was found that 9 hottest years on record occured during the past 14 years. The mean Earth temperature in 1997 was 0.43°C higher than the past 26 years.
   
   Global warming causes the polar ice sheets melt. It increases the sea-level. It will possibly rise 18 cm by 2030 and 58 cm by 2090. Flooding will probably occur in lowlands. Many cities along the coast may be under sea water.
   
   
2. Changing rainfall patterns
   Warming also affects rainfall and food production. Some places have an increment in rainfall and some will decrease. There may be flooding or drought in various farmlands. Food is important for lives. That means more people, especially in the developing countries, suffer from hunger.

Related topics

Carbon dioxide
Chloroflurocarbons (CFCs)
Ozone

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