Global Warming - Global Headache

What is Global Warming:

Global warming is a word heard everywhere nowadays. But what does it mean? Simply global warming means the average temperature increase of Earth-surface, oceans and the air near earth surface. In the 20th century, the average temperature of earth's surface has increased about 1 degree centigrade. this does not seem much, but one can not even imagine how much danger does this global warming will bring to us in the near future.

Causes of Global Warming:

The Earth has experienced many phases of warming and cooling over billions of years. Many natural factors contribute in these warming and cooling, but the effects of these factors take place very slowly, even in millions of years. So these factors are not accounted for the extra warming we currently observing in our planet. Actually it is us, the Humans, who are mainly responsible for global warming. We are accelerating the phenomenon of global warming with our human created emissions of greenhouse gases. Over the last 50 years, most of the observed temperature increase was due to the increase of greenhouse gases in atmosphere. Greenhouse gases are those which contribute to the greenhouse effect (see below). Gases such as Water vapor, Carbon dioxide, Methane, Ozone, Nitrogen oxides etc. are greenhouse gases.

Greenhouse Effect:

When sunlight reaches our earth’s surface, some percentage of them is observed by earth’s surface and they warm the earth. Rest of them are reflected and radiated back to atmosphere with a higher wavelength. These radiations would have been lost in space if there were no greenhouse gases. But greenhouse gases are present there, and they absorb some of the radiations of higher wavelength before they are lost in space. The absorption of this long wave radiant energy warms the atmosphere. In this way, the greenhouse gases act like a mirror and reflect some of the heat energy to the earth which would otherwise lost to the space. This phenomenon of reflecting back the heat energy is known as the ‘Greenhouse effect’. The gases contributing most in greenhouse effect are water vapor (36-70%), carbon dioxide (9-26%), methane (4-9%), ozone (3-7%) etc.

Greenhouse Effect at a Glance:

Global Warming by Greenhouse Effect:

Greenhouse gases act like a mirror and reflect back to earth a part of the heat radiation. These radiations would otherwise have radiated to space. The higher the concentration of greenhouse gases in atmosphere, the more heat energy is reflected back to earth. As a result the temperature of earth is increased. So the increased greenhouse gas concentration (mainly CO₂) led to a substantial warming of earth and sea, and this incident is known as global warming.

Sources of Greenhouse Gases:

The main sources of greenhouse gases are:

1.  Carbon Dioxide from:
1. Fossil Fuel
2. Deforestation
3. Failing Sinks
2. Methane from:
1. Cattle and Rice Paddies
2. the Artic Tundra
3. Clathrates
3. Nitrogen Oxides from Farming
4. Other Gases

Now let’s see the greenhouse gas emission by different sectors:

Effects Of Global Warming:

The harmful effects of global warming cannot be described in one word. Because of it the Arctic glaciers will melt, as a result the height of sea levels will increase and many place in the world will go under water. It will expand the area of subtropical deserts. Many species of animals in earth will face extinction. Agricultural productivity will be harmed. So steps must be taken to prevent this harmful phenomenon.