All about the greenhouse effect

Increased human activity, urbanisation and industrialisation have led to rapid deterioration of the environment. This has severely affected the life support system. The developmental discrepancies in different regions of the world pose a serious threat to our common global environment. Consequently, we are confronted with complex environmental issues that deserve our attention.

The important global environmental issues are:

• Greenhouse effect and global warming
• Biodiversity loss
• Desertification
• Depletion of ozone layer
• Acid rain
• Oil spills
• Hazardous wastes

What is greenhouse effect?

The temperature surrounding the earth has been constantly rising during the recent past. This is due to the ‘greenhouse effect. A green house is a glass chamber in which plants are grown in order for them to benefit from the warmth of the trapped sun light. Sunlight (a form of energy) passing through the glass gets absorbed into the chamber and releases heat radiations. These radiations unlike sunlight cannot escape through glass chamber.

Thus, even on a cold winter day, the inside of a greenhouse can become quite warm and hence support plant growth. This phenomenon of heat build-up inside a glass chamber from the absorption of solar radiation is called greenhouse effect. But, you may well ask, where is the glass around the earth that prevents escaping of the heat from the earth’s surface.

Global warming and green-house effect

The green-house effect is a natural phenomenon and has been occurring for millions of years on Earth. Life on this planet has been supported by this natural greenhouse effect which is made possible by water vapour and small particles of water present in the atmosphere.

Together, these produce more than 95 per cent of the total green-house warmth. Average global temperatures are maintained at about 15 degrees centigrade due to the natural greenhouse effect. Without this phenomenon, the average global temperatures may have been around 17 degrees centigrade and at such low temperature, life would not have been able to exist.

Before industrialisation, human activity did not cause any significant increase in the atmospheric temperature. What is particularly worrisome is the increase in the emission of greenhouse gases due to urbanisation and industrialisation. These greenhouse gases have increased significantly in the atmosphere in recent years. Some important greenhouse gases and their major sources are listed in table:

Effect on climate

• Climate and wind patterns shift.
• Harsher colder regions warm-up and become habitable.
• Water evaporates from seas leading to more rain thereby changing rainfall patterns which cause flash floods.
• Temperature regions lose soil moisture, causing a decline in agricultural productivity.
• Sea level rises due to the melting of glaciers, which inundate low regions of earth like- Egypt, Florida and Bangladesh.
• Heating up of the atmosphere results in the movement of air where hot and cold winds meet, resulting in violent weather
• conditions like tornadoes and hurricanes.

Effect on living beings

Increased carbon dioxide concentration in the atmosphere increases photosynthetic productivity of plants. This in turn produces more organic matter.

• Weeds proliferate rapidly at the expense of useful plants.
• Insects and other pests that feed on plants also increase in number.
• Survival of other organisms gets affected.

Strategies to cope with greenhouse effect

We must take immediate steps to minimise global warming by reducing emission of greenhouse gases, especially carbon dioxide. The following steps will reduce emissions/release of greenhouse gases into the atmosphere:

• Increased fuel efficiency of power plants and vehicles
• Development/implementation of solar energ/non-fossil fuel alternatives
• Curbing of deforestation
• Tree-planting (afforestation)
• Reduction of air-pollution