What Are Greenhouse Gases?

Climate change and global warming that are such a buzz nowadays, owe their origin to the greenhouse gases. To understand how the gases present in the atmosphere can stifle life on earth, you should first understand how life forms survive on earth. Life on earth survives because of the energy it receives from the sun. A part of the light energy that comes towards the earth is deflected by the atmosphere. A majority of the light that reaches the atmosphere is again reflected back in the form of radiation. It is at this stage that various gases like carbon dioxide, methane, water vapor, etc, absorb the heat caused by the infrared radiation, and trap most of the heat inside the atmosphere. This leads to an increase in the earth’s atmosphere. This phenomenon is known as the “greenhouse effect”, and the gases that trap the heat as the greenhouse gases, since the heat is trapped by those gases like in a greenhouse. The greenhouse effect is a natural phenomenon and it is bound to happen. Earlier, greenhouse gases constituted a minimal portion of the earth’s atmosphere. So, very less heat was trapped which didn’t lead to any adverse effects on the environment. However, due to human interference like rapid deforestation and drastic increase in industrial and vehicular pollution these gases have increased manifold in the atmosphere. As a result, more heat is trapped leading to the change in climate and heating of the earth. And the signs of such adverse effects have never been more urgent. From melting glaciers to drying rivers, from severe draughts to raging floods, from tornadoes to stifling heat are all due to the increase in greenhouse gases and the resultant effects. To know more read below for information on greenhouse gases.

 

Water vapor is the gaseous phase of water and it is generated continuously by evaporation. Since, it is lighter than air it forms clouds. Approximately 99.13% of water vapor is concentrated in the troposphere. The heat from vaporization causes tropical cyclones and thunderstorms. The content of water vapor in the atmosphere increases in warmer temperatures which results in water vapor feedback. This increases the climate warming effect because of the increase in carbon dioxide. Among all the green house gases, water vapor results in the largest percentage of green house effect.

Carbon dioxide is a potent greenhouse gas as it is able to absorb infrared and near-infrared light. The concentration of carbon dioxide varies according to the season and region. The large amount of carbon dioxide in the atmosphere is mostly due to deforestation and the burning of fossil fuels.

 

Methane is also a very potent greenhouse gas. Methane of the same mass as carbon dioxide has twenty five times more impact over a hundred-year period. It has a very brief net lifetime in the atmosphere compared to other gases and it also accounts for 20% of radiative forcing from the greenhouse gases.

 

This is more commonly known as laughing gas. Nitrous oxide is a major air pollutant, and it has 298 times more impact over a hundred-year period for the same amount of carbon dioxide. Nitrous oxide accounts for almost 6% of heating effect in the atmosphere. It is also considered to be the most important ozone-depleting substance emission. Almost 30% of nitrous oxide in the atmosphere is attributed to human activity.

 

While ozone in the upper layer of the atmosphere is beneficial, it is considered as an air pollutant when present in the lower atmosphere. Throughout the earth’s atmosphere, ozone is present in low concentration. In the upper troposphere, ozone acts as a greenhouse gas as it absorbs the infrared energy emitted by the earth.

 

Chlorofluorocarbon is the major cause of ozone depletion. It is only used now for medicinal purposes.