Chemical Concept

Enhanced greenhouse effect is caused by the increase in emission of natural gases such as carbon dioxide from human activities. The discovery of harnessing energy from fossil fuels has led to the increase in such gases, thus increasing the amount of energy being trapped in the atmosphere.

Examples of human activities that leads to the increase in such gases are the burning of fossil fuels, deforestation, and the increase in resources required to support the increase in human population (refer to Figure 1).

Figure 1 – Illustration of how these gases lead to enhanced greenhouse effect

Explanation 

In terms of chemical concepts, these gases have the ability to absorb radiation. Hence, the increase of such gases from human activities create warmer climate. The common gases include carbon dioxide (CO 2 ) that is a product from burning fossil fuels and methane (CH 4 ) which is a result of the increased agriculture activity to support human population growth.

In addition, there are several industrial gases that are not commonly occurring such as chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs).

All of the greenhouse gas molecules have three or more atoms and are capable of absorbing and emitting infrared radiation.

For example, molecules of CO 2 absorbs infrared radiation. The energy from the photon causes theCO 2 molecule to vibrate. The molecule gives up this extra energy by emitting another infrared photon. Once, the extra energy is removed by the emitted photon, the carbon dioxide stops vibrating.

This ability to absorb and re-emit infrared energy is what makes CO 2 an effective heat-trapping greenhouse gas (refer to Figure 2).

Figure 2 – Illustration of how greenhouse gas absorbs and re-emits infrared radiation

References:

Carbon Dioxide Absorbs and Re-emits Infrared Radiation. (n.d.). Retrieved March 29, 2017, from https://scied.ucar.edu/carbon-dioxide-absorbs-and-re-emits-infrared-radiation

Global Warming. (n.d.). Retrieved March 29, 2017, from http://www.chemistryexplained.com/Ge-Hy/Global-Warming.html

Causes of the Greenhouse Effect. (2017, January 05). Retrieved March 29, 2017, from http://www.conserve-energy-future.com/greenhouseeffectcauses.php

(n.d.). Retrieved March 29, 2017, from https://www.nccs.gov.sg/nccs-2012/images/chapter-1/pic-01.jpg