Explain relation between greenhouse effect and global warming.

Greenhouse gases such as $C{O}_2$, methane, etc. are gases that absorb the heat of the sun and then emit it back to the Earth's surface. Thus, these gases prevent a part of the heat rays from escaping into the atmosphere. This cycle is repeated several times to maintain the Earth's temperature to an optimum temperature. Therefore, upto a normal level, greenhouse gases help in maintaining the temperature on the Earth. However, the concentration of these gases has increased because of increased industrialization, which has lead to the heating up of the Earth's surface resulting in climatic changes. During the last century, the temperature of the Earth has increased by $0.6^{o}C$. This has lead to global warming.