AIPMT Biology Aspirants, read out the next AIPMT Biology Study material/ Notes of Greenhouse Effect and Global Warming, important for AIPMT Biology.Free online notes for AIPMT.

Greenhouse effect is what makes this planet suitable for life. Greenhouse effect is a natural phenomenon that is responsible for heating of Earth’s surface and atmosphere. As without greenhouse effect the average temperature at surface of Earth would be around chilly -18ºC rather than the present average of 15ºC.

• Small amounts of certain gases Carbon dioxide (CO₂), Methane (CH₄), and Nitrous oxide (N₂O), in the atmosphere play a role in determining the earth’s average temperatures and its climates.

Energy Flow to and from the Earth

• Greenhouse gases allow visible light and some infrared radiation and ultraviolet (UV) radiation from the sun to pass through the atmosphere. The earth’s surface absorbs much of this solar energy and transforms it to longer-wavelength infrared radiation (heat), which then rises into the lower atmosphere. Some of this heat escapes into space, but some is absorbed by molecules of greenhouse gases and emitted into the lower atmosphere (troposphere) and warms the lower atmosphere and the earth’s surface.

• Carbon dioxide and Methane are major gases responsible for the greenhouse effect.
• Contribution of greenhouse gases : Carbon dioxide- 60%, Methane- 20%, CFCs(Chlorofluorocarbons)- 14%, N2O – 6% 

Greenhouse gases and their contribution in Global Warming

• Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming.
• During the past century, temperature of Earth has increased by 0.6ºC. This rise in temperature is leading to deleterious changes in the environment and resulting in odd climatic changes (e.g. El Nino effect) , thus leading to increased melting of polar ice caps as well as of other places like the Himalayan snow caps.
• Global warming can be controlled by reducing the cutting down use of fossil fuel, improving efficiency of energy usage, reducing deforestation, planting trees and slowing down the growth of human population.

NOTE: El Nino is a climate cycle in the Pacific Ocean with a global impact on weather patterns. El Nino cycle begins when warm water in the western tropical Pacific Ocean shifts eastward along the equator toward the coast of South America, which suppresses the normal upward movement of cold, nutrient-rich water from the bottom of the ocean. The decrease in nutrients reduces primary productivity and causes a sharp decline in the populations of some fish species.