Question

Meaning of Green House Effect . Impacts of Green House Effect. 

Answer 1

The greenhouse effect refers to the phenomena by which the earth's atmosphere traps infrared radiation or heat. Gases that cause the greenhouse effect are for the most part natural compounds- water vapour, CO2, Methane and nitrous oxide that keep the earth habitable. But human activity is increasing the concentration of these and other gases. For example, the industrial compounds known as chlorofluorocarbons. The trend, if continues, is expected by atmospheric scientists to lead to global climate change with uncertain but potentially grave long-term effects.

The most direct evidence of global warming comes from the analysis of temperature records covering the last 130 years. Recent re- examination of the records confirms the IPCC's original view that global mean temperatures have risen 3°C to 6°C during this time. Nonetheless, the view that warming has accelerated during the last two decades is supported by a strong evidence that the rapid melting of glaciers outside the polar zone over the last 30 years and a decrease in snow cover in some areas.

Some scientists are of the view that rise in humidity is increasing heat transfer from the atmosphere to ice and thus hastening melting. The IPCC reports some evidence for higher humidity levels in the tropics since 1960s. This observation is consistent with the greenhouse theory, which predicts that humidity will rise as a sea surface temperatures grow warmer and evaporation increases. Therefore we can define greenhouse effect is the difference between the earth's surface temperature and the radiative temperature.

If no greenhouse effect is present on the earth the average temperature of the world would be low nearly  -19°C, well below the freezing point of water. Therefore no life is possible. But due to greenhouse effect, the temperature of the earth remains nearly to the 15°C which sustains the life comfortably. Therefore the greenhouse effect is one of the vital element of our life. But too good of a thing is bad or have the opposite effect. Due to excessive global warming, it is estimated that there will be 0.5°C to 4.5°C rise in temperature before the next middle of the century.

Impacts of Green House Effect

following are the impacts of Green House Effect-

(1)- Sea Level Rise - with the warmer climate, the sea level may rise due to two reasons- (a) thermal expansion of sea level, and (b) melting of snow and ice of arctic regions. This sea level rise up to meters into next 20 years. This will bring the disastrous effect on the low lying coastal areas of the world. At the present rate of the one cm/year sinking of the land, the days are not far away that countries like Bangladesh, Indonesia and Malaysia will get submerged.

(2)- Imapct on agriculture

Climate change is expected to damage agriculture in some areas but aid it  in others. The principle damage will arise from heat stress, decreased soil moisture, and an increased incidence of pests and diseases. In addition, warmer temperatures could cause the growing cycle of many plants to accelerate, allowing less time for plant development before maturity.

(3)- Impact on water resources

some regions may benefit, but climate change could in many areas put considerable stress on water supply as a result of changes in the timing, regional pattern and intensity of precipitation events. This in turn will affect the magnitude and timing of runoff, while higher temperatures will at the same time will lead to changes  in soil moisture and infiltration conditions.

(4)- Imapct on health

There are many potential health impacts arising from climate change, some beneficial and some adverse. Although generally difficult to foresee and quantify, these impacts could arise from diverse events, including disturbance in natural or managed ecosystems. They could either be direct as in the age case of heatwave deaths or indirectly as when caused by changes in the range and transmissibility of the vector - born infectious diseases. 

The  phenomenon by which Earth's atmosphere traps infrared radiation or heat.