GREEN HOUSE EFFECT:
When sun’s energy enters the earth, some of it is absorbed while other is reflected back. A part of this reflected energy is absorbed by a few gases like Carbon dioxide, water vapour, Methane etc. present in earth’s atmosphere. This process is called Green House Effect. The gases responsible for greenhouse effect are called Green House Gases. The Green House gases are responsible for presence of appropriate temperature on earth. In the absence of these gases, extreme weather conditions would prevail on earth, making life impossible on it as there would have been a temperature difference of about 330 C between the temperatures of day and night on earth. However, excess of greenhouse gases is not desired as it leads to global warming. GLOBAL WARMING:
The rise in average temperature of earth’s atmosphere due to greenhouse effect is called Global Warming. CAUSES
Increase in amount of greenhouse gases like Carbon dioxide, Methane, Nitrogen dioxide etc. due to human activities such as petroleum refining, burning of fossil fuels in vehicles, factories, deforestation and industrialisation. Certain natural phenomena like volcanic eruptions leads to emission of greenhouse gases like CO2, NO2. EFFECTS OF GLOBAL WARMING:
Melting polar ice caps will raise ocean and sea levels. It is predicted that Arctic could be ice free by 2050. Global sea levels could rise by more than 20 feet devastating coastal areas worldwide. Catastrophic weather such as hurricanes will increase.
Heat waves and wildfires could be more frequent.
More than a million species could be extinct by 2050.
Extreme weather conditions would prevail leading to increase in number of droughts and floods. Warming of troposphere is accompanied by cooling of upper strata of atmosphere. Cooling of Stratosphere will tend to increase the size of ozone hole.