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Environment & Health

Question
24 out of 72
 

Which of the following is true regarding Global Warming? (AIIMS May 11)



A CO2 is the major greenhouse gas emission
B Stratosphere ozone layer is harmful
C CFCs increase stratosphere ozone layer
D Kyoto protocol recommends 20% reduction in greenhouse gas emissions

Ans. A CO2 is the major greenhouse gas emission Ref: Park; 22nd edi, pg –694

Some very important facts about climate change:

a. ‘Climate change’ is generally used when referring to changes in our climate.

The energy from the sun warms land, water and air.

b. In turn the warmed up land, water and air give off heat, which rises up towards the sky.

c. Gases such as water vapor present in earth’s atmosphere capture some of that heat and prevent it from escaping into space.

d. This heat trap keeps the earth warm and make our planet a habitable world.

e. This process is known as greenhouse effect. It is a natural phenomenon. However, adding more greenhouse gases increases the warming effect to the point that it is no longer beneficial but has negative consequences for life on earth. For over 10,000 years the earth has had relatively stable temperatures. But for the past 150 years our planet has been warming up fast.

f. This phenomenon is called global warming. This change is result of human activities.

MAIN GREENHOUSE GASES:

a. Water vapor: one of the most abundant gases in atmosphere and builds up with evaporation from water bodies on earth.

b. Carbon dioxide: produced by combustion of fossil fuels and from forest fires is the next most important gas responsible for global warming. (option A )

c. Methane: released from animal husbandry, irrigated agriculture and oil extraction.

d. Nitrous oxide: by-product of burning fossil fuels and also released when ploughing farm soils

e. Ozone: main element of protective layer in upper atmosphere, which shields earth from the sun’s harmful UV radiation.(option B) Ozone is both natural and man made gas. Produced in excess as a result of smog and severe air pollution, becomes harmful to health.

f. Chlorofluorocarbons: used for refrigerators, air conditioners, aerosol sprays etc. they cause depletion of ozone layer. (Option c)

Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750.

Average global temperature is expected to rise by 0.2 degree Celsius per decade over the next 100 years.

A warmer atmosphere also disrupts wind and rain patterns leading to excessive floods and/or prolonged droughts. When sea level rises, it may be due to thermal expansion, from melting of glaciers or due to changes in salinity

As far as option D is concerned please remember that Kyoto Protocol lays down the norms for cutting down the CO2 emmision but it doesn’t specify 20% emission cut. In fact it lays down separate norms for the developed and the developing countries in tune of emission cuts ranging up to 5%.

Montreal protocol was also laid down with regard to global warming but in contrast to Kyoto protocol it talks about the harmful effects of the depleting ozone layer rather than about emission cuts.

Environment & Health Flashcard List

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