Climate Change and Global Warming Questions and Answers

Answer: D

The gas mostly responsible for global warming is carbon dioxide.

Carbon dioxide, released mainly by burning coal, oil and natural gas and by deforestation, is the largest contributor to human-caused global warming because of the huge quantities emitted and its long life in the atmosphere. It accounts for roughly two-thirds or more of the warming effect of long-lived greenhouse gases.

Methane, nitrous oxide and CFCs trap more heat per molecule, but they are present in much smaller amounts, so their total contribution is smaller than that of carbon dioxide.

Answer: D

The answer is Both (A) and (B).

The National Action Plan on Climate Change, released in June 2008, set up eight national missions: solar, enhanced energy efficiency, sustainable habitat, water, sustaining the Himalayan ecosystem, Green India, sustainable agriculture, and strategic knowledge for climate change.

Since both the missions named are among the eight, the options naming only one, or neither, are wrong.

Answer: B

International Ozone Day is celebrated on 16th September.

The UN General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, marking the date in 1987 on which the Montreal Protocol on substances that deplete the ozone layer was signed.

16 October is World Food Day, and 21 January and 26 October are not international ozone days.

Answer: A

The gas mainly responsible is carbon dioxide.

Molecule for molecule, methane, nitrous oxide and chlorofluorocarbons trap more heat than \(\mathrm{CO_{2}}\). But carbon dioxide is emitted in vastly greater quantities, mainly by burning fossil fuels and clearing forests, and stays in the atmosphere for a long time, so it accounts for the largest share of the enhanced greenhouse effect, roughly two-thirds of the warming from long-lived greenhouse gases.

Methane is the second most important contributor, and nitrogen dioxide is chiefly a local air pollutant rather than a major greenhouse gas.

Answer: B

The ozone layer is in the stratosphere.

About 90% of atmospheric ozone lies in the stratosphere, at roughly 15 to 35 km, where ultraviolet radiation splits oxygen molecules and the atoms combine with \(\mathrm{O_2}\) to form \(\mathrm{O_3}\). This layer absorbs most of the Sun's harmful UV-B radiation.

Some ozone does occur in the troposphere, where it is a pollutant in smog, but the ozone layer meant here is stratospheric. The mesosphere and exosphere contain very little.

Answer: A

The main factor is chlorofluorocarbon.

CFCs, once used in refrigerators, air conditioners and aerosol sprays, are stable enough to reach the stratosphere. There ultraviolet light breaks them up and releases chlorine atoms, each of which can destroy many thousands of ozone molecules in a chain reaction. They are being phased out under the Montreal Protocol of 1987.

Chloroform, acetaldehyde and benzene are pollutants and solvents but are not the main cause of ozone depletion.

Answer: B

Ozone protects the biosphere from high-energy ultraviolet rays.

The ozone layer in the stratosphere, about 15 to 35 km up, absorbs most of the sun's ultraviolet-B and almost all ultraviolet-C radiation. These wavelengths damage DNA, causing skin cancer and cataracts in people and harming plants and plankton, which is why ozone-depleting substances are controlled under the Montreal Protocol (1987).

Infrared radiation is absorbed mainly by water vapour and carbon dioxide, not ozone. X-rays and gamma rays from space are stopped high in the atmosphere by ordinary oxygen and nitrogen, so the ozone layer is not what protects us from them.

Answer: A

The World Summit on Sustainable Development, 2002 was held in South Africa.

The summit, also called Rio+10, met in Johannesburg from 26 August to 4 September 2002 to review progress since the 1992 Earth Summit and adopted the Johannesburg Declaration and Plan of Implementation.

Brazil hosted the 1992 Earth Summit and the 2012 Rio+20 conference, and Sweden hosted the 1972 Stockholm Conference on the Human Environment. Argentina has hosted climate conferences (COP4 and COP10 in Buenos Aires), but not this summit.

Answer: C

\(\text{SO}_{2}\) (sulphur dioxide) is not a greenhouse gas.

Sulphur dioxide is an air pollutant that causes acid rain. It forms sulphate aerosols that reflect sunlight, so its effect on climate is cooling rather than warming, and it is not listed among the greenhouse gases.

Carbon dioxide, methane and the chlorofluorocarbons all absorb the infrared radiation emitted by the Earth and trap heat in the atmosphere, which makes them greenhouse gases; CFCs also destroy ozone.

Answer: C

The incorrect statement is India, Azerbaijan, Nigeria and Morocco are the participants of the Decarbonising Transport in Emerging Economies (DTEE).

The 'Decarbonising Transport in India' project, launched in June 2020 by NITI Aayog with the International Transport Forum, is part of the ITF's DTEE project. The four participants of DTEE were India, Argentina, Azerbaijan and Morocco; Nigeria was not one of them, so this statement is wrong.

The other two statements describe the project correctly: it aims to develop a pathway to a low-carbon transport system for India, and it designs a transport emissions assessment framework tailored to India. Because one statement is incorrect, 'None of the above' cannot be the answer.