Climate Change: UPSC Previous Year Questions (Environment and Ecology)

Explanation

For slowing down global warming, carbon sequestration involves the capture and storage of CO₂. It is captured from the air, industries or power stations and stored permanently underground. This promotes Long-term reserve of CO₂ or forms of carbon to control temperatures. Carbon sequestration aids in lowering the amount of GHGs (due to combustion of fossil fuels) present in the air.

Statement 2 is correct: The photosynthesis by phytoplankton in the oceans is natural carbon sequestration and it is responsible for much of CO₂ being moved from lower atmosphere to oceans:

Statements 1 is incorrect: CO₂ is a heavy gas that primarily accumulates in the troposphere and lower stratosphere but does not escape into the outer stratosphere or space. The primary removal mechanisms of CO₂ involve absorption by oceans, photosynthesis by plants, and geological sequestration rather than atmospheric escape. Statements 3 is incorrect: Polar ice caps and glaciers are not a major active carbon sink. Ice trapping does not remove a significant amount of CO₂ from the atmosphere on short time scales. While some CO₂ gets sealed in glaciers but melting due to climate change can release CO₂ back into the atmosphere thereby making this process less effective in long-term carbon storage.

Explanation

Emissions of all the above-mentioned gases i.e. Carbon dioxide, Oxides of Nitrogen and Oxides of Sulphur take place from coal combustion at thermal power plants. Gas Sources Carbon dioxide (CO₂) Burning of fossil fuels, deforestation Oxides of Sulphur Burning fossil fuels, Smelting ores, Volcanic eruptions, Vehicles, etc Nitrogen oxides (N₂O) Burning of fossil fuels, fertilizers; burning of wood and crop residue. Carbon Monoxide (CO) Iron ore smelting, burning of fossil fuels, burning e-waste.

Explanation

Antarctic Ozone Hole was discovered by British Antarctic Survey scientists Farman, Gardiner and Shanklin in 1985. The formation of the ozone hole in the Antarctic has been an annual occurrence (in the months of September, October and November, due to a set of special meteorological and chemical conditions that arise at the South Pole, such as the presence of strong polar front, polar stratospheric clouds and increasing inflow of human-made chemicals like CFCs, etc.

Explanation

Carbon Credit is a permit that allows the company the right to emit 1 tonne of CO₂ or its equivalent. One credit permits the emission of a mass equal to one ton of carbon dioxide. Statement (a) is correct: The carbon credit system was established as part of the Kyoto Protocol (1997) to allow countries to meet their emission reduction targets via flexible mechanisms such as Carbon Trading, Clean Development Mechanism (CDM), etc. Statement (b) is correct: Under Kyoto mechanisms, countries or entities that emit less than their allowed quota can earn carbon credits, which they can then sell to others who are exceeding limits. Statement (c) is correct: The core objective is to create a market-based incentive to limit global greenhouse gas emissions, especially CO₂. Statement (d) is incorrect: Carbon credit prices are not fixed by UNEP (United Nations Environment Programme). They are determined by market forces in various carbon exchanges, such as the European Union Emission Trading Scheme (EU-ETS). UNEP does not set or fix prices.