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Difficulty: HardClimate Change, Global Warming and Ozone Layer Depletion

With reference to atmospheric ozone and ozone-depleting substances, consider the following statements:

1. Tropospheric ozone acts as a powerful greenhouse gas and is a major secondary air pollutant, whereas stratospheric ozone absorbs harmful solar ultraviolet radiation.
2. Hydrofluorocarbons (HFCs) cause significant depletion of the stratospheric ozone layer and possess a very low Global Warming Potential (GWP).
3. The Kigali Amendment to the Montreal Protocol explicitly aims to phase down the production and consumption of Hydrofluorocarbons (HFCs).

Which of the statements given above is/are correct?

  1. A
    1 and 2 only
  2. 1 and 3 onlyAnswer
  3. C
    2 and 3 only
  4. D
    1, 2 and 3

Answer

Statements 1 and 3 only are correct.
The statement option '1 and 3 only' is correct. Tropospheric ozone acts as a secondary pollutant and greenhouse gas, while stratospheric ozone protects against UV radiation. Additionally, the Kigali Amendment legally binds countries to phase down HFCs under the Montreal Protocol architecture.

Step-by-Step Solution

1
Analyze Statement 1 regarding tropospheric and stratospheric ozone.
Statement 1 is correct. Stratospheric ozone ('good ozone') absorbs harmful UV rays. Tropospheric ozone ('bad ozone') is formed secondarily via photochemical reactions and acts as a potent greenhouse gas and pollutant.
Evaluates atmospheric layer-specific properties of ozone.
2
Analyze Statement 2 regarding Hydrofluorocarbons (HFCs).
Statement 2 is incorrect. HFCs were introduced as non-ozone-depleting alternatives to CFCs and HCFCs (they have zero Ozone Depletion Potential, ODP). However, HFCs have exceptionally high Global Warming Potential (GWP), thousands of times greater than CO2CO_2.
Distinguishes Ozone Depleting Potential (ODP) from Global Warming Potential (GWP).
3
Analyze Statement 3 regarding the Kigali Amendment.
Statement 3 is correct. Adopted in 2016, the Kigali Amendment extended the scope of the Montreal Protocol to mandate a global phase-down of HFCs due to their high climate-warming impact.
Verifies international legal frameworks controlling greenhouse gases and ODS.

Key Concept

Ozone chemistry, Ozone Depleting Potential vs. Global Warming Potential, and Kigali Amendment provisions
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Topics

Climate Change, Global Warming and Ozone Layer Depletion