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Difficulty: MediumClimate Change, Global Warming and Ozone Layer Depletion

Short-lived climate pollutants (SLCPs) contribute significantly to global warming alongside long-lived greenhouse gases. Regarding the atmospheric behavior, warming mechanisms, and environmental impacts of climate forcing agents, which of the following statements are correct?

  1. Black carbon accelerates glacial melting by reducing surface albedo when deposited on ice and snow, while also absorbing direct solar radiation in the atmosphere.Answer
  2. B
    Hydrofluorocarbons (HFCs) contribute significantly to stratospheric ozone depletion in addition to having high global warming potential.
  3. Tropospheric ozone acts as a greenhouse gas and is formed primarily through photochemical reactions involving nitrogen oxides (NOxNO_x) and volatile organic compounds (VOCsVOCs).Answer
  4. D
    Sulfur hexafluoride (SF6SF_6) is classified as a short-lived climate pollutant due to its rapid photochemical breakdown in the lower atmosphere.

Answer

The correct statements are that black carbon accelerates glacial melting by reducing surface albedo and absorbing solar radiation, and tropospheric ozone acts as a greenhouse gas formed photochemically from NOxNO_x and VOC precursors.
Black carbon deposits darken snow and ice, lowering surface albedo and accelerating thermal energy absorption, while directly heating the surrounding atmosphere. Tropospheric ozone is a secondary pollutant formed via sunlight-driven reactions between NOxNO_x and volatile organic compounds (VOCsVOCs), functioning as a major radiative forcing agent in the lower atmosphere.

Step-by-Step Solution

1
Analyze the impact and physical properties of black carbon.
Black carbon absorbs solar radiation and reduces snow albedo, accelerating melting.
Black carbon particles absorb sunlight directly and darken reflective snow cover.
2
Evaluate the chemical composition and ozone-depleting capability of hydrofluorocarbons (HFCs).
HFCs do not deplete stratospheric ozone because they lack chlorine and bromine.
Ozone depletion mechanisms require catalytic halogen radicals like Cl∙Cl^\bullet or Br∙Br^\bullet, which HFCs do not carry.
3
Assess the origin and climate role of tropospheric ozone.
Tropospheric ozone is a key short-lived climate pollutant formed from NOxNO_x and VOCs.
Unlike stratospheric ozone, tropospheric ozone acts as a greenhouse gas and is synthesized photochemically from precursor gases.
4
Examine the atmospheric lifetime of sulfur hexafluoride (SF6SF_6).
SF6SF_6 is one of the most persistent greenhouse gases, not a short-lived pollutant.
SF6SF_6 has an atmospheric lifetime of approximately 3,200 years.

Key Concept

Short-Lived Climate Pollutants (SLCPs) and Atmospheric Forcing Mechanisms
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Topics

Climate Change, Global Warming and Ozone Layer Depletion