Unit 5: Environmental Pollution and Mitigation of Climate Change

1. Atmospheric Pollution

Atmospheric Pollution is the introduction of harmful contaminants (pollutants) into the atmosphere at concentrations high enough to cause harm to human health, wildlife, or the environment.

Type of Pollutants

• Primary Pollutants: Emitted *directly* from a source.
  • Examples: Carbon Monoxide (CO) from cars, Sulfur Dioxide (SO₂) from power plants, soot.
• Secondary Pollutants: Not emitted directly. They are *formed in the atmosphere* through chemical reactions.
  • Example: Ground-level ozone, acid rain.

Various Sources of Emissions

• Stationary Sources: Power plants, factories, and industrial facilities that burn fossil fuels.
• Mobile Sources: Transportation, including cars, trucks, ships, and airplanes.
• Agricultural Sources: Fertilizers (releasing N₂O) and livestock (releasing CH₄).
• Natural Sources: Volcanoes, wildfires, dust storms.

Trace Gases

These are gases present in very small amounts ("traces"). While some are harmless (like neon), others are potent pollutants and/or greenhouse gases. Examples include sulfur dioxide (SO₂), nitrogen oxides (NOx), methane (CH₄), and ozone (O₃).

2. Stratospheric and Tropospheric Ozone

Ozone (O₃) is a single molecule, but its effect depends entirely on *where* it is in the atmosphere.

Stratospheric Ozone ("Good Ozone")

• Location: In the stratosphere (the "Ozone Layer").
• Production: Formed naturally when high-energy UV radiation from the sun splits an O₂ molecule, and the resulting single O atoms join with other O₂ molecules (O + O₂ → O₃).
• Function: It is beneficial. It absorbs ~99% of the sun's harmful UV-B radiation, protecting life on Earth from skin cancer, cataracts, and DNA damage.
• Loss Processes: It is naturally destroyed by reactions with other chemicals. This balance was disrupted by human-made chemicals called CFCs (Chlorofluorocarbons), which led to the "ozone hole."

Tropospheric Ozone ("Bad Ozone")

• Location: In the troposphere (the layer we live in).
• Production: It is a secondary pollutant. It is *not* emitted directly. It forms when sunlight triggers chemical reactions between:
  • Nitrogen Oxides (NOx) - from cars and power plants.
  • Volatile Organic Compounds (VOCs) - from gasoline, solvents, and industry.
  (NOx + VOCs + Sunlight → Ground-level Ozone)
• Function: It is harmful. It is the main component of smog, is toxic to breathe (damaging lung tissue), and is also harmful to plants and crops.

3. International Legal and Policy Framework

This refers to the global agreements and treaties designed to address climate change.

The Kyoto Protocol

• What it was: An international treaty adopted in 1997 that extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC).
• Main Feature: It was the first agreement to set legally binding emission reduction targets for greenhouse gases.
• Main Issues:
  1. It only set binding targets for developed nations. Developing nations, including major emitters like China and India, had no binding targets.
  2. The world's largest emitter at the time, the United States, signed the treaty but never ratified it, so it was not bound by it.

The Kyoto Protocol has since been superseded by the Paris Agreement (2015), which uses a different, non-binding approach where all countries (developed and developing) set their own national targets (NDCs).

4. Climate Change Adaptation and Mitigation

These are the two main strategies for responding to climate change.

Developmental Planning

This involves incorporating both adaptation and mitigation into long-term national planning, such as in infrastructure, agriculture, and urban design, to ensure sustainable development.

5. Geo-engineering

Geo-engineering refers to the deliberate, large-scale, and highly technological intervention in the Earth's climate system to counteract global warming. These ideas are highly controversial and largely hypothetical.

There are two main categories:

1. Solar Radiation Management (SRM): Aims to cool the planet by reflecting sunlight back to space.
   • Example: Injecting sulfate aerosols into the stratosphere to mimic a large volcanic eruption, which is known to cause global cooling.
   • Risk: Unknown side effects (e.g., on rainfall patterns), does not solve the root cause (CO₂), and would need to be done continuously.
2. Carbon Dioxide Removal (CDR): Aims to remove CO₂ that is already in the atmosphere.
   • Example: Building large "Direct Air Capture" (DAC) machines that chemically scrub CO₂ from the air; "ocean fertilization" to promote plankton blooms.
   • Risk: Extremely expensive, very slow, and has its own environmental impacts.

6. Concept of Panchamrit

"Panchamrit" (meaning "five nectars") is the name for India's five key climate pledges announced at the 26th UN Climate Change Conference (COP26) in Glasgow in 2021.

India's five pledges are:

1. To reach 500 GW of non-fossil energy capacity by 2030.
2. To get 50% of its energy requirements from renewable energy by 2030.
3. To reduce total projected carbon emissions by one billion tonnes from now until 2030.
4. To reduce the carbon intensity of its economy by 45% by 2030 (relative to 2005 levels).
5. To achieve the target of Net Zero emissions by 2070.