Climate Change, Causes, and Global Environmental Impact

Quick Summary

• Earth's climate has changed throughout geological history, with cold glacial periods alternating with warmer interglacial periods.
• Climate change results from natural factors such as Milankovitch cycles, volcanic eruptions and solar variability, as well as human activities that increase greenhouse gas concentrations.
• Major greenhouse gases include carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons and water vapour.
• Human-induced greenhouse gas emissions are the primary driver of current global warming.
• Ozone depletion and climate change are different environmental issues, although some gases, such as CFCs, contribute to both.

Why This Topic Matters

Climate change is important for Preliminary examinations of UPSC, BPSC and other State PCS examinations. Important areas include historical climate indicators, Milankovitch cycles, greenhouse gases, ozone depletion and international environmental agreements.

1. Evidence of Past Climatic Changes

• Geological Evidence: Glacial landforms, moraines and tillite deposits in regions that are warm today provide evidence of past glacial conditions.

• Biological and Proxy Indicators:

  • Tree Rings or Dendrochronology: Tree-ring width and structure help reconstruct past climate conditions. Wider rings may indicate favourable growing conditions, while narrower rings may indicate environmental stress.
  • Ice Cores: Oxygen isotope ratios (O-18 and O-16) and trapped atmospheric gas bubbles in Antarctic and Greenland ice cores provide evidence of past temperatures and atmospheric composition.
  • Pollen Analysis: Fossil pollen preserved in lake sediments helps identify past vegetation patterns and reconstruct historical climate changes.
  • Marine Sediments: Deep-sea sediment cores contain fossils and chemical indicators that help reconstruct past ocean and climate conditions.
  • Coral Records: Coral growth bands and chemical composition provide information about past sea temperatures and ocean conditions.

• Evidence of Contemporary Climate Change:

  • Rising global average temperatures.
  • Retreat of glaciers and loss of ice sheets.
  • Rising sea levels due to thermal expansion and melting of land ice.
  • Ocean warming and acidification.
  • Changes in the frequency or intensity of several extreme weather events.

2. Causes of Climate Change

2.1 Astronomical Causes - Milankovitch Cycles

Milankovitch cycles are long-term variations in Earth's orbital and rotational geometry that influence the distribution of incoming solar radiation.

1. Eccentricity: Changes in the shape of Earth's orbit around the Sun, from more circular to more elliptical. A major cycle lasts approximately 100,000 years.

2. Obliquity or Axial Tilt: Changes in Earth's axial tilt, approximately between 22.1° and 24.5°, over a cycle of about 41,000 years. It affects the intensity of seasons, particularly at high latitudes.

3. Precession: Changes in the orientation of Earth's rotational axis. The commonly cited climatic precession cycle is approximately 21,000 years.

Important: Milankovitch cycles influence the seasonal and geographical distribution of solar radiation and are associated with glacial and interglacial cycles.

2.2 Geological and Anthropogenic Causes

• Volcanic Eruptions: Sulphur dioxide released into the stratosphere forms sulfate aerosols that reflect incoming solar radiation, causing temporary global cooling. The effect generally lasts a few years.

• Solar Variability and Sunspots: Changes in solar activity influence the amount of solar energy received by Earth. However, solar variability cannot explain the recent long-term global warming trend.

• Anthropogenic Greenhouse Effect: Fossil fuel combustion, deforestation, industrial processes and agricultural activities increase greenhouse gas concentrations, enhancing the greenhouse effect.

Major Greenhouse Gases:

Important Facts:

• Water vapour is the largest contributor to the natural greenhouse effect.
• Carbon dioxide is the main driver of current human-induced global warming among long-lived greenhouse gases.
• Methane has a higher Global Warming Potential (GWP) than CO₂ over a 100-year period, but its atmospheric lifetime is much shorter.
• Nitrous oxide is both a greenhouse gas and an ozone-depleting substance.
• HFCs are potent greenhouse gases but generally do not deplete the ozone layer.
• CFCs contribute to both global warming and ozone depletion.

Carbon Sources and Sinks:

• Carbon Source: Releases more carbon into the atmosphere than it absorbs.
• Carbon Sink: Absorbs more carbon than it releases. Examples include forests and oceans.

3. Ozone Layer Depletion and Global Treaties

Ozone Layer Depletion

• Ozone Layer: Located in the stratosphere, mainly between approximately 15 and 35 km above Earth's surface. It absorbs most harmful ultraviolet radiation.
• Tropospheric Ozone: Acts as an air pollutant and greenhouse gas.
• Ozone Depletion: Chlorine and bromine released from substances such as CFCs and halons destroy stratospheric ozone through catalytic reactions.
• Ozone Hole: Severe seasonal depletion of stratospheric ozone, particularly over Antarctica.
• Polar Stratospheric Clouds: Promote chemical reactions that release active chlorine, accelerating ozone depletion.
• UV Radiation: Ozone depletion increases the amount of harmful UV-B radiation reaching Earth's surface.

Important International Environmental and Climate Agreements

4. Carbon Markets and Carbon Credits

4.1 What is a Carbon Market?

A carbon market is a system in which carbon credits or emission allowances are traded to reduce greenhouse gas emissions.

• Carbon Credit: A tradable certificate representing one tonne of carbon dioxide equivalent (tCO₂e) reduced, removed, or avoided.
• Carbon Trading: Buying and selling carbon credits or emission allowances.
• Carbon Tax: A tax imposed on greenhouse gas emissions or the carbon content of fuels.

4.2 Types of Carbon Markets

Important Market Mechanisms:

• Cap-and-Trade: A regulatory authority sets an emission limit and allows trading of emission allowances.
• Baseline-and-Credit: Credits are generated when emissions are reduced below an established baseline.

4.3 Article 6 of the Paris Agreement

Article 6 enables countries to cooperate voluntarily to achieve their climate targets.

Remember: Article 6.2 and Article 6.4 involve market-based cooperation, while Article 6.8 focuses on non-market approaches.

4.4 India's Carbon Credit Trading Scheme (CCTS)

• India notified the Carbon Credit Trading Scheme (CCTS) in June 2023 under the Energy Conservation Act, 2001, as amended in 2022.
• It provides the framework for establishing the Indian Carbon Market (ICM).
• The scheme has two mechanisms:
  • Compliance Mechanism: Covers obligated entities required to meet prescribed emission-intensity targets.
  • Offset Mechanism: Allows eligible non-obligated entities to register projects that reduce, remove, or avoid greenhouse gas emissions.
• The Bureau of Energy Efficiency (BEE) is the administrator of the Indian Carbon Market.
• One Carbon Credit Certificate represents one tonne of carbon dioxide equivalent (tCO₂e).

Prelims Fact: Do not confuse a carbon credit with a carbon tax. A credit represents an emission reduction or removal, while a carbon tax is a price imposed on emissions.

5. Climate Finance

5.1 What is Climate Finance?

Climate finance refers to local, national, or international funding used to support actions addressing climate change.

It is broadly classified into three categories:

1. Mitigation Finance: Funding activities that reduce greenhouse gas emissions, such as renewable energy and energy efficiency.
2. Adaptation Finance: Funding activities that help communities and ecosystems adjust to climate change, such as flood protection and drought-resistant agriculture.
3. Loss and Damage Finance: Funding to address climate-related losses and damages that cannot be avoided through mitigation or adaptation.

5.2 Major International Climate Funds

Important Facts:

• The GEF has served as an operating entity of the UNFCCC financial mechanism since 1994.
• The GCF is headquartered in Songdo, South Korea.
• The LDCF and SCCF are managed by the GEF.
• The Adaptation Fund was established under the Kyoto Protocol.
• The FRLD focuses on addressing loss and damage in vulnerable developing countries.
• Article 9 of the Paris Agreement deals with climate finance and the obligations of developed countries to provide financial resources to developing countries.

5.3 Important Differences for Prelims

Important Exam Facts:

• Ramsar Convention (1971): Focuses on the conservation and wise use of wetlands.
• CITES (1973): Regulates international trade in endangered wild animals and plants.
• Vienna Convention (1985): Framework agreement for protecting the ozone layer.
• Montreal Protocol (1987): Controls and phases out ozone-depleting substances.
• UNFCCC (1992): Provides the international framework for addressing climate change.
• Kyoto Protocol (1997): Established emission-reduction commitments for participating developed countries.
• Paris Agreement (2015): Aims to keep global temperature rise well below 2°C and pursue efforts to limit it to 1.5°C above pre-industrial levels.
• Kigali Amendment (2016): Provides for the phasedown of HFCs.

Important Distinction: The Montreal Protocol focuses on ozone-depleting substances, whereas the Kyoto Protocol and Paris Agreement address climate change. The Kigali Amendment targets HFCs, which are greenhouse gases but generally do not deplete ozone.

Key Terms and Definitions

Exam Insights and Memory Aids

• Greenhouse Gas Contributions: Water vapour is the largest contributor to the natural greenhouse effect. CO₂ is the principal driver of current human-induced global warming among long-lived greenhouse gases.
• Common Confusion: The greenhouse effect primarily involves outgoing longwave terrestrial radiation, not the direct blocking of all incoming shortwave solar radiation.
• Important Distinction: The Montreal Protocol protects the ozone layer, whereas the Kyoto Protocol and Paris Agreement address climate change.
• HFCs vs CFCs: CFCs deplete ozone and contribute to global warming. HFCs contribute to global warming but generally do not deplete ozone.
• Milankovitch Cycles: Remember the three main components: eccentricity, obliquity and precession.
• Volcanic Eruptions: Stratospheric sulfate aerosols generally cause temporary cooling, unlike the long-term warming caused by increasing greenhouse gas concentrations.
• Ozone Hole: The most prominent seasonal ozone hole occurs over Antarctica.

Quick Revision Checklist

• Can you distinguish tree rings, ice cores, pollen, marine sediments and coral records?
• Can you explain eccentricity, obliquity and precession?
• Can you identify major greenhouse gases and their sources?
• Do you understand the difference between CFCs and HFCs?
• Can you distinguish ozone depletion from the greenhouse effect?
• Can you match major environmental agreements with their years and objectives?
• Can you distinguish the Montreal Protocol, Kyoto Protocol, Paris Agreement and Kigali Amendment?
• Can you explain the difference between incoming shortwave solar radiation and outgoing longwave terrestrial radiation?