Climate Change – Summary Notes (Expanded)
Definition (IPCC)
Climate change refers to a long-term alteration in Earth’s average temperature and weather patterns.
While natural processes can cause climate variation, recent rapid changes are primarily driven by human activities.
Scientific Basis – Greenhouse Effect
- The Earth’s atmosphere contains greenhouse gases (GHGs) such as CO₂, CH₄, N₂O, and water vapour.
- These gases trap a portion of the Earth’s outgoing infrared radiation, maintaining a habitable global temperature.
- Excessive accumulation of GHGs increases heat retention → raises average temperatures → alters climate patterns.
- Positive Feedback Loops:
- Melting ice reduces Earth’s reflectivity (albedo), causing more solar absorption and further warming.
- Thawing permafrost releases methane, a potent greenhouse gas, accelerating warming.
Science Behind Contemporary Climate Change
Primary driver: Increased anthropogenic GHG emissions from:
- Burning of fossil fuels (coal, oil, natural gas)
- Deforestation (reduces CO₂ absorption)
- Vehicular emissions
- Industrial processes
Major Impacts:
- Global warming (rise in average global temperature)
- More frequent extreme weather events (storms, floods, droughts, heatwaves)
- Sea level rise (melting ice caps & thermal expansion)
- Ecosystem and biodiversity loss
- Impact on agriculture, health, and livelihoods
4. Evidence of Climate Change:
- Rising global average temperatures
- Melting glaciers and polar ice
- Rising sea levels (~3.3 mm/year)
- Increased frequency of extreme weather events (heatwaves, floods, droughts, cyclones)
Economics of Climate Change
1. Definition
The economics of climate change examines the allocation of scarce resources to mitigate and adapt to climate-related externalities, evaluating the opportunity cost of action versus inaction.
Free Markets Fail to Address Climate Change because :
Negative Externalities: GHG emissions impose unpriced social costs (e.g., 2022 Pakistan floods causing $30B losses).
Public Goods Problem: Climate stability is non-excludable and non-rivalrous, leading to underinvestment in mitigation.(Paris Agreement benefits all).
Tragedy of the Commons: Overuse of atmospheric carbon sink (e.g., global CO₂ exceeding 420 ppm).
Economic Costs of Inaction
- Loss of GDP Output: Heat stress and supply chain disruptions reduce productivity (e.g., India’s agriculture & construction).
- Capital Stock Destruction: Extreme events damage infrastructure (e.g., Hurricane Katrina, $125B loss).
- Agricultural Yield Decline: Climate stress cuts crop productivity (e.g., Sahel cereals ↓20%).
- Human Capital Erosion: Health impacts and migration reduce growth (e.g., Sundarbans displacement)
4. Economic Rationale for Action
- Cost-Benefit Analysis (CBA): Discounted present value of avoided damages exceeds mitigation costs.
- Co-Benefits: Air quality improvement, energy security, job creation.
- Risk Management: Applying the precautionary principle against catastrophic tail risks.
Policy Instruments – Key Points (50 words)
- Pigouvian Taxes: Sweden’s €120/ton carbon tax cut emissions without GDP loss.
- Cap-and-Trade: EU Emissions Trading System reduces industrial emissions since 2005.
- Green Investment Subsidies: India’s FAME scheme supports EV adoption.
- Climate Finance: Green Climate Fund aids Pacific islands’ coastal protection.
Ask ChatGPT
Any external factor that originates from outside the climate system and can become a cause of climate change is called Climate Forcing. These factors are specifically known as forcings because they drive the climate to change. There are natural forcings and man-made forcings. For examples:
- Surface reflectivity (Albedo).
- Human-caused, or anthropogenic climate forcing include emissions of heat-trapping gases (also known as greenhouse gases) and changes in land use that make land reflect more or less sunlight energy.
- Atmospheric aerosols due to human activity or volcanic eruption etc. that put light-reflecting particles into the upper atmosphere.
The peculiar feature of all climate forcing is that they influence the balance of the energy entering and leaving the Earth system i.e, the amount of energy we receive from the sun, and the amount of energy we radiate back into space. Climate change refers to the change of climate that alters the composition of the global atmosphere. It is usually measured in major shifts in temperature, rainfall, snow, and wind patterns lasting decades or more.
The causes of climate change can be classified into two types; natural and anthropogenic.
Natural causes:
- Solar Irradiance: The change in energy output of the sun brings changes in climate. Solar output varies according to the 11 year solar cycle.
- Volcanic Eruptions: When volcanoes erupt, thousands of tons of sulfur dioxide is released into the atmosphere which cause cooling and warming of the earth respectively.
- Plate tectonics: Tectonic plates rearrange the topography of the earth which brings changes in the circulation of oceans and subsequently changes the patterns of the global climate.
- Variations in the Earth’s Orbit: Variations in the orbit of the planet bring changes in seasonal and geographical distribution of the light from the sun that affects the global climate.
Anthropogenic causes:
- Emission of Greenhouse Gases: Release of greenhouse gases like Carbon dioxide is one of the main reasons for climate change. For example, human activities such as deforestation, burning of fossil fuels, surface mining, agriculture, emissions from industries etc. are also releasing other greenhouse gases into the atmosphere.
- Land Use Change: Climate change is also assisted by changes in land use and land cover that are caused because of human activities such as agriculture.
Science of Climate Change
- Introduction to Climate Change:
Climate change is the long-term alteration of Earth’s climate, mainly caused by increasing greenhouse gas emissions from human activities. - The Greenhouse Effect Explained:
Certain gases trap heat in the atmosphere, warming the planet. This natural process is intensified by human-produced CO2 and methane. - Key Greenhouse Gases and Their Sources:
Main gases include carbon dioxide (fossil fuel burning), methane (agriculture, livestock), and nitrous oxide (fertilizers). - Climate Forcings and Natural Drivers:
External factors like volcanic eruptions and solar variations also affect climate, but less than human emissions currently. - Climate Feedback Mechanisms:
Warming causes ice to melt, reducing reflectivity and increasing heat absorption, amplifying climate change. - Climate Models and Their Role:
Simulations forecasting future climate scenarios based on emission levels, used for policy planning. - Evidence of Climate Change:
Measurable signs include rising global temperatures, melting glaciers, sea level rise, and extreme weather. - Impacts on Ecosystems and Weather Patterns:
Shifts in habitats, more storms, droughts, and unpredictable rainfall patterns. - Tipping Points and Abrupt Changes:
Possible irreversible changes like ice sheet collapse or rainforest dieback if warming continues unchecked. - Future Climate Projections and Scenarios:
Predictions show more intense heatwaves and sea-level rise unless emissions are cut drastically.