Climate Change, Global Warming and International Initiatives

Introduction

Climate change and global warming rank among the most consequential topics in the CGPSC General Studies Paper 1 syllabus on Science and Environment. The subject bridges physical science, ecology, economics, and geopolitics — making it a favourite testing ground for examiners who want to assess both conceptual understanding and awareness of current affairs. Questions from this subtopic have appeared in CGPSC 2020, 2021, 2023, and 2024 — that is, four separate papers across four consecutive examination cycles — placing it among the most consistently tested science topics in the entire examination. The pattern shows no sign of receding; if anything, global climate diplomacy has accelerated since the Paris Agreement and the aspirant who is unprepared risks losing straightforward marks.

The topic demands a three-level understanding. First, the physical and chemical science of the greenhouse effect, the gases involved, their relative potencies, and the specific unit used to measure atmospheric ozone — all examined directly in CGPSC 2020 and 2023. Second, the policy and treaty architecture at the international level — the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol, the Paris Agreement, successive Conferences of the Parties (COPs), and India's specific national commitments, tested in CGPSC 2021 through a close-reading question about India's pledge at COP26. Third, an awareness of what India and individual states, including Chhattisgarh, are doing in practice to meet obligations on renewable energy, emission reduction, and forest protection.

Chhattisgarh is particularly relevant within this topic. The state is one of India's most forested — roughly 44 per cent of its geographical area is under forest cover — and its forests serve as one of the country's largest terrestrial carbon sinks. The REDD+ (Reducing Emissions from Deforestation and Forest Degradation) mechanism under the UNFCCC specifically recognises tropical forest states like Chhattisgarh as climate assets. At the same time, the state's economy depends heavily on coal-based thermal power and mineral extraction, creating a local tension between development imperatives and climate commitments that CGPSC examiners have contextualised in environment-related questions. Understanding this dual identity — climate asset and carbon-intensive economy — equips the aspirant to write nuanced answers in the Mains examination as well.

The four PYQs span a useful range of difficulty. The 2020 question on the greenhouse-gas contribution ranking is essentially factual and tests whether the candidate can correctly order CO₂, CH₄, N₂O, and CFCs by their contribution to the greenhouse effect. The 2021 question on India's COP26 commitments tests current-affairs awareness and the ability to distinguish accurately stated targets from incorrect ones. The 2023 question on Dobson units is a precise unit-of-measurement question — exactly the kind of detail that separates thorough preparation from superficial reading. The 2024 question on which gas is NOT a greenhouse gas is a conceptual discrimination question requiring the candidate to know that nitrogen (N₂), the most abundant gas in the atmosphere, does not trap infrared radiation. Together these PYQs trace a clear pedagogical arc: the examiner wants candidates who understand the mechanism, know the gases, can distinguish correct from incorrect policy numbers, and are alert to terminological precision.

This chapter builds the full foundation — atmospheric physics, the chemistry of greenhouse gases, the history and current state of international climate diplomacy, India's Nationally Determined Contributions (NDCs), and the specific relevance of Chhattisgarh — while also equipping the aspirant with worked examples of past questions, a forward-looking prediction of what else could be asked, classic error patterns to avoid, and memory devices for examination day.

Core Concepts & Foundations

The Atmosphere and Its Layers

Atmosphere: The thin gaseous envelope surrounding the Earth, held in place by gravity. It consists of several concentric layers — troposphere, stratosphere, mesosphere, thermosphere, and exosphere — each with distinct temperature gradients and chemical compositions.

Troposphere: The lowest atmospheric layer, extending approximately 12 km above the Earth's surface. It contains about 75 per cent of atmospheric mass and virtually all water vapour and weather phenomena. Temperature decreases with altitude here. Almost all greenhouse warming occurs within the troposphere.

Stratosphere: The layer from roughly 12 km to 50 km altitude. It contains the ozone layer (ozonosphere), concentrated between 15 and 35 km. Temperature increases with altitude in this layer because ozone absorbs ultraviolet (UV) radiation from the Sun. This temperature inversion suppresses vertical mixing, trapping pollutants that reach the stratosphere.

The Greenhouse Effect

Greenhouse Effect: A natural atmospheric process whereby certain gases allow short-wave solar radiation (visible light) to pass through to Earth's surface but absorb and re-emit the long-wave infrared (heat) radiation emitted by the surface, warming the lower atmosphere. Without this natural effect, Earth's average surface temperature would be approximately −18 °C instead of the current +15 °C.

The mechanism works in three steps. The Sun emits energy predominantly as short-wave radiation (visible light and near-ultraviolet). Earth's surface absorbs this and warms up. The warmed surface then re-emits energy as long-wave infrared (heat) radiation directed back toward space. Greenhouse gases (GHGs) in the troposphere absorb this outgoing infrared radiation and re-radiate it in all directions, including back toward the surface — effectively acting as a thermal blanket.

Enhanced Greenhouse Effect (Global Warming): The amplification of the natural greenhouse effect due to an anthropogenic (human-caused) increase in the concentration of greenhouse gases, primarily from burning fossil fuels, deforestation, agriculture, and industrial processes. This enhanced warming is commonly called "global warming" and drives "climate change".

Climate Change: Long-term shifts in global or regional climate patterns, including changes in temperature, precipitation, storm frequency and intensity, sea level, and ocean chemistry, attributed largely to increased concentrations of greenhouse gases since the Industrial Revolution.

Greenhouse Gases and Their Relative Contributions

Not all greenhouse gases are equal. Their relative importance is determined by three factors: their global warming potential (GWP), their atmospheric concentration, and their atmospheric lifetime. CGPSC 2020 tested the correct ordering of greenhouse gases by their contribution to the greenhouse effect.

Carbon Dioxide (CO₂): The most abundant anthropogenic greenhouse gas and the principal driver of long-term climate change. Primary sources are combustion of fossil fuels (coal, petroleum, natural gas), cement production, and deforestation. While its molecule-for-molecule warming power is lower than other GHGs, its sheer volume in the atmosphere makes it the largest contributor overall.

Methane (CH₄): A potent greenhouse gas with a GWP approximately 25–28 times that of CO₂ over a 100-year horizon (the multiplier used in the IPCC Fifth Assessment Report). Sources include livestock (enteric fermentation), rice paddies, landfills, natural gas extraction and distribution, and wetlands. Methane degrades more rapidly in the atmosphere than CO₂ (about 12 years vs. hundreds of years).

Nitrous Oxide (N₂O): Produced primarily from agricultural soils (nitrogen fertilisers), livestock manure, and combustion processes. Its 100-year GWP is approximately 265–298 times that of CO₂. It also depletes stratospheric ozone.

Chlorofluorocarbons (CFCs): Synthetic halogenated compounds used as refrigerants, aerosol propellants, and foam-blowing agents. They have extraordinarily high GWPs — many thousands of times that of CO₂ — but their atmospheric concentrations are far lower than CO₂ or CH₄. CFCs are also the primary agents responsible for stratospheric ozone depletion. They are regulated under the Montreal Protocol.

The correct ordering by overall contribution to the greenhouse effect is: CO₂ > CH₄ > N₂O > CFCs. This ranking considers both GWP and atmospheric abundance; CO₂ dominates because of volume even though other gases are molecule-for-molecule more potent.

Water Vapour (H₂O): The most abundant natural greenhouse gas, responsible for about 50 per cent of the natural greenhouse effect. However, it is a feedback rather than a direct forcing — it amplifies warming initiated by other GHGs rather than being itself controlled directly by human activity.

Ozone (O₃): In the troposphere, ground-level ozone is a secondary pollutant and a greenhouse gas. In the stratosphere, ozone is essential for absorbing UV radiation. The distinction between tropospheric ozone (harmful) and stratospheric ozone (protective) is crucial.

Nitrogen (N₂): The most abundant gas in the atmosphere at approximately 78 per cent. It is NOT a greenhouse gas because its molecular structure (homonuclear diatomic molecule) does not absorb or emit infrared radiation. This was tested directly in CGPSC 2024.

The Ozone Layer and Dobson Units

Ozone Layer: A concentration of ozone (O₃) in the stratosphere, roughly 15–35 km above the Earth's surface, that absorbs the majority of the Sun's ultraviolet-B and ultraviolet-C radiation, protecting living organisms from DNA damage and skin cancer.

Ozone Hole: A seasonal thinning of the stratospheric ozone layer, primarily over Antarctica (and to a lesser extent, the Arctic), first scientifically documented in the mid-1980s. Caused principally by halogen compounds — especially CFCs — that release chlorine and bromine atoms when exposed to UV radiation.

Dobson Unit (DU): The unit used to measure the total amount (column) of ozone in the atmosphere from the ground to the top of the atmosphere. One Dobson unit represents a layer of pure ozone 0.01 mm thick at standard temperature and pressure (0 °C, 1 atmosphere). The average global ozone column is approximately 300 DU. Ozone hole conditions are typically defined as values below 220 DU. This was the direct answer tested in CGPSC 2023.

The Dobson unit is named after Gordon Dobson, a British meteorologist who built the first spectrophotometer capable of measuring total column ozone from the ground in the 1920s. Understanding the unit contextualises why ozone depletion is reported as a percentage change from baseline DU values rather than parts per million.

Key Distinguishing Concepts

Note that CFCs are implicated in both phenomena: they trap heat (greenhouse effect) and destroy ozone (depletion). This dual role makes them especially hazardous and underlies their near-total prohibition under the Montreal Protocol.

Radiative Forcing: Measuring Warming Influence

Radiative Forcing (RF): A measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth's atmosphere. It is expressed in watts per square metre (W m⁻²). A positive radiative forcing warms the climate system; a negative forcing cools it. Pre-industrial CO₂ concentration was ~280 ppm; current concentrations exceed 420 ppm, contributing a radiative forcing of approximately +2.1 W m⁻² — the largest single anthropogenic forcing factor.

Understanding radiative forcing is important because it contextualises news reports about atmospheric CO₂ levels. Each new ppm of CO₂ contributes a smaller marginal forcing than the previous (logarithmic relationship) — but the cumulative effect is enormous. Methane, despite lower concentration, has higher per-molecule RF because its absorption bands are less saturated. This is why the climate science community expresses concern about methane leaks from natural gas infrastructure: a small proportional increase in methane concentration has a disproportionate short-term effect on warming.

Global Warming Potential (GWP): A relative measure expressing how much heat a greenhouse gas traps in the atmosphere over a specified time horizon (usually 100 years), compared to CO₂ (which has a GWP of 1). GWP100 for CH₄ is ~27; for N₂O ~273; for some HFCs and CFCs, in the thousands. GWP is used to convert emissions of all GHGs into a CO₂-equivalent figure (CO₂e) for accounting purposes.

CO₂ Equivalent (CO₂e): A standardised unit expressing the total climate impact of a mix of greenhouse gases, calculated by multiplying each gas's mass by its GWP and summing the results. India's emission reduction targets are typically stated in CO₂e to allow aggregation across all GHGs.

Carbon Cycle: The Movement of Carbon Through Earth Systems

Understanding why CO₂ persists and accumulates requires understanding the carbon cycle — the continuous movement of carbon between the atmosphere, oceans, soils, vegetation, and geological reservoirs:

• Photosynthesis: Plants and phytoplankton absorb CO₂ from the atmosphere, converting it into organic carbon (biomass). This is the primary terrestrial and oceanic carbon sink mechanism.
• Respiration: Living organisms (including plants) release CO₂ back into the atmosphere through cellular respiration.
• Decomposition: Dead organic matter is broken down by microorganisms, releasing CO₂ or methane (in anaerobic conditions — e.g., wetlands and rice paddies).
• Ocean exchange: The ocean absorbs CO₂ from the atmosphere through physical dissolution (enhanced when water is cool and CO₂ partial pressure is high) and the biological pump (phytoplankton fix CO₂, die, and sink to the ocean floor).
• Geological stores: Fossil fuels (coal, oil, natural gas) are carbon stored over millions of years. Burning them releases this ancient carbon as CO₂ in decades — a geological blink of an eye, overwhelming the natural carbon cycle's ability to absorb the excess.

Deforestation disrupts the carbon cycle by destroying the biotic sink (trees that absorbed CO₂) and releasing stored carbon as trees decompose or burn. This double effect makes deforestation the second-largest source of anthropogenic CO₂ after fossil fuel combustion, and directly explains why protecting Chhattisgarh's forests is a climate-relevant action.

International Climate Architecture: Treaties and Institutions

The UNFCCC and Its Structure

The United Nations Framework Convention on Climate Change (UNFCCC) was adopted in 1992 at the Rio Earth Summit (United Nations Conference on Environment and Development, UNCED) and entered into force in 1994. It is the foundational treaty in global climate governance, establishing the principle that industrialised (Annex I) countries bear a "common but differentiated responsibility and respective capability" (CBDR-RC) for addressing climate change, given their historical dominance of cumulative emissions.

The UNFCCC has near-universal membership, with India as a Party from the outset. The treaty's ultimate objective is the "stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system."

The UNFCCC structure operates on a categorisation of countries into three groups. Annex I countries are developed nations and economies in transition (including OECD members and former Soviet bloc states) that must submit detailed emission inventories and face the expectation of emission reductions. Annex II countries are a subset of Annex I — specifically the wealthy OECD members — which have obligations to provide financial and technological support to developing countries. Non-Annex I countries are developing nations, including India, which are encouraged to take actions but face no binding emission-reduction targets under the UNFCCC itself (this distinction was later addressed under the Paris Agreement).

The Conference of the Parties (COP) is the supreme decision-making body of the UNFCCC, meeting annually. Each COP is numbered sequentially: COP1 was held in Berlin in 1995; the landmark Paris Agreement was adopted at COP21 in Paris in 2015; and COP26, which is directly tested in CGPSC 2021, was held in Glasgow, Scotland in November 2021.

The Subsidiary Body for Scientific and Technological Advice (SBSTA) and the Subsidiary Body for Implementation (SBI) support the COP by providing expert advice and monitoring implementation. The UNFCCC Secretariat, headquartered in Bonn, Germany, provides administrative and technical support.

The Kyoto Protocol

The Kyoto Protocol, adopted at COP3 in Kyoto, Japan, in 1997 and entering into force in 2005, was the first binding international climate treaty. Its key features:

• It established legally binding emission reduction targets for Annex I (developed) countries only. Developing countries, including India and China, had no binding targets under Kyoto — a major point of contention.
• It defined the First Commitment Period (2008–2012) with an average cut of about 5.2 per cent below 1990 levels for Annex I nations.
• It introduced three "flexible mechanisms": Emissions Trading, the Clean Development Mechanism (CDM), and Joint Implementation. The CDM was particularly important for India, as it allowed Indian entities to earn Certified Emission Reductions (CERs) by implementing clean-energy or afforestation projects.
• The United States signed the Protocol but never ratified it. Canada withdrew in 2011.

India engaged actively with the Kyoto CDM, earning CERs from projects in renewable energy and energy efficiency. Chhattisgarh hosted several registered CDM projects, especially in hydropower and biomass energy.

The Paris Agreement (2015)

The Paris Agreement, adopted at COP21 on 12 December 2015 and entering into force on 4 November 2016, replaced the Kyoto architecture with a more inclusive but less legally binding framework. Key features:

• Universal participation: All Parties (developed and developing alike) submit Nationally Determined Contributions (NDCs) — national climate action plans. Unlike Kyoto, no country is exempt.
• Temperature goal: Limit global average temperature increase to well below 2 °C above pre-industrial levels, pursuing efforts to limit it to 1.5 °C.
• Ratchet mechanism: NDCs must be updated every five years, with each successive NDC representing a progression beyond the previous one.
• Finance: Developed countries committed to mobilising USD 100 billion per year by 2020 for developing nations' climate action (a goal that was repeatedly missed and renegotiated).
• Loss and Damage: For the first time, the Agreement acknowledged the concept of loss and damage — harm caused by climate impacts beyond what adaptation can address — though it did not create liability or compensation.
• Transparency: A common transparency framework requires all Parties to report on emissions and progress toward NDCs.

The Paris Agreement was a major diplomatic achievement because it brought together both the USA and China (the two largest emitters) in a binding framework. However, critics argue the NDCs as initially submitted are collectively insufficient to meet the 2 °C goal.

COP26 Glasgow (2021) and India's Panchamrit Pledge

COP26, held in Glasgow in November 2021, was the first major climate summit since the Paris Agreement came into force, and it marks the point at which India's commitments were prominently tested in CGPSC 2021.

India, under Prime Minister Narendra Modi, announced five commitments known collectively as the "Panchamrit" (five nectars / five elements) at COP26:

1. 500 GW non-fossil energy capacity by 2030: Reach 500 gigawatts of non-fossil fuel-based electricity generation capacity by 2030.
2. 50 per cent energy from renewables by 2030: Generate 50 per cent of cumulative energy requirements from renewable energy sources by 2030.
3. Reduce carbon emissions by 1 billion tonnes by 2030: Through the energy transition, reduce the total projected carbon emissions of India by one billion tonnes (1,000 million tonnes CO₂ equivalent) cumulatively by 2030.
4. Reduce carbon intensity by 45 per cent by 2030: Reduce the carbon intensity (emissions per unit of GDP) of the economy by less than 45 per cent below 2005 levels by 2030.
5. Net-zero emissions by 2070: Achieve the target of net zero carbon emissions by the year 2070.

The CGPSC 2021 question tested knowledge of these specific figures. The correctly stated commitments involve: 500 GW non-fossil capacity, 50 per cent of energy from renewables (NOT 60 per cent), and reduction of emissions by one billion tonnes. An answer choice stating "60 per cent of total energy requirement by renewable energy" would be incorrect — the actual pledge is 50 per cent. This is a precise figures-based question that rewards careful memorisation.

The Montreal Protocol and Ozone Governance

While not strictly a climate treaty, the Montreal Protocol on Substances that Deplete the Ozone Layer (1987) is the most successful environment treaty in history, having achieved the phase-out of nearly all ozone-depleting substances (ODS), including CFCs. The Protocol is supervised by the Meeting of the Parties (MoP) and supported by the Multilateral Fund for developing nations.

The Kigali Amendment (2016) to the Montreal Protocol extended the phase-down to hydrofluorocarbons (HFCs) — refrigerants that replaced CFCs and do not deplete ozone but are extremely potent greenhouse gases. Eliminating HFCs under the Kigali Amendment is estimated to prevent up to 0.5 °C of warming by 2100. India ratified the Kigali Amendment.

India's Climate Policy and Nationally Determined Contributions

India's Initial NDC (2015) and Updated NDC (2022)

India's first NDC submitted under the Paris Agreement in 2015 included three main targets for 2030 (relative to 2005 baseline):

• Reduce the emissions intensity of GDP by 33–35 per cent.
• Achieve about 40 per cent cumulative electric power installed capacity from non-fossil sources by 2030.
• Create an additional carbon sink of 2.5–3 billion tonnes of CO₂ equivalent through additional forest and tree cover by 2030.

After COP26 and the Panchamrit pledges, India submitted its updated NDC in 2022, revising these targets:

• Reduce emissions intensity of GDP by 45 per cent by 2030 (from the previous 33–35 per cent).
• Achieve 50 per cent cumulative electric power from non-fossil sources by 2030 (up from 40 per cent).
• The carbon sink target of 2.5–3 billion tonnes was retained.

India argues that its per capita emissions are among the lowest of any major economy — approximately 1.9 tonnes CO₂ per person per year, compared to 14 tonnes for the USA and 7 tonnes for China — and that it bears a disproportionate burden if it is required to take the same pace of transition as historically high-emitting developed nations. India's position in international climate negotiations is that developed nations must front-load their emission reductions and provide finance and technology to enable the developing world's transition.

Renewable Energy in India: Progress and Targets

India has made rapid progress in renewable energy, particularly solar:

• Installed renewable capacity crossed 200 GW by mid-2024 (solar + wind + hydro + biomass + small hydro).
• Solar alone reached approximately 85–90 GW installed by early 2024.
• The National Solar Mission (now PM Surya Ghar Muft Bijli Yojana and related programmes) has driven rooftop solar adoption.
• Wind energy is concentrated in Tamil Nadu, Gujarat, Rajasthan, Maharashtra, and Andhra Pradesh.
• India is a founding member of the International Solar Alliance (ISA), co-founded with France and launched in 2015, headquartered in Gurugram.

India's renewable energy ambitions face grid-integration challenges — storage technology (batteries, pumped hydro) must scale alongside generation capacity to handle the intermittency of solar and wind. This is an area of active policy development.

India's Emissions Profile

India is currently the third-largest emitter of CO₂ globally, after China and the United States, contributing approximately 7 per cent of global annual CO₂ emissions. However, its cumulative historical emissions are far below those of the USA and Europe, forming the basis for India's CBDR argument. The energy sector (coal-based thermal power) accounts for the largest share of India's emissions, followed by industry, agriculture (primarily methane from livestock and rice), and transport.

Coal dominates India's electricity generation, providing roughly 70 per cent of total generation. India's "coal dilemma" — the tension between energy access for hundreds of millions without reliable electricity, economic development, and the global imperative to decarbonise — is one of the defining policy challenges of the 21st century. At COP26, India resisted language calling for a "phase-out" of coal, succeeding in diluting it to a "phase-down" — a diplomatic distinction with real consequences.

Chhattisgarh is central to this dilemma: it hosts major coal mines and thermal plants (including the NTPC Sipat plant in Bilaspur, one of India's largest thermal power stations) while simultaneously holding vast forests that the world's climate needs. The Korba Super Thermal Power Plant complex in Chhattisgarh is one of India's largest generating clusters, powering multiple states.

National Action Plan on Climate Change (NAPCC)

India's National Action Plan on Climate Change (NAPCC), launched in 2008, was the first overarching domestic policy framework for climate action. It identified eight national missions:

1. National Solar Mission (now PM Surya Ghar Muft Bijli Yojana and related programmes): Promote solar energy for power generation and other uses.
2. National Mission for Enhanced Energy Efficiency (NMEEE): Reduce energy intensity in large industries through market mechanisms.
3. National Mission on Sustainable Habitat: Promote energy efficiency in buildings, waste management, and urban planning.
4. National Water Mission: Conserve water and enhance water-use efficiency.
5. National Mission for Sustaining the Himalayan Ecosystem: Protect glaciers and biodiversity in the Himalayas.
6. National Mission for a Green India (GIM): Increase forest and tree cover and improve quality of forest carbon stock.
7. National Mission for Sustainable Agriculture: Develop strategies to make Indian agriculture more resilient to climate change.
8. National Mission for Strategic Knowledge for Climate Change: Build a knowledge platform and improve capacity for climate research.

India and the IPCC

The Intergovernmental Panel on Climate Change (IPCC), established jointly by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) in 1988, is the preeminent scientific body that periodically publishes assessment reports synthesising climate science. The IPCC does not conduct original research; it reviews and synthesises published peer-reviewed work. India has participated actively in IPCC working groups, with several Indian scientists serving as lead authors.

The Sixth Assessment Report (AR6), completed in 2021–2023, confirmed with "unequivocal" certainty that human influence has warmed the climate at an unprecedented rate, and that warming of 1.5 °C above pre-industrial levels will be crossed in the early 2030s under all considered scenarios unless drastic emission cuts occur immediately.

Chhattisgarh, Carbon Sinks, and Climate Vulnerability

Forests as Carbon Sinks

Chhattisgarh's ecological significance in climate change cannot be overstated. The state has roughly 55,717 square kilometres of recorded forest area, placing it among the top five most forested states in India. The forests of Bastar, Surguja, Kanker, and Dhamtari districts contain dense sal, teak, and mixed tropical moist deciduous forests that actively sequester atmospheric carbon.

A "carbon sink" is any reservoir that absorbs more carbon from the atmosphere than it releases. Living trees absorb CO₂ during photosynthesis and lock it into biomass. Deforestation — whether from agricultural expansion, mining, infrastructure, or timber felling — releases this stored carbon, contributing to atmospheric CO₂ concentration. India's NDC target of adding 2.5–3 billion tonnes CO₂ equivalent in carbon sinks by 2030 depends critically on protecting and expanding forest cover in states like Chhattisgarh.

REDD+ Mechanism

REDD+ (Reducing Emissions from Deforestation and Forest Degradation, plus the role of conservation, sustainable management of forests, and enhancement of forest carbon stocks in developing countries) is a UNFCCC mechanism that provides results-based finance to developing countries that demonstrate measurable reductions in deforestation and forest degradation. Chhattisgarh, with its vast forested tribal belt, is directly relevant to REDD+ implementation in India.

The mechanism involves three phases: readiness (capacity building and policy design), implementation, and results-based payments. India's national REDD+ strategy, developed by the Forest Survey of India (FSI) and the Ministry of Environment, Forest and Climate Change (MoEFCC), positions states like Chhattisgarh as key implementers.

Chhattisgarh's Climate Vulnerability

Despite being a net carbon sink, Chhattisgarh is simultaneously highly vulnerable to the effects of climate change:

• Erratic monsoon patterns: The Chhattisgarh plains (especially the Chhattisgarh Basin / Mahanadi drainage system) depend on kharif rice cultivation anchored to the southwest monsoon. Delayed onset, irregular distribution, and increasingly frequent dry spells threaten the agrarian economy.
• Flood and drought cycles: Climate models project increasing frequency of extreme rainfall events in central India, with floods alternating with droughts within the same season — a pattern already observable in the Chhattisgarh plains.
• Impact on tribal communities: The forest-dependent tribal communities (Gond, Baiga, Korku, Halba, Muria, etc.) depend on forest produce, rainfall, and river systems for food and livelihood. Climate disruptions disproportionately affect these communities.
• Coal economy tension: Chhattisgarh is one of India's leading coal-producing states (Korba, Raigarh, and Sarguja coalfields). The state's thermal power sector is a significant source of CO₂ emissions, creating a structural tension between economic development and climate commitments.

State-Level Climate Initiatives

Chhattisgarh has undertaken several state-level actions relevant to climate change:

• Solar energy expansion: Under the PM Kusum scheme and state solar policies, Chhattisgarh has been expanding solar capacity, particularly in rural and agricultural applications. Solar pumps for irrigation reduce dependence on grid power (largely coal-based) in the state.
• Forest rights and JFM: The Joint Forest Management (JFM) programme and the Forest Rights Act (FRA), 2006 — particularly robust in Chhattisgarh given the large tribal population — formally recognise community rights over forests, incentivising local conservation that indirectly supports carbon sequestration.
• Green India Mission participation: Chhattisgarh has been a state-level implementer of the National Mission for a Green India, targeting afforestation and forest quality improvement in degraded areas.
• Compensatory Afforestation: Under the Compensatory Afforestation Fund Management and Planning Authority (CAMPA), Chhattisgarh receives significant funds for afforestation in compensation for forest diversion to coal mining and infrastructure projects.
• Bioenergy and biomass: Chhattisgarh's large biomass availability from forest produce and agricultural residue (paddy straw, sugarcane bagasse) presents opportunities for biomass-based power generation and biogas, reducing reliance on coal-based grid power for rural areas.

The Biodiversity-Climate Nexus in Chhattisgarh

Climate change and biodiversity loss are increasingly recognised as twin crises that amplify each other. Chhattisgarh's forests — including the Indravati National Park, Kanger Valley National Park, Achanakmar Tiger Reserve, and the extensive Bastar forest complex — host significant populations of tigers, elephants, gaur, and hundreds of bird and reptile species. Climate-driven shifts in vegetation zones, altered rainfall patterns, and increased fire frequency threaten these habitats.

The concept of ecosystem services is critical here: Chhattisgarh's forests provide not only carbon sequestration (a climate service) but also watershed protection, flood buffering, biodiversity conservation, and livelihood support for tribal communities. These services are interconnected — deforestation for coal mining or agriculture simultaneously releases carbon, reduces biodiversity, increases flood risk, and harms tribal livelihoods. Sustainable management that maintains forest cover therefore delivers a "co-benefit bundle" relevant to multiple SDGs and India's NDC targets simultaneously.

The State Action Plan on Climate Change (SAPCC) framework, developed under the NAPCC, requires all Indian states to develop their own climate action plans. Chhattisgarh's SAPCC identifies agriculture, water, forests, and energy as priority adaptation and mitigation sectors, reflecting the state's specific vulnerabilities and assets described above.

Impacts of Climate Change: Science, Sectors, and India

The Carbon Budget and 1.5 °C Target

The concept of a carbon budget is central to understanding the Paris Agreement's temperature goals. The total cumulative amount of CO₂ (and CO₂-equivalent from other GHGs) that can be emitted while keeping warming below a given threshold is finite. The IPCC AR6 estimated that the remaining carbon budget for a 50 per cent probability of limiting warming to 1.5 °C is approximately 500 GtCO₂ from 2020 onwards — at current global emission rates of ~40 GtCO₂ per year, this budget would be exhausted in about 12–13 years from 2020, i.e., by the early 2030s.

This framing makes the urgency of action viscerally clear: every year of high emissions consumes an irreplaceable fraction of the remaining budget. Climate scientists refer to this as the concept of "carbon budget exhaustion" — once the budget is spent, no future action can restore the temperature to below 1.5 °C without negative emissions (active removal of CO₂ from the atmosphere).

Negative emissions technologies (NETs) — such as Bioenergy with Carbon Capture and Storage (BECCS), Direct Air Capture (DAC), and enhanced weathering — are frequently mentioned in scenarios that achieve net-zero or net-negative emissions. India's net-zero-by-2070 pathway implicitly relies on some combination of massive renewable deployment, forest sink enhancement, and possibly NETs for hard-to-abate sectors.

Global Physical Impacts

The IPCC AR6 documents a comprehensive set of observed and projected impacts of ongoing climate change:

Temperature: Global mean surface temperature has already risen approximately 1.1–1.2 °C above pre-industrial levels. Each of the last four decades has been successively warmer than any preceding decade since 1850.

Sea Level: Global mean sea level has risen about 20 cm since the late 19th century. Accelerated ice-sheet melt in Greenland and Antarctica is increasing the rate of rise. Projections for 2100 range from 0.3 to 1 m (or higher under high-emission scenarios), threatening coastal cities and small island nations.

Extreme Weather: Frequency and intensity of heat waves, extreme precipitation events, tropical cyclones, and droughts are increasing in most regions. Climate attribution science can now quantify the contribution of human-caused warming to individual extreme events.

Ocean Acidification: Oceans have absorbed about 30 per cent of anthropogenic CO₂ emissions, causing a reduction in surface ocean pH (acidification). This threatens coral reefs and shellfish that depend on calcium carbonate for shells and skeletons. The Great Barrier Reef (Australia) and India's Lakshadweep coral ecosystems are particularly at risk.

Arctic Amplification: The Arctic is warming at 2–4 times the global average rate, accelerating permafrost thaw (which releases methane), reducing summer sea ice, and disrupting polar jet stream patterns that influence mid-latitude weather.

Impacts on India

India is among the countries most exposed to climate-change impacts given its geography, population density, agricultural dependence, and coastal length. Key concerns:

• Monsoon variability: The Indian Summer Monsoon is the lifeblood of agriculture and freshwater systems. Climate models suggest increasing variability, more extreme rainfall over shorter periods, and shifts in monsoon onset and withdrawal dates.
• Himalayan glacier retreat: Glaciers in the Himalayas and Hindu Kush feed perennial river systems including the Ganga, Yamuna, Brahmaputra, and their tributaries. Initial acceleration of glacial melt (increased runoff) followed by eventual "peak water" and decline will affect water security for hundreds of millions.
• Heatwaves: India already experiences severe heatwaves. WBGT (Wet Bulb Globe Temperature) projections suggest regions of India could become lethally hot for outdoor workers for months per year under high-emission scenarios.
• Coastal inundation: India has a coastline of approximately 7,500 km. Cities like Mumbai, Chennai, Kolkata, and Kochi, and large parts of coastal states, face increasing flood risk from sea-level rise and storm surge intensification.
• Agricultural stress: Changes in temperature, precipitation patterns, and CO₂ concentrations affect crop yields. Studies suggest rice and wheat yields in India could decline by 6–25 per cent by 2050 under business-as-usual emission scenarios.

The Science of Ozone Depletion and Its Climate Linkages

Stratospheric Ozone: Formation and Destruction

Stratospheric ozone is formed and destroyed continuously through the Chapman cycle — a sequence of photochemical reactions involving atomic oxygen (O), molecular oxygen (O₂), and ozone (O₃). The cycle begins when UV radiation at wavelengths below 242 nm splits O₂ into two highly reactive oxygen atoms. Each oxygen atom then combines with an O₂ molecule to form O₃. Simultaneously, ozone itself is destroyed when UV radiation (240–320 nm) splits it back into O₂ and O. Under undisturbed conditions, a steady state exists in which ozone is continuously formed and destroyed, maintaining a relatively constant concentration.

Ozone destruction is accelerated by catalytic cycles involving halogen radicals (particularly Cl and Br from CFCs and halons), nitrogen oxides (NOₓ), and hydroxyl radicals. The catalytic cycle for chlorine, for instance, proceeds: Cl + O₃ → ClO + O₂; then ClO + O → Cl + O₂. The chlorine atom is regenerated at the end, enabling it to destroy another ozone molecule. A single chlorine atom can destroy tens of thousands of ozone molecules before it is deactivated into a stable compound — explaining why even small quantities of CFCs at the surface can cause large-scale ozone depletion at stratospheric altitudes.

The ozone depletion potential (ODP) is an index, analogous to GWP but for ozone destruction, that quantifies how much a given mass of a substance depletes the ozone layer relative to CFC-11. CFCs (such as CFC-11 and CFC-12) have ODP values of 1 by definition. HCFCs, which were interim replacements for CFCs, have ODP values of 0.01–0.1. HFCs, which replaced HCFCs, have ODP = 0 (they do not destroy ozone) but are potent GHGs — hence the need for the Kigali Amendment to the Montreal Protocol.

UV-B radiation impacts: Stratospheric ozone absorbs approximately 97–99 per cent of UV-B radiation. UV-B damages DNA, causes skin cancer (particularly melanoma) and cataracts in humans, suppresses immune systems, reduces agricultural yields (many crops are UV-B sensitive), and reduces marine phytoplankton productivity. The recovery of the ozone layer following the Montreal Protocol's phase-out of ODS is expected to prevent millions of cases of skin cancer globally over the coming decades — a direct human-health benefit of international environmental cooperation.

The Antarctic Ozone Hole

The Antarctic ozone hole forms seasonally (August–October) over Antarctica. During the polar winter, a stratospheric polar vortex (a circulating mass of extremely cold air) forms, creating Polar Stratospheric Clouds (PSCs). The ice surfaces of PSCs provide sites for heterogeneous reactions that activate chlorine from reservoir compounds. When polar spring sunlight returns, UV-driven chain reactions rapidly destroy ozone, creating the hole.

The Antarctic ozone hole was first reported in a landmark 1985 Nature paper by Joe Farman, Brian Gardiner, and Jonathan Shanklin of the British Antarctic Survey. This discovery catalysed the Montreal Protocol negotiations.

Ozone and Climate Interactions

Ozone depletion and climate change are interrelated in multiple ways:

• CFCs warm and also deplete ozone: As already noted, CFCs are potent GHGs AND the primary ODS. Their phase-out under Montreal achieves both objectives simultaneously — the Montreal Protocol inadvertently delivered more climate benefit (through its GHG co-benefit) than the Kyoto Protocol during the 1990s.
• Ozone recovery and climate feedback: As stratospheric ozone recovers, the stratosphere will warm (because ozone absorbs UV). This affects circulation patterns including the polar vortex, with downstream effects on mid-latitude climate.
• Surface UV and biosphere: Increased UV-B reaching the surface reduces phytoplankton productivity in polar oceans, reducing the biological carbon pump — a feedback that could slightly accelerate atmospheric CO₂ rise.
• HFCs as successor gases: HFCs introduced to replace CFCs (which solve the ozone problem) are powerful GHGs — hence the Kigali Amendment targeting them.

Worked Examples & Applications

Example 1: Greenhouse Gas Ranking (CGPSC 2020)

The 2020 CGPSC paper asked candidates to identify the correct decreasing order of contribution to the greenhouse effect among CO₂, CH₄, N₂O, and CFCs.

To reason through this, one must remember that "contribution to the greenhouse effect" combines two variables: how much of a given gas is present (concentration) and how strongly each molecule traps heat (GWP). CO₂ is present in the atmosphere at roughly 420 parts per million (ppm). CH₄ is present at about 1.9 ppm. N₂O is present at about 0.335 ppm. CFCs combined are at a few hundred parts per trillion.

Even though methane is 25–28 times more potent per molecule than CO₂, and CFCs are thousands of times more potent per molecule, their low concentrations mean CO₂ wins decisively as the largest contributor overall. Methane's combination of moderate concentration and high per-molecule potency places it second. N₂O, despite its high per-molecule potency (~270× CO₂), is far less concentrated than CH₄, placing it third. CFCs, though extremely potent per molecule, are present in vanishingly small concentrations, placing them last.

The correct sequence is therefore CO₂ > CH₄ > N₂O > CFCs. An answer suggesting CFCs rank higher than N₂O confuses per-molecule GWP with actual atmospheric contribution. An answer putting CH₄ before CO₂ makes the same category error — it confuses molecular potency with total forcing.

Example 2: India's COP26 Commitments (CGPSC 2021)

The 2021 question asked which of the following was NOT true about India's commitment at COP26. The choices included: reducing carbon emissions by one billion tonnes by 2030; meeting 60 per cent of energy requirement from renewables by 2030; increasing non-fossil energy capacity to 500 GW by 2030; and "none of the above."

To work through this, one must have memorised the Panchamrit figures precisely. The correct targets are: 500 GW non-fossil capacity (correct), 50 per cent energy from renewables (correct), 1 billion tonne cumulative emission reduction (correct), 45 per cent reduction in carbon intensity (correct), and net-zero by 2070 (correct).

The figure "60 per cent of total energy requirement from renewable energy" does not match any of India's official Panchamrit pledges — the actual figure is 50 per cent. Therefore, the statement that "India will meet 60 per cent of its total energy requirement by renewable energy by 2030" is NOT true, making it the correct answer to a "which is not true" question.

The pitfall here is confusing "non-fossil energy capacity" (500 GW — an installed capacity figure) with "energy from renewables" (50 per cent — a generation share figure). These are distinct metrics and candidates must not conflate them.

Example 3: Dobson Units (CGPSC 2023)

The 2023 paper asked which unit measures the thickness of ozone in a column of air from the ground to the top of the atmosphere.

The correct answer is the Dobson unit. This is a precision unit-knowledge question. The distractors — "ozone unit" and "Thomson unit" — are not standard units used in atmospheric science. An "ozone unit" is not a recognised measurement; "Thomson" is associated with the Thomson scattering cross-section in nuclear physics, not atmospheric ozone.

One Dobson unit equals 0.01 millimetres of pure ozone at standard temperature and pressure (STP). A typical healthy ozone column is about 300 DU. The ozone hole is characterised by values below 220 DU. The unit is named after Gordon Dobson, not to be confused with physicist J.J. Thomson (who discovered the electron) or any other Thomson.

Example 4: Which Gas is NOT a Greenhouse Gas (CGPSC 2024)

The 2024 paper asked candidates to identify which of methane, chlorofluorocarbon, carbon dioxide, or nitrogen is NOT a greenhouse gas.

The correct answer is nitrogen (N₂). The mechanism for this exclusion is molecular structure: greenhouse gases must be able to absorb infrared radiation. A molecule absorbs IR radiation only if the absorption causes a change in its dipole moment. Homonuclear diatomic molecules — N₂ and O₂, both composed of identical atoms — are perfectly symmetrical and have no permanent or changing dipole moment. Therefore, they cannot absorb or emit infrared radiation and do not contribute to the greenhouse effect.

Methane (CH₄) is a potent GHG (as discussed above). CFCs are potent GHGs and ozone-depleting substances. CO₂, despite being a linear symmetrical molecule, has asymmetric vibrational modes (bending and asymmetric stretch) that do change the dipole moment and therefore absorb IR. Nitrogen, by contrast, has only one vibrational mode (symmetric stretch between two identical atoms) which causes no dipole change — making it IR-inactive.

PYQ Trends & Patterns

What CGPSC Has Tested and Why

Across four examination years (2020, 2021, 2023, 2024), CGPSC's climate change questions reveal a consistent multi-dimensional testing strategy.

Factual science (gases and measurements): Two of the four questions — 2020 and 2024 — are pure science questions about greenhouse gases. The 2023 question on Dobson units is a measurement-precision question. Together these three constitute 75 per cent of the tested PYQs, indicating that CGPSC examiners treat the physical science foundation as non-negotiable. The examiner expects candidates to know not just that CO₂ causes warming, but how it ranks relative to other gases; not just that CFCs deplete ozone, but what unit is used to quantify ozone abundance; and not just that nitrogen is abundant, but why it does not trap heat.

Policy and current affairs (COP commitments): The 2021 question is a precise current-affairs question demanding knowledge of specific numerical pledges made at COP26. This pattern — introducing a current-affairs climate question one or two years after a major international event — is likely to repeat. COP27 (Sharm el-Sheikh, 2022) created the Loss and Damage Fund; COP28 (Dubai, 2023) produced the first Global Stocktake and language about transitioning away from fossil fuels. Either of these could be tested in a 2025 or 2026 paper.

Selective difficulty: The questions range from straightforward identification (nitrogen is not a GHG — a manageable question for a prepared candidate) to nuanced ranking (CO₂ > CH₄ > N₂O > CFCs — requiring understanding of GWP vs. concentration) to close-reading of policy texts (60 per cent vs. 50 per cent renewable energy pledge). This graduated difficulty rewards thorough preparation.

No direct Chhattisgarh angle yet: None of the four PYQs directly name Chhattisgarh in the context of climate. This could reflect the examiner using a national/global framing for this science subtopic. However, CGPSC Mains questions and interview panels frequently ask about the state's coal-forest tension, CAMPA funds, and forest rights — suggesting that aspirants preparing comprehensively for Mains should internalise the Chhattisgarh-specific dimensions even if Prelims has thus far remained at the general level.

Recurring Question Styles and Their Implications

The four CGPSC PYQs reveal three recurring question styles the aspirant must prepare for:

Style 1 — Ordering/ranking: "Which is the correct decreasing order of X?" These questions require not just knowing the list but understanding the principle behind the ordering so that a distractor placing elements in the wrong sequence can be recognised. The greenhouse gas contribution question is the clearest example. Future variants: order countries by CO₂ emissions (China > USA > India); order protocols chronologically; order temperature anomalies.

Style 2 — Unit/term precision: "The thickness of ozone is measured in terms of?" These questions test technical literacy — the candidate who has skimmed a summary without engaging with the precise vocabulary fails. Future variants: what unit measures GWP? (dimensionless, relative to CO₂). What is the term for the ratio of CO₂ emissions to GDP? (carbon/emissions intensity). What is the UNFCCC body that meets annually? (COP).

Style 3 — "Which is NOT" identification: "Which of the following is NOT a greenhouse gas?" or "Which commitment was NOT made at COP26?" These reverse-formulation questions require comprehensive knowledge of the set (all GHGs, all Panchamrit pledges) so the outlier is recognisable. They are designed to trap candidates who have partial knowledge.

Emerging Patterns

The question from 2024 (nitrogen is not a GHG) shows that CGPSC is willing to test conceptual understanding through negative-identification (what is NOT a GHG) rather than positive recall (what IS a GHG). This style of question — designed to trap candidates who have not thought through the mechanism — is likely to continue. Future variants could ask: which is NOT a measure of greenhouse gas potency? Which protocol does NOT address greenhouse gas emissions directly? Which of the following is NOT a component of the Panchamrit?

The 2023 Dobson unit question confirms that obscure but precise measurement terminology is fair game. Candidates should be equally prepared for a question on the unit of measurement for carbon dioxide concentration in air (ppm — parts per million), radiative forcing (watts per square metre, W m⁻²), the unit of carbon in carbon credits (tonnes CO₂ equivalent), or the atmospheric lifetime of methane (~12 years) versus CO₂ (centuries to millennia).

The COP26 question in 2021 establishes a clear pattern: within two to three years of a major climate summit, CGPSC tests knowledge of what was agreed there. COP27 (Sharm el-Sheikh, 2022) produced the Loss and Damage Fund — a financially significant breakthrough demanded by small island states and climate-vulnerable developing nations. COP28 (Dubai, 2023) produced the first Global Stocktake and landmark language about "transitioning away from fossil fuels." Both are prime candidates for 2025–2026 CGPSC questions.

What Else Could Be Asked

Common Mistakes & Traps

Confusing GWP with Total Contribution

The most common error on greenhouse gas ranking questions is ordering gases purely by their global warming potential per molecule rather than by their total atmospheric contribution. If ordered purely by GWP (molecule for molecule), the sequence would be CFCs (highest) > N₂O > CH₄ > CO₂. But the question asks for contribution to the greenhouse effect, which is GWP × concentration. CO₂ wins overwhelmingly because of volume. This trap is built into the CGPSC 2020 answer choices — the distractors "CO₂ > CFCs > CH₄ > N₂O" and "CH₄ > CO₂ > CFCs > N₂O" exploit exactly this confusion.

Confusing 50% with 60% on India's COP26 Pledge

The CGPSC 2021 question specifically exploited the distinction between India's actual pledge (50 per cent energy from renewables by 2030) and an inflated figure (60 per cent). This is a common error in reading current-affairs sources that paraphrase rather than quote. Always work from the original Panchamrit list.

Treating Ozone Depletion and Greenhouse Effect as the Same Problem

Students frequently conflate ozone depletion (stratospheric, UV-B, CFCs, Montreal Protocol) with the enhanced greenhouse effect (tropospheric warming, infrared, CO₂/CH₄/N₂O, UNFCCC). While CFCs are involved in both, the mechanisms, atmospheric layers, impacts, and governing treaties are entirely different. Examiners can and do test this distinction.

Confusing Dobson with Other Scientists/Units

"Thomson unit" is a plausible-sounding distractor. Remember: Dobson unit = ozone column measurement. Thomson is associated with the electron (J.J. Thomson) and light scattering (Thomson scattering). The Dobson unit is specifically and exclusively about ozone column abundance.

Treating All Atmospheric Gases as Greenhouse Gases

Nitrogen (N₂, 78% of atmosphere), oxygen (O₂, 21%), and argon (Ar, ~0.9%) are NOT greenhouse gases. Only trace gases with asymmetric molecular vibrations — CO₂, CH₄, N₂O, water vapour, O₃ (tropospheric), and halocarbons — qualify. CGPSC 2024 tested exactly this, and the trap is choosing methane or CFCs (which ARE GHGs) rather than nitrogen.

Confusing the IPCC with a Policy Body

The IPCC provides scientific assessment — it does not negotiate treaties or set emission targets. Treaty negotiation and target-setting happens under the UNFCCC at COP sessions. Students sometimes attribute IPCC findings as UNFCCC decisions or vice versa.

Net-Zero by 2070 vs. Carbon Neutrality by Other Years

India's target is net zero by 2070, not 2050. The USA, EU, and UK target 2050. China targets 2060. Confusing these, especially in a "which country has a 2050 net-zero target" question, will lose a mark. India's 2070 date was a contentious choice at COP26 because it is later than what climate science recommends for limiting warming to 1.5 °C.

A related error is confusing "net-zero" with "carbon neutral" or "climate neutral." Net-zero means residual emissions are balanced by removals; carbon-neutral typically means emissions are offset but not necessarily structurally reduced. The IPCC and UNFCCC use "net zero GHG emissions" as the formal target concept.

Confusing Rio Earth Summit Products

The Rio Earth Summit of 1992 produced multiple agreements simultaneously, and students frequently mix them up. The UNFCCC (climate change) is one; the Convention on Biological Diversity (CBD) (biodiversity) is another; the United Nations Convention to Combat Desertification (UNCCD) is a third, though it came slightly later. The UNFCCC is specifically about climate, not biodiversity. A question asking which convention was produced at Rio 1992 may offer CBD and UNCCD as distractors — the UNFCCC is the correct climate-specific answer.

Confusing the ISA with the UNFCCC

The International Solar Alliance (ISA) is an India-led intergovernmental body headquartered in Gurugram, India, focused on promoting solar energy deployment globally. It is a separate body from the UNFCCC. Do not attribute ISA outcomes to UNFCCC or confuse its mandate (solar energy finance and technology) with the UNFCCC's mandate (greenhouse gas reduction architecture). India co-founded the ISA with France at COP21 — this is a genuinely Indian-led global initiative worth knowing for a question on India's international climate leadership.

Memory Aids & Mnemonics

Mnemonic 1: "CCN Trap" — Greenhouse Gas Ranking

To remember CO₂ > CH₄ > N₂O > CFCs (decreasing order of contribution to greenhouse effect), use the phrase:

"Carbon Methane Nitrous Chlorine — Concentration Makes Numbers Count"

Or the acronym C-M-N-C (CM-NC, said like "Cinematic"): C for Carbon dioxide, M for Methane, N for Nitrous oxide, C for Chlorofluorocarbons.

A visual story: Imagine a carbon cathedral (CO₂ — huge, dominant) dwarfing a methane monastery (CH₄ — smaller but intense), which looks down on a nitrous-oxide nunnery (N₂O), which in turn overlooks a tiny CFC chapel (CFCs — minuscule but potent). Size reflects total contribution; the smallest chapel (CFCs) is per-stone the most luxurious (highest GWP per molecule).

Mnemonic 2: "PANCH AMRIT 5-5-1-45-70" — India's COP26 Pledges

To remember India's five Panchamrit targets, use the code: 5-5-1-45-70

• 500 GW non-fossil capacity (5 × 100)
• 50% energy from renewables (5 × 10)
• 1 billion tonnes cumulative emission reduction
• 45% reduction in carbon intensity
• 2070 — net-zero year

Alternatively, the Hindi word Panchamrit itself (पंचामृत = "five nectars") anchors the idea that India offered five sweet promises to the world at Glasgow. Recite: "Paan Se Ek Chaar Sattar" — P (500 GW), S (50%), E (1 billion tonnes), Ch (45%), S (70 in 2070).

Mnemonic 3: "DU = DO Understand" — Dobson Units

Dobson Unit = DO Understand (the ozone column). Or more simply: "Dobson measures the Depth of ozone" — both words start with D.

Normal ozone = ~300 DU; Ozone hole = below 220 DU. Remember: 300 normal, 220 hole — subtract about a third.

Mnemonic 4: "N₂ No Trapping" — Nitrogen is Not a GHG

Nitrogen is N₂. It is the No. 1 gas by volume BUT does No trapping of heat. "N₂ — No infrared Notion." Its symmetrical two-atom bond vibrates without any change in electric dipole — like two equal-weight sacks on a balance beam, they move together and cancel out, generating no electrical signal that can interact with infrared photons.

Quick Revision

Core Science

• Greenhouse effect = short-wave solar radiation in, long-wave infrared trapped by GHGs, Earth warms
• Natural greenhouse effect maintains Earth at +15 °C; without it, −18 °C
• GHGs: CO₂, CH₄, N₂O, H₂O (vapour), O₃ (tropospheric), CFCs, HFCs
• NOT a GHG: N₂, O₂, Ar (homonuclear or noble — no IR absorption)
• Contribution order (total): CO₂ > CH₄ > N₂O > CFCs (concentration × GWP)
• GWP order (per molecule): CFCs >> N₂O >> CH₄ >> CO₂
• Ozone column unit: Dobson Unit (DU); normal ~300 DU; hole < 220 DU
• Ozone hole: stratospheric; caused by CFCs; seasonal over Antarctica
• Montreal Protocol (1987): eliminates CFCs and other ODS
• Kigali Amendment (2016): phase-down of HFCs (no ozone depletion but powerful GHG)

International Architecture

• UNFCCC (1994): foundational treaty; CBDR-RC principle
• Kyoto Protocol (1997, in force 2005): binding targets for Annex I only; CDM for India
• Paris Agreement (2015, in force 2016): universal NDCs; 2 °C / 1.5 °C goal; 5-year ratchet
• COP26 (Glasgow, 2021): India's Panchamrit; Glasgow Climate Pact; coal "phase-down"
• COP27 (Sharm el-Sheikh, 2022): Loss and Damage Fund created
• COP28 (Dubai, 2023): first Global Stocktake; "transition away from fossil fuels"
• IPCC: scientific body (WMO + UNEP); assesses science; does NOT set targets

India's Commitments (Panchamrit, COP26)

• 500 GW non-fossil capacity by 2030
• 50% energy from renewables by 2030
• Reduce cumulative emissions by 1 billion tonnes by 2030
• Reduce carbon intensity by 45% below 2005 levels by 2030
• Net-zero by 2070

India's NDC (Updated 2022)

• Emissions intensity reduction: 45% by 2030 (vs. 2005)
• Non-fossil capacity: 50% by 2030
• Carbon sink: +2.5–3 billion tonnes CO₂ eq. by 2030

NAPCC — 8 Missions Solar | Energy Efficiency | Habitat | Water | Himalayas | Green India | Agriculture | Knowledge

Chhattisgarh Relevance

• ~44% geographic area under forest cover — major carbon sink
• REDD+ mechanism directly applies; forest protection = climate contribution
• Coal economy (Korba, Raigarh) = CO₂ emission conflict
• Tribal communities most climate-vulnerable
• CAMPA funds for afforestation linked to mining diversion
• Monsoon variability threatens kharif (paddy) agriculture

CGPSC PYQ Quick Hits

• 2020: CO₂ > CH₄ > N₂O > CFCs (contribution order)
• 2021: India's COP26 pledge — 50% renewables (NOT 60%)
• 2023: Ozone thickness unit = Dobson unit
• 2024: Nitrogen (N₂) is NOT a greenhouse gas

International Solar Alliance (ISA)

• Co-founded by India and France at COP21 (2015)
• Headquartered in Gurugram (Haryana), India
• Focused on solar energy mobilisation for member countries (mostly intertropical zone)
• Separate from UNFCCC; specifically solar-focused

Key Comparative Table: Greenhouse Gas Properties

Key Net-Zero Targets by Country

• India: 2070
• China: 2060
• USA: 2050
• EU: 2050
• UK: 2050
• Japan: 2050
• Brazil: 2050

Dobson Unit Quick Facts

• Named after: Gordon Dobson (British meteorologist)
• 1 DU = 0.01 mm of pure ozone at STP
• Normal ozone column: ~300 DU
• Ozone hole threshold: < 220 DU
• Measured by: Dobson spectrophotometer; satellite instruments (TOMS, OMI)