Climate change science, IPCC & India's NDCs

The radiative basis of climate change

Climate change science rests on a measurable physical mechanism: greenhouse gases (GHGs)—carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases—absorb outgoing longwave (infrared) radiation and re-emit it, warming the lower atmosphere. This is the enhanced greenhouse effect, distinct from the natural greenhouse effect that keeps Earth habitable. Svante Arrhenius first quantified the CO2-temperature link in 1896; the Keeling Curve, begun at Mauna Loa in 1958, provided the empirical record of rising atmospheric CO2, which crossed 420 ppm in 2023 against a pre-industrial baseline of about 280 ppm.

Key metrics and concepts

Gases differ in warming potency. Global Warming Potential (GWP) indexes a gas against CO2 over a horizon (usually 100 years): methane's GWP-100 is roughly 28–34, nitrous oxide about 265–298, and sulphur hexafluoride over 23,000. Radiative forcing, measured in W/m2, expresses the net change in energy balance; CO2 contributes the largest positive forcing. Carbon sinks—oceans and terrestrial vegetation—absorb roughly half of anthropogenic emissions, while the residual stays airborne, giving CO2 an effective atmospheric lifetime of centuries.

The IPCC's Sixth Assessment Report (AR6, Working Group I, 2021) concluded it is unequivocal that human influence has warmed the climate, with global surface temperature about 1.1°C above 1850–1900 levels. The carbon budget concept is exam-critical: to keep warming below 1.5°C with 50% probability, AR6 estimated a remaining budget of roughly 500 GtCO2 from 2020. Feedback loops amplify warming—ice-albedo feedback (melting ice exposes dark surfaces), permafrost methane release, and water-vapour feedback.

Impacts of relevance to India

India is acutely exposed. The IPCC and the Ministry of Earth Sciences' 2020 assessment Climate Change Over the Indian Region document accelerating sea-level rise along the 7,500-km coastline, intensifying heatwaves, erratic monsoons, glacial retreat in the Hindu Kush Himalaya, and increased cyclone intensity in the Arabian Sea. Distinguish mitigation (reducing emissions/enhancing sinks) from adaptation (adjusting to impacts)—a recurring Prelims-Mains hinge. Note also climate justice and Common But Differentiated Responsibilities (CBDR-RC), the equity principle India consistently invokes, grounded in Article 3.1 of the 1992 UNFCCC.

Understanding the science prevents factual errors that examiners exploit: confusing ozone depletion (a stratospheric chemistry problem governed by the 1987 Montreal Protocol) with global warming, or conflating weather with climate. The 2016 Kigali Amendment to the Montreal Protocol, which India ratified in 2021, links the two regimes by phasing down hydrofluorocarbons (HFCs)—potent GHGs introduced as ozone-friendly substitutes.

The IPCC's role and architecture

The Intergovernmental Panel on Climate Change was established in 1988 by the World Meteorological Organization (WMO) and the UN Environment Programme (UNEP). Crucially, the IPCC does not conduct original research; it assesses published science. It works through three Working Groups—WG-I (physical science), WG-II (impacts, adaptation, vulnerability), WG-III (mitigation)—plus a Task Force on national GHG inventories. Its Assessment Reports (FAR 1990, SAR 1995, TAR 2001, AR4 2007, AR5 2014, AR6 2021–2023) feed the UNFCCC process. The AR4 won the 2007 Nobel Peace Prize jointly with Al Gore. The 2018 Special Report on 1.5°C (SR1.5) catalysed the global net-zero-by-2050 framing.

From UNFCCC to Paris

The UN Framework Convention on Climate Change (UNFCCC), adopted at the 1992 Rio Earth Summit, set the objective of stabilising GHG concentrations. The 1997 Kyoto Protocol imposed binding targets only on Annex I (developed) countries via a top-down model. The 2015 Paris Agreement (COP21, entered into force November 2016) replaced this with a bottom-up architecture: every party submits Nationally Determined Contributions (NDCs), subject to a five-yearly Global Stocktake (first concluded at COP28, Dubai, 2023) and a ratchet mechanism requiring progressively ambitious updates. Paris Article 2 sets the goal of holding warming well below 2°C and pursuing efforts toward 1.5°C.

India's NDCs and net-zero pledge

India submitted its first NDC in 2015 and an updated NDC in August 2022. The headline commitments to memorise:

• Reduce emissions intensity of GDP by 45% by 2030 from 2005 levels (raised from the earlier 33–35%).
• Achieve about 50% cumulative installed electric power capacity from non-fossil-fuel sources by 2030 (raised from 40%).
• Create an additional carbon sink of 2.5–3 billion tonnes of CO2 equivalent through additional forest and tree cover by 2030.

At COP26 (Glasgow, 2021), Prime Minister Narendra Modi announced the Panchamrit (five nectars): 500 GW non-fossil capacity by 2030; 50% energy from renewables by 2030; reducing projected emissions by 1 billion tonnes by 2030; reducing emissions intensity by 45%; and net-zero by 2070. India's domestic instruments include the National Action Plan on Climate Change (NAPCC, 2008) with eight missions, the International Solar Alliance (co-launched with France in 2015), the Energy Conservation (Amendment) Act 2022 enabling a domestic carbon credit trading scheme, the LiFE (Lifestyle for Environment) initiative, and the National Green Hydrogen Mission (2023). India's long-term low-emission development strategy was submitted at COP27 (Sharm el-Sheikh, 2022).

Why this matters for the exam

Climate change is among the highest-frequency themes across the UPSC examination. In Prelims (GS Paper I), it generates factual MCQs on institutions and instruments—the IPCC's parent bodies, what the IPCC does and does not do, GWP rankings, the Kigali Amendment, NDC numbers, and the distinction between the Montreal Protocol and the UNFCCC regime. Examiners routinely test confusion points: ozone vs. warming, Kyoto's top-down model vs. Paris's bottom-up NDCs, and 'carbon neutrality' vs. 'net-zero.'

How it is tested in Mains

In Mains GS Paper III (under conservation, environmental pollution, and disaster management), climate change appears as analytical questions demanding the equity argument. Recurring PYQ angles include: assessing whether India's climate commitments are adequate; the tension between CBDR-RC and developed-country pressure for universal mitigation; the adequacy of climate finance against the unmet USD 100 billion/year pledge (set at COP15 Copenhagen 2009, formalised at COP16 Cancun 2010) and the Loss and Damage Fund operationalised at COP28 (2023). The 2022 PYQ 'Describe the major outcomes of the 26th session of the COP to the UNFCCC' is illustrative—so memorise COP-by-COP outcomes.

High-yield facts to retain

1. IPCC = WMO + UNEP, 1988; assesses, does not research; AR6 in 2021–23; SR1.5 in 2018.
2. UNFCCC 1992 → Kyoto 1997 (binding, Annex I) → Paris 2015 (NDCs, ratchet, Global Stocktake).
3. India's 2022 updated NDC: 45% emissions intensity cut; 50% non-fossil capacity; 2.5–3 bn t CO2e sink.
4. Panchamrit at COP26; net-zero by 2070; first Global Stocktake at COP28 (2023).
5. Loss and Damage Fund operationalised at COP28; CBDR-RC from UNFCCC Article 3.1.

A disciplined candidate links each instrument to its date and forum. Vague answers that omit the precise NDC percentages or misattribute the IPCC's mandate lose marks that the well-prepared candidate banks. Treat the COP timeline as a memorisable ladder, and always frame India's position through the equity and climate-finance lens that distinguishes a top-decile Mains answer.