---
title: "Climate Science, IPCC & India's NDCs Explained"
description: "Cover climate change science fundamentals, the IPCC's assessment architecture, the UNFCCC-Paris framework and India's updated NDCs and net-zero pledge for GS-3."
url: "https://modeldiplomat.com/learn/lessons/upsc-environment-ecology-climate-change-science-ipcc-india-s-ndcs"
---

[New](https://modeldiplomat.com/)

Climate change science, IPCC & India's NDCs

Read 1 of 4

1/80 XP so far this lesson

Lesson 18 min 20 XP

# Climate change science, IPCC & India's NDCs

Climate change science fundamentals, the IPCC's assessment architecture, the UNFCCC-Paris framework, and India's updated NDCs and net-zero pledge for UPSC.

## 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.

One question, then back to the lesson

Ask about this lesson