BharatNotes Why this chapter matters for UPSC: This is Chapter 11 of Fundamentals of Physical Geography in the current rationalised NCERT (2026-27 reprint); it was Chapter 12 in earlier editions. Its first half classifies the world's climates on Koeppen's scheme. Its second half covers climate change in the past, its causes, greenhouse gases and global warming. Mains returns to it often: global warming and the Kyoto Protocol, shrinking Himalayan glaciers, the cryosphere, sea-level rise, food security and India's climate diplomacy.
Contemporary hook: WMO's State of the Global Climate 2025, released on 23 March 2026, found that 2015–2025 were the eleven warmest years on record and that 2025 was the second or third warmest, about 1.43°C above the 1850–1900 average (WMO, 23-Mar-2026). Two days later, on 25 March 2026, the Union Cabinet approved India's Nationally Determined Contribution for 2031–2035 (PIB, 25-Mar-2026).
🧠 First Principles — Read This First
Weather is the state of the air today. Climate is the pattern of weather over many years. To compare climates around the world, geographers group places with similar temperature and rainfall. NCERT describes three ways of doing this: empirical classifications use measured data; genetic ones group climates by their causes; applied ones serve a particular purpose. The most widely used scheme, Koeppen's, is empirical. Koeppen noticed that vegetation follows climate closely, so he chose temperature and rainfall limits that match vegetation boundaries and gave each climate a letter code. A cricket scorecard turns a long match into a few symbols in the same way; once you know the code, "Cwa" or "BWh" tells you the climate at a glance.
Climate also changes over time. NCERT gives the evidence: glacial landforms, lake sediments, tree rings and historical records all show warm and cold, wet and dry periods. Natural causes include changes in the Sun's output, slow cycles in the Earth's orbit and tilt, and volcanic dust.
The present concern is global warming. Some gases, such as carbon dioxide and methane, let sunlight in but absorb the heat the Earth radiates back. A car parked in the sun with its windows shut gets hotter inside than outside for a similar reason. Burning coal, oil and gas adds more of these gases, so the planet warms.
The chapter is the base for climate types, greenhouse gases and climate treaties, and for questions on glaciers, sea level, food security and India's climate commitments.
PART 1 — Quick Reference
Table 1: Koeppen's climatic groups (NCERT Table 11.1)
| Group | Defining condition |
|---|---|
| A – Tropical | Average temperature of the coldest month is 18°C or higher |
| B – Dry | Potential evaporation exceeds precipitation |
| C – Warm temperate (mid-latitude) | Coldest month above –3°C but below 18°C |
| D – Cold snow-forest | Coldest month –3°C or below |
| E – Cold | Average temperature of all months below 10°C |
A, C, D and E are humid climates; B is dry. Four groups are defined by temperature and one (B) by precipitation. Small letters mark dry seasons: f no dry season, m monsoon, w winter dry season, s summer dry season. The small letters a, b, c and d show how severe the temperature is. Within B, S is steppe (semi-arid) and W is desert. Source: NCERT FoPG (2026-27), Ch 11, pp. 91–92. NCERT says Koeppen's scheme was developed in 1918 and modified over time.
Table 2: Koeppen's climatic types (NCERT Table 11.2)
| Group | Type | Code | Characteristics |
|---|---|---|---|
| A | Tropical wet | Af | No dry season |
| A | Tropical monsoon | Am | Monsoonal; short dry season |
| A | Tropical wet and dry | Aw | Winter dry season |
| B | Subtropical steppe | BSh | Low-latitude semi-arid |
| B | Subtropical desert | BWh | Low-latitude arid |
| B | Mid-latitude steppe | BSk | Mid-latitude semi-arid |
| B | Mid-latitude desert | BWk | Mid-latitude arid |
| C | Humid subtropical | Cfa | No dry season; warm summer |
| C | Mediterranean | Cs | Dry hot summer |
| C | Marine west coast | Cfb | No dry season; warm and cool summer |
| D | Humid continental | Df | No dry season; severe winter |
| D | Subarctic | Dw | Winter dry and very severe |
| E | Tundra | ET | No true summer |
| E | Polar ice cap | EF | Perennial ice |
NCERT also describes a fourth C type in its text, Cwa (humid subtropical with dry winter), which is not in its Table 11.2. Source: NCERT FoPG (2026-27), Ch 11, pp. 92–93.
Table 3: Where each climate is found, and its key numbers (NCERT)
| Code | Main areas | NCERT figures and features |
|---|---|---|
| Af | Amazon Basin, western equatorial Africa, islands of the East Indies | Afternoon thunder showers every month; daily max ~30°C, min ~20°C; negligible annual range; tropical evergreen forest |
| Am | Indian subcontinent, north-eastern South America, northern Australia | Heavy summer rain; dry winter |
| Aw | North and south of the Amazon forest in Brazil, adjoining Bolivia and Paraguay, Sudan, south of Central Africa | Less, more variable rain than Af/Am; long dry season; greatest diurnal range in the dry season; deciduous forest and tree-studded grassland |
| BSh, BWh | 15°–35° latitude; subtropical highs; west coasts beside cold currents | Rain in short intense thundershowers; fog on coastal deserts by cold currents; high annual and diurnal ranges |
| BSk, BWk | 35°–60° latitude; continental interiors, areas ringed by mountains | Beyond the reach of maritime winds |
| Cwa | North Indian plains, South China interior plains | Like Aw, but with a warm winter |
| Cs | Around the Mediterranean; Central California, Central Chile, coasts of SE and SW Australia (30°–40°) | Subtropical high in summer, westerlies in winter; summer ~25°C, winter below 10°C; 35–90 cm |
| Cfa | Eastern USA, southern and eastern China, southern Japan, NE Argentina, coastal South Africa, east coast of Australia | 75–150 cm, rain all year; summer ~27°C, winter 5°–12°C; summer thunderstorms, winter frontal rain |
| Cfb | NW Europe, west coast of North America north of California, southern Chile, SE Australia, New Zealand | Summer 15°–20°C, winter 4°–10°C; 50–250 cm, all year |
| Df | Poleward of Cfb and mid-latitude steppe (40°–70°N) | Cold snowy winters; short frost-free season; large annual range |
| Dw | Mainly north-eastern Asia | Winter anticyclone gives monsoon-like wind reversal; below freezing for up to seven months; 12–15 cm, mostly in summer |
| ET | Beyond 70° latitude | Permafrost; mosses, lichens, low flowering plants; long summer daylight |
| EF | Interior Greenland and Antarctica | Below freezing even in summer; very little precipitation; Plateau Station (79°S) is NCERT's example |
Source: NCERT FoPG (2026-27), Ch 11, pp. 92–94.
Table 4: Current climate indicators (latest primary figures)
| Indicator | Latest figure | Source and date |
|---|---|---|
| Global temperature, 2024 | 1.55 ± 0.13°C above 1850–1900; warmest year on record | WMO, 10-Jan-2025 |
| Global temperature, 2025 | 1.43 ± 0.13°C above 1850–1900; 2nd or 3rd warmest | WMO State of the Global Climate 2025, 23-Mar-2026 |
| Long-term warming | About 1.3°C (initial estimate, as assessed in 2024) | WMO, 10-Jan-2025 |
| CO₂, Mauna Loa annual mean | 427.35 ppm (2025); 424.61 ppm (2024) | NOAA GML data file, created 5-Sep-2026 |
| CO₂, global mean | 423.9 ± 0.2 ppm (2024) | WMO State of the Global Climate 2025 |
| Methane; nitrous oxide (global) | 1,942 ± 2 ppb; 338.0 ± 0.1 ppb (2024) | WMO State of the Global Climate 2025 |
| Sea-level rise | 4.75 mm/yr over 2012–2025, against 2.65 mm/yr over 1993–2011 | WMO State of the Global Climate 2025 |
| Sea-level rise, 2024 alone | 5.9 mm (expected 4.3 mm); about 10 cm since 1993 | NASA, 13-Mar-2025 |
| Arctic sea ice (September minimum) | Shrinking 12.2% per decade, relative to the 1981–2010 average | NASA Earth Indicators (page updated Sep-2025) |
| Ocean heat | About 90% of the excess heat from global warming is stored in the ocean | WMO, 10-Jan-2025 |
The Mauna Loa figure and the WMO global figure measure different things: one is a single high-altitude station, the other a global average built from many stations. They are a year apart, so the gap between 427.35 and 423.9 ppm is expected. NOAA's file notes that its latest year's value is subject to change.
Table 5: NCERT's figures and the current figures
| Topic | NCERT (2026-27 reprint) | Current position |
|---|---|---|
| Warmest year | "The year 1998 was the warmest year" | 2024, at 1.55°C above 1850–1900 (WMO, 10-Jan-2025) |
| Highest shade temperature | 58°C at Al Aziziyah, Libya, 13 September 1922 | The WMO's table of world records lists 56.7°C at Furnace Creek (Death Valley), USA, 10 July 1913; Africa's record is 55.0°C at Kebili, Tunisia, 7 July 1931 (WMO, as of 30-Jan-2024). A WMO evaluation rejected the Libyan 58°C as an official record (El Fadli et al., Bulletin of the AMS, 2013) |
| CO₂ growth | "rising at about 0.5 per cent annually" | Mauna Loa annual means rose from 424.61 to 427.35 ppm between 2024 and 2025, about 0.65% (arithmetic from NOAA data) |
| Warming since pre-industrial times | About 0.6°C by the end of the 20th century, against the end of the 19th | Long-term warming about 1.3°C above 1850–1900, as assessed in 2024 (WMO, 10-Jan-2025); single years run higher: 1.55°C in 2024, 1.43°C in 2025 |
| Kyoto Protocol | Proclaimed 1997, in force 2005, ratified by 141 nations, binding 35 industrialised countries to cut emissions "by 2012" to 5% below 1990 | Adopted 11 December 1997; in force 16 February 2005; 192 parties (UN Treaty Collection, October 2026). The first commitment period ran from 2008 to 2012, for overall cuts of "at least 5 per cent below 1990 levels" (Art. 3); the Doha Amendment for a second period entered into force on 31 December 2020 |
| Paris Agreement | Not in NCERT | In force 4 November 2016; 194 parties; the United States' withdrawal took effect on 27 January 2026 (UN Treaty Collection) |
In an NCERT-based answer, give NCERT's figure; in a current-affairs answer, use the dated figure.
PART 2 — Concepts & Narrative
Koeppen's classification
Koeppen's is an empirical scheme based on mean annual and mean monthly temperature and precipitation. He found a close relationship between vegetation and climate, chose temperature and precipitation values that fit vegetation boundaries, and used capital and small letters to label climate groups and types (Tables 1 and 2).
Reading a Koeppen code. The capital letter is the group (A–E). The second letter gives the dry season (f, m, w, s) or, for group B, steppe (S) or desert (W). The third letter gives temperature: h for hot low-latitude dry climates, k for cold mid-latitude ones, and a/b/c/d for decreasing summer warmth. So Cwa reads: warm temperate (C), dry winter (w), hot summer (a). BWh reads: dry (B), desert (W), hot low-latitude (h).
Group A: tropical humid climates
These lie between the Tropic of Cancer and the Tropic of Capricorn. With the Sun overhead all year and the ITCZ nearby, they are hot and humid, with a low annual range of temperature and high rainfall.
- Af (tropical wet) lies near the equator. Rain falls every month, mainly as afternoon thunder showers.
- Am (tropical monsoon) covers the Indian subcontinent in NCERT's text, and NCERT's exercise keys "Am" for most of the Indian Peninsula. NCERT's own companion book was more precise: the pre-2023 edition of India: Physical Environment put "Aw" (tropical savannah) over "most of the Peninsular plateaus, south of the Tropic of Cancer", Amw on the west coast south of Goa and As on the Coromandel coast. Give NCERT's key in an NCERT question.
- Aw (tropical wet and dry) lies north and south of the Af belts. It borders dry climates on the western side of continents and Cf or Cw climates on the eastern side.
Group B: dry climates
Dry climates have too little rain for plant growth and cover large areas between 15° and 60° in both hemispheres. At 15°–30° they lie under the subtropical highs, where subsidence and temperature inversion prevent rain. On west coasts beside cold currents, especially in South America, they extend further towards the equator and reach the coast. At 35°–60° they are confined to continental interiors and to areas surrounded by mountains.
Steppe (BS) gets slightly more rain than desert (BW), enough for sparse grassland. Rainfall in both is highly variable, and this variability affects life in the steppe more than in the desert, often causing famine.
Group C: warm temperate (mid-latitude) climates
These lie between 30° and 50°, mainly on the eastern and western margins of continents, with warm summers and mild winters (Table 3).
Why the Mediterranean climate has dry summers
The Mediterranean climate (Cs) lies on the west coasts of continents between 30° and 40°. In summer the pressure belts shift poleward and the region comes under the subtropical high, where sinking air prevents rain. In winter the belts shift towards the equator and the region comes under the westerlies, which bring rain-bearing depressions. The result is a hot, dry summer and a mild, rainy winter, the reverse of the monsoon pattern. The same logic places Cfb (rain all year from the westerlies) poleward of Cs on the same west coasts, and Cfa (rain all year from unstable air masses) on the eastern sides of continents in the same latitudes as Cs.
Groups D and E: cold climates
NCERT places D climates over large continental areas of the northern hemisphere between 40° and 70°N, in Europe, Asia and North America; the southern hemisphere has little land in those latitudes. Df has snowy winters; Dw, mainly in north-eastern Asia, has very dry, extremely cold winters under a strong anticyclone, with a monsoon-like reversal of wind in summer.
Polar climates lie beyond 70°. In the tundra (ET) the subsoil is permanently frozen (permafrost), and the short growing season and waterlogging allow only low plants. On the ice caps (EF) snow and ice build up until the pressure deforms the ice sheets, which break and float away as icebergs.
Climate change in the past
NCERT notes that today's climate has probably prevailed for about the last 10,000 years, with minor and occasionally wide fluctuations. The evidence for earlier change includes glacial landforms at high altitudes and latitudes, warm and cold layers in glacial-lake sediments, tree rings showing wet and dry periods, and historical records.
| Period | Event (NCERT) |
|---|---|
| 500–300 million years ago (NCERT's dates) | Earth warm through the Cambrian, Ordovician and Silurian periods (on the current geological time scale these periods run from about 539 to 443 million years ago) |
| Pleistocene | Glacial and interglacial periods; last major glacial peak about 18,000 years ago |
| About 10,000 years ago (NCERT) | Present interglacial began (the Holocene epoch is now dated from 11,700 years ago, International Commission on Stratigraphy) |
| Around 8,000 BC | Rajasthan desert wet and cool |
| 3,000–1,700 BC | Higher rainfall in the region; 2,000–1,700 BC it was the centre of the Harappan civilisation; dry conditions increased afterwards (NCERT's Class XII history book dates the Mature Harappan phase to 2600–1900 BCE) |
| 10th–11th centuries | Warm, dry conditions in Europe; Vikings settled in Greenland |
| 1550 to about 1850 | "Little Ice Age" in Europe |
| 1885–1940 | Upward trend in world temperature; slower rise after 1940 |
| 1930s | "Dust bowl": severe drought in the south-western Great Plains of the USA |
| 1967–1977 | Worst drought in the Sahel, south of the Sahara |
| 1990s | Warmest decade of the 20th century; some of the worst floods |
Source: NCERT FoPG (2026-27), Ch 11, p. 95.
Causes of climate change
NCERT groups the causes as astronomical and terrestrial, and treats human causes separately.
- Sunspots. Sunspots are darker, cooler patches on the Sun that increase and decrease in cycles. Some meteorologists link more sunspots with cooler, wetter, stormier weather and fewer sunspots with warmer, drier conditions, but NCERT notes these findings are not statistically significant. (An NCERT exercise asks what conditions would follow an increase in sunspots; the textbook answer is cooler and wetter weather with more storms.)
- Milankovitch oscillations. Cycles in the Earth's orbit around the Sun, the wobble of the Earth and changes in its axial tilt alter the insolation received and may affect climate.
- Volcanism. Eruptions throw aerosols into the atmosphere that stay for a long time and reduce the sunlight reaching the surface. NCERT notes that the Earth's average temperature fell for some years after the Pinatubo and El Chichón eruptions (spelt "Pinatoba" and "El Cion" in the NCERT text).
- Anthropogenic. The most important human effect is the rising concentration of greenhouse gases.
Greenhouse effect and greenhouse gases
The atmosphere lets incoming short-wave solar radiation through but absorbs most of the long-wave radiation emitted by the Earth's surface. Gases that absorb long-wave radiation are greenhouse gases, and the warming they cause is the greenhouse effect, named after a glass greenhouse, which is transparent to incoming sunlight but holds in outgoing heat.
NCERT's list of the main greenhouse gases: carbon dioxide (CO₂), chlorofluorocarbons (CFCs), methane (CH₄), nitrous oxide (N₂O) and ozone (O₃). Nitric oxide and carbon monoxide react with greenhouse gases and change their concentrations.
What makes a greenhouse gas effective (NCERT)
A gas's warming effect depends on three things: how much its concentration increases, how long it stays in the atmosphere, and the wavelengths of radiation it absorbs. CFCs are highly effective. Ozone in the stratosphere absorbs ultraviolet radiation, but in the lower troposphere it is very effective at absorbing terrestrial radiation. The longer a gas lasts, the longer the climate takes to recover from it.
CO₂ is the largest greenhouse gas by concentration. It comes mainly from burning oil, gas and coal. Forests and oceans are its sinks, so deforestation also raises its concentration. NCERT gives 20–50 years as the time for atmospheric CO₂ to adjust to changes in sources and sinks (a simplification: part of the CO₂ emitted today stays in the air for centuries), and notes that climate models use a doubling of CO₂ over the pre-industrial level as a benchmark.
CFCs, produced only by human activity, drift into the stratosphere and destroy ozone. The large depletion over Antarctica is the ozone hole, which lets ultraviolet rays pass into the troposphere.
Global warming: NCERT's record
NCERT gives the world's annual average near-surface air temperature as about 14°C. The greatest warming of the 20th century came in two periods, 1901–44 and 1977–99, each with a rise of about 0.4°C, with slight cooling between them, more marked in the northern hemisphere. By the end of the 20th century the global mean was about 0.6°C above the end of the 19th century. The seven warmest years of 1856–2000 were in the last decade, and NCERT calls 1998 the warmest year (now superseded; see Table 5).
NCERT lists the expected effects: sea-level rise from melting glaciers and ice caps and from thermal expansion of seawater, flooding of coastal areas and islands, and harm to life-support systems. It notes that the effects will not be uniform and that warming, once it sets in, will be hard to reverse.
What the latest data show (to October 2026)
- Temperature. WMO confirmed 2024 as the warmest year on record at about 1.55°C above 1850–1900, likely the first calendar year above 1.5°C. WMO stresses that one year above 1.5°C does not mean the Paris goal has been missed, since that goal is measured over decades; its experts put long-term warming, as assessed in 2024, at about 1.3°C (WMO, 10-Jan-2025). 2025 was the second or third warmest year, at about 1.43°C (WMO, 23-Mar-2026).
- 2026 so far. NASA's GISTEMP record puts the monthly global anomalies of 2026 (January to August) at 1.09°C to 1.40°C above its 1951–1980 base, against an annual 1.29°C in 2024 and 1.19°C in 2025 on the same base (NASA GISS, GISTEMP v4). IMD reported a strong El Niño by the end of the 2026 monsoon season.
- Greenhouse gases. In 2024, CO₂, methane and nitrous oxide reached their highest levels in at least 800,000 years (WMO State of the Global Climate 2025 at a glance). Mauna Loa's annual mean CO₂ was 427.35 ppm in 2025 (NOAA GML).
- Sea level. Sea level rose 4.75 mm a year over 2012–2025, against 2.65 mm a year over 1993–2011 (WMO, Mar-2026). In 2024 it rose 5.9 mm, and two-thirds of that came from thermal expansion rather than melting ice, reversing the usual split (NASA, 13-Mar-2025).
- Ice. Glacier mass loss in the 2024/25 hydrological year was among the five most negative on record for WMO's reference glaciers, and the 2025 Arctic sea-ice maximum was the lowest in the record (WMO, Mar-2026).
International response
NCERT names the Kyoto Protocol as the most important international effort: proclaimed in 1997, in force from 2005, ratified by 141 nations, binding 35 industrialised countries to cut their emissions by 2012 to 5% below 1990 levels. The later framework is below.
| Agreement or meeting | Year | What it did | Source |
|---|---|---|---|
| Kyoto Protocol | 1997 (in force 2005) | Emission cuts for industrialised countries (NCERT figures above) | NCERT |
| Paris Agreement | 2015 | Hold warming "well below 2°C" and pursue efforts to limit it to 1.5°C; countries set Nationally Determined Contributions | WMO, 10-Jan-2025 (quotes the temperature goal); PIB, 25-Mar-2026 (NDCs under the Paris Agreement) |
| COP28, Dubai | 30 Nov–13 Dec 2023 | Outcome of the first Global Stocktake; Loss and Damage Fund operationalised (about US$700 million pledged after the decision) | PIB, 18-Dec-2023 |
| COP29, Baku | 2024 | New Collective Quantified Goal: mobilise US$300 billion a year by 2035. India called it "substantially insufficient" against needs of US$5.1–6.8 trillion up to 2030 | PIB, 11-Aug-2025 |
| COP30, Belém | Closing plenary 22 Nov 2025 | India's account: Just Transition Mechanism established, progress on the Global Goal on Adaptation, a start on developed countries' finance obligations under Article 9.1. UN News: countries "agreed to develop a just transition mechanism", to mobilise $1.3 trillion a year by 2035 for climate action, and to triple adaptation finance by 2035 | PIB, 23-Nov-2025; UN News, 22-Nov-2025 |
On climate finance: the OECD reports that developed countries provided and mobilised US$115.9 billion for developing countries in 2022, reaching the US$100 billion goal for the first time, and US$132.8 billion in 2023 and US$136.7 billion in 2024 (OECD, Climate Finance Provided and Mobilised by Developed Countries in 2013–2024, May 2026).
India: commitments and exposure
India's NDC for 2031–2035 (Cabinet approval, 25 March 2026)
| Target | 2015 NDC (for 2030) | 2022 update (for 2030) | 2031–35 NDC (for 2035) |
|---|---|---|---|
| Cut in emissions intensity of GDP (from 2005) | 33–35% | 45% | 47% |
| Non-fossil share of cumulative installed electric power capacity | 40% | about 50% | 60% |
| Additional carbon sink from forest and tree cover | 2.5–3 billion t CO₂e | Not restated in the PIB release | 3.5–4.0 billion t CO₂e (from 2005 level) |
Progress reported by PIB: emissions intensity fell 36% between 2005 and 2020; non-fossil capacity reached 52.57% in February 2026, meeting the 2030 target five years early; an additional sink of 2.29 billion t CO₂e had been created by 2021. Long-term goal: net-zero by 2070. The NDC is implemented through the National Action Plan on Climate Change (NAPCC) and its nine national missions, and State Action Plans. Sources: PIB, 25-Mar-2026 for the 2031–35 NDC and progress; PIB, 3-Aug-2022 for the 2015 NDC and the 2022 update. PIB (25-Mar-2026) says the two 2015 targets were met 11 and 9 years ahead of schedule.
Adaptation. MoEFCC is preparing India's first National Adaptation Plan (NAP), which PIB describes as covering "nine key sectors", among them water; agriculture; disaster management and infrastructure resilience; health; forests, ecosystems and biodiversity; poverty alleviation and livelihoods; traditional knowledge and heritage; and adaptation resourcing (PIB, 18-Mar-2025).
Exposure. India's coastline was re-assessed by the National Hydrographic Office with the Survey of India at 11,098.81 km, against the earlier 7,516.6 km. The revised length was promulgated by a Ministry of Ports, Shipping and Waterways circular of 29 April 2025 (PIB, 4-Dec-2025). NCERT's India: Physical Environment uses the older figure (about 7,517 km). The faster sea-level rise in Table 4 therefore applies to a longer measured coast than the textbook gives. Himalayan glacier loss, rising heat and more erratic rain are the other exposures.
PART 3 — UPSC Integration
Mains frameworks
- Global warming and Kyoto. NCERT's greenhouse mechanism and gas list, then the effects (Table 4 data, dated), then control measures: Kyoto (NCERT's figures and the treaty record), Paris and India's NDC targets.
- Glaciers and the cryosphere. Glacier mass loss (WMO), then the short-term rise in meltwater and glacial-lake flood risk, then the long-term fall in dry-season flow; Arctic sea ice (NASA, 12.2% per decade) affects albedo and weather, while Antarctic land ice adds to sea level.
- Sea-level rise. The two causes named by NCERT (ice melt, thermal expansion), the current rate (WMO 4.75 mm a year over 2012–2025), then India's 11,098.81 km coastline, deltas and island territories.
Cross-paper relevance
- GS1 (Geography): Koeppen types; glaciers and cryosphere; climate and food security.
- GS2 (International relations): India's position in climate negotiations (CBDR-RC, equity, finance).
- GS3 (Environment): greenhouse gases, Kyoto, COP outcomes, India's NDC and adaptation plan.
Exam Strategy
Prelims fact-traps from this chapter
- Koeppen is empirical, not genetic or applied (NCERT exercise). Genetic schemes group climates by cause.
- Group A = every month's mean 18°C or more (the coldest month ≥18°C); E = every month below 10°C.
- Humid groups are A, C, D and E; B is the dry group.
- Most of the Indian Peninsula = Am in NCERT's exercise; North Indian plains = Cwa.
- Mediterranean regions are on west coasts (Central Chile, California, SW Australia, the Cape), not the south-east coast of South America.
- Dw (dry, severe winter) is in north-eastern Asia; NCERT places D climates in the northern hemisphere (40°–70°N).
- NCERT's greenhouse gases include CFCs and ozone, not only CO₂ and methane.
- Pinatubo and El Chichón caused cooling for some years (volcanic aerosols).
- Warmest year. NCERT's answer is 1998; the current record is 2024 (WMO).
- Non-fossil target is a share of installed capacity, not of electricity generated.
- Coastline: 11,098.81 km (re-assessed; MoPSW circular 29-Apr-2025); textbook figure about 7,517 km.
Mains question patterns
- "Discuss ... in the light of" a treaty (Kyoto 2022): mechanism, effects, then the treaty's provisions.
- Impact questions on India (2017, 2023): split by region (Himalayan states, coasts) and by sector (water, food).
Practice Questions
Practice (UPSC-pattern, not past papers). Questions 1 to 5 are NCERT's own exercise MCQs.
Prelims:
Which one of the following is suitable for Koeppen's "A" type of climate?
(a) High rainfall in all the months
(b) Mean monthly temperature of the coldest month more than freezing point
(c) Mean monthly temperature of all the months more than 18°C
(d) Average temperature for all the months below 10°CKoeppen's system of classification of climates can be termed as:
(a) Applied
(b) Systematic
(c) Genetic
(d) EmpiricalMost of the Indian Peninsula will be grouped according to Koeppen's system under (NCERT's key):
(a) Af
(b) BSh
(c) Cfb
(d) Am
See the note under Group A: much of the interior fits Aw on Koeppen's thresholds.Which one of the following years is supposed to have recorded the warmest temperature the world over (NCERT's key)?
(a) 1990
(b) 1998
(c) 1885
(d) 1950
NCERT's answer; the record year is now 2024 (WMO).Which one of the following groups of four climates represents humid conditions?
(a) A–B–C–E
(b) A–C–D–E
(c) B–C–D–E
(d) A–C–D–FMediterranean climate is found in all of the following regions except:
(a) Central Chile
(b) South-western Australia
(c) South-western parts of South Africa
(d) South-east coast of South AmericaConsider the following pairs (climate type : region): 1. Cwa : North Indian plains 2. Dw : North-eastern Asia 3. Cfb : Eastern USA. Which of the pairs given above are correctly matched?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Eastern USA is Cfa.
Mains (practice):
- Make a comparison of the climatic conditions of the "A" and "B" types of climate. (NCERT Ex. 3(i), 150 words)
- What do you understand by the term "greenhouse gases"? Make a list of them. (NCERT Ex. 3(iii), 150 words)
- "Climate change is a natural and continuous process, but the present warming is different." Discuss with evidence from the past and the present. (250 words)
Short answers (NCERT Ex. 2, about 30 words): Koeppen used temperature and precipitation. A genetic classification groups climates by their causes, an empirical one by observed data. Climates with a very low range of temperature are the tropical humid (A) climates. NCERT says that when sunspots increase, cooler and wetter weather and greater storminess occur (and fewer sunspots go with warm, dry conditions), though the link is not statistically significant.
📦 Revision Capsule
Hard Facts
- Current NCERT numbering: Chapter 11 of FoPG (2026-27 reprint); Chapter 12 in older editions
- Koeppen's scheme: empirical; first published in 1900, with NCERT's 1918 version a revision and Köppen's last in 1936; five groups A, B, C, D, E (B dry, the rest humid)
- A: coldest month ≥18°C; C: coldest month between –3°C and 18°C; D: coldest month ≤ –3°C; E: all months <10°C
- Am: Indian subcontinent; Cwa: North Indian plains and South China interior
- Cs: 30°–40° west coasts; 35–90 cm; Cfa: 75–150 cm; Cfb: 50–250 cm; Dw: 12–15 cm
- Dry climates: 15°–60°; BSh/BWh at 15°–35°, BSk/BWk at 35°–60°
- Polar climates beyond 70°; D climates 40°–70°N (NCERT)
- Last glacial peak ~18,000 years ago; present interglacial ~10,000 years; Little Ice Age 1550–~1850; Sahel drought 1967–77; Dust Bowl 1930s
- NCERT greenhouse gases: CO₂, CFCs, CH₄, N₂O, O₃
- Kyoto (NCERT): 1997; in force 2005; 141 nations; 35 industrialised countries; 5% below 1990 by 2012
- Warmest year: NCERT 1998; WMO 2024 (1.55°C above 1850–1900)
- 2025: 1.43°C above 1850–1900 (WMO, Mar-2026); Mauna Loa CO₂ 427.35 ppm (2025, NOAA)
- Sea level: 4.75 mm/yr over 2012–2025 vs 2.65 mm/yr over 1993–2011 (WMO)
- India NDC 2031–35: 47% intensity cut; 60% non-fossil capacity; 3.5–4.0 bn t CO₂e sink; net-zero 2070
- Non-fossil capacity 52.57% (Feb 2026, PIB); NAPCC has nine missions
- Coastline 11,098.81 km (MoPSW circular, 29-Apr-2025)
Core Concepts
- Koeppen fitted temperature and rainfall limits to vegetation boundaries
- The position of the pressure belts explains where each climate occurs (Mediterranean: subtropical high in summer, westerlies in winter)
- Climate has always changed; natural causes are sunspots, orbital cycles and volcanic aerosols
- Greenhouse gases let in short-wave radiation but absorb long-wave radiation
- Single years above 1.5°C do not mean the Paris goal has been missed; it refers to decades
Confused Pairs
- Empirical (observed data) vs genetic (causes) vs applied (purpose) classification
- Cfa (east coasts, rain all year) vs Cs (west coasts, dry summer)
- Df (humid winter) vs Dw (dry winter, NE Asia)
- Mauna Loa CO₂ (single station, 427.35 ppm, 2025) vs WMO global mean (423.9 ppm, 2024)
- Installed capacity share vs electricity generation share
PYQ Pattern
- Mains has asked about global warming and the Kyoto Protocol, Himalayan glaciers and the cryosphere, sea-level rise, climate change and food security, and India's climate diplomacy; Prelims has asked about Mediterranean regions, the Paris Agreement and India's climate response.
Sources
Sources
- NCERT, Fundamentals of Physical Geography, Class XI, Chapter 11 "World Climate and Climate Change", Reprint 2026-27: https://ncert.nic.in/textbook/pdf/kegy211.pdf
- J. El Fadli et al., "World Meteorological Organization Assessment of the Purported World Record 58°C Temperature Extreme at El Azizia, Libya (13 September 1922)", Bulletin of the American Meteorological Society 94(2) (2013): doi:10.1175/BAMS-D-12-00093.1.
- M.C. Peel, B.L. Finlayson and T.A. McMahon, "Updated world map of the Köppen-Geiger climate classification", Hydrology and Earth System Sciences 11 (2007): 1633–1644: hess.copernicus.org.
- OECD, Climate Finance Provided and Mobilised by Developed Countries in 2013–2024 (May 2026): oecd.org.
- UN Treaty Collection, Kyoto Protocol text: treaties.un.org.
- WMO, State of the Global Climate 2025, 23-Mar-2026: https://wmo.int/publication-series/state-of-global-climate/state-of-global-climate-2025
- WMO, State of the Global Climate 2025 at a glance (one-page summary), Mar-2026: https://wmo.int/sites/default/files/2026-03/State of the Climate 2025_1 pager_final.pdf
- WMO, "WMO confirms 2024 as warmest year on record at about 1.55°C above pre-industrial level", 10-Jan-2025: https://wmo.int/news/media-centre/wmo-confirms-2024-warmest-year-record-about-155degc-above-pre-industrial-level
- WMO, Records of Weather and Climate Extremes, as of 30-Jan-2024: https://wmo.int/sites/default/files/2024-01/Table_Extreme_Records_30Jan2024.pdf
- NOAA Global Monitoring Laboratory, Mauna Loa CO₂ annual mean data (file created 5-Sep-2026): https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_mlo.txt
- NASA, "NASA Analysis Shows Unexpected Amount of Sea Level Rise in 2024", 13-Mar-2025: https://sealevel.nasa.gov/news/282/nasa-analysis-shows-unexpected-amount-of-sea-level-rise-in-2024/
- NASA, Arctic Sea Ice Minimum Extent (Earth Indicator): https://science.nasa.gov/earth/explore/earth-indicators/arctic-sea-ice-minimum-extent/
- PIB (Cabinet), India's NDC 2031–2035, 25-Mar-2026: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2245209
- PIB (Cabinet), India's updated NDC, 3-Aug-2022: https://www.pib.gov.in/PressReleasePage.aspx?PRID=1847812
- PIB (MoEFCC), National Workshop on India's National Adaptation Plan, 18-Mar-2025: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2112351
- PIB (MoES), "Coastline of the Country", 4-Dec-2025: https://www.pib.gov.in/PressReleseDetailm.aspx?PRID=2198800®=3&lang=2
- PIB (MoEFCC), "Major outcomes from 28th Session of the UN Climate Change Conference (COP 28)", 18-Dec-2023: https://www.pib.gov.in/PressReleasePage.aspx?PRID=1987760
- PIB (MoEFCC), "Outcome of COP-29", 11-Aug-2025: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2155199®=3&lang=2
- PIB (MoEFCC), "India Welcomes Key Outcomes at UNFCCC CoP30", 23-Nov-2025: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2193076®=3&lang=2
