NCERT Solutions for Class 11 Geography Chapter 11: World Climate and Climate Change (NCERT 2026–27)

These Class 11 Geography Chapter 11 solutions cover World Climate and Climate Change from Fundamentals of Physical Geography, updated for the 2026–27 session. The chapter explains the three approaches to classifying climate (empirical, genetic and applied), describes Koeppen’s scheme of classification with its five major climatic groups and their types, and discusses climate change — its evidence, causes (astronomical and terrestrial), the greenhouse effect, global warming, greenhouse gases and global efforts such as the Kyoto Protocol. Below you get step-by-step answers to every NCERT exercise question, key terms, extra practice, MCQs, Assertion–Reason and FAQs.

Class: 11 Subject: Geography Book: Fundamentals of Physical Geography Chapter: 11 Topic: World Climate and Climate Change Session: 2026–27
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Class 11 Geography Chapter 11 – Overview

Chapter 11, World Climate and Climate Change, first organises the world’s climates into manageable units. Three broad approaches are used — empirical (based on observed temperature and precipitation data), genetic (organising climates by their causes) and applied (for a specific purpose). The most widely used is V. Koeppen’s empirical scheme, which links vegetation to climate and uses capital and small letters to label five major groups: A – Tropical, B – Dry, C – Warm temperate (mid-latitude), D – Cold snow-forest, and E – Cold (polar). Four groups (A, C, D, E) are temperature-based and one (B) is precipitation-based. The chapter then turns to climate change — the evidence from glaciers, sediments, tree rings and historical records, the astronomical and terrestrial causes, and the modern concerns of the greenhouse effect, global warming, greenhouse gases, ozone depletion and international action like the Kyoto Protocol.

Key Terms & Concepts

Empirical classification: a classification of climate based on observed data, particularly on temperature and precipitation.

Genetic classification: a classification that attempts to organise climates according to their causes (such as air masses and the factors that produce them) rather than their observed effects.

Applied classification: a classification of climate designed for a specific purpose (for example, for agriculture or human comfort).

Koeppen’s scheme: an empirical scheme developed by V. Koeppen (1918, later modified) using mean annual and mean monthly temperature and precipitation; it uses capital letters for groups and small letters for types and seasonality.

Five major groups: A – Tropical (coldest month 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/polar (all months below 10°C).

Seasonality letters: the small letters indicate dryness — f = no dry season, m = monsoon (short dry season), w = winter dry season, s = summer dry season; a, b, c, d show the severity of temperature; and for dry climates S = steppe (semi-arid) and W = desert.

Greenhouse effect: the atmosphere transmits incoming short-wave solar radiation but absorbs most of the long-wave radiation re-emitted by the Earth’s surface, warming the lower atmosphere — just as glass warms a greenhouse.

Greenhouse gases (GHGs): gases that absorb long-wave radiation — carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4), nitrous oxide (N2O) and ozone (O3).

Global warming: the increasing trend in the Earth’s near-surface temperature caused mainly by the rising concentration of greenhouse gases in the atmosphere.

Astronomical & terrestrial causes: astronomical causes include changes in solar output (sunspot cycles) and Milankovitch oscillations (variations in the Earth’s orbit, wobble and axial tilt); terrestrial causes include volcanism (aerosols) and the human (anthropogenic) increase in greenhouse gases.

Ozone hole & Kyoto Protocol: the depletion of stratospheric ozone (largest over Antarctica) caused by CFCs is the ‘ozone hole’; the Kyoto Protocol (1997, in effect 2005) bound 35 industrialised countries to cut emissions to 5% below 1990 levels by 2012.

Table 11.1 — Climatic Groups According to Koeppen

GroupCharacteristics
A – TropicalAverage temperature of the coldest month is 18°C or higher
B – Dry ClimatesPotential evaporation exceeds precipitation
C – Warm Temperate (Mid-latitude) ClimatesAverage temperature of the coldest month is higher than −3°C but below 18°C
D – Cold Snow Forest ClimatesAverage temperature of the coldest month is −3°C or below
E – Cold ClimatesAverage temperature for all months is below 10°C

Table 11.2 — Climatic Types According to Koeppen

GroupTypeLetter CodeCharacteristics
A – Tropical Humid ClimateTropical wetAfNo dry season
Tropical monsoonAmMonsoonal, short dry season
Tropical wet and dryAwWinter dry season
B – Dry ClimateSubtropical steppeBShLow-latitude semi-arid or dry
Subtropical desertBWhLow-latitude arid or dry
Mid-latitude steppeBSkMid-latitude semi-arid or dry
Mid-latitude desertBWkMid-latitude arid or dry
C – Warm temperate (Mid-latitude) ClimatesHumid subtropicalCfaNo dry season, warm summer
MediterraneanCsDry hot summer
Marine west coastCfbNo dry season, warm and cool summer
D – Cold Snow-forest ClimatesHumid continentalDfNo dry season, severe winter
SubarcticDwWinter dry and very severe
E – Cold ClimatesTundraETNo true summer
Polar ice capEFPerennial ice

NCERT Exercise — Full Solutions

All questions below are reproduced verbatim from the NCERT textbook’s end-of-chapter Exercises section. Answers are original, written in exam-ready style.

1. Multiple choice questions

(i) 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°C

ANSWER (c) Mean monthly temperature of all the months more than 18°C. Koeppen’s “A” (Tropical) group is defined by warmth throughout the year — the average temperature of even the coldest month is 18°C or higher, so all months are consistently above 18°C.

(ii) Koeppen’s system of classification of climates can be termed as: (a) Applied    (b) Systematic    (c) Genetic    (d) Empirical

ANSWER (d) Empirical. Koeppen based his scheme on observed temperature and precipitation data and their relationship with vegetation, which makes it an empirical classification rather than a genetic or applied one.

(iii) Most of the Indian Peninsula will be grouped according to Koeppen’s system under: (a) “Af”    (b) “BSh”    (c) “Cfb”    (d) “Am”

ANSWER (d) “Am”. Most of the Indian Peninsula experiences a tropical monsoon climate — heavy rainfall in summer with a short dry season — which Koeppen designates as “Am”.

(iv) Which one of the following years is supposed to have recorded the warmest temperature the world over? (a) 1990    (b) 1998    (c) 1885    (d) 1950

ANSWER (b) 1998. The year 1998 was the warmest year recorded during 1856–2000 — probably the warmest not only of the 20th century but of the whole millennium.

(v) 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—F

ANSWER (b) A—C—D—E. In Koeppen’s scheme the capital letters A, C, D and E delineate the humid climates, while B represents the dry climates. (There is no group “F”.)

2. Answer the following questions in about 30 words.

(i) Which two climatic variables are used by Koeppen for classification of the climate?

ANSWER Koeppen used temperature and precipitation as the two climatic variables for his classification. He selected certain values of mean annual and mean monthly temperature and precipitation, relating them to the distribution of vegetation.

(ii) How is the “genetic” system of classification different from the “empirical one”?

ANSWER The empirical system is based on observed data, mainly temperature and precipitation. The genetic system, in contrast, organises climates according to their causes — the factors and air masses that produce them — rather than their observed effects.

(iii) Which types of climates have very low range of temperature?

ANSWER The tropical humid climates (Group A), especially the tropical wet (Af) type near the equator, have a very low annual range of temperature because the sun is nearly overhead throughout the year. Marine west coast (Cfb) climates also show small annual and daily ranges due to maritime influence.

(iv) What type of climatic conditions would prevail if the sun spots increase?

ANSWER According to some meteorologists, when the number of sunspots increases, cooler and wetter weather with greater storminess occurs. (A decrease in sunspots is linked with warmer, drier conditions, though these findings are not statistically significant.)

3. Answer the following questions in about 150 words.

(i) Make a comparison of the climatic conditions between the “A” and “B” types of climate.

ANSWER The “A” Tropical Humid climates lie between the Tropic of Cancer and the Tropic of Capricorn. With the sun overhead through the year and the ITCZ present, they are hot and humid: the average temperature of the coldest month is 18°C or higher, the annual range of temperature is very low, and annual rainfall is high. They support dense tropical evergreen and deciduous forests and are divided into Af, Am and Aw types. The “B” Dry climates, by contrast, are defined by precipitation: potential evaporation exceeds precipitation. Rainfall is very low and inadequate for plant growth. They cover large areas from about 15°–60° north and south — in subtropical highs and in continental interiors shielded by mountains. Temperatures, especially summer maxima, are very high, and annual and diurnal ranges are large. They are subdivided into steppe (BS, semi-arid) and desert (BW). Thus A climates are humid with even temperatures, while B climates are dry with extreme temperatures.

(ii) What type of vegetation would you find in the “C” and “A” type(s) of climate?

ANSWER In the “A” Tropical Humid climates, the hot, humid conditions and high rainfall support luxuriant growth. The tropical wet (Af) areas have tropical evergreen (rainforest) vegetation with a dense canopy and very large biodiversity. The tropical wet and dry (Aw) areas, with a longer dry season, have deciduous forests and tree-scattered grasslands (savanna). In the “C” Warm temperate (mid-latitude) climates, found between about 30° and 50° latitude with warm summers and mild winters, the vegetation is more varied. The humid subtropical (Cfa/Cwa) areas have temperate forests and grasslands; the Mediterranean (Cs) areas, with hot dry summers and mild rainy winters, have drought-resistant evergreen scrub, shrubs and trees (Mediterranean / sclerophyll vegetation); and the marine west coast (Cfb) areas, with rain throughout the year, support mixed and deciduous temperate forests. Overall, A climates carry rich tropical forests, while C climates carry temperate forests, grasslands and Mediterranean scrub.

(iii) What do you understand by the term “Greenhouse Gases”? Make a list of greenhouse gases.

ANSWER Greenhouse gases (GHGs) are the gases in the atmosphere that absorb the long-wave (terrestrial) radiation emitted upward by the Earth’s surface, instead of letting it escape to space. By trapping this heat they warm the lower atmosphere — a process called the greenhouse effect. The effectiveness of any GHG depends on the increase in its concentration, how long it stays in the atmosphere, and the wavelength of radiation it absorbs. The primary greenhouse gases of concern today are: 1. Carbon dioxide (CO2) — the largest concentration, mainly from fossil-fuel combustion and deforestation. 2. Chlorofluorocarbons (CFCs) — highly effective, also responsible for ozone depletion. 3. Methane (CH4). 4. Nitrous oxide (N2O). 5. Ozone (O3). Other gases such as nitric oxide (NO) and carbon monoxide (CO) react with GHGs and affect their concentration in the atmosphere.

Project Work

Collect information about Kyoto declaration related to global climate changes.

ANSWER · GUIDANCE This is a project activity, so prepare a short report in your own words. Key points to include about the Kyoto Protocol (Kyoto declaration): • It was an international agreement proclaimed in 1997 at Kyoto, Japan, to reduce the emission of greenhouse gases into the atmosphere. • It went into effect in 2005 after being ratified by 141 nations. • It bound 35 industrialised countries to reduce their emissions by the year 2012 to 5 per cent less than the levels prevalent in 1990. • Add the aim (limiting global warming), the idea of common but differentiated responsibility, India’s position, and later steps such as the Paris Agreement (2015) and the International Solar Alliance to make your report current and complete.

Extra Practice Questions

Short Answer Type Questions

Q1. Name the three broad approaches used for classifying climate.

ANSWERThe three broad approaches are empirical (based on observed temperature and precipitation data), genetic (organising climates by their causes) and applied (designed for a specific purpose).

Q2. On what basis are Koeppen’s five major groups divided — how many on temperature and how many on precipitation?

ANSWERKoeppen recognised five major climatic groups. Four of them (A, C, D, E) are based on temperature, and one (B – Dry climates) is based on precipitation.

Q3. What do the small letters f, m, w and s stand for in Koeppen’s scheme?

ANSWERThey indicate the seasonality of precipitation: f = no dry season, m = monsoon climate (short dry season), w = winter dry season, and s = summer dry season.

Q4. What is the greenhouse effect?

ANSWERThe greenhouse effect is the warming of the lower atmosphere that occurs because greenhouse gases let in short-wave solar radiation but absorb most of the long-wave radiation re-emitted by the Earth’s surface, trapping heat — just as glass keeps a greenhouse warm.

Q5. Name any two terrestrial causes of climate change.

ANSWERTwo terrestrial causes are volcanism (volcanic eruptions throw aerosols into the atmosphere that reduce incoming solar radiation) and the anthropogenic (human) increase in greenhouse gases, mainly from fossil-fuel burning and deforestation.

Long Answer Type Questions

Q1. Describe the main characteristics of the Mediterranean (Cs) climate.

ANSWERThe Mediterranean climate (Cs) occurs around the Mediterranean Sea and along the west coasts of continents in subtropical latitudes between about 30° and 40° — for example, central California, central Chile, and south-eastern and south-western Australia. These regions come under the influence of the subtropical high in summer and the westerly winds in winter. Hence the climate is marked by a hot, dry summer and a mild, rainy winter. The monthly average temperature in summer is around 25°C and in winter below 10°C, while annual precipitation ranges between about 35 and 90 cm. Because of the summer drought, the natural vegetation is drought-resistant evergreen scrub and shrubs, and the region is well known for fruit cultivation such as citrus, olives and grapes.

Q2. Explain the astronomical causes of climate change.

ANSWERAstronomical causes of climate change relate to changes in the amount of solar energy the Earth receives. The first is the change in solar output associated with sunspot activity. Sunspots are dark, cooler patches on the sun that increase and decrease in a cyclical manner; some meteorologists believe that more sunspots bring cooler, wetter and stormier weather, while fewer sunspots bring warmer, drier conditions, though these findings are not statistically significant. The second is the Milankovitch oscillations — cycles in the variations of the Earth’s orbital characteristics around the sun, the wobbling of the Earth, and changes in the Earth’s axial tilt. All these alter the amount of insolation received from the sun at different latitudes and seasons, which in turn can have a bearing on the climate over long periods of time.

Q3. What is global warming? Discuss its causes and possible consequences.

ANSWERGlobal warming is the increasing trend in the Earth’s near-surface temperature. The annual average near-surface air temperature of the world is about 14°C, and a clear warming trend was discernible through the 20th century — the globally averaged temperature at the end of the century was about 0.6°C above that at the end of the 19th century, with 1998 the warmest year recorded. The main cause is the rising concentration of greenhouse gases — chiefly carbon dioxide from fossil-fuel combustion and deforestation, along with CFCs, methane, nitrous oxide and ozone — which intensify the greenhouse effect and trap more heat. The likely consequences include a rise in sea level due to the melting of glaciers and ice caps and the thermal expansion of sea water, which may inundate low-lying coastal areas and islands and create serious social problems. Once global warming sets in, it is difficult to reverse, so international efforts such as the Kyoto Protocol have been initiated to reduce GHG emissions and leave a liveable world for future generations.

MCQs & Assertion–Reason

1. The most widely used empirical climate classification was developed by:

(a) Thornthwaite    (b) V. Koeppen    (c) Trewartha    (d) Stamp

2. In Koeppen’s scheme, the capital letter “B” stands for:

(a) Tropical climates    (b) Dry climates    (c) Cold climates    (d) Warm temperate climates

3. The small letter “w” in Koeppen’s scheme indicates:

(a) no dry season    (b) monsoon climate    (c) winter dry season    (d) summer dry season

4. The letter code “BWh” refers to a:

(a) low-latitude (subtropical) desert    (b) mid-latitude steppe    (c) tundra    (d) Mediterranean climate

5. The highest shade temperature of 58°C was recorded at:

(a) Death Valley, USA    (b) Al Aziziyah, Libya    (c) Jacobabad, Pakistan    (d) Timbuktu, Mali

6. The largest concentration of greenhouse gas in the atmosphere is:

(a) methane    (b) ozone    (c) carbon dioxide    (d) nitrous oxide

7. Europe witnessed the “Little Ice Age” from about:

(a) 1300 to 1500    (b) 1550 to 1850    (c) 1885 to 1940    (d) 1940 to 1990

8. The Kyoto Protocol was proclaimed in the year:

(a) 1990    (b) 1992    (c) 1997    (d) 2005

9. The depletion of stratospheric ozone, largest over Antarctica, is caused mainly by:

(a) carbon dioxide    (b) methane    (c) chlorofluorocarbons (CFCs)    (d) nitric oxide

10. Milankovitch oscillations refer to variations in the Earth’s:

(a) volcanic activity    (b) sunspot numbers    (c) orbit, wobble and axial tilt    (d) ocean currents

Answer key: 1-(b), 2-(b), 3-(c), 4-(a), 5-(b), 6-(c), 7-(b), 8-(c), 9-(c), 10-(c).

For each Assertion–Reason question, choose: (A) Both true and the Reason correctly explains the Assertion; (B) Both true but the Reason is not the correct explanation; (C) Assertion true, Reason false; (D) Assertion false, Reason true.

A-R 1. Assertion: Koeppen’s classification of climate is empirical.

Reason: It is based on observed data of temperature and precipitation and their relationship with vegetation.

A-R 2. Assertion: The capital letters A, C, D and E in Koeppen’s scheme delineate humid climates.

Reason: The capital letter B delineates the dry climates where potential evaporation exceeds precipitation.

A-R 3. Assertion: Tropical wet (Af) climate has a very low annual range of temperature.

Reason: It lies near the equator where the sun is nearly overhead throughout the year.

A-R 4. Assertion: Carbon dioxide is the only greenhouse gas in the atmosphere.

Reason: Greenhouse gases absorb long-wave radiation emitted by the Earth’s surface.

A-R 5. Assertion: Volcanic eruptions can cool the Earth for some years.

Reason: Eruptions throw aerosols into the atmosphere that reduce the sun’s radiation reaching the Earth’s surface.

Answer key: 1-(A), 2-(B), 3-(A), 4-(D), 5-(A).

Exam Tips & Common Mistakes

How to score full marks in this chapter

Memorise the five Koeppen groups (A, B, C, D, E) with their exact temperature/precipitation definitions from Table 11.1, and remember that four are temperature-based and only B is precipitation-based. Learn the meaning of the small letters (f, m, w, s and a, b, c, d; S and W for dry climates) so you can decode codes like Af, Am, Aw, BSh, BWh, Cfa, Cs, Cfb, Df, Dw, ET and EF. For climate-change questions, organise causes neatly into astronomical (sunspots, Milankovitch oscillations) and terrestrial (volcanism, anthropogenic GHGs), and keep key facts ready — 1998 warmest year, Kyoto Protocol 1997/2005, ozone hole over Antarctica, 58°C at Al Aziziyah.

Common mistakes to avoid

  • Thinking all five Koeppen groups are based on temperature — B (Dry) is based on precipitation.
  • Confusing the seasonality letters — w = winter dry, s = summer dry, f = no dry season, m = monsoon.
  • Saying there is a group “F” — Koeppen has only A, B, C, D and E (EF is a type within group E).
  • Mixing up empirical (observed data) with genetic (causes) classification.
  • Writing that CO2 is the only greenhouse gas — CFCs, methane, nitrous oxide and ozone are also GHGs.
  • Confusing astronomical causes (sunspots, Milankovitch) with terrestrial causes (volcanism, human GHGs) of climate change.

Frequently Asked Questions

What is Chapter 11 of Class 11 Geography (Fundamentals of Physical Geography) about?

Chapter 11, World Climate and Climate Change, explains the three approaches to classifying climate (empirical, genetic, applied), describes Koeppen’s empirical scheme with its five groups (A, B, C, D, E) and types, and discusses climate change — its evidence, astronomical and terrestrial causes, the greenhouse effect, global warming, greenhouse gases, ozone depletion and the Kyoto Protocol.

What are the five major climatic groups in Koeppen’s classification?

Koeppen recognised five major groups: A – Tropical, B – Dry, C – Warm temperate (mid-latitude), D – Cold snow-forest, and E – Cold (polar). Four of them (A, C, D, E) are based on temperature and one (B) on precipitation.

What are greenhouse gases according to this chapter?

Greenhouse gases are gases that absorb the long-wave radiation emitted by the Earth’s surface and warm the lower atmosphere. The primary GHGs of concern are carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4), nitrous oxide (N2O) and ozone (O3).

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