Current Affairs · · GS1 · Geography

Semi-arid zone grows in northwest India; study links shift to Pacific pattern

An IMD analysis finds India's hot semi-arid steppe zone grew from about 24% of the country in 1951–80 to 33% in 1991–2020. It links falling rainfall over north India to a sea-temperature pattern in the North Pacific called the Victoria Mode. The finding points to remote ocean influences on India's climate beyond El Niño.

Event date:

REq1
  1. Note1 / 5

    WHY IN NEWS?

    • A study by India Meteorological Department scientists, presented at a WMO workshop hosted by IITM Pune, mapped India's Köppen climate zones over five 30-year periods.
    • The hot semi-arid steppe zone expanded from about 24.2% (1951–80) to 33.1% (1991–2020).
    • The tropical savannah zone in the east is reported to have shrunk.
    • The study links lower rainfall over north India to the negative phase of the North Pacific's Victoria Mode.
  2. Note2 / 5

    HOW INDIA'S CLIMATE ZONES SHIFTED

    The table shows IMD's figures for two arid zones, as a share of India's area.

    Climate zone (% of area)1951–801971–20001991–2020
    Hot semi-arid steppe24.227.633.1
    Arid desert13.815.213.8

    The steppe grew steadily, while the true desert stayed about the same size.

  3. Note3 / 5

    KEY CONCEPTS

    1. What is the Köppen classification?

    It divides climates by temperature and rainfall. India has six broad types, from tropical monsoon on the Malabar coast to arid desert in the Thar.

    1. What is a semi-arid steppe?

    It is a dry climate with some rain, too little for forests but enough for grasses and dryland crops. Large parts of Rajasthan, Gujarat and the Deccan fall in it.

    1. What is the Victoria Mode?

    It is a pattern of warm and cool sea temperatures in the North Pacific, separate from the Pacific Decadal Oscillation. Its negative phase is linked to weaker moisture flow over north India.

    1. What is the Pacific Decadal Oscillation?

    It is a long-lasting shift in North Pacific sea temperatures, changing over decades. It can strengthen or soften El Niño's effects.

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    WHY IT MATTERS

    • Farming: A drier northwest strains rain-fed crops and groundwater.
    • Water: Lower rainfall reduces recharge in already stressed aquifers.
    • Forecasting: Tracking North Pacific patterns could improve long-range monsoon forecasts.
    • Livelihoods: Expanding dry zones may push migration from rural areas.
    • Caution: Rising temperatures also raise evaporation, so not all drying is due to the Pacific.
  5. Note5 / 5

    WAY FORWARD

    These are suggested measures, not approved policy.

    • Improve models by adding North Pacific patterns to monsoon forecasts.
    • Shift crops towards millets and drought-tolerant varieties in drying areas.
    • Conserve water through watershed development and groundwater recharge.
    • Plan locally with district-level adaptation strategies.

Sources

Syllabus

PaperSubjectSub-topic
GS1GeographyIndian monsoon, climatic regions, geophysical phenomena
GS3EnvironmentClimate change, agriculture, water security
PrelimsGeographyKöppen classification, PDO, Victoria Mode, ENSO

Topics

Agriculture and EnvironmentWorld Map-Based GeographyPhysics

Practice questions

  1. In the Köppen classification, the climate of much of western Rajasthan's Thar region is:

    1. Tropical monsoon
    2. Arid desert
    3. Temperate
    4. Tropical savannah
    Show answer

    Answer: B. The surrounding areas form a semi-arid steppe belt.

    Difficulty: medium · statement

  2. The Victoria Mode is a pattern of sea surface temperature variability in the:

    1. Indian Ocean
    2. North Pacific
    3. North Atlantic
    4. Southern Ocean
    Show answer

    Answer: B. It is distinct from the Pacific Decadal Oscillation.

    Difficulty: medium · statement

  3. Consider the following statements: 1. The Pacific Decadal Oscillation changes over decades. 2. ENSO cycles typically last two to seven years. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both
    4. Neither
    Show answer

    Answer: C. The PDO is slower than ENSO.

    Difficulty: medium · statement

Mains practice

Answer-writing practice on this article. Attempt it first, then open the hints.

  1. GS1 · 150 words

    Climate zones in India are shifting, with semi-arid areas expanding. Discuss the drivers and the implications for agriculture and water security.

    Show hints
    1. Köppen zones
    2. rainfall decline
    3. warming and evaporation
    4. remote ocean patterns
    5. crop shifts, groundwater.