CLAT GurukulSamudraManthan

Topic 230 · Answers

AMOC slowdown and India's monsoon

All 10 answers, each with its Book 1 RATNA fact. Try the questions first

  1. Question 1Answer A

    A Bordeaux/CNRS study published on 15 April 2026 projected AMOC weakening of how much by 2100?

    • Correct answer: 51 ± 8%
    • 71 ± 8%
    • 25 ± 5%
    • 35 ± 10%

    Core Trigger: A Bordeaux/CNRS study in Science Advances, published 15 April 2026, projected AMOC weakening of 51 ± 8% by 2100.From Book 1 RATNA, topic 230, point 1

  2. Question 2Answer B

    How many authors does the study 'Observational constraints project a ~50% AMOC weakening by the end of this century' have?

    • Nine
    • Correct answer: Four
    • Two
    • Six

    Study Title: 'Observational constraints project a ~50% AMOC weakening by the end of this century'; four authors.From Book 1 RATNA, topic 230, point 2

  3. Question 3Answer A

    Who is the lead author of the study?

    • Correct answer: Valentin Portmann
    • Niklas Boers
    • Jonathan Bamber
    • Stefan Rahmstorf

    Lead Author: Valentin Portmann of the EPOC laboratory, University of Bordeaux/CNRS, France.From Book 1 RATNA, topic 230, point 3

  4. Question 4Answer C

    One sverdrup, the unit of AMOC strength, equals how much water per second?

    • Ten thousand cubic metres
    • A billion cubic metres
    • Correct answer: A million cubic metres
    • A thousand cubic metres

    Unit: AMOC strength is measured in sverdrups; one equals a million cubic metres of water per second.From Book 1 RATNA, topic 230, point 4

  5. Question 5Answer D

    Under SSP2-4.5, CMIP6 models give what AMOC weakening?

    • 60 ± 20%
    • 12 ± 7%
    • 22 ± 17%
    • Correct answer: 32 ± 37%

    Data / Report: The 51% estimate spans about 43–59%, 60% above the model average; CMIP6 models give 32 ± 37% under SSP2-4.5.From Book 1 RATNA, topic 230, point 5

  6. Question 6Answer B

    Consider: 1) IPCC AR6 projects that AMOC will strengthen this century. 2) Nimmakanti Mahendra led a separate AGU Advances monsoon study. Which is/are correct?

    • Only 1
    • Correct answer: Only 2
    • Both 1 and 2
    • Neither

    Stakeholders: IPCC AR6 projects AMOC decline this century; Nimmakanti Mahendra led a separate AGU Advances monsoon study.From Book 1 RATNA, topic 230, point 6

  7. Question 7Answer A

    At which latitude does the RAPID array measure the AMOC?

    • Correct answer: 26.5°N
    • 16.5°N
    • 6.5°N
    • 46.5°N

    Monitoring Site: The RAPID array at 26.5°N, between the Bahamas and Canary Islands, measures the AMOC.From Book 1 RATNA, topic 230, point 8

  8. Question 8Answer D

    Since which year has the RAPID array recorded the AMOC?

    • 2012
    • 1998
    • 1992
    • Correct answer: 2004

    Measured Since: RAPID has recorded the AMOC since 2004; it averaged 15–17 Sv in 2011–2020, down from 18–19 Sv in 2004–08.From Book 1 RATNA, topic 230, point 9

  9. Question 9Answer B

    Meltwater and heavier rain freshen the North Atlantic, so surface water does what?

    • Evaporates faster
    • Correct answer: Sinks less easily
    • Freezes sooner
    • Sinks faster

    Mechanism: Meltwater and heavier rain freshen the North Atlantic, so water sinks less easily and the AMOC slows.From Book 1 RATNA, topic 230, point 10

  10. Question 10Answer C

    Consider: 1) SSP2-4.5 is the intermediate IPCC emissions scenario used for CMIP6 projections. 2) A tipping point is a threshold beyond which change may not reverse. Which is/are correct?

    • Only 1
    • Only 2
    • Correct answer: Both 1 and 2
    • Neither

    Scenario: SSP2-4.5 is the intermediate IPCC emissions scenario used for CMIP6 projections.From Book 1 RATNA, topic 230, point 11

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