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The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35 ℃. Which of the following statements best reflect(s) the implication of the above-said report? I. Peninsular India will most likely suffer from flooding, tropical cyclones and droughts. II. The survival of animals including humans will be affected as shedding of their body heat through perspiration becomes difficult. Select the correct answer using the code given below.
Explanation
The correct answer is option B (II only).
Wet-bulb temperatures above 35°C represent a critical threshold beyond which the human body cannot survive for more than[1] a few hours, as even fit and acclimatized young people cannot withstand such[2] conditions. At these temperatures, bodies become unable to cool themselves through sweating, thus increasing the risk of fatal heatstroke.[3] Therefore, Statement II correctly reflects the implication of the World Bank warning.
However, Statement I is incorrect because wet-bulb temperature exceeding 35°C is specifically related to heat and humidity combinations that impair thermoregulation. While climate change projections do indicate temperature increases of 3-5°C in various parts of India and a potential 50% increase in tropical cyclone frequency by the end of the 21st century[4], these are separate consequences of general climate change, not direct implications of the wet-bulb temperature threshold. The wet-bulb warning specifically addresses human survivability under extreme heat-humidity conditions, not flooding or cyclone patterns.
Sources- [1] https://www.undp.org/sites/g/files/zskgke326/files/2025-09/58590_lac_hdr_uk_web.pdf
- [2] https://documents1.worldbank.org/curated/en/099062325172010940/pdf/P500641-44dd85ad-548c-4043-acf4-abcd02a81147.pdf
- [3] https://www.livemint.com/mint-lounge/business-of-life/explained-is-india-at-risk-of-wet-bulb-temperatures-111680173072716.html
- [4] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > consequences of climate change in India > p. 17
PROVENANCE & STUDY PATTERN
Full viewThis is a classic 'Hybrid' question: Statement I is static Geography (Majid Husain) while Statement II is Applied Science from Current Affairs. You didn't need to read the specific World Bank report; you needed to understand the *definition* of wet-bulb temperature (physics of sweating) and the general climate vulnerability of Peninsular India.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Statement 1: Does the World Bank warning that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C indicate that Peninsular India is likely to experience increased flooding, tropical cyclones, and droughts?
- Statement 2: Does the World Bank warning that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C indicate that survival of humans and other animals would be threatened because sweating/perspiration would no longer effectively shed body heat?
- Reports projected warming in Peninsular India (3–4°C by end of 21st century).
- Explicitly links warming to more violent/stormy weather and an approximate 50% rise in tropical cyclone frequency.
- Identifies tropical cyclones and heavy precipitation as primary meteorological causes of floods.
- Specifies cloudbursts and intense rainfall (including from cyclones) as drivers of flood events.
- Notes Peninsular rivers are generally seasonal, causing scarcity in dry months.
- Explains that the same regions can experience floods during rains and drought in dry months, indicating vulnerability to both extremes.
- Explicitly states the 35°C wet-bulb threshold as the limit beyond which the human body cannot survive for more than a few hours.
- Directly links wet-bulb temperature to the body's inability to cool by sweating in prolonged hot-humid conditions.
- Specifically says that if wet-bulb were to be above 35°C, bodies would be unable to cool themselves through sweating.
- Connects that failure of sweating to increased risk of fatal heatstroke, matching the claim about threatened survival.
- Presents laboratory research showing wet-bulb combinations in the 31–35°C range exceed what even fit, acclimatized people can withstand.
- Notes that at high humidity, air temperatures as low as 35°C can result in theoretically unlivable heat, supporting the survival threat.
Describes the wet-bulb thermometer and explains that evaporation from a wet wick produces cooling when air is not saturated — linking wet-bulb readings to the air’s capacity to evaporatively cool.
A student can combine this with the definition of wet-bulb temperature (measure of evaporative cooling potential) to infer that very high wet-bulb values mean little or no evaporative cooling is possible.
States that under excessive heat and high humidity people perspire profusely and suffer physical handicaps and weakened resistance — linking heat+humidity to impaired human performance.
A student could extend this by noting that if humidity prevents evaporation of sweat, perspiration won’t cool people effectively, increasing heat stress.
Gives concrete regional temperatures (day temperatures of 35°C common in central India) showing that high dry-bulb temperatures already occur in India.
Combined with a map and humid coastal/monsoon regions, a student could judge where high wet-bulb values are likely if humidity is also high.
Describes seasonal high temperatures across Indian regions (38–45°C common in March–May), showing temporal and spatial patterns of heat exposure.
A student could use this to identify seasons/areas where heat+humidity overlap, increasing chances of extreme wet-bulb values that undermine evaporative cooling.
Notes that climate change may lead to more heat waves and affect fauna, implying increased frequency/intensity of extreme heat events.
A student could combine this with regional temperature and humidity trends to assess whether conditions conducive to dangerously high wet-bulb readings could become more common.
- [THE VERDICT]: **Doable Hybrid**. Statement I is standard text (Majid Husain, Ch 7 & 4). Statement II is conceptual science frequently discussed in climate news (The Hindu/LiveMint explainers).
- [THE CONCEPTUAL TRIGGER]: **Climate Extremes & Human Physiology**. The shift in UPSC from asking about 'Global Warming' (rising temps) to 'Heat Stress' (Temperature + Humidity limits).
- [THE HORIZONTAL EXPANSION]: 1. **Wet-Bulb vs. Heat Index**: Wet-bulb measures evaporative cooling potential; Heat Index measures 'feels like' temp. 2. **The 35°C Threshold**: At 35°C Wet-Bulb, the air is saturated at body temperature; sweat cannot evaporate, leading to hyperthermia. 3. **Peninsular Vulnerability**: High dependence on seasonal rivers (drought risk) + long coastline (cyclone risk) + urban heat islands (flood risk). 4. **IMD Heat Wave Criteria**: Max Temp ≥40°C (Plains) or departure of 4.5°C+.
- [THE STRATEGIC METACOGNITION]: When a question cites a report (World Bank/IPCC), ignore the report title and analyze the **scientific mechanism**. Ask: 'What physically happens at high wet-bulb temps?' (Sweating fails). 'Is Peninsular India immune to extremes?' (No, it has coasts and rain-shadows). The report is just a hook; the science is the key.
Higher regional temperatures increase the likelihood and intensity of tropical cyclones.
High-yield for questions on climate change impacts and disaster risk: links temperature rise to cyclone frequency and coastal vulnerability; connects to coastal management, early warning, and adaptation policy discussions.
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > consequences of climate change in India > p. 17
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 4: Climate of India > Origin of Tropical Cyclones > p. 28
Heavy rainfall, cloudbursts and cyclones are primary meteorological causes of floods.
Essential for disaster management and geography questions: explains flood causation, helps evaluate mitigation measures (drainage, forecasting), and links hydrology to extreme-weather policy responses.
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 4: Climate of India > Causes of Floods > p. 46
Seasonal rivers and unequal rainfall make Peninsular India prone to both floods in wet months and droughts in dry months.
Useful for policymaking and resource-management questions: informs understanding of inter-basin transfer ideas, national water grid, and planning for alternating water extremes.
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 3: The Drainage System of India > NATIONAL WATER GRID > p. 41
- INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 6: Natural Hazards and Disasters > Drought Prone Areas in India > p. 64
Evaporation from a wet surface produces cooling; when air is saturated evaporation (and thus evaporative cooling) is prevented.
High-yield for questions on human thermal comfort, heat stress, and instrumentation that links temperature and humidity. Connects basic thermodynamics to climate-health impacts and helps analyze claims about thresholds where evaporative cooling fails.
- Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > Notes > p. 120
Excessive heat combined with high humidity leads to profuse perspiration, reduced vigor, and risks such as sunstroke and weakened disease resistance.
Important for environment and health topics—links climate extremes to public health, labour productivity, and vulnerability assessments. Useful for essay and mains answers on climate change impacts on human wellbeing.
- Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 15: The Hot, Wet Equatorial Climate > Factors Affecting the Development of Equatorial Regions > p. 154
Large parts of India regularly experience very high daytime temperatures (e.g., 35–45°C) during the hot season, creating potential for dangerous heat–humidity combinations.
Core geographic knowledge for UPSC: underpins arguments about regional vulnerability to heat waves, agricultural stress, and health impacts. Enables evidence-based discussion of climate risk in India and policy responses.
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > The Hot Dry Season (March To Mid-June) > p. 432
- CONTEMPORARY INDIA-I ,Geography, Class IX . NCERT(Revised ed 2025) > Chapter 4: Climate > The Hot Weather Season (Summer) > p. 30
The Arabian Sea Anomaly. While Statement I mentions general cyclone increase, the specific 'Shadow Trend' is the rapid warming of the Arabian Sea, causing a higher percentage increase in cyclones there compared to the Bay of Bengal (historically the active basin). Expect a comparison question on 'Cyclone frequency: BoB vs. Arabian Sea'.
Apply 'Physiological Logic' to Statement II. Why do we measure 'Wet-Bulb' instead of just temperature? Because it accounts for humidity/evaporation. If high wet-bulb didn't affect perspiration (evaporation), the metric would be useless. Therefore, Statement II *must* be true by the very definition of the term.
GS3 Economy & Disaster Management: Wet-bulb > 30°C drastically reduces **Labor Productivity** (outdoor work becomes fatal). This links Climate Change directly to **GDP Loss** and the necessity for 'Heat Action Plans' (HAPs) in urban planning, moving beyond just 'health' to 'economic survival'.