The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C. 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.
Contents13
- AI only
- BII only
- CBoth I and II
- DNeither I nor II
Show answer
Answer: (C) Both I and II
The wet-bulb temperature is a measure that combines heat AND humidity.
At a wet-bulb temperature of 35°C, the human body can no longer cool itself through sweat evaporation because the air is too saturated with moisture — this makes it potentially lethal for humans and animals.
(I) 'Peninsular India will suffer from flooding, tropical cyclones and droughts' — CORRECT.
The same warming patterns that cause extreme wet-bulb temperatures are associated with broader climate disruptions in peninsular India:
- intensified monsoons leading to flooding,
- warmer sea surface temperatures fueling more powerful cyclones,
- and irregular rainfall patterns causing droughts in some regions.
These are all documented implications of the warming trend that the World Bank report highlights. ✓
(II) 'Survival of animals including humans affected as perspiration becomes difficult' — CORRECT.
This is the core danger of wet-bulb temperatures exceeding 35°C.
At this threshold, even a healthy person resting in shade with unlimited water will die within hours because sweat cannot evaporate effectively when humidity is too high.
The body continues to produce heat through metabolism but cannot shed it, leading to hyperthermia and organ failure.
This affects all mammals and many other animals that rely on evaporative cooling. ✓
Both statements correctly reflect the implications. Answer is (c).
Wet-bulb temperature of 35°C is the physiological threshold where human death becomes inevitable within hours, even for healthy people in shade with water.
The World Bank's 2022-2023 climate reports highlighted South Asia, particularly India's Indo-Gangetic plains and coastal areas, as approaching this deadly threshold due to combined heat and humidity extremes.
UPSC is testing whether students understand that wet-bulb temperature measures the combined effect of heat AND humidity, not just temperature alone.
Wet-Bulb Temperature & Heat Index
Environment wet-bulb temperatures 35°C
Wet-Bulb Temperature: The Lethal Heat-Humidity Combination
Wet-bulb temperature combines air temperature and humidity into a single lethal heat stress measure
35°C wet-bulb = death threshold where human body cannot cool itself through sweating
India's humid coastal regions and river valleys most vulnerable to crossing this threshold
Even healthy humans die within 6 hours at 35°C wet-bulb despite unlimited water and shade
Wet-bulb temperature measures the coolest temperature achievable through water evaporation — it combines both heat AND humidity. Unlike regular temperature, wet-bulb temperature determines whether mammals can survive because it directly measures evaporative cooling potential.
Temperature Types Comparison
Measure | What It Shows | Critical Threshold | Key Point |
|---|---|---|---|
Dry-bulb (regular) | Air temperature only | 50°C+ survivable | Ignores humidity |
Wet-bulb | Heat + humidity combined | 35°C = lethal | Evaporation limit |
Heat Index | Feels-like temperature | 54°C dangerous | Human perception |
Why 35°C Wet-Bulb Kills
Sweat evaporation is the only way mammals shed excess body heat when air temperature exceeds body temperature
At 35°C wet-bulb, air is so saturated with moisture that sweat cannot evaporate effectively
Body continues producing metabolic heat but cannot release it, causing fatal hyperthermia
Even young, healthy humans in shade with unlimited water die within 6 hours
Air conditioning becomes literally life-saving, not just comfort
This directly answers the PYQ: Statement II is correct because perspiration becomes ineffective at 35°C wet-bulb, threatening survival of humans and animals. The World Bank warned that India's humid coastal areas and Indo-Gangetic Plain could regularly cross this threshold.
Trap: Confusing wet-bulb with regular temperature — 35°C wet-bulb is far more dangerous than 35°C air temperature
Trap: Thinking air conditioning is just comfort — at wet-bulb 35°C, it's literally life-saving technology
Trap: Assuming young/healthy people are safe — wet-bulb threshold kills regardless of fitness level
Climate Change Impacts on India
Environment India flooding tropical cyclones droughts
Climate Change Impacts on Peninsular & Coastal India
Peninsular India faces triple threat: flooding, cyclones, and droughts from same warming trend
Warmer sea surface temperatures fuel more intense cyclones in Arabian Sea and Bay of Bengal
Irregular monsoons cause both flooding during heavy spells and droughts during weak periods
Coastal regions most vulnerable to wet-bulb temperature crossings due to high humidity
The same warming patterns that push wet-bulb temperatures toward dangerous thresholds also drive broader climate disruptions across peninsular India. These impacts are interconnected, not separate phenomena.
Climate Impacts on Indian Regions
Impact | Primary Regions | Climate Driver | Recent Examples |
|---|---|---|---|
Flooding | Western Ghats, Eastern coast | Intensified monsoon rainfall | Kerala 2018, Mumbai floods |
Tropical Cyclones | Eastern & Western coasts | Warmer sea surface temps | Amphan, Tauktae intensity |
Droughts | Deccan Plateau, Maharashtra | Irregular monsoon patterns | Marathwada crisis |
Wet-bulb extremes | Humid coastal areas, IGP | Heat + humidity combination | Jacobabad crossing 35°C |
Interconnected Climate Mechanisms
Sea surface warming increases cyclone intensity and frequency along both Indian coasts
Monsoon disruption creates extreme rainfall variability — heavy downpours alternating with dry spells
Urban heat islands in coastal cities amplify wet-bulb temperatures beyond regional averages
Agricultural stress from droughts reduces crop yields, affecting food security
This explains PYQ Statement I: Peninsular India will suffer flooding, cyclones, and droughts — all correct implications of the warming trend that also drives dangerous wet-bulb temperatures. The World Bank report connects these regional climate risks.
Vulnerable Regions
Source: LinkedIn — Climate Change Impacts India's Regions Differently | Aarathi ... · www.linkedin.com
Trap: Thinking climate impacts are separate — flooding, cyclones, droughts are interconnected effects of same warming trend
Trap: Focusing only on temperature — humidity makes coastal India more vulnerable than inland areas at same temperature
Trap: Missing regional specificity — Peninsular India particularly vulnerable due to coastal exposure and monsoon dependence
Human Thermoregulation & Climate Limits
Science And Technology perspiration body heat survival
How Climate Change Overwhelms Human Cooling Systems
Perspiration (sweating) is the primary cooling mechanism when air temperature exceeds body temperature
Evaporative cooling fails when humidity prevents sweat evaporation, causing fatal heat buildup
All mammals including humans face same physiological limits at extreme wet-bulb temperatures
Metabolic heat production cannot be stopped, making cooling failure rapidly lethal
Heat Stress Progression
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Body Temperature Rises**
Core temp exceeds **37°C** normal range`"]
s2["`**Sweating Activates**
Body produces sweat for **evaporative cooling**`"]
s3["`**High Humidity Blocks Evaporation**
Sweat cannot evaporate at **35°C wet-bulb**`"]
s4["`**Heat Accumulates**
**Metabolic heat** continues without cooling`"]
s5["`**Hyperthermia & Death**
Organ failure within **6 hours**`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5Cooling Mechanisms & Climate Limits
Cooling Method | How It Works | Climate Limitation | Failure Point |
|---|---|---|---|
Radiation | Body radiates heat to environment | Air temp > body temp | Above 37°C air |
Convection | Air movement carries heat away | Still air, humidity | No wind + high humidity |
Evaporation | Sweat evaporation cools skin | High humidity blocks it | 35°C wet-bulb |
Conduction | Direct contact with cool surfaces | All surfaces hot | Heat waves affect all surfaces |
Why Animals Are Also Affected
All mammals rely on similar evaporative cooling through panting or sweating
Livestock particularly vulnerable as they cannot seek artificial cooling like humans can
Wildlife in humid regions face population stress as heat refuge areas shrink
Urban animals face additional heat from concrete and reduced vegetation
This biological reality explains PYQ Statement II: survival of animals including humans affected as perspiration becomes difficult. The 35°C wet-bulb threshold represents a fundamental physiological limit that no amount of fitness, acclimatization, or water can overcome.
Trap: Thinking acclimatization helps — 35°C wet-bulb kills regardless of adaptation to local climate
Trap: Assuming water solves the problem — unlimited water cannot overcome evaporation failure
Trap: Missing animal vulnerability — mammals and birds face same physiological limits as humans
World Bank Climate Risk Assessments
World Affairs (International Relations) World Bank warned
World Bank's Role in Climate Risk Assessment & Adaptation
World Bank produces detailed climate risk assessments for developing countries including India
Wet-bulb temperature projections part of broader climate adaptation planning and development finance
Reports focus on economic development impacts, not just environmental consequences
The World Bank produces comprehensive climate risk assessments as part of its development mandate. These reports guide adaptation financing and help countries prepare for climate impacts that could undermine economic progress.
World Bank Climate Work
Climate Change Action Plan commits to align all financing with Paris Agreement goals
Turn Down the Heat report series specifically warned about South Asia heat extremes
Adaptation financing helps countries build resilience to unavoidable climate impacts
Economic modeling quantifies GDP losses from climate impacts like extreme heat
The wet-bulb temperature warning for India reflects the Bank's focus on development implications of climate change — extreme heat threatens economic productivity, public health systems, and poverty reduction efforts in developing countries.
Trap: Confusing World Bank with IPCC or other climate bodies — World Bank focuses on development finance angle
Trap: Missing the economic focus — World Bank warnings emphasize poverty and development impacts, not just environmental science