India's rising temperatures, urban heat islands, and El Niño's impact on monsoons
India is experiencing increasing heatwave conditions, with a long-term trend of rising heatwave frequency and duration, particularly with night-time temperatures rising faster than daytime. The article clarifies that claims of all 50 hottest cities being in India in April should be viewed with caution, as such rankings often rely on specific datasets and single-day observations. It explains urban heat islands, where concrete surfaces absorb and release heat, making cities hotter than rural areas, exacerbated by air-conditioning. El Niño is expected to heighten the risk of hotter, drier monsoon seasons, potentially leading to more humid heatwaves and affecting agricultural output.
Key Points
- India is facing a long-term trend of increasing heatwave frequency and duration, with night-time temperatures rising faster than daytime.
- Claims about India hosting all the world's hottest cities need careful scrutiny, as they often depend on specific data sources and short-term observations.
- Urban heat islands are created when natural landscapes are replaced by concrete and asphalt, causing cities to absorb and slowly release heat, making them significantly warmer.
- Air-conditioning exacerbates urban heat islands by expelling heat outdoors, further contributing to higher city temperatures.
- The emerging El Niño phenomenon is likely to lead to a hotter and drier monsoon season, increasing the risk of heatwaves and 'break' spells.
Exam Facts
- IMD (India Meteorological Department) outlook.
- Core Heatwave Zone (CHZ) study (1961–2020) found heatwave frequency rising 0.1 days/decade and duration 0.44 days/decade.
- Nights warmed faster than days (0.21°C/decade).
- Urban warming in Indian cities: 0.53°C/decade vs. national average 0.26°C/decade (Nature Cities 2024 study).
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