Notably, the national capital witnessed one of its most intense heatwave conditions during this summer season, with the mercury feeling like it was touching 50 degrees Celsius.
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Why is India getting hotter? Science behind rising heat stress, humidity and climate change – EXPLAINED | Image: AI
Why Is India Getting Hotter? After facing scorching summer heat for weeks, residents of Delhi and the adjoining National Capital Region (NCR) are going to witness rain and thunderstorms as the southwest monsoon, which has already reached several states, is expected to hit the region by July 4. However, the capital city witnessed its warmest morning in two years on Sunday amid the delayed monsoon season.
Why Is Delhi Reeling Under Extreme Heat Stress
Notably, the national capital witnessed one of its most intense heat wasve conditions during this summer season, with the mercury reaching 50 degrees Celsius. The month of June also recorded its warmest night in two years. Increasing humidity, longer heatwaves and unpredictable weather across the country are making extreme heat, even before the monsoon fully sets in.
The summery heat is expected to continue its movement over some more parts of Uttar Pradesh, Uttarakhand, Himachal Pradesh, Ladakh and southeast Rajasthan for the next three days.
What’s Fueling Delhi’s Heat Stress?
- Global Climate Change: Heat wave conditions are becoming more prevalent as climate change progresses.
- The Urban Heat Island (UHI) Effect: The urban areas in the capital city can be 8 degrees Celsius hotter than the rural regions. This phenomenon is expected to surge 9 degrees Celsius by 2050.
- Loss of Natural Cooling Sinks: We all know that the loss of greenery and water increases the heat and reduces the region’s ability to cool itself through natural shading and evaporation
- Dense Built Environment and Poor Design: It is also evident that closely packed buildings, poor ventilation and inadequate shade are increasing the city’s heat.
- Interaction with Air Pollution: Air pollution is also a main reason of reinforcing heat in the capital city.
How Climate Change And Urbanisation Are Fueling Extreme Heat?
- Compounding Effects: Climate changes due to urbanisation, growing infrastructure and higher CO2 emissions is worsening the heat.
- Regional Trends: Global cities have reported a surge of approx. 1.12 percent in cooling demand in the last 20 years.
- Increased Duration: Rising mercury in the city means air conditioning is needed for longer periods. If we talk about Indian cities, several now need cooling for around 273 days a year.
Humidity Plays A Major Role?
- Perceived Temperature: Humidity is a major factor when it comes to heat as it influences thermal comfort through latent heat.
- Regional Variation: Eastern coastal Indian cities require the highest cooling demand (2514 ± 224 °C-year) due high overall temperatures and high humidity.
Urbanisation And Volumetric Growth
It is not a secret that rapid urbanisation is making cities hotter in several ways, including Delhi. The construction of taller buildings reduces airflow, which traps more heat.
In major cities like Delhi and Kolkata, limited land has led to vertical growth and dense development. Green spaces are replaced by roads and concrete structures. These absorb and trap more heat. The growing use of air conditioners also plays a major role as it releases waste heat into the environment.
Why Nights Becoming Warmer In Delhi, Other Cities?
- The Urban Heat Island Effect: Urbanisation significantly increases temperatures, making cities around 60 percent hotter than non-urban areas.
- Atmospheric Conditions and “Heat Domes”: Massive atmospheric patterns play a vital role in trapping heat.
- Pollution and Humidity: During the day pollution sometimes blocks sunlight and high water vapour content, acting as a greenhouse gas.
How Extreme Heat Is Affecting India
- Physiological Stress: Extended hours of daytime and nighttime temperatures create physiological stress.
- Heat-Related Illnesses: Overexposure can lead to illnesses, including heatstroke and hyperthermia.
- Vulnerable Populations: Elderly, minor kids and outdoor workers are majorly affected.
- Crop Yield Failures: Crops like rice and wheat are highly sensitive to intense heat and thermal thresholds.
- Physiological Damage: Mercury above 35 degrees Celsius can cause temperature failure points in plants. This can lead to sterile pollen, aborted embryos with reduced nutritional value.
- Livestock Stress: Intense heat can cause reduced appetite in cattle and poultry. Poultry mortality can also spike to eight times the regular average.
