The Rising Challenge of Warm Nights in India

WARM NIGHTS IN INDIA: THE RISING CHALLENGE

This summer, India has experienced an alarming rise in night-time temperatures, causing significant discomfort and health risks for many, especially vulnerable populations like the homeless.

Key Insights:

• Record-Breaking Temperatures: The India Meteorological Department (IMD) recorded unprecedented high minimum temperatures across the country, with places like Alwar experiencing a minimum of 37°C — the highest since records began 55 years ago.
• Consistent Highs: In Delhi, night temperatures remained 4-7°C above the average, similar to daytime temperatures, resulting in continuous heat stress.
• Health Impacts: The relentless heat has contributed to increased mortality, with 192 bodies found in public spaces in Delhi over a week in June. These deaths are attributed to the compounded effects of high day and night temperatures.

Why Are Nights Warming Faster Than Days?

• Global Trends: Research indicates a global pattern of increasing night-time temperatures. Factors include enhanced moisture in the atmosphere, which acts like a blanket, trapping heat at night more than during the day.
• Local Observations: In India, a study from the Centre for Science and Environment noted that Delhi’s average night-time temperature in May and June has significantly risen, with night-time warming more pronounced than daytime increases.

Coping and Adaptation:

• Public Awareness: The IMD has started issuing warm-night alerts, though it does not set an absolute temperature threshold, making it hard for the public to gauge the severity.
• Shelter and Aid: Observations during visits to shelter homes and settlements reveal that many are struggling to cope, with common complaints of sleeplessness and heat-related illnesses.

The Broader Impact:

• Climatic Changes: The trend of warmer nights is linked to broader climatic changes, influenced by increased carbon emissions and subsequent atmospheric changes.
• Policy Response: There is a critical need for comprehensive heat action plans that include special measures not just for winter but also for the increasingly harsh summer months.

This situation highlights the urgent need for adaptive strategies and robust policy interventions to mitigate the health risks associated with rising temperatures, particularly during the night.

IMD Definitions:

• Warm Nights: Defined by the IMD as nights when the minimum temperature is 4°C to 6.4°C above the normal (long-term average) for a location.
• Severe Warm Nights: When the increase in minimum temperature exceeds 6.4°C above normal.

These classifications are crucial for IMD to characterize and communicate the intensity of heat events during the night, particularly in contexts where the daytime maximum temperatures are also notably high, often exceeding 40°C. This systematic categorization helps in issuing targeted alerts and preparing for potential health risks associated with unusually warm night-time temperatures.