Heatwave: Causes & Impacts

North and west India are experiencing unusually early summer and heatwave conditions, as the cool winter days of February were suddenly replaced by unusually warm days in March.

About Heatwaves

A heatwave is a period of abnormally high temperatures over a region for several consecutive days, significantly higher than the normal climatic conditions.
Criterion for Declaring Heat Wave: According to the India Meteorological Department (IMD),
- A heatwave is declared when the maximum temperature reaches at least 40°C in plains, 37°C in coastal areas, and 30°C in hilly regions, and is 4.5–6.4°C above the normal temperature.
- If the temperature is more than 6.4°C above normal, it is classified as a severe heatwave.
- A heatwave may also be declared when the maximum temperature reaches 45°C or more, regardless of the normal temperature.

Current Heatwave Conditions in North India

High Temperatures: Several regions in north and west India are recording temperatures 8–13°C above normal, leading to heat-wave conditions.
Hill Regions: Even Himalayan areas like Shimla have recorded temperatures above 25°C, which is uncommon in March.
Heatwave Alerts: The India Meteorological Department (IMD) has warned of early heatwave conditions and above-normal heatwave days across several parts of the country.

Causes of Early Summer and Heatwaves

Deficient Winter Rainfall: Winter rainfall during January–February was about 60% below normal, reducing soil moisture and accelerating heating.
Weak Western Disturbances: Fewer winter disturbances reduced cloud cover, snowfall, and rainfall in north India.
Dry Soil: Lack of moisture limits evaporative cooling, causing a faster rise in surface temperatures.
Clear Skies: Reduced cloud cover allows more sunlight to heat the land surface.
Poor Wind Convergence: Weak interaction between westerly and easterly winds limited moisture transport from nearby seas.

Impact on Agriculture

Stress on Rabi Crops: High temperatures during the grain-filling stage can reduce yields of crops like wheat, mustard, and gram.
Higher Irrigation Demand: Increased evapotranspiration forces farmers to irrigate more frequently, putting pressure on groundwater and water resources.
Horticulture Crops: Crops like potatoes and apples may face reduced quality and productivity due to temperature stress.

Government Initiatives to Tackle Heatwaves in India

Heat Guidelines: The National Disaster Management Authority’s (NDMA) 2019 revised guidelines ensure preparedness, early warnings, and community outreach across states and Union Territories.
Action Plans: Over 250 cities implement Heat Action Plans (HAPs) for alerts, medical readiness, and public advisories to reduce heatwave risks.
Early Warnings: NDMA and the India Meteorological Department (IMD) provide location-based alerts and five-day lead advisories for heatwave preparedness.
Climate Missions: The National Action Plan on Climate Change (NAPCC), via its National Water and Sustainable Habitat Missions, promotes water management and urban heat mitigation.

Strategies for Heatwave Management

Heat Action Plans (HAPs): Implement early warning systems, public advisories, cooling centres, and emergency health services to reduce heat-related mortality.
Climate-Resilient Agriculture: Promote heat-tolerant crop varieties, adjust sowing dates, and adopt efficient irrigation methods like drip and sprinkler systems.
- National Action Plan on Climate Change (NAPCC) promote sustainable agriculture and water management.
Urban Heat Mitigation: Increase urban green cover, cool roofs, reflective materials, and improved city planning to reduce the urban heat island effect.
- Ahmedabad’s Cool Roof Programme lowered indoor temperatures by up to 5°C, and Telangana has introduced Cool Roof Policies (2023) for buildings.
Water Resource Management: Strengthen rainwater harvesting, groundwater recharge, and efficient irrigation practices to cope with rising water demand.
Public Awareness: Educate citizens on hydration, avoiding peak heat hours, and protecting vulnerable groups such as the elderly and outdoor workers.

Early heatwaves threaten crops and water, but as Sir David Attenborough warns, ‘The climate is changing, and we are the cause.’ Urban cooling, green cover, and climate-resilient actions ensure adaptation.

Reference: The Indian Express

PMF IAS Pathfinder for Mains – Question 585

Q. “The seasonal cycle in India is increasingly marked by weak winters and prolonged summers.” In this context, examine how deficient winter precipitation and climate variability are contributing to early heatwaves in North India and discuss their impacts. (250 Words) (15 Marks)

Approach

Introduction: Write a brief introduction about the early and intense heatwaves in North India.
Body: Write how deficient winter precipitation and climate variability are contributing to early heatwaves in North India, also mention their impacts and suggest mitigation and adaptation strategies.
Conclusion: Emphasis on sustainable mitigation and adaptation strategies for heatwave resilience.