Growing Impact of Heatwaves in India Introduction 

• India is increasingly grappling with the rising threat of heatwaves, which have become longer, more intense, and more frequent in recent years.
•  The India Meteorological Department (IMD) has raised concerns about another year of extreme heat, with cities like Delhi recording the hottest February in 74 years and Mumbai facing multiple heatwaves before mid-March. 
• As the intensity of heatwaves continues to escalate, it is essential to understand their impacts, the government’s actions, and the necessary steps moving forward to minimize these extreme conditions and their effects on public health, the economy, and the environment.

What Are Heatwaves and How Are They Defined in India?

• • A heatwave is defined as a prolonged period of excessively hot weather that can cause serious health risks, damage the environment, and disrupt economic activities. In India, the India Meteorological Department (IMD) defines heatwaves based on specific criteria, which are essential in understanding and managing heat-related risks.

• Criteria for Heatwaves in India:

• Physiography of Regions:
  • Plains: A heatwave is declared when the maximum temperature recorded at a station reaches 40°C or more.
  • Coastal Areas: A heatwave is declared when the maximum temperature recorded at a station is 37°C or more.
  • Hills: A heatwave is declared when the maximum temperature recorded at a station is 30°C or more.
• Based on Departure from Normal Temperature:
  • Heat Wave: When the temperature departure from normal is between 4.5°C to 6.4°C.
  • Severe Heat Wave: When the temperature departure from normal is greater than 6.4°C.
• Based on Actual Maximum Temperature:
  • Heat Wave: When the actual maximum temperature reaches ≥ 45°C.
  • Severe Heat Wave: When the actual maximum temperature reaches ≥ 47°C.
• A heatwave is declared if these criteria are met in at least two stations in a meteorological subdivision for at least two consecutive days.

What is the Current Status of Heatwaves in India? 

• India has been experiencing intense heatwaves for decades, but in recent years, these events have become more frequent and severe, with significant impacts on human health and the environment. 
• Regions Most Affected by Heatwaves: Rajasthan, Gujarat, Uttar Pradesh, Delhi, Haryana, Punjab, and Madhya Pradesh are among the states that have been hit hardest by heatwaves. These areas experience extreme heat during the summer months, with temperatures often exceeding 45°C for several consecutive days.

The Growing Impacts of Heatwaves in India

• Impact on Human Health: Heatwaves are particularly dangerous for vulnerable populations such as the elderly, children, and those with chronic illnesses. Rapid increases in temperature can compromise the body’s ability to regulate its temperature, leading to various heat-related illnesses, including:

• • • Heat cramps: Painful muscle spasms due to dehydration.
    • Heat exhaustion: Fatigue, dizziness, nausea, and heavy sweating.
    • Heatstroke: A life-threatening condition where the body temperature rises above 40°C, causing potential organ failure.
    • Hyperthermia: Excessive heat that disrupts bodily functions.

• Impact on Energy Systems: Heatwaves lead to a significant increase in electricity demand as people use more cooling devices (e.g., air conditioners, fans). This results in power grid strain and potential blackouts. In Delhi in 2019, the temperature rose above 45°C, and electricity demand surged by 30%, causing widespread power outages and affecting daily life.

• Impact on the Economy: Heatwaves disrupt economic activities, particularly in sectors like agriculture, construction, and manual labor. The demand for cooling (which can be expensive and inconsistent) and the reduction in work productivity due to extreme temperatures hurt worker productivity. According to a 2015 ILO study, at 34°C, workers can lose up to 50% of their productivity.

• Agricultural productivity in Uttar Pradesh and Madhya Pradesh saw a 15% decline during the 2016 heatwave, as farmers struggled with both extreme temperatures and water scarcity.

• Impact on Water Resources: Heatwaves exacerbate water scarcity by drying up water bodies and lowering the groundwater table. This intensifies competition for water resources, particularly in regions that rely heavily on groundwater for agriculture and drinking water.

• • • In 2016, the Cauvery water dispute between Tamil Nadu and Karnataka worsened during a severe heatwave, as both states faced water shortages, which increased tensions over water allocation.

• Impact on Food Security: Heatwaves contribute to droughts, crop failure, and reduced agricultural output, thus worsening food security. The demand for irrigation increases, straining available water resources.

• The 2015 heatwave significantly impacted Maharashtra’s agricultural output, with wheat and pulses production declining sharply, leading to food price hikes and shortages in local markets.

Key Factors Causing Heatwaves in India

• • Natural Causes of Heatwaves in India: Heatwaves in India are driven by both natural and human-induced factors, with several natural causes playing a significant role in the frequency and intensity of these extreme events. 

• High Atmospheric Pressure Systems: High atmospheric pressure systems are one of the primary natural causes of heatwaves. These systems trap warm air near the Earth’s surface and prevent the normal circulation of air masses. This leads to prolonged hot weather in regions affected by such systems, particularly during the summer months.

• Climate Variability: Climate variability, particularly natural climate phenomena such as El Niño and La Niña, plays a crucial role in shaping weather patterns across India. For instance, during El Niño events, warmer ocean temperatures in the Pacific Ocean disrupt atmospheric circulation, leading to hotter and drier conditions over much of the Indian subcontinent. These changes can cause increased frequency and intensity of heatwaves.

• Drought and Dry Conditions: Prolonged drought and dry conditions significantly exacerbate heatwaves. The absence of rainfall and moisture in the soil leads to quicker heating of the land during heatwaves, further intensifying the high temperatures. Areas with reduced moisture tend to experience much higher temperatures, as dry land heats up faster than moist soil.

• Changes in Wind Patterns: Shifts in wind patterns are another natural cause of heatwaves. These shifts can transport hot air from regions that typically do not experience extreme temperatures, intensifying heatwaves in areas that are not accustomed to such conditions. Changes in wind direction and strength are often linked to global climate shifts and the widening of atmospheric systems.

• Geography and Topography: Geographic features and topographical conditions can also contribute to heatwaves. Regions that are surrounded by mountains or are landlocked tend to trap hot air, leading to localized heat islands. These areas can experience significant temperature spikes compared to other regions.  Jaipur and parts of Churu in Rajasthan are examples of landlocked valleys that often trap hot air, resulting in temperatures that exceed 47°C during heatwaves. The mountainous terrain and lack of breeze contribute to these extreme conditions, causing intense heat for extended periods.

Human-Induced Causes of Heatwaves in India

• • While natural causes contribute significantly to heatwaves, human activities, particularly global warming and urbanization, have intensified the frequency and severity of these extreme weather events. Below are the main human-induced causes:

• Global Warming: Global warming, primarily driven by human activities such as burning fossil fuels, deforestation, and industrial emissions, has significantly increased global temperatures. This long-term rise in Earth’s average temperature contributes to more frequent and intense heatwaves in India, as the global atmospheric system continues to warm.

• • • Example: Rajasthan, Uttar Pradesh, and Gujarat have experienced steadily rising average temperatures over the past few decades. For instance, Rajasthan’s capital, Jaipur, has seen a rise of 1.2°C in average temperatures from 1980 to 2010, leading to an increase in heatwave days. As a result, heatwaves have become more frequent and prolonged in these regions.

• Urban Heat Island Effect: Urbanization has exacerbated heatwaves, particularly in highly populated cities like Delhi, Mumbai, and Bangalore. The urban heat island effect occurs when urban areas experience higher temperatures than their rural surroundings due to factors such as extensive concrete, asphalt surfaces, and limited vegetation. These surfaces absorb and retain more heat, resulting in localized zones of higher temperatures.

• • Example: In Delhi, temperatures can be 5-7°C higher than in surrounding rural areas due to the urban heat island effect. During June 2019, Delhi experienced a record-high temperature of 48°C, partly due to the dense concrete infrastructure and lack of green spaces in the city. This phenomenon not only makes heatwaves more intense but also increases energy consumption due to higher demand for air conditioning and cooling.

Government Actions to Address Heatwaves

• Heat Action Plans: The government has developed Heat Action Plans across 23 states to improve heatwave preparedness. These plans involve early warnings, emergency response measures, and public health initiatives to help reduce the impact of heatwaves on human health and infrastructure.

• • • Example: Ahmedabad has been a pioneer in implementing heat action plans, and since the plan’s launch in 2013, the city has reduced heat-related deaths by 30%.

• Public Health Preparedness: The Union Ministry of Health periodically reviews heat-related illness preparedness, ensuring hospitals and healthcare workers are ready to respond swiftly to heat emergencies, such as heatstroke and dehydration.

• • • Example: The National Centre for Disease Control (NCDC) has provided guidelines for healthcare workers on handling heatstroke cases and preventing heat-related illnesses.

• Focus on Vulnerable Groups: The government prioritizes vulnerable populations, including children, pregnant women, the elderly, and individuals with chronic illnesses, by providing them with specific heat protection measures and public health initiatives.

• • • Example: During the 2019 heatwave, special cooling centers and water distribution points were set up in Delhi and Madhya Pradesh to protect vulnerable groups.

• Awareness Campaigns: Around 100 districts have initiated public awareness campaigns to educate citizens about the risks of heatwaves and provide guidance on heatwave safety measures such as hydration, appropriate clothing, and avoiding the sun.

• • Example: Bihar launched a statewide campaign to educate the public about the importance of drinking fluids and staying cool during extreme heat, reaching over 1 million people.

What Should Be the Way Forward?

• Effective Implementation of Heatwave Action Plans: States must play a leading role in effectively implementing heatwave action plans, working with other stakeholders such as local authorities, NGOs, and health professionals to ensure timely responses to heat-related risks.

• Sustainable Cooling Solutions: India must prioritize sustainable cooling solutions such as passive cooling technologies, including ventilated buildings, cool roofs, and the use of environmentally-friendly materials like porotherm bricks in construction. These solutions will help mitigate the urban heat island effect in cities. Delhi is focusing on promoting green rooftops in urban housing to combat the rising temperatures caused by urbanization.

• Heatwave Mitigation Plans: Comprehensive heatwave mitigation plans must include access to safe drinking water, oral rehydration solutions (ORS), shade structures in public spaces, and flexible working hours in workplaces, particularly in sectors like construction and agriculture.

• Creation of More Green Spaces: Increasing urban greenery and tree plantation efforts can help reduce urban temperatures. According to the United Nations, investing US$ 100 million in street trees globally can reduce urban temperatures by 1°C.  The Haritha Haram project of the Telangana government aims to increase the green cover from 24% to 33%, which will help mitigate the effects of heatwaves in the state.

• Adoption of Energy-Efficient Solutions: Encouraging the use of energy-efficient cooling solutions, such as desert coolers in dry areas, can significantly reduce energy consumption and alleviate the strain on power grids during heatwaves. The Gujarat Energy Development Agency (GEDA) promotes the use of desert coolers in rural and semi-urban areas to reduce dependence on air conditioning, thereby improving energy efficiency.