Heatwaves warnings

Heat waves, characterised by unusually high temperatures, pose significant health risks, including heat cramps, exhaustion, and potentially fatal heat strokes. Nearly 90% of India falls within a "danger zone" from heatwave impacts. The IMD classifies heat waves based on departure from normal temperatures, with severe heat waves declared at temperatures exceeding 45°C. Factors contributing to heat waves include weather patterns, anthropological events like deforestation and industrial pollution, rising sea temperatures, and El Nino events. NDMA guidelines emphasize early warning systems, vulnerability assessments, and inter-agency emergency response plans. The Heat Index, introduced by IMD, assesses apparent temperature and indicates heat stress levels, aiding in heat-related illness prevention

Status in India and Worldwide:

• A study in PLOS Climate indicates that nearly 90% of India falls within a "danger zone" from heatwave impacts.
• According to National Crime Records Bureau data, over 11,000 individuals died from heatstroke between 2012 and 2021.
• Extreme heat waves were observed in various parts of the Northern Hemisphere, including the Southwest US, Mexico, Southern Europe, and China in July 2023.

• Heat waves are periods of unusually high temperatures exceeding the normal maximum during the summer season, leading to physiological stress and sometimes fatalities among affected populations.
• Heatwaves are recognized when the maximum temperature of a station reaches at least 40°C for Plains and 30°C for Hilly regions. A heat wave cannot be declared if the normal maximum temperature of a station is less than or equal to 40°C.

• For normal maximum temperatures up to 40°C,
  • A departure from normal of 5°C to 6°C signifies a Heat Wave and
  • A departure of 7°C or more indicates a Severe Heat Wave.
• For normal maximum temperatures exceeding 40°C,
  • A departure from normal of 4°C to 5°C is classified as a Heat Wave, and
  • A departure of 6°C or more is a Severe Heat Wave.
• A Heat Wave is declared when the actual maximum temperature remains 45°C or higher, regardless of the normal maximum temperature.

• Weather Factors, such as the upper air anticyclone over Rajasthan and Gujarat transporting hot, dry desert air to regions like Madhya Pradesh, Andhra Pradesh, Telangana, and Odisha.
• Anthropological events like deforestation, urban heat-island effect, and industrial pollution also contribute to heat waves.
• Rising sea temperatures, particularly in the Indian Ocean, may reduce moisture over the Indian mainland, leading to prolonged hot spells.
• El Nino events have been linked to an increase in heat waves as well

Reasons why it is formed >

• Albedo Effect of Concrete Houses: Concrete structures have a higher albedo, reflecting more terrestrial radiation compared to soil and green cover. This contributes to the trapping of heat by greenhouse gases, leading to a rise in temperature in urban areas.
• Pollution Impact: Greenhouse gases, sulfur and nitrogen oxides, and aerosols from various sources, especially coal-based power plants near urban areas, absorb infrared radiation, exacerbating heat retention in the atmosphere.
• Heat Release at Night: Urban surfaces made of materials like metal and asphalt have high heat storage capacity, releasing stored heat rapidly at night. Additionally, their impermeable nature mimics desert landscapes, exacerbating heat retention.
• Impact on Airflow and Heat Loss Haphazard building structures disrupt natural wind flow, reducing heat loss through horizontal movement. This interruption in airflow contributes to further heat retention in urban areas.
• Human Activities and Heat Generation Human activities, particularly electricity and fossil fuel consumption, release a significant amount of heat, further contributing to urban heat islands.

• Heat waves have detrimental effects on human health, including:
  • Heat Cramps: Characterized by swelling and fainting, often accompanied by fever below 39 degrees Celsius (102 degrees F).
  • Heat Exhaustion: Manifests as fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps, and excessive sweating.
  • Heat Stroke: Occurs when body temperatures reach 40 degrees Celsius (104 degrees F), potentially resulting in fatalities.
• Urban Heat island : Heatwaves contribute to the formation of urban heat islands, which are characterized by elevated temperatures in urban areas compared to their surrounding rural area.

• Implementing an Early Warning System to forecast high temperatures and impending heat waves, enabling people to take precautions.
• Developing a Heat Action Plan at the state level with input from relevant stakeholders, including government leaders, health agencies, disaster management authorities, and local partners.
• Appointing State Nodal Agency and District level Officers to oversee the Heat Action Plan.
• Conducting Vulnerability Assessment exercises to identify at-risk areas, establish thresholds for heat alerts, and prioritize activities.
• Establishing an inter-agency emergency response plan with clear roles and responsibilities for each agency.
• Evaluating the efficacy of the heat action plan annually after the heat wave cycle and updating it based on stakeholder feedback.
• A training initiative designed for local healthcare professionals to identify and manage heat-related health issues.

• The Heat Index has been launched by the India Meteorological Department (IMD).
• This index considers both
  • 96259-21993,
  • 93132-18122

  • 96259-21993,
  • 93132-18122

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