Recently, over 37 cities in the northern and central regions experienced temperatures exceeding 45°C, posing severe risks to millions of vulnerable people.
About Heatwaves
Heatwaves are a period of unusually high temperatures as compared to what is normally expected over a region.
Therefore, the temperatures at which Heatwaves are declared differ from place to place based on the temperature, and climatology of that region.
Factors contributing to Heatwave: Meteorological and climatic factors as well as Anthropogenic factors such as Rapid Urbanization and Human-induced Global Warming.
Other declarations by IMD:
Marine Heatwaves (MHW): It is defined when seawater temperatures exceed a seasonally-varying threshold (usually the 90th percentile) for at least 5 consecutive days.
MHWs have increased by up to four-fold in the tropical Indian Ocean, aided by rapid warming in the Indian Ocean and strong El Niños.
A warm night: It’s declared only when the maximum temperature remains 40°C or more. It is defined based on departures of actual minimum temperatures as follows:
Warm night: minimum temperature departure is 4.5°C to 6.4°C
Very warm night: minimum temperature departure is >6.4°C.
Hot and Humid Weather: When observed maximum temperatures over any station remains 3°C above normal along with the above normal relative humidity, it is termed as Hot & Humid Weather over that station.
Effects of Heat waves
On Human Health
Heat Cramps: Ederna (swelling) and Syncope (Fainting) generally accompanied by fever below 102oF.
Heat Exhaustion and Heat Stoke: Body temperatures of 104oF or more along with delirium, seizures or coma.
According to the IMD, between 2000 and 2020, over 10 thousand people lost their lives to heat waves.
On Environment
Increases the energy demand due to the usage of cooling appliances.
Wildfires and Droughts: Heat waves trigger and exacerbate droughts and wildfires.
Worsens air quality and pollution: Heat waves, compounded by wildfires and desert dust, can lead to measurable worsening air quality in a region
Soil Moisture Depletion: High temperatures cause the soil moisture to evaporate rapidly which also impacts plant growth and overall soil health.
On Economy and Society
Loss in productivity: As per the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) study, India is expected to lose around 5.8% of daily working hours due to rising temperatures by 2030.
Induces migration: As the effects of heat waves directly affect the vulnerable sections of the society they are forced to migrate from one region to the other.
Affects crop productivity and livestock: The temperature rise directly affects the yield of the plants and life stocks adding distress to overall food security.
Initiatives taken to mitigate heat waves
National Guidelines on Heat Wave Management: Developed by NDMA to guide states and other stake holders on heat wave management.
Action taken by IMD-
Early Warning System and inter agency co-ordination: IMD Communicate Heatwave alerts/warnings promptly.
Heat Action Plans: Started by IMD in collaboration with NDMA and local health departments in around 23 states that are prone to heat waves.
Rescheduling Working hours: Centre has issued advisory to states to reschedule the working hours for workers and labourers across sectors to save them from health hazards.
Way forward: Mitigation measures that can be taken
Providing cool shelters: Similar to cyclone and disaster relief centres, public cooling centres can be built where people can go to cool off during extreme heat.
The concept has been explored in Barcelona, Paris and Rotterdam among others.
Improving the built environment: By making them more heat-resilient through the incorporation of better insulation and ventilation systems in buildings, planting more trees etc.
Utilising indigenous knowledge: Usage of indigenous protective methods against heat waves and strokes must be tapped, documented, and researched.
Inclusion of regulative provisions: For example, making it mandatory for components like passive ventilation and cool roof technologies in the Building bylaws to increase thermal comfort.
Capacity building for health care professionals: at the local level to recognize and respond to heat-related illnesses.
