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Heat Wave Disaster Management in India

Description: Managing Heat Waves in India: Causes, Impacts, and Key Strategies. Explore the causes and impacts of heat waves in India and discover crucial strategies for disaster management and public safety.

A Heat Wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India. Heat Waves typically occur between March and June, and in some rare cases even extend till July. The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

The Indian Meteorological Department (IMD) has given the following criteria for Heat Waves:

•  Heat Wave need not be considered till maximum temperature of a station reaches atleast 400C for Plains and atleast 300C for Hilly regions

•  When normal maximum temperature of a station is less than or equal to 40*C Heat Wave Departure from normal is 50C to 60C Severe Heat Wave Departure from normal is 70C or more. 

•  When normal maximum temperature of a station is more than 400C Heat Wave Departure from normal is 40C to 50C Severe Heat Wave Departure from normal is 60C or more

•  When actual maximum temperature remains 450C or more irrespective of normal maximum temperature, heat waves should be declared. 

The World Meteorological Organization (WMO) identifies a heat wave ‘when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 50oC, the normal period being 1961-90.

Causes of Heat waves

•  High Atmospheric pressure: A heat wave occurs when a system of high atmospheric pressure moves into an area. In such a high-pressure system, air from the upper levels of our atmosphere is compressed. This high concentration of pressure makes it difficult for other weather systems to move into the area, which is why a heat wave can last for several days or weeks. The high pressure inhibits winds and also prevents clouds from entering the region, which in turn leads to heating up the area even more. 

•  Weakening of Jet stream: Another important factor in the formation of heat waves is the location of the jet streams. Jet streams are narrow, fast-flowing air currents near the tropopause formed by the earth’s rotation and atmospheric heating. During a heat wave, a jet stream lies above an affected area disallowing transported polar air mass to cool the area. Heat waves are also seasonally bound because of a slower, meandering jet stream during summertime. Jet streams are formed by changes in temperature between colliding Arctic and tropical air masses, which are weaker during summer causing it to slow down. A slower jet stream causes less change in weather patterns, therefore increasing stationary weather conditions explaining why heat waves occur during summer.

•  Weakening of monsoon: The heat wave intensities are linked to sparser pre-monsoon season rain showers in many areas, as there has been much less moisture than normal of that area, leaving large parts of India arid and dry. The sudden end of pre-monsoon rain showers, thus contribute to the heat waves. This weather pattern, coupled with the El Niño effect, which often increases temperatures in Asia, combined to create record-high temperatures.

•  Urban heat Island: Landscapes with surfaces that hold heat can amplify the effect of a heat wave. Building materials are usually very good at insulating, or holding in heat. This insulation makes the areas around buildings warmer. Displacing trees and vegetation minimizes the natural cooling effects of shading and evaporation of water from soil and leaves (evapotranspiration). Tall buildings and narrow streets can heat air trapped between them and reduce airflow. Waste heat from vehicles, factories, and air conditioners may add warmth to their surroundings, further exacerbating the heat island effect. This exacerbates the impact of heat waves.

•  Global Warming: Global warming boosts the probability of extreme weather events, like heat waves. 

Impact of Heat waves

a)  On Human Health

•  Direct health impacts include cardiac arrest, heat stroke, and dehydration, while secondary impacts can include gastroenteritis and organ damage as a result of dehydration.

•  Human bodies operate at a core temperature of 37°C. As human beings produce heat during daily activities, the heat is released through sweating to maintain a steady core body temperature. If core body temperature rises to 38°C for several hours, heat exhaustion occurs, and mental and physical capacity becomes impaired or may lead to death. 

•  Heatwaves also cause specific heat-related illnesses such as heat cramps, heat rash, heat oedema (swelling, usually in the ankles), heat syncope (dizziness and fainting due to dehydration), and heat exhaustion which can lead to potentially fatal heatstroke.

b)  On Economy:

•  Increased heat and extreme heatwaves can impact on the performance of infrastructure. 

For example, due to heatwave:

o  transport failed, particularly trains, partly because of the buckling of rail lines 

o  air-conditioning system may fail

o  Critical infrastructures such as drinking water and electricity systems may fail under high demand, with power cuts greatly magnifying the number of people at risk.

•  The Intergovernmental Panel on Climate Change (IPCC) records in its 5th Assessment Report that the work output of the global economy would fall by as much as 20% by the end of the century in the event of a 4 degrees Celsius warming of the planet, with the most damaging impact being felt in the tropics, especially South Asia.

•  Crop loss is encountered due to flower drop and higher mortality in new plantations.  Kharif crops are more impactful. Within Kharif, particularly rice production is significantly affected by decreased grain yield.

c)  On plants and animals

•  Heat-related mass mortality in individual animal species (e.g. flying foxes) has been recorded

•  Plants can die following extreme heat events, with some species more vulnerable than others. The long-term outcomes of such events include changes in species assemblages, extinction of the most vulnerable species, and increased forest fuel levels – with the latter being a risk factor in bushfires.

Key strategies

The heat-wave action plan is intended to mobilize individuals and communities to help protect their neighbors, friends, relatives, and themselves against avoidable health problems during spells of very hot weather. Broadcast media and alerting agencies may also find this plan useful. Severe and extended heat waves can also cause disruption to general, social and economic services. For this reason, Government agencies will have a critical role to play in preparing and responding to heat- waves at a local level, working closely with health and other related departments on long-term strategic plans.

•  Establish an Early Warning System and Inter-Agency Coordination to alert residents on predicted high and extreme temperatures. Who will do what, when, and how is made clear to individuals and units of key departments, especially for health.

•  Capacity building/training programme for health care professionals at the local level to recognize and respond to heat-related illnesses, particularly during extreme heat events. These training programmes should focus on medical officers, paramedical staff, and community health staff so that they can effectively prevent and manage heat - related medical issues to reduce mortality and morbidity.

•  Public Awareness and community outreach - Disseminating public awareness messages on how to protect against the extreme heat - wave through print, electronic, and social media and Information, Education, and Communication (IEC) materials such as pamphlets, posters and advertisements, and Television Commercials (TVCs) on Do's and Don'ts and treatment measures for heat-related illnesses.

•  Collaboration with non-government and civil society - Collaboration with non-governmental organizations and civil society organizations to improve bus stands, building temporary shelters, wherever necessary, improved water delivery systems in public areas, and other innovative measures to tackle Heatwave conditions.

Here is a link to an article on Minamata Convention: Safeguarding Health and the Environment from Mercury