Heat Waves

WHY IN NEWS:

• As per India Meteorological Department (IMD) the heat wave conditions in Central India in summer of 2021 were occasional and also for shorter periods over very small pockets. The major reason for fewer heat waves is that we are experiencing La Nina conditions this year.

DEFINITION:

• 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 and South Central parts of India.
• Heat waves typically occur between March and June, and in some rare cases even extend till July.
• Heat wave is considered if maximum temperature of a station reaches at least 40⁰C or more for Plains and at least 30⁰C or more for Hilly regions.
  • (a) Based on Departure from Normal
    • Heat Wave: Departure from normal is 4.5⁰C to 6.4⁰C
    • Severe Heat Wave: Departure from normal is >6.4⁰C
  • (b) Based on Actual Maximum Temperature
    • Heat Wave: When actual maximum temperature ≥ 45⁰C
    • Severe Heat Wave: When actual maximum temperature ≥47⁰C
• If above criteria met at least in 2 stations in a Meteorological sub-division for at least two consecutive days and it declared on the second day.

VULNERABILITIES:

• Globally:
  • As per World Meteorological Report, 2018 >> 2015-2018 have been 4 warmest year on record
  • World Meteorological Organization (WMO) statements suggests that Heat-waves are projected to increase in number, intensity and duration over the most land area in the 21^st century
  • IPCC 5^th Assessment report pointed out that number of warm days and nights increased on global scale between 1951 and 2010
• India:
  • Since 2004, India has experienced 11 of its 15 warmest recorded years.
  • Year 2015 saw one of the world's five deadliest heat waves on record (more than 2,300 deaths).
  • India is particularly vulnerable to extreme heat due to low per capita income, social inequality and heavy reliance on agriculture.

CAUSES OF HEAT WAVES:

• Climate Change:
  • Climate change is driving global temperature higher and increasing the frequency and severity of heat waves.
  • According to IPCC special report >> global warming of 1.5⁰ C- 2.5⁰C will worsen the situation
• El Nino and La Nina:
  • El Nino can result in bad monsoons >> which means less evaporation of water from vegetation and soil.
• Shifting jet streams
  • In 2010, South-Western strip of Russia was devastated by a very severe heat wave.
  • A strong upper-atmospheric high located over European Russia diverted the meandering Sub-Tropical Jet Stream farther north than usual.
  • Desert heat from central Asia, the Arabian Peninsula and North Africa began to flow northward into Russia.
• Hot local winds like Loo
  • Loo is a hot wind that originates in the desert regions of Iran, Pakistan and Thar Desert and blows eastwards into the Indian plain region in the months of May and June, usually in the afternoons.
  • Its temperature invariably ranges between 45°C and 50°C and causes severe heat waves in the plain region.
• Anthropogenic causes:
  • Deforestation and increased constructed area:
    • Reduced level of evapotranspiration due to rise of concrete jungles and urban sprawls >> leads to Urban Heat Islands effect.
  • Pollution:
    • High pollution levels and high concentration of GHGs like CO2 (thermal power plants and vehicles) >> GHGs, aerosols, particulate matter are good at absorbing outgoing infrared radiation (long wave radiation).
  • Maladaptation:
    • Land use change, widespread installation of air conditioning, degraded agriculture practices etc.

NDMA GUIDELINES

• Establish Early Warning System and Inter-Agency Coordination
  • To alert residents on predicted high and extreme temperatures.
  • Early warning systems can also enhance the preparedness of decision-makers and their readiness to harness favorable weather conditions.
• Capacity building or training programme:
  • For health care professionals at 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 NGOs 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 Heat wave conditions.
• Appointing a State nodal agency and officer:
  • The State should appoint a nodal officer at State or district levels to oversee Heat Action Plan
• Vulnerability assessment and establishing heat-health threshold temperatures:
  • It is important to identify vulnerable areas and populations in order to establish priorities and minimum thresholds for heat alert and activities  
• City level measures
  • Identification of factors leading to disproportionate increase in temperature within city
  • Generating a heat wave risk and vulnerability map
  • Mapping hot-spots within city
  • Adhering to building codes in the city

IMPACTS OF HEAT WAVES:

• Ecological impact
  • Increase the risk of disasters:
    • Exacerbates already existing risks disasters like droughts and forest fires.
  • Loss of biodiversity:
    • Heat waves increases the risk of loss of wildlife habitat and loss of biodiversity.
• Economic Impact
  • GDP loss:
    • Heat waves resulted in a total of nearly USD 60 billion in damage globally in 2018.
  • Threat to agricultural and allied sector:
    • Combined heat waves and drought can lead soil to dry out and cause severe harvest failures.
    • Heat waves also led to deaths of poultry, cattle etc.
  • Loss of work hours:
    • India would lose 5.8% of its working hours due to heat stress, equivalent to 34 million full time jobs (ILO).
• Social Impact:
  • Called as Silent Disaster:
    • It develops slowly and kills and injures humans and animals.
  • Increased mortality:
    • 24,000 deaths between from 1992-2015 (NDMA report)
    • However due to efforts from various stakeholders mortality due to heat waves reduced from 2040 in 2015 to 25 in 2018
  • Reduced productivity:
    • Due to physiological stress, sometimes leading to illness & death.
  • Affects public order:
    • May create resource crunch >> leads to riots and lack of trusts in government machinery
  • Disruption in community infrastructure
    • For ex: Power supply, Public transport, etc.

BEST PRACTICE:

• Heat wave Action Plan of Ahmedabad:
  • Ahmedabad was among the first city to prepare Heat wave Action Plan.
  • This plan provides a framework for other Indian cities to emulate and help protect their citizens from the extreme heat.
  • The key lesson learnt from Ahmedabad Heat Wave Action Plan:
    • Recognize Heat Wave as a major Health Risk.
    • Map out the 'High Risk' Communities.
    • Setting up of 'Public Cooling Places'.
    • Issue Heat wave alerts through different media.

PRACTICE QUESTION:

Q. What are heat waves? Explain the exacerbating factors contributing to the increased frequency and intensity of heat waves