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General Studies 1 >> World Geography

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HEATWAVE

HEATWAVE

 

1. Context

Last week, the India Meteorological Department (IMD) warned that the maximum temperatures over northwest, west, and central India would be 3­5°C higher than the long­term average. On February 21, the national capital recorded its third hottest February day (33.6° C) in more than five decades.

2. What is a Heat Wave?

  • A heatwave is a period of abnormally high temperatures, a common phenomenon in India during the months of May-June and in some rare cases even extends till July.
  • Indian Meteorological Department (IMD) classifies heat waves according to regions and temperature ranges. As per IMD, the number of heatwave days in India has increased from 413 over 1981-1990 to 600 over 2011-2020.
  • This sharp rise in the number of heatwave days has resulted due to the increasing impact of climate change.
  • The last three years have been La Niña years, which has served as a precursor to 2023 likely being an El Niño year. (The El Niño is a complementary phenomenon in which warmer water spreads west­east across the equatorial Pacific Ocean.)
  • As we eagerly await the likely birth of an El Niño this year, we have already had a heat wave occur over northwest India.
  • Heat waves tend to be confined to north and northwest India in El Niño years.
 
Image Source:News18

3. How do Heat waves Occur?

  • Heat waves are formed for one of two reasons warmer air is flowing in from elsewhere or it is being produced locally.
  • It is a local phenomenon when the air is warmed by higher land surface temperature or because the air sinking down from above is compressed along the way, producing hot air near the surface.
  • First of all, in spring, India typically has air flowing in from the west­northwest. This direction of air­flow is bad news for India for several reasons.
  • Likewise, air flowing in from the northwest rolls in over the mountains of Afghanistan and Pakistan, so some of the compression also happens on the leeward side of these mountains, entering India with a bristling warmth.
  • While air flowing over the oceans is expected to bring cooler air, the Arabian Sea is warming faster than most other ocean regions.
  • Next, the strong upper atmospheric westerly winds, from the Atlantic Ocean to India during spring, control the near-surface winds.
  • Any time winds flow from the west to the east, we need to remember that the winds are blowing faster than the planet which also rotates from west to east.
  • The energy to run past the earth near the surface, against surface friction, can only come from above. This descending air compresses and warms up to generate some heat waves.

4. Impacts of heat waves in India

  • The frequent occurrence of heat waves also adversely affects different sectors of the economy.
  • For instance, the livelihood of poor and marginal farmers is negatively impacted due to the loss of working days.
  • Heatwaves also have an adverse impact on daily wage workers' productivity, impacting the economy.
  • Crop yields suffer when temperatures exceed the ideal range.
  • Farmers in Haryana, Punjab, and Uttar Pradesh have reported losses in their wheat crop in the past rabi season. Across India, wheat production could be down 6-7% due to heat waves.
  • Mortality due to heat waves occurs because of rising temperatures, lack of public awareness programs, and inadequate long-term mitigation measures.
  • According to a 2019 report by the Tata Center for Development and the University of Chicago, by 2100 annually, more than 1.5 million people will be likely to die due to extreme heat caused by climate change.
  • The increased heat wave will lead to an increase in diseases like diabetes, circulatory and respiratory conditions, as well as mental health challenges.
  • The concurrence of heat and drought events is causing crop production losses and tree mortality. The risks to health and food production will be made more severe by the sudden food production losses exacerbated by heat-induced labor productivity losses.
    These interacting impacts will increase food prices, reduce household incomes, and lead to malnutrition and climate-related deaths, especially in tropical regions.

5. How does air mass contribute to heat waves?

  • The other factors that affect the formation of heat waves are the age of the air mass and how far it has traveled.
  • The north northwestern heatwaves are typically formed with air masses that come from 800-1600 km away and are around two days old.
  • Heat waves over peninsular India on the other hand, arrive from the oceans, which are closer (around 200-400km) and are barely a day old. As a result, they are on average less intense.

6. Way ahead for Heat waves

  • Identifying heat hot spots through appropriate tracking of meteorological data and promoting timely development and implementation of local Heat Action Plans with strategic inter-agency coordination, and a response that targets the most vulnerable groups.
  • Review existing occupational health standards, labor laws, and sectoral regulations for worker safety in relation to climatic conditions.
  • Policy intervention and coordination across three sectors health, water, and power are necessary.
  • Promotion of traditional adaptation practices, such as staying indoors and wearing comfortable clothes.
  • Popularisation of simple design features such as shaded windows, underground water storage tanks, and insulating house materials.
  • Advance implementation of local Heat Action Plans, plus effective inter-agency coordination is a vital response that the government can deploy in order to protect vulnerable groups.

For Prelims & Mains

For Prelims: Heat Wave, India Meteorological Department (IMD), El Nino, Equatorial Pacific Ocean, La Nina, Malnutrition, Heat Action Plans.
For Mains: 1. Examine the various adverse impacts caused by heat waves and how India should deal with them.
 
Source: The Hindu

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