Searing changes – Rising average temperature and instances of heat waves in India | 2nd March 2023 | UPSC Daily Editorial Analysis

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What's the article about?

  • It talks about the rising average temperature and instances of heat waves in India.


  • GS-1: Important Geophysical Phenomena, geographical features and their location-changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes;
  • GS3: Disaster Management;
  • Prelims


  • February 2023 had been the warmest since 1901 with the average maximum temperature at nearly 29.54°C as per IMD.
  • Usually IMD considers February as  ‘spring’ and a ‘winter month’, but the minimum temperatures are also rising.
    • Average maximum temperatures were 1.73°C above normal and minimum, 0.81°C above what is usual.
  • These trends are likely to spill over into summer.
  • Heatwaves during March-May are likely over most parts of India, except for the north-east, Jammu and Kashmir, Uttarakhand, Himachal Pradesh, Kerala and coastal Karnataka.

What are heat waves?

  • Qualitatively, a heat wave is a condition of air temperature which becomes fatal to the human body when exposed.
  • Quantitatively, it is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal.

What is criterion for declaring heat wave?

  • Heat wave is considered if maximum temperature of a station reaches at least 40°C or more for Plains and at least 30°Cor more for Hilly regions.

a) Based on Departure from Normal:

  • Heat Wave: Departure from normal is 4.5°C to 6.4°C
  • Severe Heat Wave: Departure from normal is >6.4°C

b) Based on Actual Maximum Temperature:

  • Heat Wave: When actual maximum temperature ≥ 45°C
  • Severe Heat Wave: When actual maximum temperature ≥47°C

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.


Impact of rising average temperature and heat waves:

  • Decline in the yield of wheat:
    • The searing temperatures over the years have impacted the yield of wheat.
    • India produced 106.84 million tonnes of wheat in the 2021-22 crop season, less than the 109.59 million tonnes in 2020-21 season, due to a hotter than usual March that impacted the crop during its growth phase.
  • Increased uncertainty regarding the intensity of the monsoon:
    • Three of the last four years saw above normal rainfall in India primarily due to a La Niña, or cooler than usual temperatures in the Equatorial Pacific.
    • While this is expected to subside, whether it will eventually swing to an El Niño and draw moisture away from India’s coasts remains to be seen.
  • Loss of human lives:
    • A Lancet study reported a 55% rise in deaths due to extreme heat and that excessive heat also led to a loss of 167.2 billion potential labour hours among Indians in 2021.

Way Forward:

  • The interplay between local weather and climate is complex and while it is tempting to blame rising heatwave intensity as ‘climate change,’ the science continues to be uncertain.
  • This, however, should be a wake-up call to buttress public health systems and make them more responsive to the challenges from rising temperatures.
  • Several States have action plans and early warning initiatives but inadequate outreach, particularly in rural India.
  • Along with promoting newer crop varieties that mature early, there should be greater stress on aiding farmers to tweak soil and water management practices to adapt to these changes.

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