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;
- 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.
- 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.