Will India experience more heat wave days this summer?
How does the IMD forecast heat wave days across different regions of India? What factors contribute to India's struggle to meet power demand, and how does this relate to falling hydroelectricity output?
The story so far: he India Meteorological Department (IMD) on Monday announced aboveaverage heat wave days for India, impacting southern, central, east, and northwestern regions. The announcement comes even as India is already struggling to keep up with its power demand. A Reuters analysis reported that India’s hydroelectricity output fell at the steepest pace in at least 38 years. Hydroelectric output will remain low in the coming months, leading to a greater dependence on coal at a time when India has, in its Nationally Determined Contributions under the
Paris Agreement, promised to reduce the emissions intensity of its GDP by 45% by 2030, compared to the 2005 level.
TWhat does the forecast say?
The IMD forecast has said most of India will experience abovenormal maximum and minimum temperatures.
The El Niño event, which causes weak rainfall and more heat over India, has weakened since the beginning of the year, the forecast noted. However, moderate El Niño conditions still exist over the equatorial Pacific, increasing the sea surface temperature. The heat redistribution affects airflows above the ocean. Since the Pacific Ocean covers almost a third of the earth, changes in its temperature and changes in wind patterns can disrupt weather worldwide.
January 2024 was the warmest in 175 years, the U.S. National Oceanic and Atmospheric Administration noted. The average global land and ocean surface temperature was also higher.
The El Niño is, however, likely to weaken during the upcoming season. Some models have even predicted the possibility of La Niña conditions developing during the monsoon, which can intensify rainfall across South Asia.
What is a heat wave?
A period of abnormally high temperatures is called a heat wave. The IMD declares a heat wave if the maximum temperature of a weather station reaches at least 40 degrees C in the plains and at least 30 degrees C in hilly regions, with a departure of around 4.56.4 degrees C from the normal maximum temperature. The IMD can also declare a heat wave if the actual maximum temperature crosses 45 degrees C, and a ‘severe heat wave’ if it crosses 47 degrees C. Qualitatively, a heat wave can also occur when the temperature of the air becomes fatal to the human body.
Heat waves in India are typically recorded between March and June and tend to peak in May.
What is causing an increase in heat wave days?
A study published in the journal PLOS Climate in April 2023 found heat waves all over the world are getting more “recurrent, intense and lethal” due to climate change. Data from April 2022 used in the study also showed abnormal temperatures caused due to climate change could have a severe impact on over 90% of India.
An increase in the number of heatwave days and their intensity can exact steep costs affecting livelihoods, food production, disease spread, and more, the study noted.
Higher temperatures can affect human health by causing heat stress and even death, according to the World Health Organization.
The ongoing El Niño weather condition also contributes to higherthanusual temperatures, driving an increased occurrence of heat waves.
What measures has the EC advised to manage the impact of heat waves?
Starting on April 19, general elections will be conducted in seven phases until June 1, coinciding with India’s summer and possibly several heat waves. The Election Commission (EC) has issued an advisory to manage the impact of heat waves during voting, including carrying a water bottle and protecting oneself from direct sunlight.
The heat itself can be deadly outside a heat wave if the wet bulb temperature crosses 3035 degrees C. The wet bulb temperature is the lowest temperature to which a surface can be cooled by water evaporating from it. In other words, it’s the lowest temperature at which the surface of the skin can be cooled by sweating. Beyond this threshold, even short periods spent idling in ambient conditions can have deadly health effects.
Indian Meteorological Department predicts aboveaverage heat wave days for India, impacting multiple regions.
El Niño event weakens but contributes to warmer temperatures globally, exacerbating heat wave conditions. Climate change is cited as a key factor in the recurrence and intensity of heat waves.
General elections in India coincide with the summer season and potential heat waves, prompting the EC to issue advisories to manage the impact of heat waves during voting.