Heat Waves 2022: Definition, Causes, Impacts and Way Forward

Heat waves 2022: Relevance

• GS 1: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.,

Heat waves in India: Context

• Recently, ICAR- Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad has released a new report titled Heat Wave 2022: Causes, Impacts, and Way Forward for Indian Agriculture.

हीट वेव्स 2022: परिभाषा, कारण, प्रभाव एवं आगे की राह

What is heat wave?

• A heat wave is a prolonged period of unusually high temperatures or hot weather, as felt by the general public and scientifically defined as the occurrence of temperatures greater than normal in a certain region.

Favourable conditions for heatwave in India

• Transportation / prevalence of hot dry air over a region (There should be a region of warm dry air and appropriate flow pattern for transporting hot air over the region).
• Absence of moisture in the upper atmosphere.
• The sky should be practically cloudless.
• Large amplitude anti-cyclonic flow over the area. Heat waves generally develop over northwest India and spread gradually eastwards & southwards but not westwards (since the prevailing winds during the season are westerly to northwesterly).
• In addition, if the soil is very dry, all the solar radiation heat this, allowing the warming of the air in contact with the soil, promoting even higher temperatures.

Recent reason for recent heatwave

• Anti-cyclones over western parts of Rajasthan in March and the absence of western disturbances had triggered the early and extreme heat waves.

Impacts on agriculture

Physical impacts

• Water resources: Because of the close relationship between climate and water, heat wave intensifies the water crises in several regions, especially in arid and semi-arid areas.
• Wild/Forest fires: Heat waves account for more deaths than all other natural hazards combined in Australia.

Physiological impacts

• Crops: High temperatures beyond certain optimum level reduce plant growth. High temperature is thus one of the most important factors limiting crop production.
• Livestock: Thermal stress lowers feed intake and reduces animal productivity in terms of milk yield, body weight and reproductive performance. Moreover, heat stress reduces libido, fertility and embryonic survival in animals.
• Poultry: Heat stress interferes with the broilers comfort and suppresses productive efficiency, growth rate, feed conversion and live weight gain due to changes in behavioural, physiological and immunological responses.
• Fisheries: Increased temperature may affect the distribution pattern of some fish species where some of them may migrate to the higher latitude for cooler place. Moreover, changes in temperature will have direct effects on swimming ability.

Heat waves: Way forward

• Concerted efforts are needed to forecast such events in advance, monitor their occurrence and to understand their impacts comprehensively.
• There is a need to intensify such efforts across agriculture, horticulture, livestock, fisheries and poultry sectors in view of the impending increase in frequency and severity of such extreme events.
• There is a need to popularize the promising technologies so that they can reach large number of farmers.
• Practices related to residue management by way of machinery can be scaled through custom hiring centers, farm machinery banks and through National Submission on Agricultural Mechanization (SMAM).
• There is also a need to strengthen the weather forecasts including extreme weather events and agro-advisory services so that farmers can take informed decisions about the impending weather.

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