Explainer: Heatwaves and their impact on Indian economy

On Sunday, the India Meteorological Department (IMD) sounded heat wave warnings for several places in Odisha, Chhattisgarh, Karnataka, and Maharashtra. Seven districts in Jharkhand reported a temperature of above 40 degree Celsius while the Karnataka government advised the people to spend their afternoons indoors. Let’s understand these factors - what is a heat wave, how do the weathermen define heat waves and what is its impact on India in this explainer.

What is a heat wave?

Heat wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season. The temperatures at which heat waves are declared differ from place to place. Heat waves typically occur between March and June, and in some rare cases even extend till July.

How is a heat wave defined?

The IMD follows a certain criteria before declaring the unusually high temperature as a heat wave. Heat waves are not considered till the maximum temperature of a station reaches at least 40 degree Celsius for plains and at least 30 degree Celsius for hilly regions.

The weather department declares a heat wave in a certain region where the maximum temperature remains 45 degree Celsius and ‘severe’ heat wave if the mercury level is above 47 degree Celsius.

While in coastal areas, if the maximum temperature departure is 4.5 degree Celsius or more from normal and the actual maximum temperature is 37 degree Celsius or more, a heat wave alert is issued for those regions.

Impact of heat wave on Indian Economy

As India is increasingly experiencing severe heat waves, it’s impact can be felt across various sectors including health, agriculture, and the economy. According to IMD, several states may experience an intense summer this year. February was the warmest month in the country since 1901.

Health impact:

Heat waves can lead to various health-related problems such as dehydration, heat exhaustion, heatstroke and even death in extreme cases.

Last year, more than 40,000 suspected heat stroke cases and at least 110 confirmed deaths between March 1 and June 18 were reported across the country.

Economic losses:

Heat waves cause a significant impact on the agricultural sector. Severe temperature can damage crops, affect the produce and even lead to a crop failure. This will eventually disrupt the demand and supply of the food chain and as a result food prices are increased etc. India faced extensive damage to property and agriculture during the last summer.

A 2023 Lancet study pegs potential income loss in India from labour capacity reduction due to heat in 2023 at USD 141 billion. The report said a 50 percent increase in potential labour hours lost to extreme heat since the 1990s. This has led to economic losses valued at USD 141 billion in 2023.

Soaring temperatures impact the productivity of outdoor workers who are involved in heavy labour, specifically in construction, agriculture, fisheries and forestry sectors. As many as one billion outdoor workers live in the tropics and if the tropics warm up by an additional 1 degree Celsius it would result in nearly 800 million people losing over half of their working hours per year

The study estimates the cost of lost potential labour productivity for outdoor workers due to heat from several hundred billion to over 2 trillion dollars per year.

Wildfires:

Heat waves can increase the risk of wildfires, particularly in dry and forest areas. According to a report released by Forest Survey of India (FSI), India has managed to bring down the forest fires down to 2.03 lakh in 2023-24 from 2.23 lakh in 2021-22.

“The top three states where fire incidents were observed the most in 2023-24 forest fire season were Uttarakhand (21,033), Odisha (20,973) and Chhattisgarh (18,950),” the report stated.