Heatwaves in India- Explained Pointwise

Heatwaves in India have become more severe and intense having severe effect on human health. Recently, The India Meteorological Department (IMD) has predicted an increase in the maximum temperature and the frequency of heatwaves in the forthcoming days over eastern and southern India. Hence, India must remain prepared for tackling these recurring heatwaves.

What are heatwaves? How are they defined in India?

Heatwaves- Heat waves are prolonged periods of excessively hot weather that can cause adverse impacts on human health, the environment, and the economy.

Definition of Heatwave- In India IMD defines heatwave based on the following criteria.

Physiography of regions

Plain– The maximum temperature recorded at a station is 40 degrees Celsius or more.
Coast- The maximum temperature recorded at a station is 37 degrees Celsius or more.
Hills- The maximum temperature recorded at a station is 30 degrees Celsius or more.

Based on Departure from Normal Temperature

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

Based on Actual Maximum Temperature

Heat Wave- When actual maximum temperature ≥ 45°C 
Severe Heat Wave- When actual maximum temperature ≥47°C
*Heat Wave is declared if above criteria are met in at least 2 stations in a Meteorological subdivision for at least two consecutive days.

What is the status of Heatwaves in India?

India has been affected by the Heatwaves since a long time. However, during the last few decades, due to increased instances of climate change, the impact of heat waves has also enhanced quite significantly.

a. States like Rajasthan, Gujarat, Uttar Pradesh, Delhi, Haryana, Punjab, Madhya Pradesh have been affected the most by the Heatwaves.

b. According to IMD, between 1981 and 1990 there were 413 heatwave days in India. However, the heatwave days have increased to 600 days between 2011 and 2020.

c. The number of deaths from heat-related causes increased from 5,457 between 1981 and 1990 to 11,555 between 2011 and 2020.

What are the factors behind the increase in Heatwaves in India?

Heatwaves can be caused by a combination of natural and human-induced factors. The main causes are mentioned below-

Natural causes

1. High Atmospheric Pressure Systems- Heatwaves occur when high-pressure systems stall over a region. These systems trap warm air near the Earth’s surface and prevent the normal movement of air masses, leading to prolonged periods of hot weather.

2. Climate Variability- Natural climate variations, such as El Nino and La Nina events, influence weather patterns and increase the likelihood of heatwaves. For ex- During El Nino events, warmer ocean waters in the tropical Pacific lead to changes in atmospheric circulation and weather patterns.

3. Drought and Dry Conditions- Prolonged periods of drought and lack of precipitation reduces the overall moisture of the soil, causing the land to heat up more quickly during heat waves.

4. Changes in Wind Patterns- Shifts in wind pattern transports hot air from one region to another which intensifies heat waves in areas that are not typically prone to such extreme temperatures.

4. Geography and Topography- Geographic features and topographical conditions also contribute to the development of heat waves. For ex- Landlocked valleys and regions surrounded by mountains trap hot air and lead to temperature spikes.

Human-Induced Factors

1. Global Warming- The long-term increase in Earth’s average temperature, primarily driven by human activities such as burning fossil fuels, deforestation, and industrial processes, contributes to the frequency and intensity of heat waves.

2. Urban Heat Island Effect- Urban areas with high population density, extensive concrete and asphalt surfaces, and limited vegetation tend to absorb and retain more heat, has created localized zones of higher temperatures. This phenomenon, known as the urban heat island effect, has intensified heat waves in cities.

What are the impacts of Heatwaves?

1. Impact on Human Health- Rapid rises in heat compromises the body’s ability to regulate temperature resulting in a cascade of illnesses, including heat cramps, heat exhaustion, heatstroke, and hyperthermia.

2. Impact on Energy- Heatwaves increase the electricity demand for cooling purposes, leading to strain on power grids and potential blackouts.

3. Impact on the economy- Heatwaves disrupt economic activities, affecting productivity of workers and labourers, lacking the access to reliable electricity for cooling during heatwaves. According to an ILO study at 34°C, workers can lose up to 50% of their work capacity.

4. Impact on Water Resources- Heatwaves exacerbate water scarcity issues in India due to drying up of water bodies and decrease in the groundwater table. This exacerbates the inter-state conflict over water. For ex- Cauvery water Dispute.

5. Impact on the food security- The rise in heat waves increase the probability of droughts,  enhance demand of irrigation water, which impacts agricultural production and increases food insecurity.

What steps have been taken by the government to address the issue of heatwaves?

What should be the way Forward?

1. Effective implementation of Heat Wave Action Plan-  Effective implementation of the Heat wave action plan with the State playing a leading role and sharing responsibility with other stakeholders is now the need of the hour.

2. Sustainable Cooling- Passive cooling technology like construction of ventilated buildings and the use of porotherm bricks, can be a vital alternative to address the urban heat island for residential and commercial buildings.

3. Heatwave Mitigation Plans- Heatwave mitigation plans which includes access to drinking water, oral rehydration solutions (ORS), shade at public places, flexible working hours in workplaces must be effectively designed and implemented.

4. Creation of more Green Spaces- According to the UN, investment of US$ 100 million in street trees globally can bring 1°C temperature reduction. India must scale up its reforestation and tree plantation efforts. For ex- Haritha Haram project of Telangana Govt to increase the green cover in Telangana from the current 24% to 33%.

5. Adoption of energy efficient solution- The masses should be encouraged to adopt more energy efficient solutions like using desert coolers in place of air conditioners in dry areas.