India will get its own index to quantify heat impact next year: IMD chief

New Delhi: India will launch its own composite index next year to measure the impact of heat on its population and generate impact-based heat wave alerts for specific locations, the India Meteorological Department (IMD) has said. The IMD last week began releasing an experimental heat index for different parts of the country, taking into account air temperature and relative humidity to determine how hot it actually is.

“Heat Index is an experimental product. It is not validated and we have also mentioned this (on IMD’s website). Now we are coming up with our own system, a multi-parameter product called ‘Heat Hazard Score’ We hope it will be better than others.

Along with temperature and humidity, it will integrate other parameters such as wind and duration. This would be an effective indicator of heat stress for the people, he said.

The IMD chief said the hazard score will be ready in about two months and “it will be operational in the next summer season”. Asked whether the IMD has incorporated health data into the product, he said the weather bureau will do it gradually. “We are working on it but in some places the health data is not easily available,” he added.

Mohapatra and his team analyzed the heat wave threat for the entire country last year, taking into account the maximum temperature, minimum temperature, humidity, wind and duration of the heat wave. The analysis will help generate a heat hazard score that will be used as a threshold for issuing impact-based heat wave alerts for specific locations.

According to IMD data, there has been a 24 per cent increase in the number of heat waves during 2010-2019 as compared to 2000-2009. However, there is a declining trend after 2015. Between 2000 and 2019, the death rate for tropical cyclones decreased by 94 percent, while it increased by 62.2 percent for heat waves.

The fifth assessment report of the Intergovernmental Panel on Climate Change states that the major climate risk for South Asian countries will be increased mortality due to heat waves.

A slight increase in average temperature or a slight increase in the duration of heat waves would lead to a significant increase in mortality in India, unless remedial and response measures are taken. However, heat waves are yet to be notified as a natural disaster at the national level in the country.

Heat waves have extreme effects on human health, causing cramps, exhaustion, stress and heat stroke, and very severe heat waves even causing death. Children and the elderly especially people who suffer from heart and respiratory problems, kidney diseases and mental disorders are also affected. Extreme periods of high temperatures can lead to significant reductions in crop yields and lead to reproductive failure in many crops.