Heat Waves

Why is in news? Union Minister Dr. Jitendra Singh says, NDMA and IMD are working with 23 States to develop Heat Action Plans

As per studies, the stress induced due to the heat waves for livestocks increases respiration and mortality, reduces fertility, modifies animal behavior, and suppresses the immune and endocrine system, thereby increasing animal susceptibility to some diseases.

The Heat Action Plan is a comprehensive early warning system and preparedness plan for extreme heat events.

The Plan presents immediate as well as longer-term actions to increase preparedness, information-sharing, and response coordination to reduce the health impacts of extreme heat on vulnerable populations.

As an adaptive measure, IMD in collaboration with local health departments have started heat action plan in many parts of the country to forewarn about the heat waves and also advising action to be taken during such occasions. Heat action plan became operational since 2013.

According to a report by Lancet, India’s vulnerability to extreme heat increased 15% from 1990 to 2019. The five warmest years ever recorded in India have all been in the last decade.

A Heat Wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India.

Heat Waves typically occur between March and June, and in some rare cases even extend till July.

The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

India Meteorological Department (IMD) classifies heat waves according to regions and their temperature ranges. As per IMD, the number of heatwave days in India has increased from 413 over 1981-1990 to 600 over 2011-2020.

This sharp rise in the number of heatwave days has resulted due to the increasing impact of climate change.

India too is feeling the impact of climate change in terms of increased instances of heat waves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heat wave casualties.

The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.

Criteria for Heat Waves :

Heat Wave need not be considered till maximum temperature of a station reaches atleast 40°C for Plains and atleast 30°C for Hilly regions

When normal maximum temperature of a station is less than or equal to 40°C Heat Wave Departure from normal is 5°C to 6°C Severe Heat Wave Departure from normal is 7°C or more

When normal maximum temperature of a station is more than 40°C Heat Wave Departure from normal is 4°C to 5°C Severe Heat Wave Departure from normal is 6°C or more

Reasons why India is experiencing more heat waves:

Magnified effect of paved and concrete surfaces in urban areas and a lack of tree cover.

Urban heat island effects can make ambient temperatures feel 3 to 4 degrees more than what they are.

More heat waves were expected as globally temperatures had risen by an average 0.8 degrees in the past 100 years. Night-time temperatures are rising too.

Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.

High intensity of UV rays in medium-high heat wave zones.