Why in News?
- Severe heatwave conditions have been consistently reported over large parts of India since the beginning of the summer season in March. In May 2022, the mercury touched nearly 50 degrees Celsius in some areas of north india.
- An international team of climate scientists published the report which says this phenomenon caused widespread human suffering and hit global wheat supplies, was about 30 times more likely to happen due to human-caused climate change.
- It is time now that concrete plans are put in place to deal with heat waves and closely linked extreme weather events.
What are Heat Waves?
- Qualitatively, heat wave is a condition of air temperature which becomes fatal to human body when exposed.
- It is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal.
- In certain countries it is defined in term of the heat index based on temperature and humidity or based on extreme percentile of the temperatures.
Criteria for declaring heat wave
- Heat wave is considered if maximum temperature of a station reaches at least 40 degree celsius or more for Plains and at least 30 degree celcius or more for Hilly regions.
a) Based on Departure from Normal
- Heat Wave: Departure from normal is 4.5 to 6.4 degree celcius
- Severe Heat Wave: Departure from normal is >6.4 degree Celcius
b) Based on Actual Maximum Temperature
- Heat Wave: When actual maximum temperature ≥ 45 degree celcius
- Severe Heat Wave: When actual maximum temperature ≥47 degree celcius
- If above criteria met at least in 2 stations in a Meteorological sub-division for at least two Consecutive days and it declared on the second day.
Occurance of Heat Waves-
- The proximate causes for the searing heat are an absence of rain-bearing Western Disturbances or tropical storms that bring rain from the Mediterranean over North India.
- The combination of global warming and population growth in already-warm cities in India is the primary driver of increased heat exposure.
- The Urban Heat Island (UHI) also elevates temperatures within cities, which will be amplified during the heatwaves.
Monitoring of the Heat wave-
- IMD has a big network of surface observatories covering entire country to measure various metrological parameters like Temperature, Relative humidity, Pressure, Wind speed & direction etc.
- Based on daily maximum temperature station data, climatology of maximum temperature is prepared for the period 1981-2010 to find out normal maximum temperature of the day for particular station. Thereafter, IMD declared heat wave over the region as per its definition.
Impact of Heat Waves
- Human health-Heat-related mortality is caused by rising temperatures, a lack of public awareness programmes, and insufficient long-term mitigating efforts.
- Environment- Heat stress poses a serious risk in altering the soil profile, limiting plant development. Heat stress differs from drought.
- Extreme heat reduces photosynthetic and transpiration efficiencies of plants, causing retarded growth of plant root and shoot.
- Economy- According to a 2019 ILO research, India lost roughly 4.3 percent of working hours owing to heat stress in 1995, and it is anticipated to lose 5.8 percent in 2030.
- The loss of working days and there has been a detrimental impact on the livelihood of poor and marginal farmers. Heat waves reduce the productivity of these employees, affecting the economy.
- Food Security-The over all interacting impacts between environment and economy will increase food prices, reduce household incomes, and lead to malnutrition and climate-related deaths, especially in tropical regions.
Long-Term Strategies that India need to adopt to Mitigate the Impacts of Heat Waves-
- A Heat Waves Action Plan: Improved disaster adaption techniques and more strong disaster management policies are needed in heatwave zones to mitigate the effects of heat waves.
- Heat-related deaths are preventable, the government must make developing a long-term action plan to protect human lives, livestock, and wildlife a top priority.
- The Sendai Framework for Disaster Risk Reduction 2015-30 must be implemented effectively, with the government taking the lead and sharing responsibilities with other stakeholders.
- Early warning system-Death from heat waves can be prevented by installing improved early warning systems that communicate heatwave threats, recommend different preventative measures, and constrain disaster impacts.
- Disseminating public awareness through print, electronic and social media, providing heat-proof shelter facilities during summer, easing access to public drinking water, and huge afforestation in urban and rural areas would help mitigate heatwave fatalities.
- Declaration of Heat Waves as a Natural Disaster-India has a long way to go in terms of raising public knowledge, especially on how people and small groups can care for themselves.
- There should also be clear recommendations for when schools should be closed, the best temperature ranges for a domestic air conditioner, and how long people should stay outside if it is necessary.
- Ground level strategy- Passive cooling technologies can be a vital alternative to address the urban heat island for residential and commercial buildings.
- Cross ventilation,Stack Ventilation, Site orientation,Evaporate cooling, Night flush cooling, among all the techniques under ground level cooling strategy.
- Effective implementation of the Sendai Framework for Disaster Risk Reduction 2015-30, which emphasises disaster risk reduction with the State playing a leading role and sharing responsibility with other stakeholders such as local governments and the NGO sector, is now the need of the hour.