Heat Hazards In India Must Be Defined Based On Local Conditions, Action Plans Should Use Scientific Data: Report
The report recommends that heat hazards in India must be defined based on local conditions, and that heat action plans should be strengthened by using available scientific data.
Heat action plans, which are guidance documents designed to prepare for, respond to, and recover and learn from heat waves, must perform the important task of defining the localised conditions under which heat becomes a hazard. These action plans must define a maximum threshold temperature at which there are significant increases in mortality rates in a given biogeography, says the report on the first critical assessment of heat action plans in India.
The Centre for Policy Research, an independent institution dedicated to conducting research that helps address issues impacting life in India, assessed 37 heat action plans across 18 states published between 2016 and 2022, to understand how well-prepared the country is to deal with heat waves.
Factors which define how extreme heat affects a particular region
The report says that daily maximum temperature is not the only factor that has significant implications for the experience of heat waves, heat-related stress, morbidity, and mortality, but concurrent hot days and hot nights, relative humidity and indoor temperature also play an important role in defining how a particular region and the people living there will be impacted by extreme heat.
Heat hazards must be defined based on local conditions
The report recommends that heat hazards in India must be defined based on local conditions, and that heat action plans should be strengthened by using available scientific data. This will help understand the changing nature of the hazard, based on heat and humidity interactions, the compounding of heat with other hazards such as drought and forest fires, and impacts across sectors beyond human health.
Thresholds to declare heat waves do not adequately consider local conditions
According to the report, thresholds to declare heat waves do not adequately consider local conditions such as built-up area ratio, type of land surface, and density of vegetation, and do not incorporate indicators like humidity and hot nights.
Of the 37 heat action plans assessed as part of the report, 24 plans indicate the need to use localised temperature and mortality thresholds. However, only ten heat action plans listed thresholds different from the national threshold set by the Indian Meteorological Department (IMD). But it is unclear which variables were used in determining these thresholds.
Some heat action plans recognise factors such as urban heat island effect, UV index
According to the report, some heat action plans also acknowledge parameters such as heat index value, which refers to what the temperature feels like to the human body when relative humidity is combined with air temperature, urban heat island effect, and UV index, which is a measure of the level of ultraviolet radiation.
As many as 12 heat action plans consider daily variations in temperature, the report says. However, most heat action plans focus on seasonal variability, depicted through pre-heat, heat, and post-heat periods.
Heat action plans of Gujarat and Odisha recognise all local parameters
The report says that the state heat action plans of Gujarat and Odisha, and the city heat action plans of Rajkot and Bhubaneswar recognise the importance of all parameters in preparing a response plan.
How heat action plans can be strengthened
Long-term heat action plan actions can be strengthened by using localised mediums to strengthen long-term heat projections. This means that the heat action plans must focus on localised factors to project how a particular area will be impacted by heat waves.
Heat action plans focus on secondary sources
The report states that all the reviewed heat action plans rely on secondary sources to understand the nature of climate change. The plans have cited anthropogenic climate change as the primary reason behind increasing temperatures and rising intensity of heat waves.
Several plans rely on past temperature trends
A drawback of several heat action plans is that they report past temperature trends based on observed data to inform their planning. The exceptions are the heat action plans for Himachal Pradesh and Arunachal Pradesh, which use 'Providing Regional Climate for Impact Studies (PRECIS)' model-based projections of temperature and rainfall change in their plans.
Some plans recognise that heat waves occur in conjunction with other hazards
The report says that heat action plans can help governments prepare for unexpected heatwave consequences by systematically identifying cascading secondary impacts. As many as 21 heat action plans recognise that heat waves either occur in conjunction with or result in other hazards such as drought, forest fires, high levels of water stress and high winds. As many as 18 heat action plans note the cascading impacts of these hazards on sectors such as water supply, education, power supply, public transport, and animal husbandry, among others.
The report says that thresholds to declare heat waves are not adequately tailored for local conditions in cities or habitations. Also, the thresholds do not adequately incorporate indicators like humidity and hot nights, among others.
Heat action plans must use climate projections
The report suggests that thresholds to declare heat waves must be adequately tailored for local conditions in specific Indian cities, and incorporate indicators such as humidity and hot nights.
The report warns that India is projected to see increased frequency and intensity of heat waves, along with hotter days and nights, and seasonal shifts with heat coming earlier and staying longer. Therefore, heat action plans must use the high-resolution climate projections available for India, and not just focus on past temperature trends, the report suggests.
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