As the already hot Indian summer gets hotter due to climate change, there is need for urgent action to combat debilitating heat stress and to build climate-resilient infrastructure
Indian summers were always hot. Now, they have turned lethal. Globally, we have seen a spate of record temperatures, with 2015, 2016 and 2017 being the trio of hottest years recorded so far. Future summers will see new record highs.
Studies indicate that temperatures across more than half of the districts in India will exceed by 2 degrees Celsius by the end of the century. This implies that a population of close to 450 million is likely to be exposed to the risk of heat stress. India must gear up for this emerging public health challenge.
In India this summer, the Meteorological Department has already reported heat waves across Delhi, Gujarat, Haryana, Madhya Pradesh, Maharashtra, Rajasthan and Uttar Pradesh.
A rise in global average temperatures — from 1.5 degrees Celsius to 2 degrees — will lead to non-linear increases in mortality risks across Indian cities, according to a study by the Council on Energy, Environment and Water (CEEW), Indian Institute of Management Ahmedabad and Indian Institute of Technology Gandhinagar.
For instance, the risk of future mortality for Ahmedabad due to heat stress is likely to increase from 23% if the average temperature increases by 1.5 degrees to 34% if it rises by two degrees compared to the baseline. Science as well as our subjective experiences has made it unequivocally clear that longer, hotter and deadlier summers are poised to become the norm due to climate change.
In recent years, several cities such as Ahmedabad, Bhubaneswar, Chandrapur and Nagpur have developed heat health warning systems. These are now being expanded to other cities such as Jhansi and Sagar. There is now a need to focus on smaller towns and villages. For instance, the 2015 heat wave resulted in over 2,000 deaths in rural Andhra Pradesh.
Additionally, heat stress in rural areas adversely impacts local economies. For example, heat waves could reduce the productivity of agricultural labour by 2%. Further, extreme heat adversely impacts livestock, leading to reduced milk production in affected areas. This has adverse consequences on millions of livelihoods, especially smallholder farmers. As we continue to scale up heat-warning systems across the country, there is a need to focus on three areas to reduce heat stress-related impacts.
First, we must improve current metrics on heat stress. More often than not, heat-related warnings are communicated based on the single metric of temperature. However, from the perspective of physiology, the heat stress experienced by humans is a combination of temperature as well as humidity.
The National Disaster Management Authority guidelines on managing heat show similar levels of heat stress for combinations of low temperature with high humidity and high temperature with low humidity. To illustrate, 42 degrees Celsius and 40% humidity or 33 degrees and 90% humidity impose similar levels of heat stress. In both cases, the subjective experience of heat stress is equivalent to being exposed to a temperature of 54 degrees Celsius.
This is important because the interplay of temperature and humidity determines the physiologic limit, beyond which survival is threatened.
New thresholds for issuing heat-related warnings could incorporate information based on temperature-humidity combinations. This could follow the same grading system of yellow, amber and red warnings that correspond to low, moderate, and high risk of adverse health impacts seen in current heat-action plans. Alternatively, the thresholds could be more nuanced as observed in air quality indices.
Secondly, we must invest in climate-resilient infrastructure. Heat action plans tend to overlook the underlying infrastructure, such as energy, water and transportation. These play a crucial role in mitigating heat stress or responding to it.
The outgoing Indian government had come up with a list of ‘smart cities’ that it would focus on for development. Of the cities on this list, those in Madhya Pradesh as well as Amaravati, the new capital city of Andhra Pradesh, are likely to the average temperature increase by 1-1.5 degrees by the middle of the century, an analysis by CEEW, University of East Anglia and Mott MacDonald shows. Potential impacts on infrastructure include damage to roads and pavements as well as reduction in energy production as a result of extreme heat or water shortages.
These first-order impacts may trigger second-order problems such as breakdown of communication services, given the highly interdependent nature of infrastructure services. Consequently, infrastructure impacts may render services such as reliable water supply, adequate cooling to community areas, and prompt mobilisation of emergency response teams ineffective.
A clear implication of this is the urgent need for systemic thinking towards developing heat-action plans. India’s urban transformation plans may fall short without climate resilient infrastructure at their core. Smartness is not enough.
Thirdly, we have to monitor and evaluate heat-action plans. Successful plans require constant monitoring and evaluation for processes as well as outcomes. In most cases, detailed analyses of processes are yet to happen. Such analyses would include questions such as how frequently are warnings being issued? Are communications reaching desired populations? Are high-risk populations taking necessary preventive actions?
Globally, outcome evaluations such as those focusing on reductions in mortality and morbidity are common. However, in India, lack of reliable health data is a key barrier to such evaluations. On an average, in India, only two-thirds of all deaths are registered. Many lack information on causes of death. Improving our vital registration systems is critical to assessing the effectiveness of heat-action plans.
Extremely hot summers might be the new normal. Associated impacts on electricity and water may leave people scorched, parched and in the dark. Heat combined with acute water stress had recently brought life in the mountain city of Shimla to a standstill. The water crisis in Shimla is a harbinger of future climate impacts. Other cities may experience a similar situation. Improving the design of our heat action plans might be our best defence.
Hem H. Dholakia is Senior Research Associate at the Council on Energy, Environment and Water (CEEW), an independent research organisation