Tatsat Chronicle Magazine

Heatwaves: Chilling Facts Portend Hot Future

Extreme climate is going to be one of India’s biggest challenges in this century, according to data gleaned from a number of studies. It will adversely impact our adaptive abilities
July 27, 2023
Illustration: Pixabay

Extreme weather events are here to stay. As India experienced, summers have become more intense, followed by monsoon deluge that triggered flash floods in the North. This year’s high average summer temperatures in the plains and extreme rainfall in the Himalaya offer some more indicators of shifting weather patterns.

Over the past two years vast swathes of India experienced “wet bulb” temperatures. The wet bulb phenomenon is used to describe severe and abrupt rises in temperature during summer that potentially pose a public health challenge. The chilling facts that have emerged from a number of studies point to further rises in mercury levels in the future. Data suggests that the average temperature in India has been higher than normal for the past few years.

A report by the Ministry of Earth Sciences (MoES) projected the pre-monsoon season heatwave frequency, duration, intensity, and areal coverage over India as substantially increasing in the near future. The average total duration of summer heatwaves, it said, may increase to about 15 days per season by mid-century (2040-69) and 18 days by the end of the century (2070-99).

The “Assessment of Climate Change over the Indian Region” report was published in 2021 when the Covid-19 pandemic underscored the imperative of putting public health first. Significantly, it predicted that southern India, currently not influenced by heatwaves, is expected to be severely affected by the end of the 21st century.

More than 90% of India is at ‘extreme caution’ or dangerous levels of adverse impact on adaptive livelihood capacity, foodgrain yield, vector-borne disease spread and urban sustainability, researchers from the University of Cambridge said in the study, published in April in PLOS Climate journal.

Due to the unprecedented burdens on public health, agriculture, and other socio-economic and cultural systems, climate change-induced heatwaves in India can hinder or reverse the country’s progress in fulfilling the Sustainable Development Goals (SDGs), the study observed.

This year, Uttar Pradesh, Bihar, Tamil Nadu, Madhya Pradesh, Jharkhand, Vidarbha, Odisha, West Bengal, Andhra Pradesh, and Telangana faced severe heatwave conditions. In May, Union Health Minister Mansukh Mandaviya held a meeting to evaluate the country’s readiness to combat the ongoing heatwave crisis.

As an adaptive measure, the India Meteorological Department (IMD) in collaboration with local health departments has started a heat action plan in many parts of the country since 2013. It is intended to forewarn people about heatwaves and advise action.

India’s average temperature has risen by around 0.7°C over 1901-2018, which is largely attributed to climatic change due to emission of greenhouse gases. In 2019, India was the seventh country most affected by climate change — suffering extreme weather events.

IMD defines heatwave qualitatively as a condition of air temperature which is fatal for the human body when exposed to it. Quantitatively, it is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal. The criterion for declaring a heatwave is based either on departure from normal temperature or on actual maximum temperature. In the first instance, a heatwave is declared when the temperature rises by 4.5°C to 6.4°C above normal and categorised as severe when it spirals above 6°C.

In the second case, a heatwave would refer to conditions where the actual maximum temperature is equal to 45°C or above it and severe when it is equal to 47°C or above it.

This April, however, the usually scorched National Capital Region (NCR) experienced cooler climes with western disturbances leading to frequent rainfall and below-normal average maximum temperature. These unseasonal, intermittent thundershowers have brought some relief to other parts in urban areas but destroyed standing crops in fields (See Flimsy Cover: The Inadequacy Of Crop Insurance). In 2022, the vagaries of the monsoon adversely impacted the cultivated acreage of staple foodgrains across India (See Code Orange: The Looming Threat To Food Security).

Last year, the country witnessed the third hottest April in 122 years, according to IMD data. The preceding month had turned out to be the hottest March since the department started maintaining records. Such climatic oddities directly affect humans, especially children. In the first child-focused global climate risk index, UNICEF placed India 26th out of 163 ranked countries. This, according to the organisation, implies that children in India are among the most ‘at risk’ because of the impacts of climate change, threatening their health, education, and protection.

In the 2021 report, “The Climate Crisis Is a Child Rights Crisis: Introducing the Children’s Climate Risk Index’ (CCRI), UNICEF projected that by 2040, almost 600 million children globally would be living in areas of extremely high water stress. It stated that around 90% of the world’s children breathe poisonous air every day; air pollution is associated with some of the biggest killers of children.

The Cambridge researchers had cited the case of Delhi in their study. Examining Delhi’s urban heat risk showed that heatwaves will critically hamper SDG progress at the urban scale. The conclusion emphasised the “urgent need to improve extreme weather impact assessment by combining multiple layers of information within the existing climate vulnerability measurement frameworks that can account for the co-occurrence and collision of climate change events and non-climate structural SDG interventions”.

Thus, the case of Delhi emphasised that heat is an urban killer and can be modulated through artificial interventions. “How we design our cities strongly determines heatwave impacts, eventually affecting the SDGs. Therefore, most urgently, upcoming heat-action policies need to standardise and streamline vulnerability assessments in India,” the study argued.

The research showed that millions of Indians are more vulnerable to climate change than was first thought. More than 90% of the country could be severely impacted by heatwaves, falling into an extreme heat “danger” zone, according to the heat index, they found.

Since 1992, more than 24,000 people have died because of heatwaves in India, the study mentioned. It is expected to get worse as heatwaves become more frequent, intense, and lethal due to the climate crisis.

According to the researchers, “India is currently facing a collision of multiple cumulative climate hazards” and “long-term projections indicate that Indian heatwaves could cross the survivability limit for a healthy human resting in the shade by 2050”.

Late last year, a World Bank report had warned that parts of India could become too hot for human survival in future heatwaves. Nearly 75% of the districts are categorised as hotspots for extreme climate events. It had also found that Indian employees already work in “potentially life-threatening temperatures” at times.

A World Health Organisation (WHO) report said that climate change affects the social and environmental determinants of health—clean air, safe drinking water, sufficient food, and secure shelter. It found that between 2030 and 2050, climate change is expected to cause approximately 2,50,000 additional deaths per year, from malnutrition, malaria, diarrhoea, and heat stress.

It is clear that tackling severe heatwaves is going to be a major challenge for India. Experts point out that any action plan to tackle this life-threatening situation would require a serious multi-dimensional approach over the medium and long terms. Extreme climate is going to be one of the biggest challenges of the 21st century.  

Jayanta Bhattacharya

Journalist. Curious about astronomy, cinema, communications, digital media, geostrategy, human rights, military, tech, and nature.