Heatwaves and downpours: India’s double climate threat

While the number of extreme heat wave days in India during the March–April–May (MAM) and June–July–August–September (JJAS) months has increased by 15 times over the past three decades, the number of extreme heat wave days has increased by 19 times within the last decade alone. The study also discovered that, aside from days without rain, India's monsoon seasons are experiencing an extended summer-like state.

The research was introduced recently at a National Symposium called "How can India address climate extremes," which was organised by IPE Global, ESRI India, and its partners UNESCO and Climate Trends. The world is preparing for Climate Week in NYC, USA, where political and business leaders are anticipated to discuss their commitments to climate action.

“The current trend of catastrophic extreme heat and rainfall events is a result of the 0.6 °C temperature rise in the last century. El Nino is gaining momentum and making its early presence felt across the globe, with India facing the extreme event of turbulence more in patterns than waves. Recent Kerala landslides triggered by incessant and erratic rainfall episodes and the cities getting paralysed with sudden and abrupt downpours are a testament that climate has changed,” said Abinash Mohanty, Head, Climate Change and Sustainability Practice at IPE Global and the author of the study.

Significant effects on lives, livelihoods, and infrastructure are being brought about by the rising frequency and intensity of heatwaves combined with heavy precipitation. Informed policy decisions, resilience, and climate adaptation require a comprehensive, data-driven strategy.

“GIS technology, with advanced spatial analysis tools and the ability to integrate a variety of data, enables a comprehensive understanding of the impact of climate from economic, social, and environmental perspectives. Decision-makers in government can use it for resilient infrastructure planning & development, disaster management, and citizen engagement. Businesses can integrate climate insights for better strategic planning and building higher resilience in supply chains and business operations,” said Agendra Kumar, Managing Director, ESRI India.

Methodology

This study is the first of its kind to conduct a district-level correlation of heat risk and extreme rainfall by examining complex, non-linear trends and patterns through the development of a region-specific temperature threshold roster over a multi-decadal timescale (1993–2022). Using spatial and climatological modelling, the study generates empirical evidence on the exposure of Indian districts to extreme heatwaves and erratic rainfall, mapping the micro-seasonal variations.

Extreme rains and heat stress are causing havoc across Gujarat, Rajasthan, Uttarakhand, Himachal Pradesh, Maharashtra, Uttar Pradesh, Meghalaya, and Manipur.

According to the IPE Global report, over 84% of Indian districts are classified as extreme heatwave hotspots, and of those, almost 70% have had more frequent and continuous rainfall during the monsoon season (JJAS) during the past three decades. Furthermore, over 62% of Indian regions that are vulnerable to heatwaves have seen unpredictable and continuous rainfall in October, November, and December (OND). Globally, heatwaves are more likely when air temperatures and humidity rise, particularly in tropical locations. The following states are experiencing extremely high temperatures, according to the study's regional analysis.

• Coasts:

  Gujarat, Tamil Nadu, Andhra Pradesh, Odisha, and Maharashtra

• Plains:

  Uttar Pradesh, Rajasthan, Madhya Pradesh, Chhattisgarh, Haryana, Maharashtra, Punjab, Telangana, Bihar, and Delhi

• Hills:

  Tripura, Mizoram, Jammu and Kashmir, Uttarakhand, Meghalaya, and Himachal Pradesh

IPE has been continuously striving to develop and implement strategies that convert environmental risks into competitive advantage. “This study is a  testament to how we can bring innovations from margins to mainstream that make India and Global South climate ready. Then, in a true sense, India can become the climate solutions capital to the world,” he added.

Shifting patterns of climate events

The study identified a trend where extreme heatwave hotspots are increasingly experiencing frequent and intense episodes of incessant and erratic rainfall. Coastal districts, both on the eastern and western shores, have seen a rise in unpredictable rainfall events. Districts with higher occurrences of heatwaves during the June–September period are also more likely to experience these irregular rainfall patterns.

The rising atmospheric temperatures and humidity levels globally, especially in tropical regions, are heightening the probability of heatwaves. The increased frequency and intensity of heatwave days, exacerbated by climate change, are driving these erratic rainfall events, presenting significant challenges that demand comprehensive strategies for mitigation and adaptation to safeguard vulnerable communities.

The study recommends that risk assessment principles should be central to India’s strategy for building resilience against heatwaves and extreme rainfall. As an initial step, it proposes establishing a Heat Risk Observatory (HRO), which would help identify, assess, and project chronic and acute heat risks at a hyper-granular level, enhancing preparedness against heat-related challenges like urban heat islands, water stress, vector-borne diseases, crop loss, and ecosystem collapse.

The study also suggests developing risk financing instruments to mitigate the impact of heat and extreme rainfall events. Moreover, appointing heat-risk champions within district disaster management committees is recommended to prioritise and unify heat-risk mitigation efforts at the district level, thereby accelerating resilience.

The study, “Managing Monsoons in a Warming Climate,” can be accessed here.