A new report from the India Meteorological Department (IMD) reveals that heatwaves will last 12-18 days longer in most parts of India, including peninsular India and the coasts, by 2060. In another study, released last week, it was revealed that over 90% of India's total area falls under the “extremely cautiousâ€_x009d_ or “danger zoneâ€_x009d_ for heatwaves, which are now occurring more frequently due to climate change. The study conducted by the researchers at the University of Cambridge identified Delhi as particularly vulnerable to severe heatwave impacts. 

With the last three years being dominated by La Niña, experts predict that 2023 is likely to witness the arrival of the complementary weather phenomenon, El Niño, characterised by warmer water spreading across the equatorial Pacific Ocean from west to east. Not surprisingly, a heat wave has already swept across northwest India. India recorded its hottest February since 1877 this year. The average temperature was 29.5 degrees Celsius, around 2 degrees higher than normal.  Last year, the country faced one of the hottest summers in almost 125 years, with temperature in Delhi hitting a new record high of above 49°C in May. 

The net zero goals of countries are also not optimistic. The IPCC's synthesis report warns that global warming is likely to exceed the 1.5 degrees Celsius limit set by the Paris Agreement by 2030, even with ambitious greenhouse gas emission reductions. To stay within this limit, emissions must peak by 2025, decrease by 43% by 2030, and achieve net zero carbon by mid-century.

These findings underscore the urgent need for India to implement effective strategies to mitigate the impact of heatwaves, which pose a significant threat to the country's population and infrastructure.

What is a heatwave?

A heatwave is declared when the temperature breaches the 40°C mark and is at least 4.5°C above normal seasonal levels. According to the World Health Organisation, a heatwave for India is considered if the maximum temperature of a station reaches at least 40°C or more for plains and at least 30°C or more for hilly regions.

Heatwaves can occur due to two primary reasons– either warm air flows in from other regions or local factors produce it. Local warming happens when the land surface temperature rises, or when descending air gets compressed along its path, leading to the generation of hot air close to the surface.

Heatwaves have a widespread impact, but their effects are notably severe in urban areas. Due to the urban heat island effect, buildings, roads, and other infrastructure absorb and retain heat, causing temperatures to rise significantly.

Heatwaves have severe environmental impacts, including water shortages and stress on plants, leading to reduced growth and drying of landscapes. Hot and dry conditions also increase the risk of forest fires and melting of glaciers, besides impacting wildlife and biodiversity. The agricultural industry is also affected as is labour productivity in stressful heat conditions.

Heatwaves and health impacts

According to experts, exposure to hotter than average conditions can compromise the body’s ability to regulate temperature, leading to heat cramps, heat exhaustion, heatstroke, and hyperthermia. Rapid rises in heat can result in hospitalisations and deaths that may occur on the same day or have a lagged effect that accelerates illness or death in the already vulnerable, particularly in the initial days of heatwaves. 

Heat also has indirect health impacts, affecting human behaviour, disease transmission, healthcare delivery, air quality, and social infrastructure, including energy, transport, and water. So it is critical to prepare for the rising temperatures and to develop comprehensive adaptation strategies to mitigate the impact of heatwaves.

India’s roadmap for heatwaves

The Cambridge report also talks about how heatwaves are impeding India's efforts towards achieving the United Nations' Sustainable Development Goals (SDGs) more significantly than previously thought and that current assessment metrics may not fully capture the impact of heatwaves. According to the report, prolonged exposure to extreme heat may result in a 15% decrease in "outdoor work productivity", negatively impact the well-being of approximately 480 million individuals, and incur a cost of 2.8% of GDP by 2050.

The Climate Transparency Report has revealed that India suffered a significant loss of $159 billion, equivalent to 5.4% of its GDP, due to heatwaves in 2021. The study highlighted the adverse impact of record temperatures on the productivity and lives of workers, migrants, low-income households, and homeless individuals. The report further projected a decline of 5 per cent in labour productivity in the country if the global temperature increases by 1.5ºC.

Last month, Prime Minister Narendra Modi reviewed India's preparedness to deal with hot weather, as the country braces for unprecedented summer heat. The Prime Minister was briefed about the readiness of the states and hospital infrastructure for emergencies.

The IMD recommends a comprehensive response plan that incorporates cultural, institutional, technological, and ecosystem-based adaptation strategies to combat the effects of heatwaves. 

The recommendations of its latest report titled “Heat and Cold Waves in India Processes and Predictabilityâ€_x009d_ include: improving India’s buildings through ventilation and insulation; raising awareness about heat stress; changing work schedules; providing early warning; and creating cool shelters.