Rising Wet-Bulb Temperatures: A Growing Threat to India’s Coastal Resilience

A recent report by Azim Premji University has sounded an alarm regarding the escalating climate risks along India’s 11,000 km coastline. The study highlights that 40 coastal districts, with a significant focus on Kerala and Tamil Nadu, are witnessing summer temperature spikes of approximately 1.5°C. More critically, these regions are nearing dangerous 'wet-bulb' temperature thresholds, a metric that combines dry-air temperature with humidity.

Wet-bulb temperature is a vital indicator of heat stress. When it reaches 35°C, the human body can no longer cool itself through perspiration, leading to heatstroke or even death in healthy individuals. The report indicates that the combination of high humidity from the sea and rising ambient temperatures is pushing coastal India toward this tipping point. This poses a severe public health challenge, particularly for outdoor workers, fishers, and marginalized communities who lack access to cooling infrastructure.

Beyond immediate heat stress, the report underscores the role of rapid sea surface warming in the Indian Ocean. This warming acts as a catalyst for more frequent and intense tropical cyclones, disrupting traditional seasonal patterns and increasing the vulnerability of coastal settlements. Furthermore, the thermal expansion of water and melting ice contribute to sea-level rise, threatening to submerge low-lying areas and salinize freshwater resources. This multi-hazard environment endangers the livelihoods of millions who depend on the blue economy.

For governance and policy, these findings necessitate a shift from generic heat action plans to localized, humidity-aware strategies. Strengthening the Coastal Regulation Zone (CRZ) norms, investing in nature-based solutions like mangrove restoration, and developing climate-resilient infrastructure are imperative to safeguard India’s coastal demographic and economic interests.