Heat Stress Analysis in Tamil Nadu

Summary of the Report on Urban Growth and Thermal Stress in Tamil Nadu

An assessment conducted by the Tamil Nadu State Planning Commission (SPC) titled “Urban Growth and Thermal Stress: A Decadal Assessment of Built-Up Area and Climate Interactions in Tamil Nadu” indicates a significant increase in temperatures in urban areas due to urban sprawl, deforestation, and alterations in land use. The analysis relies on three decades of data and represents a comprehensive evaluation of heat exposure at the block level across the State.

Key Findings:

• Temperature Growth and Urban Sprawl: Major cities such as Chennai, Coimbatore, and Tiruppur are experiencing rapid urbanization, which is directly linked to rising land temperatures.

• Heat Stress Analysis: Out of 389 blocks analyzed, 94 blocks showed significant long-term temperature increases, and 64 blocks are currently experiencing extreme heat stress. Hotspots include regions in Chennai, Karur, and Ramanathapuram.

• Impact on Traditional Cooler Regions: Areas historically known for cooler climates, like Kodaikanal, have also observed warming trends, with temperature increases recorded as high as 1.2°C in places like Tiruttani due to forest degradation and tourism development.

• Future Projections: Based on climate scenarios RCP 4.5 and RCP 8.5, Tamil Nadu's annual air temperatures may rise by 0.9°C to 2.7°C by 2050, impacting agricultural productivity, water security, and public health.

• Forest Cover Decline: The SPC noted that over 3,025 sq. km. of forest cover has been lost in the last two decades, exacerbating the Urban Heat Island effect and reducing the state’s climate resilience.

• Peri-Urban Heat Intensification: Regions such as Sriperumbudur, Poonamallee, and Kundrathur, which had minimal development in 1985, now report significant heat intensities due to rapid urbanization.

• Coastal Vulnerabilities: Coastal districts, under threat from sea-level rise and cyclonic activity, face compounded risks from extreme heat, necessitating integrated adaptation strategies.

Recommendations:

• Climate-Sensitive Urban Planning: The SPC emphasizes the need for climate-sensitive urban planning, particularly in urban, peri-urban, and hilly regions. This includes the incorporation of green infrastructure such as parks and green roofs to mitigate the Urban Heat Island effect.

• Regulatory Measures: Updating building codes to include features for passive cooling, increasing green cover, and implementing rainwater harvesting systems is recommended.

• Land Mapping and Afforestation: For peri-urban and hilly areas, maintaining land suitability maps, regulating constructions, and expanding afforestation efforts are deemed vital to preserving ecological integrity.

• Enhanced Monitoring: The report advocates the creation of a real-time heat monitoring dashboard that combines satellite and on-ground data, especially in rural and data-scarce regions. Embedding heat exposure indicators into planning frameworks, such as Master Plans and Smart City proposals, will prioritize interventions in at-risk blocks.

Concluding Notes:

This detailed assessment presented to Chief Minister M.K. Stalin highlights the urgent need for action to mitigate the impacts of rising temperatures through strategic planning and adaptation measures in Tamil Nadu.

Important Points Recap:

• Rising temperatures in Tamil Nadu linked to urbanization and land use changes.
• 94 blocks show significant temperature increase; extreme heat stress in 64 blocks.
• Historical cooling regions now warming, with Kodaikanal recording up to 0.7°C rise.
• Future temperature increases projected at 0.9°C to 2.7°C by 2050.
• Over 3,025 sq. km. of forest lost in last 20 years.
• Need for climate-sensitive urban planning and green infrastructure.
• Proposals for land regulation, afforestation, and heat monitoring systems.