In a city grimly familiar with the “hot, hotter, and hottest” temperature scale, public servant Supriya Sahu has emerged as Chennai’s chief strategist. She is strategically leveraging nature, policy, and simple “cool roofs” to shield vulnerable families from extreme and increasing heat risks. The risk from these “silent killers” is growing, with 2024 delivering India’s most prolonged heatwave since 2010.
However, in the highly heat-vulnerable state of Tamil Nadu, one public servant is leveraging a deep love for nature and a 30-year career in service to create a revolutionary shield against climate change.
Supriya Sahu, the Additional Chief Secretary, Department of Environment, Climate Change, and Forest, has positioned Tamil Nadu as a global leader in heat resilience, earning the state the distinction of being the first in India to officially declare heat a state-specific disaster.
The transformation:
Sahu’s unique approach—which blends nature-based adaptation with low- and high-tech interventions—is rooted in a profound respect for India’s rich biodiversity. This respect turned into action during her time as the District Collector of the Nilgiris District.
“I saw animals eating plastic garbage, and I realized that our planet is choking. That experience became transformational for me,” Sahu recalls. This crisis prompted her to launch “Operation Blue Mountain” in 2000, an early campaign aimed at eliminating single-use plastic, long before the issue gained mainstream recognition.
Supriya Sahu’s love for the natural world is exemplified by her personal adoration of elephants, which she says teach lessons on resilience, family bonding, and leadership—qualities she now applies to her climate work.
Empowering communities:
Sahu’s greatest motivation lies in protecting the disadvantaged families and vulnerable communities who “bear the brunt” of climate change. She highlights the plight of children in government schools, where temperatures often soar above 40°C in summer months, making study difficult and threatening health.
The flagship Cool Roof Project offers a beautifully simple solution: passive cooling. By painting the roofs of 200 public “green schools” white to reflect sunlight, internal classroom temperatures can be reduced by 5 to 8°C. This low-cost strategy is combined with solar power, energy-efficient fans, shading, rainwater harvesting, and vegetable gardens.
A ripple effect:
These simple yet effective cooling strategies are now expanding to social housing projects, offering significant benefits to families who cannot afford air conditioning. These measures promise to:
• Improve quality of life by allowing families 40 percent more time to work, study, and spend quality time together.
• Reduce energy costs for cooling by up to 50 percent if residents eventually purchase an air conditioner.
By integrating these measures into state building regulations, Sahu’s work is creating a ripple effect, compelling the private real estate sector to adopt similar cooling designs.
Restoring biodiversity:
Beyond buildings, Sahu’s tenure has been marked by ambitious efforts to restore biodiversity. She has overseen the planting of over 100 million trees, the establishment of 65 new reserve forests, and the doubling of the state’s mangrove cover. Her proudest integration of nature is in Chennai itself, where urban planning now protects and expands green spaces.
“We cannot separate nature from people,” Sahu says, pointing out that Chennai boasts industrial areas where mangrove ecosystems are thriving.
Factored together, Supriya Sahu’s initiatives have created 2.5 million green jobs and significantly advanced India’s national greenhouse gas reduction targets. Yet, for Sahu, the “green school” project remains closest to her heart. “Our generation did all this damage to the planet. But when you talk to any child, you can see hope in their eyes. And if you pass a message to them, they are so quick to take it forward.”
Awards and recognition:
Supriya Sahu’s most recent major honor is the 2025 UN Champions of the Earth Award for Inspiration and Action, which is the United Nations’ highest environmental recognition. The award was presented to her by the UN Environment Programme (UNEP) for her pioneering and long-standing leadership on critical environmental challenges in India, including plastics, wildlife conservation, sustainable cooling, and ecosystem restoration. Her prior notable recognition from India is a Guinness World Record achieved for planting the greatest number of trees in a single day during her “Operation Blue Mountain” campaign in the Nilgiris District.
