In one of Indias most heat-vulnerable regions, Supriya Sahu is putting in place a suite of effective cooling regulations and nature-based adaptation measures to improve the health and safety of families.
Residents of Chennai, the capital of Tamil Nadu state in southern India, often use the saying "hot, hotter, and hottest" to describe the temperature variations in their rapidly growing city.
And the risk of extreme heat bouts, often referred to as "silent killers," is also increasing. In 2024, India experienced its most prolonged heatwave since 2010, with Tamil Nadu being one of the states most affected by high temperatures.
The problems stemming from extreme heat disproportionately impact disadvantaged communities and are often overlooked. However, one public servant made cooling initiatives and support for vulnerable families her priority, helping lead Tamil Nadu to become the first state in India to officially declare heat a state-specific disaster.
Supriya Sahu has served as Additional Chief Secretary in the Department of Environment, Climate Change, and Forest for the past four and a half years. During this time, she has positioned Tamil Nadu as a global leader in climate mitigation, adaptation and heat resilience. Her initiatives have showcased how integrated governance and nature-based solutions, along with a mix of low- and high-tech interventions, can protect vulnerable communities, while reducing greenhouse gas emissions.
Sahus love for nature started in her early childhood, when her family travelled around the country for her father's job. She adores elephants, and her Instagram account is filled with posts about them. She likes to say that elephants can teach us about resilience, family bonding and leadership.
Throughout her 30-year career as a public servant, Sahu has developed a growing fascination with India's rich biodiversity. However, she has also become acutely aware of the severe damage that irresponsible human behaviour can inflict.
"I saw animals eating plastic garbage, and I realized that our planet is choking. That experience became transformational for me," Sahu says, recalling her time as the District Collector, a top administrative officer of the Nilgiris District. In 2000, she launched a campaign called "Operation Blue Mountain" aimed at eliminating single-use plastic in Nilgiris. The issue of plastic pollution was still under the radar at the time.
In recent years, Sahu has introduced the Tamil Nadu Green Climate Company, a not-for-profit focused on coastal resilience, and a variety of projects to tackle urban heat and rising cooling demand. Thanks to their scale, ambition and coordinated work across various government sectors backed by Sahus energy and leadership these programs are making a difference in the lives of some of the most disadvantaged families.
Sahu's focus on vulnerable communities stems from knowing that they bear the brunt of climate change. "Take the example of school children in government schools, where we do not have air conditioning. In the summer months, the temperature rises above 40C. Not only is it difficult to study in these conditions, but it is also bad for their health," she explains.
Cool Roof Project is one of the passive cooling initiatives led by Sahu, being implemented in 200 public "green schools." The solution, as cheap and straightforward as painting the roofs white to reflect sunlight, brings the temperature inside the classroom down dramatically. In combination with shading, natural ventilation and nature temperatures can reduce by 5 to 8C. Along with roof painting, "green schools" have been implementing solar power, energy efficient fans, shading, harvesting rainwater and planting vegetable gardens.
These simple strategies to cool schools are now being expanded to social housing projects. This will significantly improve the lives of families unable to afford air conditioning. They'll now be able to enjoy 40 per cent more time to work, study and spend quality time together without the stress and discomfort caused by unbearable heat. If one day they do opt for an air conditioner, these measures will reduce their energy bill for cooling by up to 50 per cent. Such practical measures, along with their expected integration into the states building regulations, are having a ripple effect in the real estate market, encouraging the private sector to follow suit.
In addition to improving social housing and public buildings, Sahu has dedicated time and effort to restoring biodiversity and reintegrating nature into densely populated urban areas. She has led efforts to plant over 100 million trees and establish 65 new reserve forests in Tamil Nadu, and under her leadership, the state has doubled its mangrove cover, expanded its wetlands from 1 to 20, and launched the US$60 million Endangered Species Conservation Fund.
In Chennai, the states capital, she is applying this nature-first approach to urban planning by integrating heat resilience into new developments, mitigating intense hotspots primarily through the protection and expansion of green spaces, complemented by better urban and building design and innovations like district cooling.
Factored together, Sahu's sweep of initiatives have created 2.5 million green jobs and significantly contributed to India's national target of reducing its greenhouse gas emissions to 3 billion tonnes of carbon dioxide.
"We cannot separate nature from people. In Chennai, we have industrial areas, where mangroves are also thriving. How many cities in India or in the world can boast of a living mangrove ecosystem?" Sahu says with pride. Still, among all her achievements, Sahu holds the "green school" project particularly close. "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."
