Supriya Sahu
The Real Frontlines of Climate Leadership
Five climate leaders show practical paths to survival
In the sweltering heat of Chennai, where asphalt and concrete radiate the sun’s intensity and temperatures often climb above 40°C in peak summer months, Supriya Sahu, Additional Chief Secretary of Tamil Nadu, has quietly reshaped how cities can adapt to a warming world. Her initiatives in sustainable cooling and ecosystem restoration are not bureaucratic abstractions; they are deeply human interventions. Sahu’s programmes have created 2.5 million green jobs, expanded forest cover, and integrated heat-adaptation strategies into public infrastructure, touching the lives of nearly 12 million residents. Shaded corridors, reflective rooftops, and restored wetlands are tangible interventions that mitigate heat stress, especially in urban neighbourhoods where vulnerable populations face the brunt of rising temperatures. According to UNEP Executive Director Inger Andersen, Sahu has brought “the cooling spray of nature” into India’s concrete jungles, demonstrating that subnational leadership can have an outsized impact in climate action. The combination of ecological restoration and human-centred infrastructure illustrates the practical intersection of public service and climate resilience.
It is this model of actionable leadership that led the United Nations Environment Programme (UNEP) to recognise Sahu, alongside four other global leaders, as its 2025 Champions of the Earth, the UN’s highest environmental honour. Announced on 10 December 2025, these awards celebrate climate trailblazers whose work spans climate justice, sustainable cooling, resilient architecture, forest conservation, and methane mitigation. UNEP framed this year’s selections as exemplars of how urgent, creative, and human-centred action can protect both people and the planet. Alongside Sahu, the awardees are: the youth-led Pacific Islands Students Fighting Climate Change (Policy Leadership); architect Mariam Issoufou, Niger/France (Entrepreneurial Vision); research institute Imazon in Brazil (Science and Innovation); and the late Manfredi Caltagirone (Lifetime Achievement) for his work on methane emissions. Together, they illustrate a spectrum of strategies, from grassroots advocacy to scientific innovation, demonstrating that climate solutions require both local insight and global coordination.
From Chennai’s streets to the Pacific Ocean, the challenge of climate change manifests differently but with equally existential urgency. In the low-lying islands of the Pacific, communities confront the tangible threat of rising seas, saltwater intrusion, and shoreline erosion. Within this context, the Pacific Islands Students Fighting Climate Change turned their frustration and observation into legal advocacy. They secured a landmark advisory opinion from the International Court of Justice affirming that states have legal obligations to prevent climate harm and protect human rights. UNEP emphasises that this ruling establishes a precedent for nations whose populations are most exposed to climate-induced loss, highlighting that climate action is inseparable from climate justice. For these students, this was not an academic exercise: it represented a concrete mechanism for holding states accountable, illustrating how informed civic engagement can amplify vulnerable voices in global governance.
Across continents, climate challenges take different forms but demand equally inventive responses. In the Sahel, architect Mariam Issoufou confronts soaring temperatures, poor insulation, and energy scarcity by integrating climate-resilient design with cultural heritage. The Hikma Community Complex in Niger exemplifies her approach: structures built with locally sourced materials, passive cooling techniques, and designs reflecting indigenous construction knowledge maintain indoor temperatures up to 10°C lower than conventional buildings without air conditioning. This is crucial in a region where heat stress contributes to daily hardship, health risks, and energy poverty. By grounding her architectural practice in both science and tradition, Issoufou provides a replicable model of sustainable design that preserves dignity and identity while addressing climate vulnerability. Her work also resonates in the broader discourse on African architecture, challenging assumptions that modernity requires importing foreign materials and techniques.
Shifting hemispheres to the Amazon rainforest, the urgency takes on another scale. Imazon, a Brazilian research institute, leverages AI and geospatial analysis to monitor deforestation in real time. In an ecosystem where illegal logging, land clearance, and fires threaten biodiversity, carbon storage, and local livelihoods, early warning systems can mean the difference between preservation and irreversible loss. Imazon’s AI-driven predictive models allow authorities to anticipate deforestation patterns, strengthen enforcement, and provide evidence in legal cases, illustrating how technology can serve as both a sentinel and a tool for systemic change. As global temperatures rise and climate pledges fall short, the institute’s work underscores the importance of linking science with actionable policy, demonstrating that environmental governance can be precise, proactive, and data-driven.
In Europe, and on a more microscopic scale, Manfredi Caltagirone addressed a different but equally urgent environmental challenge: methane emissions. As former head of UNEP’s International Methane Emissions Observatory, Caltagirone championed transparency and science-based action, influencing the EU’s first regulation on methane emissions. Methane, though less abundant than CO₂, has over 80 times the warming potential over a 20-year horizon, and mitigating it offers one of the fastest pathways to reduce near-term global warming. Caltagirone’s contributions show that environmental leadership is not only about visible infrastructure or legal frameworks; it can also be about bringing attention to an invisible, but profoundly consequential, atmospheric threat. His work illustrates how targeted scientific advocacy can shape policy at national and international scales, turning technical knowledge into actionable governance.
The common thread uniting these laureates is an emphasis on practical, human-centered action. Sahu’s green infrastructure and cooling initiatives improve the daily lives of millions in Tamil Nadu. The Pacific students’ legal victory safeguards the rights of entire island populations. Issoufou’s buildings protect communities from extreme heat. Imazon’s technological vigilance shields a global carbon reservoir and local livelihoods. Caltagirone’s methane advocacy safeguards the atmosphere for billions worldwide. UNEP’s recognition of these efforts illuminates a broader truth: climate solutions require diversity in strategy, scale, and discipline.
These examples also underscore the critical role of subnational and non-state actors in climate resilience. Cities, youth organisations, research institutes, and architects operate with agility that often outpaces national governments, demonstrating that meaningful climate action emerges as much from decentralised innovation as from global treaties. In Chennai, Sahu’s integration of cooling into public infrastructure provides a model for other rapidly urbanising regions in South Asia and beyond. In the Pacific, youth-led litigation complements international climate negotiations, ensuring that legal accountability accompanies policy rhetoric. In Brazil and Niger, Imazon and Issoufou illustrate how science and design, when contextually applied, can create durable, scalable, and culturally sensitive interventions.
The stakes of such work are underscored by global trends: IPCC reports project that by 2030, more than 100 million people could be exposed to lethal heat stress, low-lying islands will face compounded flooding from sea-level rise, the Amazon faces accelerated deforestation and biodiversity loss, and methane emissions continue to rise from fossil fuels, agriculture, and waste management. UNEP emphasises that adaptation costs for developing countries may reach $310–365 billion annually by 2035, twelve times current funding levels. Against this backdrop, the 2025 Champions of the Earth show that action is possible, impactful, and measurable.
Moreover, the work of these laureates illustrates the interconnectedness of environmental and social outcomes. Sahu’s cooling initiatives, for example, not only reduce heat-related illness but also protect urban productivity and public health infrastructure. The Pacific students’ ICJ success ties climate mitigation directly to human rights, demonstrating that climate policy can be a mechanism for justice. Issoufou’s climate-smart architecture in the Sahel preserves heritage while improving habitability, and Imazon’s AI systems strengthen both governance and ecological resilience. Caltagirone’s focus on methane emphasises that invisible pollutants can have immediate consequences for air quality, climate trajectory, and policy urgency.
UNEP’s 2025 award cycle is also a statement on urgency and innovation. By honouring actors across geographies, sectors, and scales, the program highlights that solutions are neither singular nor linear. The award demonstrates that climate action is simultaneously legal, technological, ecological, social, and infrastructural. It emphasises that resilience is not only built with bricks, trees, or satellites, but also through engagement, oversight, and moral accountability.
For communities, this convergence of action matters concretely. In Chennai, residents now navigate streets shaded by newly planted trees and reflective surfaces, lessening the intensity of daytime heat. Pacific island governments now have a strengthened legal precedent to advocate for protective measures. Residents of Niger inhabit structures that shield them from dangerous high temperatures without relying on costly, energy-intensive cooling. Brazilian authorities can act swiftly against illegal deforestation with precise geospatial data. And globally, policy discussions now incorporate a more urgent understanding of methane’s role in near-term warming. Each intervention represents tangible mitigation or adaptation, demonstrating that environmental progress can be measured in lives, livelihoods, and ecological stability — not just abstract metrics.
While each laureate’s approach is distinct, together they illustrate a unified principle: effective climate solutions must be both contextually grounded and globally informed. UNEP’s recognition amplifies these lessons, providing visibility and legitimacy to approaches that might otherwise remain localised or underappreciated. The 2025 Champions of the Earth thus serve not only as exemplars but also as catalysts, inspiring other leaders, communities, and institutions to act with urgency, innovation, and empathy.
In sum, the 2025 UNEP awards tell a story of the contemporary climate landscape: rising heat, vanishing forests, creeping seas, and invisible gases pose immediate threats. But the same story demonstrates that solutions exist, can be implemented today, and have measurable human impact. The five laureates show that tackling climate change requires a multiplicity of approaches, grounded in science, law, design, and governance, and always focused on the communities most affected. Their work offers a roadmap for resilience: one that is practical, ethical, and scalable — and that transforms abstract climate policy into tangible human benefit.
As global temperatures climb and climate pressures intensify, the example set by Supriya Sahu, the Pacific Islands students, Mariam Issoufou, Imazon, and Manfredi Caltagirone is clear: action, intelligence, and commitment can create a livable future — if it is rooted in evidence, equity, and urgency.
– global bihari bureau
