UN official pushes for nature-based cooling, climate-smart construction as shield against rising heat in Mumbai

Mumbai: As Mumbai gears up for the inaugural Mumbai Climate Action Week (MCW), a top United Nations environment official said there is an urgent need to scale "nature-based cooling" and climate-smart construction practices to protect cities from rising heat, flooding and climate impacts.Martin Krause, Director of the Climate Change Division at the United Nations Environment Programme, said the megacity's low-lying position and rapidly increasing temperatures make adaptation a pressing priority. "Mumbai is a coastal megacity where sea-levels rise, flooding and extreme heat are no longer distant risks — they are already affecting people's lives. Fortunately, there are practical, affordable solutions — many of which work with nature rather than just machines," he said.
Krause pointed to solutions such as restoring wetlands, reconnecting rivers to parks to absorb rainwater, expanding urban tree cover and introducing rooftop gardens. Such measures, he said, are part of what experts refer to as nature-based solutions: low-cost, nature interventions that help reduce ambient heat."Tree cover, shaded streets, reflective roofs and green spaces can lower temperatures by several degrees. These measures help not just the environment but human health and comfort, especially for vulnerable populations," he said, adding that while such strategies can significantly mitigate heat outdoors, indoor cooling still often requires mechanical systems. He advocated pairing nature-based solutions with passive cooling in buildings, energy-efficient air conditioning and district cooling systems that minimise electricity demand and avoid peak load spikes. While passive cooling gained traction globally over the last 5 years — more than 230 cities are now exploring it as part of climate adaptation planning, Krause said."We are working with cities across Africa, Asia and Latin America to support these measures," he explained. "The evidence base is growing, but the promise is clear. In Europe, cities such as Paris already operate district cooling networks that circulate chilled water to buildings — a model that could even benefit Indian megacities," he explained.On the MoU between UNEP and the Maharashtra govt under the global "BeCool" programme, a key focus, he said, is integrating passive cooling into building regulations — a shift from pilots to mandatory practice. "It's always cheaper to build climate-smart from the outset than retrofit later," he said. "We are working with developers and builders to integrate shading, insulation, roof orientation and better materials into designs."Retrofit efforts in older buildings, schools and hospitals are also important, though often more costly, he added.Asked why green building practices remain pilots in many instances rather than mainstream norms, Krause pointed to a combination of awareness, capacity and finance gaps. "Pilots demonstrate what's possible, but the market needs incentives," he said. "Architects, engineers and builders need training — and buyers need access to affordable finance." Krause pointed to international examples where buildings with energy-efficient design or a "green label" qualify for lower interest loans — an approach UNEP is exploring with Indian financial institutions.Highlighting that extreme heat disproportionately affects the poor and vulnerable, Krause said cooling should be reframed as a matter of health and dignity."In many Indian cities, people already experience 40–45°C heat for weeks at a time," he said. "Cooling is not a luxury — it is essential for well-being." Several Maharashtra cities signed up for the Beat the Heat programme, which aims to raise awareness and catalyse action focused on vulnerable populations.To ensure climate pledges translate into measurable outcomes, Krause stressed the importance of data-driven tracking. UNEP is supporting heat-mapping using satellite and ground-based tools to identify urban heat islands and prioritise interventions. "Setting baselines and clear targets — such as retrofitting a certain percentage of public buildings — allows progress to be tracked and verified," he said.Calling the Mumbai Climate Action Week "significant", Krause said such events help link local realities with global experience. "Climate impacts are felt most strongly at the local level," he said. "Bringing municipal leaders, policymakers and international experts together accelerates learning and action."