How India's financial capital is grappling with climate change through science, data, and community-driven solutions
In Mumbai, the climate is no longer a backdrop; it is a central, forceful character in the city's story. In the span of a single year, its 12 million residents can face two seemingly opposite extremes: summer heat so intense it creates a 13-degree temperature gap between concrete-dominated neighborhoods and leafy outskirts, and monsoon rains so ferocious they can dump a month's worth of precipitation in just a few days, submerging streets and paralyzing the economic heartbeat of India 1 4 5 .
Temperature gaps of up to 13°C between urban and suburban areas
Month's worth of rainfall in just a few days, causing severe flooding
"This isn't just bad weather. It's the new reality of life in a megacity on the front lines of climate change."
Scientists point to a clear pattern: climate change is reshaping the Indian monsoon, driving fewer rainy days but more intense rainfall events 1 . At the same time, rapid urbanization has replaced natural land cover with concrete and asphalt, creating a powerful urban heat island effect (UHIE) that turns entire neighborhoods into ovens 2 .
The urban heat island effect is a phenomenon where a city is significantly warmer than its surrounding rural areas. The cause is fundamental: Mumbai's rapid development has converted natural, permeable surfaces—soil, water, and vegetation—into urban paved areas like roads, parking lots, and buildings. These materials absorb and re-radiate the sun's energy far more effectively than natural landscapes.
The result is a stark temperature divide. Measurements show that while areas on the city's outskirts with abundant vegetation and water bodies enjoy temperatures between 21°C and 23°C, highly built-up urban zones can sizzle at up to 34°C or more 2 . In the suburb of Andheri East, the construction of a metro line saw the average recorded temperature in the Marol Industrial Estate jump from 29.27°C to 38.8°C after the work was completed 2 .
If heat is a slow-burning crisis, the monsoon is its dramatic, destructive counterpart. The traditional rhythm of Mumbai's rains has been disrupted. As one expert explains, "The number of rainy days has decreased, but the quantum has increased" 1 . This means less frequent but far more intense downpours.
In one recent August, after a surprisingly dry July, the city was hammered by incessant rains for four consecutive days. By the time the skies began to clear, Mumbai had recorded more than 800 mm of rainfall, utterly surpassing its entire monthly average of 560.8 mm 4 . Such events are becoming more common, leading to localized flooding, landslides, and overwhelmed drainage systems.
"Climate change acts like a 'steroid' on the monsoon system; the warming of the Arabian Sea provides massive moisture, while warming over the Middle East increases atmospheric instability, pulling this moisture inland and resulting in devastating rainfall." 4
In June 2025, a unique experiment took place in Mumbai. More than 28 participants—including GIS experts, developers, researchers, and active citizens—gathered for a "datajam" focused on urban heat. Organized in partnership with the Maharashtra State Climate Action Cell and supported by organizations like WRI India and C40 Cities, the event aimed to move beyond broad statistics and understand how heat stress plays out at the neighborhood level 9 .
Teams gathered satellite data, specifically Land Surface Temperature (LST) maps from Google Earth Engine.
Satellite data was correlated with on-the-ground information including census data and green cover maps.
Teams pinpointed hotspots and analyzed relationships between land use, density, vegetation, and socio-economic factors.
The findings painted a stark picture of inequality. The datajam revealed that the hottest areas were consistently the city's dense informal settlements, where temperatures soared to 48°C. For comparison, green and open areas in the same wards were found to be 6-7°C cooler 9 .
| Ward | Neighborhood Type | Key Characteristics | Land Surface Temperature Range |
|---|---|---|---|
| H/East | Informal Settlements | High density, metal roofs, minimal green cover | 43°C - 47°C |
| L Ward | Informal Settlement | Lack of green areas, river pollution, stagnant water | ~48°C |
| All Wards | Green/Open Areas | Parks, race courses, natural landscapes | 6-7°C cooler than settlements |
| P/North | Deforested Areas | Recent clearing in Sanjay Gandhi National Park | Rising to 50°C |
The analysis also yielded nuanced insights. For example, the team studying the M/East ward found that while low-rise, high-density informal settlements were extreme heat hotspots, taller vertical constructions tended to be slightly cooler, likely due to the shade provided by the buildings themselves and reduced surface area exposure 9 . The data also showed a rapid escalation of the threat; in the P/North ward, the highest temperatures people were exposed to had risen from 42°C to 50°C in just the last nine years 9 .
Confronted with these daunting challenges, Mumbai is not standing still. The city is mobilizing on multiple fronts to adapt and build resilience.
This is the city's cornerstone policy. It includes a priority action to increase vegetation cover and permeable surfaces to 30-40% of the city's area by 2030 to tackle both floods and heat 2 .
This has already spurred projects like the 3.2-acre Urban Forest and Nature Conservancy Park in Marol, which is expected to reduce local temperatures by 0.4°C to 3.0°C and serve nearly 173,000 people 2 .
Experts consistently stress the need for "citizen-centric" early warning systems for urban flooding 4 .
Initiatives like IIT Bombay's Mumbai Flood Monitoring System, which provides real-time data to stakeholders, are critical steps in this direction.
The city is also looking to address the root cause of climate change. IKEA's parent company, Ingka Investments, is building a 210 MWp solar plant in Rajasthan to power its retail operations in India, part of a multi-billion-euro global commitment to renewable energy 3 .
Furthermore, Mumbai is targeting net-zero carbon emissions by 2070, aligning with India's national goals and driving a shift towards green buildings and sustainable construction 7 .
Sustainable development, low emissions
Medium-level emissions
Business-as-usual, high emissions
Source: Adapted from Scientific Reports, 2025 8
| Solution Category | Specific Actions | Primary Benefit |
|---|---|---|
| Nature-Based Solutions | Developing urban forests, increasing tree cover, preserving mangroves | Reduces urban heat island effect, mitigates flooding |
| Early Warning & Data | AI-ML Risk Atlases, citizen-centric flood monitoring systems | Improves preparedness, saves lives and property |
| Urban Planning & Infrastructure | Green building codes, cool roofs, better drainage, heat-resistant pavements | Creates a more livable and durable urban environment |
| Clean Energy Transition | Rooftop solar, corporate investment in renewables, electric vehicle infrastructure | Tackles the root cause of climate change, reduces pollution |
Mumbai stands at a crossroads, its future shaped by the interplay of global climate forces and local action. The data is clear: the heat is rising, the rains are intensifying, and the seas are inching higher. The city's experience is a microcosm of what countless coastal megacities around the world will face.
Yet, within this crisis lies a powerful lesson in resilience. From the community-driven datajams mapping heat inequities to the municipal plans for greener infrastructure, Mumbai is fighting back. The path forward requires a relentless focus on science-based policy, equitable solutions that protect the most vulnerable, and a collective commitment to a sustainable future. The story of Mumbai's struggle is not just its own; it is a letter to the world about the challenges of our time and the human capacity to meet them.