April 2026 · Illustrative model · Chennai
Why did Chennai
get hot?
Move the sliders to see how each driver contributed — and what partial recovery looks like.
Satellite record
Greenness lost, heat gained
Monthly composites showing NDVI (vegetation) and LST (surface temperature) across five decades.
Pre-satellite
See IISc LULC
reconstruction below
1973 · pre-satellite
Apr 2000 · MODIS NDVI
Apr 2024 · MODIS NDVI
Mar 2026 · MODIS NDVI
Pre-satellite
See IISc LULC
reconstruction below
1973 · pre-satellite
Apr 2000 · MODIS LST
Apr 2024 · MODIS LST
Mar 2026 · MODIS LST
NASA EOSDIS GIBS · MODIS Terra monthly composites · 1 km native resolution
The data behind the heat
50 years of urban transformation
Chennai, 1973 → 2026. Sources cited per card.
Pallikaranai marsh lost since 1965
Wikipedia — Pallikaranai marsh (2021): original extent ~5,500 ha (1965); reduced to 695.85 ha by 2021, a loss of ~87%. Care Earth Trust documentation corroborates >90% historical loss from peak extent.
Wetlands lost across Chennai 1980–2010
Care Earth Trust NGO study (cited in multiple Chennai urban ecology papers): Chennai lost 62% of its wetland area between 1980 and 2010 due to encroachment and urbanisation.
Built-up area growth 1970–2016
MDPI Entropy 2017 (doi:10.3390/e19070358): built-up expanded from 7.67% (1970) to 70.35% of CMA total landscape (2016) — a ~9.2× / 814% increase.
Land surface temperature increase 2013–2022
Environmental Monitoring and Assessment (Springer, 2024): 'LST rose by 6.53°C between 2013 and 2022 in Chennai, coinciding with a 13.33% decline in green cover' (doi cited in study).
What if it played out differently?
Move the sliders to explore how much of Chennai's temperature rise comes from tree loss, lake loss, built-up growth, and aerosols — and what a different path might have looked like.