Raising Delhi’s tree cover from 3 to 11% can lower ‘felt heat’ by 1°C: Report

Increasing tree cover in Delhi can lower summer temperatures by 1°C, outpacing urbanization's 0.6°C rise, highlighting the need for targeted urban greening.

Increasing tree cover from 3% to 11% in a one square kilometre area during peak summer conditions in Delhi can lower experienced temperatures by as much as 1 degree Celsius (°C), according to a report released by Artha Global and data.org.

The study used high-resolution geospatial data and surveys of 2,368 households across all 70 assembly constituencies (Hindustan Times)

This cooling potential far outpaces the warming caused by urbanisation, as the study – titled Mapping Heat Inequality Across Neighbourhoods in Delhi – found that increasing built-up area from 25% to 55% raises experienced temperatures by only about 0.6°C. This “asymmetry” positions modest greening as a far more effective tool for reducing heat stress than concrete is for increasing it.

“Going from a significantly underbuilt green area to a very built area, you’re seeing changes of about 0.6°, but when we increase green cover by about 5 to 10 percentage points, you’re getting a cooling effect of one degree,” said Neelanjan Sircar, one of the co-authors, while presenting the paper on Monday in New Delhi.

The report recommends shifting from city-wide averages to micro-level heat action plans that zero in on ward-level “hot pockets.” It urges urban design that treats vegetation as “essential infrastructure,” integrating wetlands and shaded corridors into the city’s master plan.

A 3°C hike in experienced heat links to a 15% rise in reported illness and a 10% jump in households missing work. AC ownership correlates with an 11.6% lower incidence of heat-related illness and 18% less work loss.

“We see that the incidence of heat-induced illness is going up from about 30% to about 40%, and we see households reporting somebody missing work due to heat also going up significantly to well over 25%,” Sircar said.