CHENNAI: Tamil Nadu’s expanding urban forestry initiatives may soon have a standardised system to measure their climate benefits, with a new roadmap proposing a methodology to quantify how tree planting helps mitigate climate change and strengthen urban resilience. The roadmap, prepared under the Indo-German Support Project for Climate Action in India, outlines a framework to assess the “climate co-benefits” of urban forestry programmes in the state. These include carbon sequestration, urban cooling, groundwater recharge, flood mitigation and biodiversity enhancement.
Urban forestry initiatives are primarily aimed at improving green cover and biodiversity, but they also deliver significant climate mitigation and adaptation benefits. However, these impacts have rarely been measured systematically, limiting their use in policy planning and climate reporting, the document notes.
I Anwardeen, principal chief conservator of forests and chief mission director of Green Tamil Nadu Mission, told TNIE that 14.16 crore seedlings were planted across the state between 2022-23 and 2025-26, covering a potential area of 1.28 lakh hectares. “Rough estimates show that 2-3 lakh tonnes of carbon dioxide are sequestered every year. We do not yet have specific data on the extent of urban plantations, but efforts are under way to segregate the data. Conservative estimates suggest around 25 lakh seedlings have been planted in urban areas so far, and another seven lakh are proposed this year. The primary challenge is the availability of land and subsequent maintenance,” he said.
The proposed methodology focuses on estimating both mitigation and adaptation benefits of urban forestry. For mitigation, it calculates carbon dioxide removal through biomass accumulation in trees, using field measurements such as diameter at breast height or default sequestration factors depending on data availability.
For adaptation, four key indicators have been identified: reduction in the urban heat island effect, improvement in groundwater recharge, enhanced flood and stormwater management, and increased biodiversity. Trees can reduce urban temperatures through shading and evapotranspiration, while vegetation also improves infiltration and reduces runoff during heavy rainfall.
The roadmap also identifies several challenges in implementing such monitoring systems. These include limited awareness of climate co-benefits among field staff, lack of baseline data, inadequate training in monitoring methods, and limited use of tools such as remote sensing and environmental sensors. More than 25 organisations were consulted during the development of the methodology.
The roadmap proposes phased implementation through policy advisories, pilot projects, capacity-building programmes, and integration of climate co-benefit monitoring into existing urban forestry schemes.
Additional chief secretary Supriya Sahu said such assessments could eventually support climate reporting under India’s Nationally Determined Contributions and help attract funding through government schemes, CSR initiatives and carbon markets. “By institutionalising the methodology across programmes and agencies, the framework aims to ensure that the climate benefits of urban tree planting are systematically measured, reported and incorporated into planning and investment decisions,” she said.