Exploring climate pollutants levels and variations in Islamabad's built-environment: A nature-based policy framework for sustainable emissions management.

The growing energy consumption in Islamabad is escalating temperatures and climate-related risks for residents, exacerbated by the absence of sustainable strategies. Therefore, this study was conducted to probe climate pollutants (carbon dioxide (CO), nitrogen dioxide (NO), ozone (O), and methane (CH)) levels in the built environment of Islamabad. Based on these emissions, a nature-based solutions (NbS) approach was then proposed to manage the identified pollutants from urban developments. Data on electricity consumption (n = 44,792), natural gas usage (n = 33,632), and carbon fluxes were collected to estimate CO emissions, while NO, O, and CH data were obtained from the Sentinel-5P satellite. The NbS policy framework was developed based on a meta-analysis of 345 available studies to extract established NbS reduction effects and community stakeholders survey of 224 participants. The analysis revealed that the residential sector contributed the highest emissions of the target climate pollutants, primarily due to its significantly larger number of units (554,754) within the study area. This was followed by the commercial sector (81,024 units), special residential sector (5576 units), and the industrial sector (2244 units). Among the building heights it was revealed that taller residential buildings (6-30m) exhibited higher emissions of the target climate pollutants (CO: 18 million tons: CH: 58.03 mega mols, NO: 2050 and O: 4109 mol/m) in comparison to the shorter non-residential dwellings (<3-6m) that had comparatively lower emissions (CO: 0.16 million tons, CH:1.71 mega mols, NO: 63 and O: 121 mol/m). Linear regression models predicted that climate pollutants from built-up areas and building heights significantly contributed to rising temperatures (p < 0.001). The comprehensive meta-analysis of available literature and sensitivity analysis of community-driven approach suggested that green routes for residential; green infrastructure for industrial; green facades for special residential; and urban forests for commercial sectors are promising NbS to reduce climate pollutant emissions in these targeted regions. The study highlighted the lack of NbS policy in Islamabad, urging the need for prioritized zoning, integration of social, economic, and ecological indicators, and the adoption of green construction permits and codes to reduce emissions from new developments.