Biochar for Urban Climate Resilience in Nature-Based Solutions: A Bibliometric Review of Trends and Outlooks

Biochar, a carbon-rich material derived from pyrolyzed biomass, is increasingly recognized for its potential in enhancing urban climate resilience through nature-based solutions (NbS). Cities face mounting challenges from climate change, including urban heat islands, stormwater surges, and degraded soils. Biochar offers multifunctional benefits carbon sequestration, improved soil water retention, pollutant adsorption, and circular waste pathways that align closely with urban adaptation and mitigation needs. This paper conducts a bibliometric review using Lens.org database, complemented by recent literature (2020–2025), to map global trends, hotspots, and research gaps. The analysis reveals a significant growth of publications post-2010, with disciplinary expansion from agronomy to environmental engineering, urban planning, and materials science. Hotspots include stormwater management, urban soils, green roofs, carbon sequestration from urban biomass, and pollution remediation. While the field demonstrates interdisciplinary integration, gaps persist in long-term urban field studies, standardization of biochar properties, and socio-economic governance analyses. The findings highlight both opportunities and challenges for scaling biochar as a viable NbS in urban climate resilience strategies.