RESEARCH PAPER PRESENTATION
Urban heat mitigation by green and blue infrastructure: Drivers, effectiveness, and future needs
This global systematic review examines how green-blue-grey infrastructure can reduce urban overheating, comparing the cooling performance of 51 intervention types across climates and methods. It is especially relevant for city planners, policymakers, and researchers designing heat adaptation strategies under climate change.
Green-blue-grey infrastructure can substantially mitigate urban overheating, but its effectiveness varies by infrastructure type, climate, scale, and implementation context, requiring more systematic evidence to guide future planning.
The article investigates which types of GBGI are most and least effective at reducing urban heat, how those effects differ across climate zones and urban settings, and what co-benefits or drawbacks accompany them. It frames urban heat mitigation as both an adaptation challenge and a planning problem, weighing immediate cooling gains against uncertainties related to future climate shifts, maintenance, equity, and multifunctionality.
The problem
Urbanization and climate change are increasing the frequency, intensity, and persistence of extreme heat, exposing urban residents to growing risks of illness, death, reduced wellbeing, and economic disruption. Although many forms of urban green and blue infrastructure are promoted as cooling solutions, the evidence base has been fragmented, uneven across intervention types, and insufficiently translated into clear implementation guidance for cities.
Key findings
The review found that GBGI can meaningfully reduce urban temperatures, but performance differs widely by intervention type, climate zone, and measurement method. Botanical gardens, wetlands, green walls, street trees, and vegetated balconies emerged among the strongest performers overall, while many potentially useful interventions remain poorly studied. The literature is heavily concentrated on a small subset of GBGI types and on micro-scale applications, indicating substantial evidence gaps for broader city-scale planning. The authors also found that co-benefits are underreported and that future climate shifts may reduce the effectiveness of some current GBGI strategies.
27,486 papers screened; 202 reviewed
The systematic review narrowed a very large literature base to 202 publications suitable for meta-analysis.
51 GBGI types in 10 categories
The paper assesses a broad typology of green-blue-grey infrastructure interventions for urban heat mitigation.
5.0 ± 3.5°C
Botanical gardens showed the highest reported average air-cooling efficiency among the reviewed GBGI types.
4.9 ± 3.2°C
Wetlands were among the strongest-performing interventions for reducing urban air temperature.
What cities should do
Cities should prioritize place-specific GBGI portfolios that match local heat risk, climate conditions, land availability, and vulnerable populations rather than relying on one-size-fits-all solutions. They should integrate green, blue, and engineered measures into urban planning and retrofitting; assess co-benefits and unintended consequences; and expand nature-positive design across streets, parks, roofs, walls, and water systems. Policymakers should also target heat-vulnerable neighborhoods, support community cooling infrastructure, and account for future climate shifts when selecting and scaling interventions.
Implementation Approach
The paper recommends a staged implementation process that begins with stakeholder engagement and feasibility assessment, followed by design, supportive policy development, installation, monitoring, evaluation, and eventual scaling. The overall approach emphasizes evidence-based planning, local adaptation, and continuous learning so that GBGI investments maximize cooling while also delivering broader social and ecological benefits.
Stage 1: Early planning
Identify stakeholders, engage communities and agencies, and assess heat-vulnerable areas and candidate sites for GBGI interventions.
Stage 2: Feasibility and design
Evaluate technical, economic, and environmental feasibility; compare co-benefits and dis-benefits; and design an appropriate mix of green, blue, and grey measures.
Stage 3: Policy and implementation
Embed GBGI into planning rules, incentives, and retrofitting frameworks, then construct and install interventions with coordinated project management.
Stage 4: Monitoring and evaluation
Track temperature reduction, vegetation health, air and water quality, and other indicators to assess performance and maintenance needs.
Stage 5: Upscaling and replication
Use lessons learned and evaluation results to expand successful interventions to larger areas or replicate them in other locations.
Ready for more?
Explore additional presentations that complement this one
Balancing green and compact city: Assessing the quality of residential surroundings
This comparative article examines whether compact urban development reduces the quality of residential green infrastructure, using multifamily housing estates in Poznan and Copenhagen as case studies. It is relevant to urban planners, housing policymakers, and sustainability practitioners interested in densification, biodiversity, and livable neighborhood design.
Read moreTowards a pattern language for green space design in high density urban developments
This article proposes a systematic framework for designing urban green space in high-density developments using a pattern language approach. It is relevant to urban designers, planners, landscape architects, and policymakers seeking to balance ecosystem services, biodiversity, and space constraints in compact cities.
Read moreSmart Cities and (Smart) Cycling
This article examines the integration of smart cycling technologies in smart city initiatives in Copenhagen and Amsterdam
Read more