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Title of the thesis: Green capture - Enhancing carbon sinks within urban residential green spaces

Thesis defender: Mari Ariluoma
Opponent: Johanna Deak Sjöman, Swedish University of Agricultural Sciences
Custos: Prof. Ranja Hautamäki,Aalto University School of Arts, Design and Architecture

Urban green spaces play a significant, yet partly underutilized role in mitigating climate change and supporting biodiversity.

Landscape architect Mari Ariluoma’s doctoral research demonstrates that urban courtyards can function as local carbon sinks while simultaneously providing multiple co-benefits, such as cooling, stormwater management, and enhanced well-being. Although an individual courtyard may be small in area, collectively the courtyards of residential neighborhoods form a substantial part of the urban green infrastructure, making them key to addressing climate and biodiversity impacts.

The study explores how the design, construction, and maintenance of urban greenery influence the cycle of organic carbon, and how green structures can be developed in a carbon-smart way. While greening courtyards alone cannot compensate for emissions caused by construction and consumption, they can offer multifunctional, localized solutions for climate mitigation and adaptation, even in densely built environments.

The dissertation highlights the considerable carbon sink potential of urban courtyards, which should be utilized more effectively. The findings show that planning decisions, diverse vegetation, and maintenance practices can significantly enhance the carbon sequestration capacity of urban courtyards. In particular, large mature trees and layered plant communities provide notable benefits for both carbon capture and biodiversity. Strengthening carbon sinks, however, requires an understanding of the carbon cycle throughout the lifecycle of green spaces, as well as changes in planning, construction, and maintenance practices.

The research emphasizes a more holistic approach that integrates climate goals with biodiversity support. It also brings attention to the challenges of design: in densely built urban environments, space allocated for vegetation is often limited and competes with other functions. Landscape design must often balance ecological objectives with social acceptability and practical constraints. In addition to scientific knowledge, local interpretation, experiential insight, and collaboration between stakeholders are needed. Landscape architecture plays a central role in this integration, as the discipline significantly contributes to ensuring urban livability. Therefore, closer cooperation between research and practice is needed, along with bold initiatives toward climate- and nature-smart cities.

Keywords: carbon sink, green space, nature-based solutions, co-benefit, carbon-smartness, landscape design

Contact: mari.ariluoma@aalto.fi, 0400 205483

Thesis available for public display 7 days prior to the defence at .