Stephanie Briers

Integrated assessment models (IAMs) are increasingly criticised as opaque and disconnected from the concerns of those affected by their results. Participatory and transdisciplinary approaches respond to this, but stakeholder input is often simplified, narrowed, or dropped once it meets a model's technical limitations, without explanation. This paper asks what happens when model tractability no longer filters which research questions (RQs) stakeholders can raise in the first place. Drawing on the Horizon Europe project DIAMOND, we describe a transdisciplinary process in which 40 RQs were co-designed with stakeholders across nine themes, eight scoped in advance and one that emerged unprompted, then triaged for tractability against six IAMs. In six of the nine themes, stakeholder input redirected or extended the project's initial framing rather than confirming it, and none of the 40 RQs was rated as requiring no model adjustment. Rather than treating these limitations as reasons to filter questions in advance, we argue that transparency about them should be an output of the process itself. Research questions IAMs cannot yet answer are documented and published as an open repository instead of being silently dropped, turning an unexamined gatekeeper into a visible, contestable record of whose futures still need modelling.

Integrated Assessment Models (IAMs) are central to informing climate policy and sustainable development, yet face longstanding criticisms related to transparency, legitimacy, and exclusion of societal actors. This paper argues that a transdisciplinary (TD) approach, offers a promising pathway to address these critiques. However, it can be overwhelming for researchers who know little about TD to grasp the core principles that ground and guide such an approach. We identify and systematise thirteen TD principles that underpin a TD approach from the literature and categorise them as project, process, and outcome principles, in an accessible format. Drawing on the DIAMOND project, which aims to expand and co-produce six IAMs through collaboration with societal actors, we use a qualitative approach to examine how these principles are perceived by modelling teams in a series of workshops. We find that while some principles, such as engaging with scientific and non-scientific actors, are embraced, others, including practicing reflexivity and systemic thinking, require strengthening or more nuanced understandings. We argue that reflecting on a project process through these TD principles and embedding the principles more intentionally can help IAMs better respond to the challenges and criticisms they face. By shifting IAMs toward more open, co-owned, and context-sensitive approaches, TD principles can support IAMs to inform more socially robust and actionable climate solutions. The paper contributes a grounded, accessible framework to advance a TD research approach not only in integrated assessment modelling, but all large-scale projects taking on a TD approach to address complex sustainability challenges.

Pedestrian activity is often measured in the formal parts of cities, yet it has rarely been studied in informal settlements, although they are typically adjacent to formal areas and residents participate in formal urban life. Route optimization and space syntax are two pedestrian activity theories that can be applied to predict path usage in urban areas. These theories have been tested in formal cities, but are they applicable in understudied informal settings? Using motion sensors, we measure pedestrian activity in a Cape Town informal settlement in the early morning and evening hours and test which theory best explains the sensor measurements. Route optimization is weakly correlated with average pedestrian activity, while space syntax performs even more poorly in predicting pedestrian activity. The predictive power of both theoretical calculations further varies by time of day. We find that both theories perform worst at the entrances/exits of the informal settlement—that is, the border between informal and formal. These results indicate that daily movement patterns in informal settlements may differ from formal areas and that the connection between the formal and informal city requires further study to better understand how pedestrian activity links these two types of areas. A new theory of route selection based on such an understanding, which also better incorporates the specific characteristics of informal urban settlements—such as high density, narrow, and constantly changing streets primarily used by residents—may be necessary to understand the needs of pedestrians within informal settlements as compared to formal areas.