In a recent virtual workshop on 22nd January 2024, titled “Representation of adaptation and maladaptation in integrated assessment models (IAMs)”, attended by over 50 participants, critical discussions unfolded about integrating climate impacts and adaptation strategies in integrated assessment modelling. Chaired by Prof. Detlef van Vuuren, the event delved into recent and forthcoming efforts to improve climate scenario development and provide better mitigation, impacts and adaptation scenarios for stakeholders.

Surveying the audience, including members of the European Commission’s DG-Clima and the Joint Research Center, revealed significant concerns about climate impacts, particularly heat stress and biodiversity loss. Key discussion points included incorporating the vulnerability of socioeconomic and natural systems and the limits and costs of adaptation. The workshop showcased insights from Horizon projects like NAVIGATE, PRISMA, SPARCCLE, and ACCREU, and aimed to align expectations and needs for further climate change adaptation research. The event, co-organized by PBL and Bruegel and featuring speakers from IIASA (Dr Edward Byers & Dr Marina Andrijevic) and Utrecht University (Kai-Ivar van der Wijst), received funding from the European Union’s Horizon Europe program.

Limited coverage of adaptation in models

Detlef van Vuuren introduced the topic, explaining the relevant aspects and the current state of adaptation in model-based research. Integrated assessment models (IAMs) show how socioeconomic developments lead to emissions, resulting in climate change and consequential damages. Mitigation activities can reduce emissions, while adaptation activities can alleviate damages from climate change. The potential level of adaptation is, in turn, determined by the adaptive capacity, which relates to socioeconomic as well as climatic factors. IAMs are much better equipped to represent mitigation than adaptation. This is particularly true for process IAMs that have a much more detailed representation of sectors than cost-benefit analysis (CBA) IAMs. While CBA IAMs currently account for adaptation in a highly aggregated way, process IAMs can potentially represent biophysical impacts and adaptation in a more detailed way in the future. Here, the socioeconomic elements from the SSP scenarios could provide relevant dimensions for adaptive capacity, such as gross domestic product per capita, education and governance. However, it is essential to note that adaptation is highly uncertain and complex to represent, also outside of IAMs, notably in climate impact models. 

Multiple research avenues

The presentation was continued by Marina Andrijevic, who showed the current and planned research activities in the PRISMA project. A goal of the project is to understand the global differences in impacts, abilities to adapt and risks of maladaptation (negative externalities resulting from adaptation) between countries over time​. This is done by looking at scenarios that explore a range of different futures and enable comparisons between models for robust assessments​. In the project, key sectoral adaptation needs and options are identified (e.g. desalination or cooling in buildings), their socioeconomic dependencies are assessed, leading to projections of future adaptation potential and an understanding of the risks of maladaptation (e.g. higher energy use, emissions and costs). Ed Byers continued with the research activities in SPARCCLE (Socioeconomic Pathways, Adaptation and Resilience to a Changing Climate in Europe​), which has a European focus and aims to provide a comprehensive climate risk assessment. By means of a probabilistic spatial emulation of climate extremes and impacts, the project can provide policy-relevant monetized, sector-specific damages, assessments of trade-offs and synergies between mitigation and adaptation and socioeconomic, distributional and welfare implications. The project has a strong dissemination emphasis with a high-resolution visual scenario explorer and an interactive EU scoreboard for a cross-country comparison. Finally, Kaj-Ivar van der Wijst discussed the activities in the ACCREU project (Assessing Climate Change Risk in the EU). The project distinguishes itself from the others with an economic focus, a strong emphasis on stakeholder engagement and co-creation as well as the use of case studies to assess impacts and adaptation potentials in European regions. ACCREU acknowledges the different standpoints held by policymakers (generally more short-term focussed and operational) and researchers (more long-term focussed and theoretical). One relevant ACCREU study, using the SSP-RCP framework, shows the diminishing effect of adaptation at higher levels of warming.

Diverse interests from stakeholders

The presentations were followed by an online interactive stakeholder session to elicit the views and needs of the stakeholders. On the question: ‘What is the most relevant information you need from modellers?’, stakeholders mainly mentioned impacts (also distributional, sectoral, spatial, and local), uncertainty, and integrated projections. Asked: ‘Which adaptation aspects are you currently focusing on in your work?’, the stakeholders replied with diverse topics but a strong representation of buildings: Built environment (also residential cooling and heat stress, air conditioning, construction safety and security, residential energy demand and heat, transport infrastructure), risks for coastal areas, political economic barriers, impacts of adaptation and climate change on power demand, agriculture, biodiversity impacts of land-use changes, adaptation of water quality monitoring framework & sea-level rise. The stakeholders were also asked about the most critical impact and adaptation categories. There was little difference between their rating of the different categories. Still, the highest score was given to natural ecosystems and biodiversity loss (7.2). In contrast, energy supply was given the lowest value (5.7), with all others (flooding/extreme weather, health, water availability, agriculture, energy demand, coastal protection/sea level rise) having values between 6.8 and 6. In the last question, stakeholders were asked about mismatches between the existing research and their interests. The answers did not reveal any clear mismatches in terms of timescale and levels of warming.

Speakers:

• Marina Andrijevic, International Institute for Applied Systems Analysis
• Edward Byers, International Institute for Applied Systems Analysis
• Kai-Ivar van der Wijst, Copernicus Institute of Sustainable Development, Utrecht University

This article’s author(s):

• Mathijs Harmsen, PBL
• Edward Byers, International Institute for Applied Systems Analysis

This meeting was part of a project that has received funding from the European Union’s Horizon Europe programme under grant agreement No 101081604 – PRISMA.

Views and opinions expressed are however those of the speaker(s) only and do not necessarily reflect those of the European Union or the European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible for them.