International climate adaptation assistance: Assessing public support in Switzerland

PLOS ONE | https://doi.org/10.1371/journal.pone.0317344 February 12, 2025 12 / 26 PLOS ONE Support for adaptation assistance in Switzerland interaction effects such as Average Marginal Component Effects (AMCEs) require the arbi- trary choice of a baseline category, which can affect the directionality, size, and significance of coefficients. In contrast, MMs summarize outcomes by averaging predicted probabilities across all levels of attribute or covariate combinations. By averaging these predicted probabil- ities, MMs provide an intuitive and comprehensive summary of the favorability of the policy package with a given attribute level [87]. Because of these advantages, MMs have become an established method for conjoint survey experiments. Thus, we interpret marginal means from a forced-choice conjoint survey experiment as the favorability of a policy package with a given attribute level to gauge public support. Fig 2 presents MMs, whereby the vertical dashed line represents the 50% (0.5) threshold. Coefficients higher than 0.5 reflect that a policy proposal with the respective attribute level increases the favorability of a climate adaptation policy (as long as the confidence interval around the point estimate stays on the right of the 0.5 level), while coefficients lower than the threshold reflect lower favorability (as along the confidence band around the point estimate stays on the left of the 0.5 level). We discuss the results along the different dimensions of our argument and specific hypotheses. Descriptive statistics are presented in Supporting informa- tion S2 Fig.

Limited unconditional support for climate aid or climate migration We found no statistically significant effects for adaptation packages at any level of climate aid. This is surprising because supporting Global South countries in climate adaptation is now an important issue in global policy conversations. Previously, Global North countries had pledged annual climate aid to the tune of US$100 billion. This was revised upwards to US$300 billion at the 29th Conference of Party meeting in Baku (although this is far below US$1.3 tril- lion demanded by Global South countries). Of course, how much of the aid will be devoted to climate adaptation remains unclear, yet climate aid has gained more prominence on the world agenda. We do not find Swiss respondents expressing a preference for policy packages with high or low levels of adaptation aid (Hypothesis 1 is not supported). While the limited preference of respondents for adaptation aid is consistent with the findings by Gampfer et al. [25] in other country contexts, it is somewhat surprising in the Swiss context, as Switzerland has a reputation for being one of the first Global North coun- tries to provide adaptation aid [88]. According to the latest available data from the OECD Development Assistance Committee (DAC), Switzerland increased climate aid as a percentage of bilateral aid to 23% in 2020–21 compared to 19.5% the previous year, with a greater share devoted to adaptation assistance compared to mitigation [89]. However, despite its stronger

emphasis on adaptation compared to other OECD countries, Switzerland still lags in terms of the share of bilateral aid directed to climate issues compared to the OECD average [89]. More recently, the Swiss Agency for Development and Cooperation and the State Secretariat for Migration have established a new program for climate change and migration “to create better prospects” for youth in North and West Africa and establish safeguards against youth traffick- ing and abuse [90]. Such policy initiatives are illustrative of the concern about proximity and the political salience of the region, as well as linkages between climate adaptation, develop- ment prospects, and migration. Such concerns, however, are not reflected at the level of public opinion according to the results of our conjoint survey experiment. Migration is also a form of adaptation: by accepting climate migrants, Switzerland could support overseas climate adaptation. However, we find that Swiss respondents favor policy packages with zero immigration and disfavor high levels of immigration (1,000, 1,250). This likely reflects the populist backlash against immigration in many European countries, includ- ing Switzerland (Hypothesis 2 is supported).