International climate adaptation assistance: Assessing public support in Switzerland

PLOS ONE | https://doi.org/10.1371/journal.pone.0317344 February 12, 2025 10 / 26 PLOS ONE Support for adaptation assistance in Switzerland The six attributes in the conjoint are: (1) the recipient developing country (Algeria, Kenya, Bangladesh, Philippines); (2) the level of climate aid Switzerland will provide to the recipient country per year (0 CHF, 30 million CHF, 60 million CHF, 90 million CHF, 120 million CHF); (3) the number of immigrants from the recipient country Switzerland will accept per year (0, 250, 500, 750, 1,000, 1,250); (4) the type of extreme weather event that the recipient country experiences (drought, sea level rise, flood, cyclones); (5) the volume of trade between Switzer- land and the recipient country (0, 500 million, 100 million); (6) the percentage of times the recipient country voted with Switzerland at the UNSC (0%, 40%, 80%). To present respondents with credible information, we set the levels of the trade attribute using official data available on the website of the Swiss Federal Department of Foreign Affairs on the trade volume between Switzerland and each one of the recipient countries (https:// www.eda.admin.ch/, accessed 2003). Table 1 displays attributes, their labels in the survey, and the possible levels. The value any attribute took randomly varied within and across choice tasks. The only restriction to randomization was that the policies constituting a pair within each choice task always referred to two different countries, to avoid instances in which a respondent would be

asked to choose between policy packages referring to the same country. Because we want to understand public support for bilateral adaptation packages, the recip- ient country always appeared first, followed by two forms of adaptation assistance, aid level and immigration level (the order in which these attributes appeared in the conjoint table varied randomly between positions 2 and 3, across respondents) and, lastly, recipient country charac- teristics such as extreme weather event, trade volume, and UNSC vote convergence (the order in which these attributes appeared in the conjoint table varied randomly between position 4, 5 and 6, across respondents). For any respondent, the order of the attributes that appeared in the conjoint table was kept constant across six iterations, to reduce cognitive burden (Fig 1). Following the completion of the six choice tasks, respondents were asked to answer ques- tions to assess their personal and/or cultural beliefs that may influence their policy prefer- ences. Given the high level of contention around immigration in Swiss politics, we posed questions about respondents’ beliefs about whether linguistic and cultural proximity might help immigrants integrate with Swiss society, whether development aid reduces poverty, and the extent to which they feel pride toward Swiss history and culture. Specifically, respondents were asked to indicate the extent to which they agreed or dis- agreed with the following statements: “Immigrants from countries whose languages are

similar to those spoken in Switzerland will integrate more easily in Switzerland”; “Immi- grants from countries that are culturally similar to Switzerland will integrate more easily Table 1. Conjoint experiment attributes and levels. Attributes Labels Levels Recipient country Recipient developing country Bangladesh/Philippines/Algeria/ Kenya Level of climate immigration Number of climate migrants to accept from this country per year 0/250/500/750/1,000/1,250 Level of climate aid Climate aid to give to this country (CHF) per year 0/30 million/60 million/90 mil- lion/120 million Trade volume Value of Swiss trade with this country (CHF) 0/500 million/1,000 million Extreme weather event Extreme weather event Drought/Sea level rise/Floods/ Cyclones UNSC voting alignment Percentage of this country’s votes in line with Switzerland’s position at the UN Security Council 0%/40%/80% https://doi.org/10.1371/journal.pone.0317344.t001