## 3 Methods and Data
### The Use of Participatory-Based Methodologies
#### 3.2.2 Delphi's Approach to Addressing Climate Change Challenges  
Several authors report that Delphi's approach facilitates the organization of group communication, through structured surveys, allowing us to deal with multifaceted and complex problems in various iterations [53, 54, 55, 56, 57]. In this investigation, it was decided to structure the technique with some modifications, as will become evident during the presentation of the method. In this context, we chose to use the designation Modified Delphi Approach (MDA), considering that it would be hard to find a consensus, but above all to synthesize measures to be delineated based on two iteration rounds. Experts (or relevant regional and local stakeholders) are invited to give their opinion in sequential questionnaires, based on group feedback from the previous round. Feedback on sequential rounds encourages participants to re-evaluate, change and/or develop their opinions [57, 58, 59]. We opted for answers from anonymous participants to ensure that none of the experts monopolized or dominated the process [60, 61], although some authors choose to reveal the identity of the participants [57, 62]. Two questionnaires were provided for this study (Appendices B and C). The first panel made it possible to evaluate and predict the measures to be developed for a tourism strategy in the context of adaptation to climate change. Several elements for discussion and reflection were proposed regarding the promotion of the tourism sector and its resources. Both questionnaires reflected the exhaustive longitudinal review of the scientific literature and previous studies conducted by the research team (Table 3). The questionnaire was tested by 8 local experts who verified the used language, comprehension and ease of response, and consistency of the instrument. An inter-observer agreement was also established based on three team meetings held prior to the start of the questionnaire application to reduce potential gaps and standardize information to be transmitted to MDA participants. The first questionnaire was organized into 4 groups, in which we sought to identify: (i) the scale of action of tourism for the adaptation of the urban tourism sector to climate change; (ii) climate change constraints in the tourism activity; (iii) measures for adaptation and mitigation of climate change in the tourism sector; and (iv) the Delphi panel technical participants selected. The questionnaire was structured in 22 questions, some of them subdivided into sub-items and open questions. In each topic, participants were invited to assess the probability of different tourism propositions in PMA in a climate change scenario, in the short, medium, and long term. This method is supported by the De Loe Model (1995) [63], using a 5-point Likert scale, with an additional option for those who 'don't know'. Each of the participants were nevertheless asked to explain their reasoning whenever they considered it useful, based on the relevant evidence of support for their decision-making. The last question allowed us to suggest relevant facts for reflection and discussion that were not considered a priori. After this round, the answers were processed and disclosed anonymously to the other members of the panel. In this study, we chose to apply the MDA to 47 experts and regional and local stakeholders from various national and international academic institutions, companies, associations, and local and regional organizations (namely, Spain, Germany, Hungary, Canada, Brazil, and Turkey) between 22 January 2021 and 12 April 2021. A total of 34 of the 47 professionals in the first round participated in the second questionnaire (72.3% of the initial sample--Table 2). According to the latest review articles in the field, the number of participants in both questionnaires was quite acceptable [64, 65, 66]. The first questionnaire sought to identify the relevance of a package of measures related to climate change.