**5. Conclusions**

Previous research conducted in the study region has suggested that living in the densest urban core areas is associated with higher carbon footprints than living in suburban areas [29–31]. Similar findings have been presented by Chen et al. [32] for Sydney. Minx et al. [27] found for London that it is the spatial accumulation of wealth that is the decisive factor, not the spatial location as such. Furthermore, it is known from previous studies that PEAs do not always correlate with less energy intensive behavior [37,39–41].

Our study included local, domestic, and international travel, which has been called for by other researchers [72]. On the one hand, the results confirmed the well-established connection between compact urban form and local travel and thus suggest that land use planning may be instrumental in reducing carbon emissions by urban dwellers [7,12]. On the other hand, emissions generated from the international travel of urban dwellers are higher than those generated from their daily travel [15,72,78]. This suggests that other processes have a stronger influence on total travel-related emissions than land use planning [14]. Our results showed a correlation between residential location and international travel, but did not explain the reasons behind it. Numerous potential explanations exist, such as compensating for a lack of urban environmental quality, monetary rebounds related to car ownership, prevalence of cosmopolitan attitudes and lifestyles among urban dwellers, or influence of their higher cultural capital and extent of their social networks [34,56,72,79,85,86]. To illuminate these relationships, future studies should supplement quantitative research designs with qualitative methods to reveal motivations behind leisure travel behavior among urban dwellers [56,85].

Several mixed-methods and qualitative studies have already investigated motivations for holiday travel in the context of sustainability. They have highlighted the discrepancies between environmental concern and holiday travel and identified barriers that may hinder behavioral change in this domain [46–48]. These include, among others, high perceived benefits of leisure long-distance travel, such as its importance for social status and personal well-being [87,88]. Some travelers use PEBs in other domains of life to justify their lack of action in leisure travel [48] or may adjust their attitudes to behaviors that are beneficial and well integrated into their lifestyles, despite being aware of climate change and its factors [47]. International leisure travel has not been as often or widely discussed as an important contribution to emissions as private car travel or household energy use. This may have contributed to the awareness–behavior gap in this domain and suggest the need for education about the environmental cost of flying among the public. Future studies should further explore the discrepancy between PEA and flying, using both quantitative and qualitative methods to inform action aimed at behavioral changes. In addition, quantitative studies should use more nuanced models, which include values, beliefs, and norms, as a single PEA index can overly simplify these relationships.

Although changes in travel behavior can directly affect personal emissions, the connection between other PEBs and emissions is less clear and has even been found to be non-existent in the case of heating and energy saving, due to structural factors [51]. Household energy consumption is said to be accountable for over 25% of the personal consumption of GHG emissions in HMA [23] and is thus a key category in lowering the GHG emissions in the area. A shift away from fossil fuels in district heat production would effectively reduce the emissions due to the wide coverage of the district heating network, whereas individual incentives to engage in more energy efficient behavior could be created by installing apartment-based meters and moving from building-level heat contracts to a pay-per-use system. One of our variables for the PEB factor related to produce was organic purchases, which, compared to conventional produce, has been found to have similar global warming potential (GWP) [89].

The effectiveness of policy that relies on "green" consumers as agents of change has been doubted [90,91]. Green consumerism is still a driver of resource depletion and pollution while sustainable consumption is not. In addition, the carbon capability of individuals—that is, how equipped they are to engage in mitigation—has been found to be limited [92] and they might evaluate the environmental impact of the product incorrectly when engaging in "green" purchasing behavior [38]. In this context, it is important to acknowledge that both PEAs and PEBs are varied and complex; an attitude that emphasizes the importance of conserving biodiversity does not necessarily translate to a willingness to mitigate climate change.

More research on the carbon footprints of people with different levels of PEAs is required to fully understand the overall climate change pressure of urban residents. Such research may shed light on how much one can mitigate their climate impacts by different levels of behavioral changes, such as making pro-environmental purchasing choices of goods in the same category, spending on different consumption categories, or reducing the spending budget rather than allocating it differently. It was found that at equal income levels, the carbon footprints of HMA residents are quite similar regardless of how they spend their money as consumption is simply reallocated from one category to another [24]. Moreover, all the carbon footprints assessed for the residents of HMA were far above the remaining global per capita quota estimated for reaching even the 2 degree warming target [93]. Connecting future assessments to the 2 degree or 1.5 degree [94] target would be an important improvement for positioning the findings and making comparisons and mitigation consideration more tangible.

**Author Contributions:** Conceptualization, Á.Á., M.C. and J.H.; Data curation, M.C. and J.H.; Formal analysis, Á.Á., M.C.; Funding acquisition, M.C. and J.H.; Methodology, M.C.; Project administration, M.C. and J.H.; Supervision, M.C. and J.H.; Visualization, Á.Á., M.C. and J.H.; Writing—original draft, Á.Á.; Writing—review and editing, Á.Á., M.C. and J.H.

**Funding:** This research was funded by the Icelandic National Planning Agency, the Icelandic Road Administration and the University of Iceland.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
