Trade-offs and synergies in urban climate policies

Abstract

Cities are at the forefront of climate policies. 1-6 However, urban climate policies are not implemented in a vacuum; they interact with other policy goals, such as economic competitiveness or social issues. These interactions can lead to trade-offs and implementation obstacles, or to synergies. 7,8 Little analysis investigating these interactions exists, in part because it requires a broad interdisciplinary approach. Using a novel integrated city model, we provide a first quantification of these trade-offs and synergies, going beyond the qualitative statements that have been published so far. We undertake a multicriteria analysis of three urban policies: a greenbelt policy, a zoning policy to reduce flood risk, and a transportation subsidy. Each of these policies appears to be undesirable because it has negative consequences with respect to at least one policy goal; however, in a policy mix, the consequences of each policy are not simply additive. This nonlinearity permits building policy combinations that are win-win strategies. In particular, flood zoning and greenbelt policies are unlikely to be accepted if they are not combined with transportation policies. Our results show that stand-alone adaptation and mitigation policies are unlikely to be politically acceptable and emphasize the need to mainstream climate policy within urban planning.Urban policies have multiple goals, such as enhancing the quality of life and the city's economic competitiveness by means of affordable housing and office space, amenities, and efficient public services. Urban policies also have social objectives aimed at poverty and social segregation issues, safety and security, and public health. They have environmental goals as well, such as reducing air and water pollution and preserving natural areas. In addition to this long list of goals, urban policies now face new challenges from climate change, including adaptation and mitigation needs. [1][2][3][4][5][6] Adaptation and emission reduction policies rely on the same tools, giving rise to both synergies and conflicts. 7,8 Synergies and conflicts with other policy goals also exist, and environmental policies can result in positive feedback with respect to economic and social issues. A decrease in car congestion increases residents' quality of life, enhances economic competitiveness, reduces accessibility inequalities among neighborhoods, and decreases air pollution and GHG emissions. Conversely, while enlarging parks and introducing more vegetation in cities can be a useful way to adapt cities to higher temperatures and can improve the quality of life, such actions may also reduce population density and lead to increased GHG

Environmental impacts of reflective materials: Is high albedo a ‘silver bullet’ for mitigating urban heat island?

“…However, development of future generations of cities essentially embraces multiple dimensions of sustainability principles that multi-scale environmental, multi-sector socioeconomic elements, and regional impacts need to be accounted for [163]. Looking beyond the mitigation potentials for UHIs, city planners and policy makers should not only be aware of but set up standards in 30 quantifying potential environmental impacts of reflective materials.…”

The barriers to low-carbon land-transport and policies to overcome them

“…There is an immediate need to improve vehicle fuel efficiency from an economic, societal and environmental perspective. Doing so harbours considerable potential for co-benefits if the efficiency technology is advanced enough to be introduced cost-effectively [47,89]. Vehicle fuel efficiency technologies are, however, substantially underutilised; while some countries have made noticeable progress in this area, others have largely failed to do so [36].…”

Urban adaptation can roll back warming of emerging megapolitan regions

“…S13-S15). Policy options focused on adaptation to urban-induced warming should recognize the importance of solutions that also address hydroclimatic implications and encourage comprehensive tradeoff assessments (25), which consider multiscale environmental and multisector socioeconomic elements as well as nonlocal implications, rather than proposed one size fits all policies.…”