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• Global and local climate change cause overheating in coastal cities like Sydney. • We modelled 2018 and 2050, with and without land-use change and heat mitigation. • We performed energy simulations assessing building adaptation technologies. • Mitigation technologies are not enough to counteract global and local climate change. • Building adaptation and urban mitigation must be combined. In several areas of the world, the population concentrates along the coastal regions, benefitting from the sea breeze, with warmer inland areas. However, increasing population is driving urban sprawl in traditionally low-density areas, enhancing the synergies between global and local climate change. Here we show that local climate mitigation can reduce the impacts of climate change, with the analysis of a new development area in Sydney, 50 km from the coast. With meso-scale climate modelling, we computed that by 2050 the peak summer temperature will increase by 0.8 °C and the daily average summer temperature by 1.6 °C. Mitigation with cool materials, greenery, and irrigation will lower the peak and average daily temperatures respectively by 2.2 °C and 1.6 °C with respect to the unmitigated future climate scenario. Mitigation techniques when applied in the whole Sydney area yield to cooling energy needs reductions by 6.7–8.6 kWh/m2 (13.4–19.3%) for typical residential, office, and school buildings, with a negligible heating penalty, compared to an unmitigated future scenario. Combined adaptation and mitigation can reduce the future cooling energy needs by 31.3 kWh/m2 (70%), 29.3 kWh/m2 (57.3%), and 20.9 kWh/m2 (59.4%) for typical residential, office, and school building, respectively. Our study indicates that the consolidated and widely available mitigation technologies alone cannot counteract the energy impact of both global and local climate change. A structured system of interventions at building and urban scale is necessary while developing novel and higher efficiency mitigation technologies. [ABSTRACT FROM AUTHOR]

Many cities around the world are increasingly developing plans and policies for mitigation and adaptation to climate change. These plans and policies are often focused on either mitigation or adaptation. This dichotomized approach can be problematic and result in trade-offs. In other words, efforts aimed at enhancing mitigation (adaptation) may hinder achieving adaptation (mitigation) objectives. Additionally, conflicts may arise as there might be inconsistencies between some mitigation and adaptation measures. Since trade-offs and conflicts between adaptation and mitigation measures can undermine effectiveness and efficiency of municipal activities, efforts should be made to avoid or minimize them. This study aims to provide a better understanding of potential trade-offs and conflicts through reviewing literature on the interactions between urban adaptation and mitigation measures. This is done through bibliographic analysis and detailed content analyses of selected papers. Results of this review show that research on trade-offs and conflict has gained traction since the publication of the fourth assessment report of The Intergovernmental Panel on Climate Change. However, there is still a lack of empirical studies. In particular, limited research exists on the Global South cities. Also, according to the findings, existing research is mainly focused on trade-offs associated with measures related to energy, land use, transport, water, building, green infrastructure, and waste sectors. It is found that mitigation measures may have negative impacts on adaptation by increasing exposure to risks such as the urban heat island effect and flooding and/or by eroding livelihood options of poor and marginalized groups and causing equity concerns. In contrast, adaptation measures may increase greenhouse gas emissions by, among other things, reducing efficiency and increasing energy demand. It is discussed that integrated assessment frameworks should be utilized to deal with trade-offs and conflicts. Finally, some recommendations for better uptake of integrated frameworks are provided. • Conflicts and trade-offs between urban adaptation and mitigation measures are explored. • Conflicts and trade-offs have received more attention since publication of IPCC AR4 report. • Most trade-offs are related to energy, land use, transport, water, and building sectors. • The most recurring trade-offs of mitigation measures are related to equity and adaptive capacity. • Integrated assessment frameworks should be used to deal with conflicts and trade-offs. [ABSTRACT FROM AUTHOR]

• The climatic mitigation potential of façade is assessed for four different climates. • The impact of facade and ground properties on T mrt is assessed. • A novel Ladybug workflow which couples indoor and outdoor is validated. Within the bounds of climate change, the design of public spaces and buildings must contribute to the local thermal mitigation. In this context, there has been a considerable body of research emphasis on reducing the Urban Heat Island (UHI) phenomenon via the resurfacing of public spaces, streets and roofs, with vegetation and cool materials. At the time of writing, minor attention has been given to how buildings' façades could affect outdoor temperature ranges. Whereas facades are studied according to their capabilities of reducing building energy demand and grant indoor comfort, but scarce attention has been given to how their surfaces properties are affecting local microclimates. The proposed work thus assesses the thermal mitigation potential of façades properties such as windows to wall ratios and finishes attribute, such as reflectivity and emissivity. The study, starting from the definition and calibration of a Ladybug Tools' simulation workflow for the assessment of outdoor comfort conditions, simulates urban canyons located in three climate types (temperate warm, temperate cold, and tropical arid), parametrises façade types, along with canyon aspect ratios and ground thermal properties. By creating a hierarchy of importance of interventions between aspect ratios, ground and façade finishes, the work offers information useful to foster site-specific climate mitigation plans. [ABSTRACT FROM AUTHOR]

Urbanisation and industrialisation led to the increase of ambient particulate matter (PM) concentration. While subsequent regulations may have resulted in the decrease of some PM matrices, the simultaneous changes in climate affecting local meteorological conditions could also have played a role. To gain an insight into this complex matter, this study investigated the long-term trends of two important matrices, the particle mass (PM 2.5) and particle number concentrations (PNC), and the factors that influenced the trends. Mann-Kendall test, Sen's slope estimator, the generalised additive model, seasonal decomposition of time series by LOESS (locally estimated scatterplot smoothing) and the Buishand range test were applied. Both PM 2.5 and PNC showed significant negative monotonic trends (0.03–0.6 μg m−3. yr−1 and 0.40–3.8 × 103 particles. cm−3. yr−1, respectively) except Brisbane (+0.1 μg m−3. yr−1 and +53 particles. cm−3. yr−1, respectively). For the period covered in this study, temperature increased (0.03–0.07 °C.yr−1) in all cities except London; precipitation decreased (0.02–1.4 mm. yr−1) except in Helsinki; and wind speed was reduced in Brisbane and Rochester but increased in Helsinki, London and Augsburg. At the change-points, temperature increase in cold cities influenced PNC while shifts in precipitation and wind speed affected PM 2.5. Based on the LOESS trend, extreme events such as dust storms and wildfires resulting from changing climates caused a positive step-change in concentrations, particularly for PM 2.5. In contrast, among the mitigation measures, controlling sulphur in fuels caused a negative step-change, especially for PNC. Policies regarding traffic and fleet management (e.g. low emission zones) that were implemented only in certain areas or in a progressive uptake (e.g. Euro emission standards), resulted to gradual reductions in concentrations. Therefore, as this study has clearly shown that PM 2.5 and PNC were influenced differently by the impacts of the changing climate and by the mitigation measures, both metrics must be considered in urban air quality management. Image 1 • Both PM 2.5 and PNC had a monotonic downward trend in all cities except Brisbane. • Extreme events due to changing climates caused positive step-changes to PM 2.5. • Negative step-changes in PNC were observed upon regulation of sulphur in fuels. • Gradual reduction of PM 2.5 and PNC was achieved by traffic and fleet management. [ABSTRACT FROM AUTHOR]