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There is a pressing need for strategies to prevent the heat-health impacts of climate change. Cooling urban areas through adding trees and vegetation and increasing solar reflectance of roofs and pavements with higher albedo surface materials are recommended strategies for mitigating the urban heat island. We quantified how various tree cover and albedo scenarios would impact heat-related mortality, temperature, humidity, and oppressive air masses in Los Angeles, California, and quantified the number of years that climate change-induced warming could be delayed in Los Angeles if interventions were implemented. Using synoptic climatology, we used meteorological data for historical summer heat waves, classifying days into discrete air mass types. We analyzed those data against historical mortality data to determine excess heat-related mortality. We then used the Weather Research and Forecasting model to explore the effects that tree cover and albedo scenarios would have, correlating the resultant meteorological data with standardized mortality data algorithms to quantify potential reductions in mortality. We found that roughly one in four lives currently lost during heat waves could be saved. We also found that climate change-induced warming could be delayed approximately 40-70 years under business-as-usual and moderate mitigation scenarios, respectively.

• Multi-criteria framework to support urban planners in heat stress management. • Decision support tool based on state-of-the-art literature and best practices. • Strong interdependency for nighttime heat stress and vegetation with an R2 of 0.67. • Overall analysis shows a decrease in heat stress with an increase in vegetation. • Research outcomes support evidence-based decision-making in urban planning. In the face of warming climates, urban planners are increasingly preparing and protecting urban communities from growing risks of heat exposure. There is a need for comprehensive decision support frameworks that can aid urban planners in their efforts to provide context-based solutions to heat exposure in urban environments. The framework proposed in this study enables evidence-based decision-making for heat stress management. The framework incorporates climate classifications, climate data, cooling strategies, heat stress indicators with thresholds, and analysis methods. The proposed framework is implemented in Phoenix-Mesa-Scottsdale Metropolitan Area using thirteen measurement points. The impact of vegetation cover on heat stress is evaluated using the Normalized Difference Vegetation Index and Heat Index from June 2023 to August 2023. The research findings indicate a strong correlation between nighttime heat stress and vegetation cover, with an R2 value of 0.46 at 50 m, 0.59 at 100 m, 0.67 at 250 m, and 0.67 at 500 m radius around the measurement points. The study demonstrates an overall decrease in heat stress with an increase in vegetation cover during summer, daytime, and nighttime analysis. This framework provides a user-friendly and easy to apply decision support framework to manage outdoor heat stress during climate change. [ABSTRACT FROM AUTHOR]

Urban greenery is a natural solution to cool cities and provide comfort, clean air and significant social, health and economic benefits. This paper aims to present the latest progress on the field of greenery urban mitigation techniques including aspects related to the theoretical and experimental assessment of the greenery cooling potential, the impact on urban vegetation on energy, health and comfort and the acquired knowledge on the best integration of the various types of greenery in the urban frame. Also to present the recent knowledge on the impact of climate change on the cooling performance of urban vegetation and investigate and analyse possible technological solutions to face the impact of high ambient temperatures. [ABSTRACT FROM AUTHOR]

Natural elements such as vegetation and water bodies may help reduce heat in urban spaces in summer or in hot climates. This effect, however, has rarely been studied during cold seasons. This paper briefly studies the effect of vegetation and water in summer and more comprehensively in winter. Both studies are done in courtyards on two university campuses in temperate climates. A scale model experiment with similar materials supports the previous studies. The summer study is done in Portland (OR), USA, and the winter study (along with the scale model) in Delft, the Netherlands. The summer study shows that a green courtyard at most has a 4.7 °C lower air temperature in the afternoon in comparison with a bare one. The winter study indicates that the air temperature above a green roof is higher than above a white gravel roof. It also shows that, although a ‘black’ courtyard has higher air temperatures for a few hours on sunny winter days, a courtyard with a water pond and with high amounts of thermal mass on the ground has a warmer and more constant air temperature in general. Both the summer and winter studies show that parks in cities have a lower and more constant air temperature compared to suburbs, both in summer and winter. The scale model also demonstrates that although grass has a lower albedo than the used gravel, it can provide a cooler environment in comparison with gravels and black roof. 1 [ABSTRACT FROM AUTHOR]

Abstract: This study explores the role of global and local warming on indoor thermal environments of representative buildings in two warm climate cities in the U.S. (Chicago IL, and Houston TX). It uses downscaled climate change scenarios to drive whole-building model simulations of representative apartment buildings. Simulations were conducted under (a) current conditions; (b) conditions that include a global warming effect; and (c) conditions that include global warming with concurrent intensification of the urban heat island. Building thermal conditions are assessed for typical operating conditions, for conditions associated with failure of cooling equipment, and for complete power loss during a heat wave. Simulations show that warming by itself may have minimal effects on indoor thermal comfort in summer. For example, in Houston the Predicted Percent Dissatisfied (PPD) comfort metric was approximately 5–6% for current and future climate scenarios under normal operating conditions. Under conditions of AC failure, however, this increased to 61.9% for the current climate and 71.4% for the 2050 climate. In the case of Chicago PPD was between 6.2% and 7.9% for all climate scenarios when equipment operated normally. Under conditions of equipment failure, however, PPD increased to 34.1% for the current climate and 39.2% for the 2050 climate. In simulations for both cities, a complete power failure resulted in peak temperatures that were approximately 2 °C cooler than the case of AC failure only. This is due to reduction in internal gains during a power blackout. [Copyright &y& Elsevier]

To bridge the gaps between traditional mesoscale modelling and microscale modelling, the National Center for Atmospheric Research, in collaboration with other agencies and research groups, has developed an integrated urban modelling system coupled to the weather research and forecasting (WRF) model as a community tool to address urban environmental issues. The core of this WRF/urban modelling system consists of the following: (1) three methods with different degrees of freedom to parameterize urban surface processes, ranging from a simple bulk parameterization to a sophisticated multi-layer urban canopy model with an indoor-outdoor exchange sub-model that directly interacts with the atmospheric boundary layer, (2) coupling to fine-scale computational fluid dynamic Reynolds-averaged Navier-Stokes and Large-Eddy simulation models for transport and dispersion (T&D) applications, (3) procedures to incorporate high-resolution urban land use, building morphology, and anthropogenic heating data using the National Urban Database and Access Portal Tool (NUDAPT), and (4) an urbanized high-resolution land data assimilation system. This paper provides an overview of this modelling system; addresses the daunting challenges of initializing the coupled WRF/urban model and of specifying the potentially vast number of parameters required to execute the WRF/urban model; explores the model sensitivity to these urban parameters; and evaluates the ability of WRF/urban to capture urban heat islands, complex boundary-layer structures aloft, and urban plume T&D for several major metropolitan regions. Recent applications of this modelling system illustrate its promising utility, as a regional climate-modelling tool, to investigate impacts of future urbanization on regional meteorological conditions and on air quality under future climate change scenarios. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Abstract: Using statistically downscaled output from four general circulation models (GCMs), we have investigated scenarios of climate change impacts on wind power generation potential in a five-state region within the Northwest United States (Idaho, Montana, Oregon, Washington, and Wyoming). All GCM simulations were extracted from the standardized set of runs created for the Intergovernmental Panel on Climate Change (IPCC). Analysis of model runs for the 20th century (20c3m) simulations revealed that the direct output of wind statistics from these models is of relatively poor quality compared with observations at airport weather stations within each state. When the GCM output was statistically downscaled, the resulting estimates of current climate wind statistics are substantially better. Furthermore, in looking at the GCM wind statistics for two IPCC future climate scenarios from the Special Report on Emissions Scenarios (SRES A1B and A2), there was significant disagreement in the direct model output from the four GCMs. When statistical downscaling was applied to the future climate simulations, a more coherent story unfolded related to the likely impact of climate change on the region''s wind power resource. Specifically, the results suggest that summertime wind speeds in the Northwest may decrease by 5–10%, while wintertime wind speeds may decrease by relatively little, or possibly increase slightly. When these wind statistics are projected to typical turbine hub heights and nominal wind turbine power curves are applied, the impact of the climate change scenarios on wind power may be as high as a 40% reduction in summertime generation potential. [Copyright &y& Elsevier]

Renewable energy resources will play a key role in meeting the world''s energy demand over the coming decades. Unfortunately, these resources are all susceptible to variations in climate, and hence vulnerable to climate change. Recent findings in the atmospheric science literature suggest that the impacts of greenhouse gas induced warming are likely to significantly alter climate patterns in the future. In this paper we investigate the potential impacts of climate change on wind speeds and hence on wind power, across the continental US. General Circulation Model output from the Canadian Climate Center and the Hadley Center were used to provide a range of possible variations in seasonal mean wind magnitude. These projections were used to investigate the vulnerability of current and potential wind power generation regions. The models were generally consistent in predicting that the US will see reduced wind speeds of 1.0 to 3.2% in the next 50 years, and 1.4 to 4.5% over the next 100 years. In both cases the Canadian model predicted larger decreases in wind speeds. At regional scales the two models showed some similarities in early years of simulations (e.g. 2050), but diverged significantly in their predictions for 2100. Hence, there is still a great deal of uncertainty regarding how wind fields will change in the future. Nevertheless, the two models investigated here are used as possible scenarios for use in investigating regional wind power vulnerabilities, and point to the need to consider climate variability and long term climate change in citing wind power facilities. [Copyright &y& Elsevier]

Abstract Urban growth and climate change will exacerbate extreme heat events and air pollution, posing considerable health challenges to urban populations. Although epidemiological studies have shown associations between health outcomes and exposures to ambient air pollution and extreme heat, the degree to which indoor exposures and social and behavioral factors may confound or modify these observed effects remains underexplored. To address this knowledge gap, we explore the linkages between vulnerability science and epidemiological conceptualizations of risk to propose a conceptual and analytical framework for characterizing current and future health risks to air pollution and extreme heat, indoors and outdoors. Our framework offers guidance for research on climatic variability, population vulnerability, the built environment, and health effects by illustrating how health data, spatially resolved ambient data, estimates of indoor conditions, and household-level vulnerability data can be integrated into an epidemiological model. We also describe an approach for characterizing population adaptive capacity and indoor exposure for use in population-based epidemiological models. Our framework and methods represent novel resources for the evaluation of health risks from extreme heat and air pollution, both indoors and outdoors. Graphical abstract Unlabelled Image Highlights • Indoor & outdoor exposure to extreme heat and air pollution affects human health. • New framework integrates social & health sciences approaches to understanding risk. • Household survey characterizes indoor and outdoor exposure and vulnerability. • Novel application of building energy modeling quantifies indoor exposure. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three heat mitigation strategies were investigated for urban courtyards. [•] E–W direction provided the longest and N–S the shortest sun at the canyons. [•] Increasing the albedo of the facades increased the mean radiant temperature. [•] Using a water pool and urban vegetation cooled the microclimates significantly. [•] ENVI-met was validated for the Netherlands with measurement. [Copyright &y& Elsevier]

Abstract: Mitigating global climate change requires not only government action but also cooperation from consumers. Population-based, cross-sectional surveys were conducted among 1202 respondents in Portland OR and Houston TX between June and September 2007 regarding awareness, concern, and behavior change related to climate change. The data were subjected to both quantitative and qualitative analyses. Awareness about climate change is virtually universal (98% in Portland and 92% in Houston) with the vast majority reporting some level of concern (90% in Portland and 82% in Houston). A multivariate analysis revealed significant predictors of behavior change: individuals with heightened concern about climate change (p<0.001); respondents with higher level of education (p= 0.03); younger compared with older individuals (p<0.001); and Portlanders more likely to change behavior compared with Houstonians (p<0.001). Of those who changed behavior, 43% reported having reduced their energy usage at home, 39% had reduced gasoline consumption, and 26% engaged in other behaviors, largely recycling. Qualitative data indicate a number of cognitive, behavioral, and structural obstacles to voluntary mitigation. Although consumers are interested in global climate change–mitigation strategies and willing to act accordingly, considerable impediments remain. Government policy must eliminate economic, structural, and social barriers to change and advance accessible and economical alternatives. Individual-level mitigation can be a policy option under favorable contextual conditions, as these results indicate, but must be accompanied by mitigation efforts from industry, commerce, and government. [Copyright &y& Elsevier]

Abstract: Background: Changes in climate systems are increasing heat wave frequency and air stagnation, both conditions associated with exacerbating poor air quality and of considerable public health concern. Objectives: Heat and air pollution advisory systems are in place in many cities for early detection and response to reduce health consequences, or severity of adverse conditions. Whereas the ability to forecast heat waves and/or air pollution episodes has become increasingly sophisticated and accurate, little is known about the effectiveness of advisories in altering public behavior. Methods: Air quality and meteorological conditions were measured during advisory and control days in Portland, OR and Houston, TX in 2005 and 2006 and 1962 subjects were interviewed by telephone about their perception and response to these conditions. Results: Elevated ambient temperatures were accurately recognized regardless of air conditioning use; in Portland, respondents resorted to active cooling behavior (AC, fan, etc.), while in Houston no such change was observed. More heat-related symptoms were reported in Portland compared to Houston, probably due to low air conditioning use in the northwest. One-third of study participants were aware of air quality advisories but only ∼10–15% claimed to have changed activities during such an episode. Not the advisory, however, drove their behavior change, but rather the perception of poor air quality, which was not related to PM2.5 or ozone measurements. Conclusions: Messages are not reaching the public during potentially hazardous weather and air quality conditions. Climatic forecasts are increasingly predictive but public agencies fail to mount an appropriate outreach response. [Copyright &y& Elsevier]