Large model structural uncertainty in global projections of urban heat waves

AbstractUrban heat waves (UHWs) are strongly associated with socioeconomic impacts. Here, we use an urban climate emulator combined with large ensemble global climate simulations to show that, at the urban scale a large proportion of the variability results from the model structural uncertainty in projecting UHWs in the coming decades under climate change. Omission of this uncertainty would considerably underestimate the risk of UHW. Results show that, for cities in four high-stake regions – the Great Lakes of North America, Southern Europe, Central India, and North China – a virtually unlikely (0.01% probability) UHW projected by single-model ensembles is estimated by our model with probabilities of 23.73%, 4.24%, 1.56%, and 14.76% respectively in 2061–2070 under a high-emission scenario. Our findings suggest that for urban-scale extremes, policymakers and stakeholders will have to plan for larger uncertainties than what a single model predicts if decisions are informed based on urban climate simulations.

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REMOTE SENSING AND NIGHT TIME URBAN HEAT ISLAND

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b3-2021-15-2021 ◽

2021 ◽

Vol XLIII-B3-2021 ◽

pp. 15-22

Author(s):

B. Arellano ◽

J. Roca

Keyword(s):

Heat Waves ◽

Urban Climate ◽

Construction Materials ◽

Thermal Inertia ◽

Cooling Capacity ◽

Night Time ◽

Urban Heat ◽

Materials Used ◽

Significant Health

Abstract. The urban climate literature has highlighted the remarkable prominence of nighttime UHI phenomenon. During nighttime the UHI effects become more evident due to the greater thermal inertia of the materials used in urban fabric. It is during the night when the heat accumulated in urban materials, especially in contexts of heat waves, can generate significant health risks. The low cooling capacity of urban construction materials negatively affects the comfort and the health of urban dwellers. However, and despite the great importance of night stress due to heat, the study of night UHIs is still underdeveloped. In this context, this paper aims to determine nighttime LST contrasting Landsat's very limited nighttime images with daytime ones. The example developed refers to heat wave situations during the summer 2015. The case study is the Metropolitan Area of Barcelona (35 municipalities, 636 km2, 3.3 million inhabitants).

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Advancement in Urban Climate Modelling at Local Scale: Urban Heat Island Mitigation and Building Cooling Demand

Atmosphere ◽

10.3390/atmos11121313 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1313

Author(s):

Aytaç Kubilay ◽

Jonas Allegrini ◽

Dominik Strebel ◽

Yongling Zhao ◽

Dominique Derome ◽

...

Keyword(s):

Climate Model ◽

Heat Waves ◽

Urban Climate ◽

Building Energy ◽

Urban Heat Islands ◽

Heat Island ◽

Meteorological Model ◽

Heat Islands ◽

Urban Heat ◽

Building Cooling

As cities and their population are subjected to climate change and urban heat islands, it is paramount to have the means to understand the local urban climate and propose mitigation measures, especially at neighbourhood, local and building scales. A framework is presented, where the urban climate is studied by coupling a meteorological model to a building-resolved local urban climate model, and where an urban climate model is coupled to a building energy simulation model. The urban climate model allows for studies at local scale, combining modelling of wind and buoyancy with computational fluid dynamics, radiative exchange and heat and mass transport in porous materials including evaporative cooling at street canyon and neighbourhood scale. This coupled model takes into account the hygrothermal behaviour of porous materials and vegetation subjected to variations of wetting, sun, wind, humidity and temperature. The model is driven by climate predictions from a mesoscale meteorological model including urban parametrisation. Building energy demand, such as cooling demand during heat waves, can be evaluated. This integrated approach not only allows for the design of adapted buildings, but also urban environments that can mitigate the negative effects of future climate change and increased urban heat islands. Mitigation solutions for urban heat island effect and heat waves, including vegetation, evaporative cooling pavements and neighbourhood morphology, are assessed in terms of pedestrian comfort and building (cooling) energy consumption.

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Climate Integration in Sustainable Urban Planning

10.4018/978-1-7998-8331-9.ch008 ◽

2022 ◽

pp. 152-173

Author(s):

Asia Lachir

Keyword(s):

Urban Planning ◽

Global Climate Change ◽

Urban Areas ◽

Global Climate ◽

Urban Climate ◽

Climate Impacts ◽

Local Climate ◽

Urban Heat ◽

Negative Impacts ◽

Tools And Methods

Currently, cities are home to more than half of the world's population. The increasing urbanization rates create an unprecedented urban sprawl that worsens the urban climate situation. Urban areas modify their local climate and face the consequent urban climate impacts, which are particularly exacerbated by global climate change. This chapter shares scientific knowledge on how cities affect their climate and how urban spatial planning can mitigate the negative impacts of urban climate. Focus is given on the urban heat island, the most documented aspect of urban climate, directly linked to city spatial characteristics and functions. This phenomenon is explained, and tools and methods to assess it and mitigate its intensity are introduced in an attempt to help urban planners and designers to use climatic knowledge in urban planning to build more sustainable and climate-resilient cities.

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A Comparative Study of the Physiological and Socio-Economic Vulnerabilities to Heat Waves of the Population of the Metropolis of Lyon (France) in a Climate Change Context

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17031004 ◽

2020 ◽

Vol 17 (3) ◽

pp. 1004 ◽

Cited By ~ 2

Author(s):

Lucille Alonso ◽

Florent Renard

Keyword(s):

Climate Change ◽

Heat Waves ◽

Global Climate ◽

Principal Component ◽

Analytic Hierarchy ◽

Island Effect ◽

The Social ◽

Change Context ◽

Eastern Periphery ◽

Urban Heat

Increases in the frequency and intensity of heat waves are direct consequences of global climate change with a higher risk for urban populations due to the urban heat island effect. Reducing urban overheating is a priority, as is identifying the most vulnerable people to establish targeted and coordinated public health policies. There are many ways of understanding the concept of vulnerability and multiple definitions and applications exist in the literature. To date, however, nothing has been done on the territory of this study, the metropolis of Lyon (France). The objective is thus to construct two vulnerability indices: physiological, focusing on the organism’s capacities to respond to heat waves; and socio-economic, based on the social and economic characteristics and capacities of the community. To this end, two complementary methodologies have been implemented: the AHP (Analytic Hierarchy Process) and the PCA (Principal Component Analysis) with Varimax rotation, respectively. The results were then spatialized to the smallest demographic census unit in France. The areas highlighted differed due to conceptual and methodological differences: the highest physiological vulnerabilities are in the center while the socio-economic ones are in the eastern periphery of the urban area. The location of these areas will enable prevention campaigns to be carried out, targeted according to the publics concerned.

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Impact of drought conditions on urban climate of Zagreb (Croatia)

10.5194/ems2021-315 ◽

2021 ◽

Author(s):

Irena Nimac ◽

Ivana Herceg-Bulić ◽

Maja Žuvela-Aloise ◽

Matej Žgela

Keyword(s):

Air Temperature ◽

Heat Load ◽

Heat Waves ◽

Urban Climate ◽

Late Winter ◽

Landsat 8 ◽

Climate Effect ◽

Spring Period ◽

Drought Conditions ◽

Urban Heat

<p>Dry periods and heat waves are becoming more frequent and intense in changing climate. Effect and impact of such specific events on local climate and ecosystems may vary spatially. One of the critical spots regarding extreme warm events are urban areas due to increased heat load. Here, we examine impact of drought conditions on characteristics of summertime urban heat island (UHI) for Zagreb, Croatia. For these purposes daily air temperature, precipitation, relative humidity, wind speed and wind direction data from the station Zagreb-Maksimir in a period 1928&#8211;2019 are used in the analysis. To define dry and wet conditions, standardized precipitation evapotranspiration index (SPEI) is used. The effect of drought conditions on summer UHI is analyzed from the perspective of preceding (i.e. wintertime and springtime) as well as concurrent (i.e. summertime) drought conditions. To estimate urban heat load in the city, urban climate model MUKLIMO_3 combined with cuboid method is used. Urban heat load is here represented as a number of summer days, i.e. days with maximum air temperature above 25&#176;C. Landsat-8 satellite data were employed to analyze land surface temperature for specific situations. Results indicated substantial increase in heat load for situations when dry summer was preceded by dry late winter-spring period. However, when late winter-spring period was wet and followed with dry summer, much weaker increase in heat load is obtained. On the other hand, decrease in heat load is found for wet summer preceded by wet late winter-spring season. It is also showed that intensity of UHI is affected with drought conditions.</p><p>&#160;</p>

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Centuries of Heat Waves over India during 20th and 21st Century

Applied Environmental Research ◽

10.35762/aer.2021.43.4.1 ◽

2021 ◽

pp. 1-13

Author(s):

Naveena Neelam ◽

Gubbala C. Satyanerayana ◽

Kota S. Rao ◽

Nandivada Umakantha ◽

Dharma Raju

Keyword(s):

21St Century ◽

Heat Waves ◽

Indian Subcontinent ◽

Coupled Model ◽

India Meteorological Department ◽

Central India ◽

Maximum Temperature ◽

Climate Simulations ◽

Index Of Agreement ◽

Recorded Temperature

An assessment of temperature extremes is made for the Indian subcontinent to identify the changes since 1951 to 2015, and for the future climate periods till 2100 for all the 21 CMIP5 (Coupled Model intercomparision Project phase 5) models and the representative concentration pathways RCP4.5 and RCP8.5 were examined for the period from 1 March to 31 May to characterize the heat waves in future climates and mean maximum and mean minimum bias were evaluated for the Indian subcontinent. Later two highest recorded temperature regions were chosen Northwest & Central India (NW&CIN) and only central India (CIN) box and the features of heat waves such as intensity and frequency were evaluated up to 2100. Corresponding temperature predictions from historical runs for the period 1951–2005 of 21 global CMIP model outputs and statistics were performed with the India Meteorological Department (IMD) gridded maximum temperature data for validation. Statistical metrics of BIAS, RMSE and MAE have indicated low BIAS, high correlation and high IOA (Index of Agreement) validating CMIP climate simulations. By analyzing the statistics of all the 21 models with respect to the observational gridded data from IMD came to conclusion that among all the 21 models 5 models were performing well for Indian region and having good index of agreement with IMD. The frequencies of the days having thresholds of 40 ºC, 42 ºC and 45 ºC for the maximum temperature over India during the pre-monsoon are evaluated up to 21st century. All models are showing that the intensity and frequency of heat waves were increasing significantly for both RCP4.5 and RCP8.5. Specifically, the characteristics of heat waves in terms of intensity, duration and area extent are calculated and compared to heat waves of the current climate.

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The Influence of Urban Climate on Bioclimatic Conditions in the City of Iași, Romania

Sustainability ◽

10.3390/su12229652 ◽

2020 ◽

Vol 12 (22) ◽

pp. 9652

Author(s):

Pavel Ichim ◽

Lucian Sfîcă

Keyword(s):

Inner City ◽

Urban Heat Island ◽

Rural Area ◽

Rural Areas ◽

Heat Waves ◽

Urban Climate ◽

Heat Island ◽

Urban Heat ◽

Bioclimatic Conditions ◽

The City

This study was carried out in order to outline the human bioclimatic stress/comfort conditions within the area of Iași city, Romania. The meteorological data were obtained over a 7-year period (December 2012–November 2019) from an observation network relying on 8 fixed observation points located in selected spots, relevant for the urban climate conditions in the region. The results demonstrate firstly that throughout the entire analyzed period, using the thermo-hygrometric index (THI), “very cold” conditions characterize 4% of the entire year in the inner parts of the city and 6% in the rural area, while the “hot” THI conditions vary from 18% in the middle of the urban heat island to 15% in the rural area. Overall, the rural areas are generally more comfortable than the inner city, especially during summer, when the urban heat island (UHI) core is starting to develop from the evening and persists during the night. On the contrary, the UHI renders the inner city more comfortable than the rural surroundings from October to April. Similar bioclimatic conditions are also presented in detail for the summer by the relative strain index (RSI), which exceeds the stress threshold value mostly during heat waves, when a significant contrast between urban and rural areas is felt. In brief, it has been determined that the most suitable area for human comfort in Iași city is inside the urban area during the winter and in the rural areas during the summer.

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Land Use Changes in a Peri-Urban Area and Consequences on the Urban Heat Island

Climate ◽

10.3390/cli7110133 ◽

2019 ◽

Vol 7 (11) ◽

pp. 133

Author(s):

Nardino ◽

Laruccia

Keyword(s):

Land Use ◽

Urban Area ◽

Rural Areas ◽

Heat Waves ◽

Energy Requirement ◽

Land Use Changes ◽

Urban Climate ◽

Small Towns ◽

Urban Heat Islands ◽

Urban Heat

The effect of urbanization on microclimatic conditions is known as “urban heat islands”. In comparison with surrounding rural areas, urban climate is characterized by higher mean temperature, especially during heat waves and during nights. This results in a higher energy requirement for air conditioning in buildings and in a greater bioclimatic discomfort for urban populations. The reasons of this phenomena are ascribable principally to the increase of solar radiation storage and to the decrease of dissipation of water by evapotranspiration in urban environment respect to rural ones. The aim of this paper is to give a quantification of the air temperature increase due to an urbanization process. This quantification is conducted by comparing surface energy balance (incoming and outcoming radiation and turbulent fluxes) in urbanized area versus rural areas. This quantitative approach will be validated using a fluidodynamic model (Envi-Met) in a case study area representative of one among the various regional models of urban area growth. In particular, the model of expansion of small towns around big cities (2003–2008 land use changes) of a plain near-urban area in the Po Valley region (Italy) was used.

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Comments about Urban Bioclimate Aspects for Consideration in Urban Climate and Planning Issues in the Era of Climate Change

Atmosphere ◽

10.3390/atmos12050546 ◽

2021 ◽

Vol 12 (5) ◽

pp. 546

Author(s):

Andreas Matzarakis

Keyword(s):

Climate Change ◽

Urban Heat Island ◽

Urban Climate ◽

Heat Island ◽

Adaptation Measures ◽

Mitigation And Adaptation ◽

Urban Heat

In the era of climate change, before developing and establishing mitigation and adaptation measures that counteract urban heat island (UHI) effects [...]

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Including Urban Heat Island in Bioclimatic Early-Design Phases: A Simplified Methodology and Sample Applications

Sustainability ◽

10.3390/su13115918 ◽

2021 ◽

Vol 13 (11) ◽

pp. 5918

Author(s):

Giacomo Chiesa ◽

Yingyue Li

Keyword(s):

Urban Heat Island ◽

Urban Climate ◽

Temperate Climate ◽

Heat Island ◽

Climate Data ◽

Degree Days ◽

Climate Conditions ◽

Early Design ◽

Correct Definition ◽

Urban Heat

Urban heat island and urban-driven climate variations are recognized issues and may considerably affect the local climatic potential of free-running technologies. Nevertheless, green design and bioclimatic early-design analyses are generally based on typical rural climate data, without including urban effects. This paper aims to define a simple approach to considering urban shapes and expected effects on local bioclimatic potential indicators to support early-design choices. Furthermore, the proposed approach is based on simplifying urban shapes to simplify analyses in early-design phases. The proposed approach was applied to a sample location (Turin, temperate climate) and five other climate conditions representative of Eurasian climates. The results show that the inclusion of the urban climate dimension considerably reduced rural HDD (heating degree-days) from 10% to 30% and increased CDD (cooling degree-days) from 70% to 95%. The results reveal the importance of including the urban climate dimension in early-design phases, such as building programming in which specific design actions are not yet defined, to support the correct definition of early-design bioclimatic analyses.

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