Building Resilient Cities for Heat Waves

Lead Research Organisation: UNIVERSITY COLLEGE LONDON
Department Name: Research Services

Abstract

As projected by IPCC (with higher confidence compared to other weather extremes e.g., precipitation, cold, extremes), heat waves (HWs), excessively hot periods, are likely to occur more frequently, with higher intensities, and with longer duration, in the coming decades. Cities differ from their surroundings in terms of built forms, materials, and intensive anthropogenic activities. These differences result in the well-known urban heat island (UHI) effect, whereby cities are often warmer than their surroundings. HWs are exacerbated by the UHI effect and cause cities to be more vulnerable to HWs resulting in greater thermal stresses for urban residents. This is of particular concern for those residents susceptible to heat-related illness, given the intensified HW scenarios in the near future, and worldwide with more people living in urban environments. As such, building resilient cities for HWs warrants urgent attention.

Resilience is "the capacity of a community or society to adapt when exposed to a hazard". In order to build resilient cities for HWs, the key is in understanding the responses of cities to HWs under varying scenarios: as climate changes, the climate extremes may also vary, which forces the urban systems through a "dose-response" function and subsequently leads to different biophysical impacts. The "dose-response" functions between climate and biophysical impacts in cities are essentially determined by the urban-atmospheric interactions, where the surface energy balance is one of the keys to greater understanding.

In this Fellowship, I will employ both modelling and observational approaches to investigate the urban-atmospheric interactions as well as the urban surface energy balance under HWs. An adaptable tool, the analytical urban climate (ANUC) framework, will be developed for better understanding the urban-atmospheric interactions under heat waves. Compared with other popular numerically-based urban climate models, the ANUC framework features analytical rather than numerical expressions of various climate variables, which relieves the framework from expensive computational burdens and facilitates the exploration of as many HW scenarios as possible. The observations will emphasise the urban-rural contrasts in surface energy balance by constructing urban-rural flux observation pairs worldwide, the results of which are expected to allow generalisation of the urban-rural characteristics of the surface energy balance under different climates. Based upon the ANUC framework and the global urban-rural SEB characteristics, I will justify the effectiveness of different engineering approaches for mitigating thermal stress under HWs of the present-day and future climates by conducting many ANUC simulations.

This Fellowship will shape a better understanding of the dynamics between cities and the atmosphere under HWs and will assess the effectiveness of mitigation strategies of cities under present-day and future climates, which will help building up HW resilient cities of the future.

Planned Impact

This fellowship will shape a better understanding of the dynamics between cities and the atmosphere under HWs and will assess the effectiveness of different heat mitigation strategies of cities under present-day and future climates, which will lead to HW resilient cities by reducing thermal stress.

The non-academic beneficiaries of this Fellowship include climate service sectors and school children.

1) Climate Service Sectors
Climate service sectors will benefit from the Analytical Urban Climate (ANUC) framework, a state-of-the-art urban climate toolkit developed in this Fellowship, by providing modelling needs and conducting climate service driven simulations. Users in these sectors include infrastructure providers, human health sectors, logistics organisations, etc. The ANUC framework is designed as an agile simulation tool so that the climate service sectors can more rapidly get informed with possible impacts of various infrastructure designs and synoptic processes on urban climate.

2) School Children
Young people are interested and concerned about the environment and climate change and it is they who are the future policy makers, scientists, engineers, etc. Given this, I propose to develop some online resources, based on the ANUC framework, to increase awareness of climate change and enhance understanding of climate science. By presenting not only the simulations and impacts of HWs on urban climate and the effectiveness of heat mitigation measures by designing and performing ANUC simulations, the underlying analytical framework will also be explained to show the importance and application of mathematics to real-world environmental issues and understanding. These resources will be appropriate for use by teachers in classrooms or interested students (KS3 level and above). Delivery of both elements will involve an interactive website to demonstrate the impacts of HWs on urban climate and the effectiveness of different heat mitigation measures under HWs in various climates. The website will be driven by the ANUC framework in the Wolfram Cloud, which will enable it to be interactive and to be able to use global climate forcing data. Interactive functions will be implemented to allow the users to design and perform simulations in their cities and other areas of interest over the world under both present-day and future climates.

Related Projects

Project Reference Relationship Related To Start End Award Value
NE/P018637/1 30/06/2017 08/05/2022 £455,689
NE/P018637/2 Transfer NE/P018637/1 09/08/2022 29/09/2023 £46,472
 
Description 1. WRF-SUEWS Development and Insights:
- Integrated the Surface Urban Energy and Water Scheme (SUEWS) with the Weather Research and Forecasting (WRF) model to enhance urban atmospheric simulations.
- Improved model accuracy through local observations, demonstrating better performance in residential areas compared to central urban locations, with clear seasonal performance patterns and adjustments for aerosol impacts.

2. GLAMOUR Dataset Contribution:
- Introduced the GLAMOUR dataset, derived from open-source satellite imagery, providing high-resolution data on global urban building morphology.
- Enabled enhanced simulations of urban climate interactions and broader applications in hydroclimate simulation, urban planning, and hazard assessment.

3. Improved understanding of Health Implications due to Urban Heat Islands in European Cities:
- Conducted a comprehensive analysis of Urban Heat Island (UHI) effects on health across 85 European cities, identifying acute mortality risks during heat extremes and protective effects during cold seasons.
- Quantified economic impacts of UHI-induced mortality, emphasising the significance of UHIs in urban health policy and planning, and highlighting the need for strategies to mitigate health risks while considering the dual role of UHIs.
Exploitation Route - Academic Sphere: Researchers in urban climate science, environmental engineering, and urban planning could leverage the WRF-SUEWS model enhancements and the GLAMOUR dataset for further studies on urban-environment interactions. These tools offer a robust framework for investigating the multifaceted impacts of urbanisation on local climates and can serve as a foundation for developing more nuanced models that account for the complexity of urban ecosystems.

- Urban Planning and Policy: Local authorities, urban planners, and policymakers could apply the insights gained from the UHI and health implications study to design more resilient and healthier urban environments. By integrating these findings into urban development strategies, cities can implement green infrastructure, optimise building designs, and adopt urban layouts that mitigate the adverse effects of UHIs, thereby enhancing public health and wellbeing.

- Public Health Sector: Public health officials and organisations could use the research outcomes to inform heatwave response strategies and urban health initiatives. The quantification of UHI-related health risks provides a valuable evidence base for targeted interventions aimed at reducing heat-related morbidity and mortality, especially in vulnerable urban populations.
Sectors Construction

Digital/Communication/Information Technologies (including Software)

Education

Energy

Environment

Healthcare

 
Description Fostering International Collaborations in Digital Research
Amount £11,500 (GBP)
Organisation University College London 
Sector Academic/University
Country United Kingdom
Start 11/2023 
End 07/2024
 
Description Sustainable Development of SuPy for the Open Urban Climate Community
Amount £8,121 (GBP)
Organisation University College London 
Sector Academic/University
Country United Kingdom
Start 07/2022 
End 07/2023
 
Title GLobAl building MOrphology dataset for URban climate modelling 
Description GLobAl building MOrphology dataset for URban climate modelling (GLAMOUR) offers the building footprint and height files at the resolution of 100 m in global urban centers. the `BH_100m` contains the building height files where each file is named as `BH_{lon_start}_{lon_end}_{lat_start}_{lat_end}.tif`. the `BF_100m` contains the building footprint files where each file is named as `BF_{lon_start}_{lon_end}_{lat_start}_{lat_end}.tif`. Here `lon_start`, `lon_end`, `lat_start`, `lat_end` denote the starting and ending positions of the longitude and latitude of target mapping areas. To avoid possible confusion, it should be clarified that the 'building footprint' in GLAMOUR represents the 'building surface fraction', i.e., the ratio of building plan area to total plan area.   We also offer the snapshot of source code used for the generation of the GLAMOUR dataset including: `GC_ROI_def.py` defines regions of interest (ROI) used in the mapping of the GLAMOUR dataset. `GC_user_download.py` retrieves satellite images including Sentinel-1/2, NASADEM and Copernicus DEM from Google Earth Engine and exports them into Google Cloud Storage. `GC_master_pred.py` downloads exported data records from Google Cloud Storage and then performs the estimation of building footprint and height using Tensorflow-based models. `GC_postprocess.py` performs postprocessing on initial estimations by pixel masking with the World Settlement Footprint layer for 2019 (WSF2019). `GC_postprocess_agg.py` aggregates masked patches into larger tiles contained in the GLAMOUR dataset. 
Type Of Material Database/Collection of data 
Year Produced 2024 
Provided To Others? Yes  
Impact This is the first-ever global dataset of urban morphology at 100m scale that can support detailed urban hydroclimate modelling. 
URL https://zenodo.org/doi/10.5281/zenodo.10608714
 
Description Arup - Digital Service Team 
Organisation Arup Group
Country United Kingdom 
Sector Private 
PI Contribution The collaboration with ARUP on the UHeat project ([https://www.arup.com/services/tools/uheat](https://www.arup.com/services/tools/uheat)), where our SUEWS model serves as the foundational computational core, showcases my expertise in urban climate modelling. I provided scientific consultancy to understand urban heat island effects during heatwave periods across ten megacities globally. What sets this project apart is not just its expansive scope-the number of cities under study continues to grow-but also its widespread recognition. Over 80 media outlets have covered our work globally, spanning more than ten countries, underscoring its importance and relevance. Moreover, the success of this venture has sparked further collaborations; internal research projects within ARUP are now being developed alongside prospective UCL consultancy contracts. This serves as a testament to how academic research can be instrumental in shaping real-world applications-a principle that sits at heart of my approach towards bridging research with impact.
Collaborator Contribution Arup has seamlessly integrated my innovative modelling technique SUEWS into their workflow for urban climate service. This strategic incorporation was aimed at enhancing the accuracy and efficiency of predicting urban heat extremes at detailed level (e.g. district), which is crucial for sustainable city planning and development. Following this integration, Arup successfully launched the product in more than ten countries across various continents including Europe, Asia, and North America. This wide-reaching success is attributed to the unique capabilities of the modelling technique which offers detailed insights into urban heat islands effect mitigation strategies among other benefits.
Impact Urban Heat Snapshot - https://www.arup.com/perspectives/publications/research/section/urban-heat-snapshot
Start Year 2022
 
Description Tsinghua University, China 
Organisation Tsinghua University China
Department Department of Hydraulic Engineering
Country China 
Sector Academic/University 
PI Contribution Co-supervision of PhD students.
Collaborator Contribution Co-supervision of PhD students.
Impact N/A
Start Year 2016
 
Title SHAFTS 
Description Deep-learning-based simultaneous extraction of building height and footprint from Sentinel imagery 
Type Of Technology Software 
Year Produced 2022 
Open Source License? Yes  
Impact SHAFTS is used in the development of a global dataset of urban morphology, which will be an essential and fundamental dataset for global urban climate modelling. 
URL https://zenodo.org/record/7717081#.ZAtXki-l20o
 
Description Interview by Common Vision 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact The interview by Common Vision is used as part of the website - Hold this space - for arousing public awareness of climate change and sustainable future.
Hold This Space is a self-guided website which helps you reflect on your emotional response to climate change, imagine a better future, and understand the actions you can take to address the climate crisis.
Year(s) Of Engagement Activity 2022
URL https://holdthis.space/about-hold-this-space/