I currently work in four areas of research, each related to broader themes of urban climate, city design, environmental sustainability, and global change.

1. Urban heat islands (UHI)

In this area, I consider myself a methodologist:  my work aims to improve the methods used to observe, measure, and document surface and atmospheric heat islands and their varied effects in cities worldwide (see Local Climate Zones below).  The UHI effect is thought to be a simple phenomenon, but in reality it is complex, in part because the urban surfaces that generate heat islands are extremely varied in their thermal, structural, moisture, and aerodynamic properties.  Different methods of observation are therefore required to measure heat islands, depending upon the scale and type of UHI being studied and the intended use of the data.  It is essential that heat island investigators adhere to scientific guidelines for experimental design, provision of metadata, and communication of results.  To help consolidate these guidelines for UHI studies, my colleague Gerald Mills (University College Dublin) and I recently published a guidebook on the urban heat island.  Visit the Guidebook tab for more information on the book.  My assessments of the heat island literature have been published in scholarly journals such as Urban Climate, Earth’s Future, and the International Journal of Climatology

Geographic distribution of heat island studies that were appraised in Stewart (2011).

Global distribution of heat island studies reviewed by Stewart (2011) in the International Journal of Climatology.


2. Local Climate Zones (LCZ)

Essential to any heat island study is the physical description of cities and the documentation of field sites.  My work in this area involves the Local Climate Zone classification scheme, which I developed with Tim Oke during my doctoral and post-doctoral studies at the University of British Columbia (2004 – 2013).  The scheme is published in the Bulletin of the American Meteorological Society.  LCZs provide an innovative approach to classify urban and rural landscapes according to the structure, cover, fabric, and metabolism of the surface.  This approach eases intercity comparisons of urban heat islands, and improves rigour in climate observation and reporting.  I am collaborating with researchers internationally to evaluate the LCZ concept in rapidly growing, high-density, and high-altitude cities.  I also advise researchers on how to implement the scheme in different urban settings.  Worldwide, the scheme has demonstrated practical uses for climatologists, planners, engineers, architects, and ecologists.  To further expand the reach of LCZs, I am developing a field guide to help users identify urban climates zones in cities.  An introductory lecture on the Local Climate Zone scheme is available on YouTube. 

                                                                          Stewart & Oke 2012_Page_01© Copyright 2012 Amer. Meteorol. Soc.


3. Urban climatic maps (UCMaps)

The purpose of UCMaps is to convey simple, graphical information about local climates to city planners and municipal policy-makers.  While many dozens of cities worldwide have processed their own UCMaps for integration with city master plans, most of these are located in mid-latitude or higher-income regions.  Few such cases exist for Latin America where the social, economic, and environmental challenges are unique.  The regional focus of my research involving UCMaps is Colombia and the Andean city of Manizales.  My colleagues and I at Universidad Nacional de Colombia have used UCMapping to gather, analyse, and communicate urban climatic information to environmental planners in Manizales.  The recommendations we reached are specific to this city, but the approach is generalizable to all mountain cities.  Our research was recently published in Cybergeo: European Journal of Geography, and it is the foundation for further work on meteorological monitoring, territorial planning, and urban climate education in Manizales. 


Planning recommendations for Manizales, published by Roncancio & Stewart (2022) in Cybergeo: European Journal of Geography.


4. Urban metabolism (UM)

The urban metabolism is a concept akin to the metabolism of living organisms.  In practice, it is studied through ‘material and energy flow analysis, which accounts for the flows of energy, water, food, and materials into an urban system, and the flows of sewerage, solid wastes, and pollutants out of that system.  Understanding these flows and their relation to urban development is essential to understanding the sustainability of cities.  Chris Kennedy (University of Victoria, Canada) and I conducted a major research investigation called Megacities: A Comparative Analysis of Urban Macrosystems, in which we documented the material and energy flows of the world’s largest cities.  Our aim was to link these flows to geographic, climatic, and economic drivers, and to quality of life and sustainable urban development.  The project was supported jointly by the University of Toronto and the Enel Foundation (Rome, Italy).  Our results have been published in the Proceedings of the National Academy of Sciences, the Journal of Urban Technology, and in the news media (e.g., NBC, Wired).


Global distribution of megacities surveyed by Kennedy et al. (2015) in the Proceedings of the National Academy of Sciences (USA).

 © Copyright Iain D. Stewart 2023