NERC-FAPESP Informed Greening of Cities for Urban Cooling (GreenCities)

Implementation of green infrastructure (GI) in urban areas is becoming popular globally, as it offers aesthetically pleasing green spaces, helps to reduce local air pollution, and sustain local ecosystems in areas that would otherwise consist of large concrete landscapes, high air pollution levels and deteriorating ecosystems.

Climate-related impacts on urban areas are increasing globally, and directly affect a large urban population. High air temperatures in cities are exacerbated by urban heat island (UHI) effects and lead to increased mortality, loss of worker productivity and greater energy consumption for cooling.

GI such as parks provides a way to partially mitigate adverse effects, primarily through shade and evapotranspiration cooling. However, there is very little evidence on its cooling potential in tropical regions, particularly for cities in the humid tropics where high relative humidity greatly exacerbates thermal comfort stress, which amplifies both health and economic impacts. The majority of GI cooling studies are based on simple transects of air temperature monitoring, conducted in single parks for relatively short durations, or 'instantaneous' measures from portable sensors along walking or cycling routes. Other studies interpret satellite data on land-surface temperature but lack a robust conversion to air temperature and thermal comfort. None of these approaches provide finely resolved spatial data with continuous and annual temporal variation.

GreenCities is a new, unique multi-disciplinary partnership that brings together expertise from UK and Brazilian scientists, who will collaborate to share their scientific ideas and carry out world-class research to develop new knowledge that cannot be achieved alone or by existing collaborations.

GreenCities is designed to address the following science question: "Are the cooling benefits provided by urban parks reduced by high humidity in the humid tropics, and does this vary with time of day and season?". The overall goal of this project is to build an international partnership around innovative monitoring approaches to better understand the cooling effects and other co-benefits that urban GI can provide. We aim to apply new technologies such as eddy covariance which give high temporal resolution information on both heat and water vapour fluxes, and a combination of additional sensors (NDVI, thermal cameras) and citizen-science monitoring using roving sensors to provide ancillary information. In combination, these will allow both fine-scale resolving of flux tower footprints, and provide the data required to support upscaling of such measurements to city-scale within a predictive model.

The project activities will focus on São Paulo in Brazil (>20 million population), taking advantage of cutting-edge eddy covariance expertise in Brazil, and UK expertise in modelling GI benefits, to establish proof of concept which can be transferred to other cities globally. Co-creation is important to improve the public acceptance and wider uptake of GI solutions. Therefore, through its citizen science engagement, the project will provide an educational role.

GreenCities will produce an international case study that can be replicated elsewhere, in the UK, Brazil and globally. It will yield high-impact joint publications, exchanges among researchers, and development of a novel methodological approach and indicators for monitoring and evaluating the benefits of GI in urban parks using citizen science. Potential impact will include the development of transdisciplinary methods to holistically assess the ecosystem services provided by urban parks through public-researcher participation, to positively influence current thinking and effective implementation of GI for a multitude of applications.