Introduction

The study of urban green spaces, climate change, and vector-borne diseases are each substantial and well-established fields of research, and all three of them impact human health. Their pairwise interactions are at least partly understood, but little attention has been paid to the intersection of all three domains simultaneously. In this article, we reflect on the urgency to better understand how we can manage human behaviour and public urban green spaces to minimise vector-borne disease risk while maximising the ecosystem services that urban green spaces must provide in our changing climate.

What we know

Urban green spaces have been proposed to deliver health and wellbeing benefits through a range of mechanisms. Benefits have typically been attributed to three broad processes: restoration, such as through stress recovery; building capabilities, such as by facilitating physical activity; and protection from harms, such as through urban cooling or flood management [1]. Consequently, a range of interventions aim to capitalise on these health and wellbeing effects and co-benefits [2]. These are typically framed in terms of the following: green/blue infrastructure developments, such as the creation of urban green corridors to facilitate active travel; social programming, including nature-based prescribing for clinical purposes; or Nature-based Solutions (NbS) designed to tackle multiple environmental, social and economic challenges such as a wetland designed to improve water quality, provide recreational opportunities and increase biodiversity [3].

The principal vector-borne diseases emerging in urban areas in Europe include tick-borne infections such as Lyme disease and mosquito-borne infections such as dengue, chikungunya and Zika. Ticks infected with Borrelia (the bacteria that causes Lyme disease) can move into new areas on birds, from Lyme-endemic rural regions into urban areas, introducing the pathogen there. Urban green space design and management, such as conservation grazing with livestock, as well as climatic changes, may increase habitat suitability for ticks, the vector of Borrelia, and their natural hosts, including rodents, birds and deer. These changes may facilitate the establishment of urban Lyme disease transmission cycles. For diseases spread by invasive Aedes mosquitoes, such as dengue, Zika, and chikungunya, increased humidity and shelter can provide resting sites for mosquitoes, similarly for the West Nile virus carried by the Culex vectors, e.g., natural wetlands, container habitats and flooded areas. Coupled with the movement of infected migratory birds, urban cycles of West Nile virus can be established. There is uncertainty in the health care burden of vector-borne diseases under future climates, but global historic costs of dengue, Zika and chikungunya have been estimated at a mean annual cost of US$3.29 billion [4]. Surveillance of disease-carrying vectors is a major public health challenge, associated with significant costs.

Climate change is one of the greatest global health threats facing the world in the 21st century. Whilst a significant health burden results from direct impacts of heat and extreme weather events, climate change also creates longer transmission seasons for vectors, an expanded vector range, and changes in pathogen survival and replication. For example, climate change increased the transmission potential of dengue by Aedes albopictus and Aedes aegypti by 48.5% and 11.6%, respectively, from 1951–60 to 2015–24 [5].

Climate change also influences the growth conditions of urban vegetation, for example drought causing increased vegetation stress. To ensure that green spaces can provide crucial climate change adaptation, their design needs to better account for climatic change. Climate change impacts how people use green spaces. A study in Germany identified a temperature threshold of 30 °C, above which visits to parks for activities such as jogging and playing with children declined [6]. Another recent study estimated that high temperature and humidity significantly reduce the recreational value of green spaces [7]. However, climate change may alter patterns of green space use and hence exposure risk, with greater use during cooler periods of the day (mornings and night) [8], and during milder seasons.

Risks, benefits, unknowns

From the above, it is clear that climate change, urban green spaces and vector-borne diseases already interact (see Fig 1) and will do so further. Yet, we know little about the specifics and the potential public health consequences. Will people still be jogging in the green spaces if they are hot and humid or full of disease-carrying ticks and mosquitos? Will more people picnic in green spaces to escape indoor heat, increasing their vector exposure risk, particularly under trees, where ticks might thrive? And given this, can we design urban green spaces to deliver climate adaptation goals without increasing vector presence or human-vector contact? What are the net public health outcomes when the benefits of green spaces are weighed against increased vector exposure?

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Fig 1. Overview of the individual and overlapping effects of climate change, urban green spaces, and vector-borne diseases.

This figure was initially generated with generative AI (ChatGPT) and edited in an image editing web application. The authors reviewed the final content as needed and take full responsibility for the content of this figure.

https://doi.org/10.1371/journal.pclm.0001016.g001

Currently, our limited understanding of the interactions and long-term feedbacks between climate change, biodiversity loss/gain, infection risk and ecosystem services make it difficult for policymakers to evaluate the trade-offs and co-benefits of interventions aimed at climate adaptation, nature recovery and public health. Economic valuation in this context is also partial – certain health endpoints are well studied (e.g., mortality risk), while morbidity valuation is relatively underdeveloped. Valuation of biodiversity loss/gain is difficult, and while some ecosystem services have been the focus of valuation studies, many cultural and spiritual aspects remain difficult to value [9]. We urgently need more research on these intersections, for example, using integrated assessment models linking climate, ecological, epidemiological, behavioural and socioeconomic data to predict how environmental change and management interventions influence greenspace use, biodiversity, vector-borne disease risks and wider societal wellbeing [10]. Similarly, systems-thinking approaches are gaining increasing visibility to understand dynamic processes, feedback loops and unintended consequences, while allowing simulation of alternative policy and management scenarios [11,12].

Research takes time to translate into impact, and as with all studies on the effects of climate change, there is significant uncertainty; we cannot predict exactly what will happen where and when, and empirical data only reflects present or past states. Investments in green spaces are currently being made, be it creating spaces in new developments or changing existing spaces through planting or change service provision. Hence, accepting there are unknowns, we need to amend current planning and environmental policies that shape the design, management and development of new and existing urban green spaces, including in the context of new building developments.

There is a need to carry out a balanced assessment of multiple risks, alongside potential benefits, based on what is currently known and include future projections. Health Impact Assessment (HIA) and/or health components of Environmental Impact Assessment (EIA) are valuable tools to ensure any urban green space-related interventions manage the risk of vector-borne diseases whilst creating the opportunities for health promotion. We call for a denser monitoring system of urban green spaces so that if issues such as widespread tick-infestation are spotted, actions to mitigate health risks can be taken swiftly. We also emphasise the importance of community participation in the management of urban green spaces in the context of climatic and disease-risk changes to ensure inclusive designs and achieve desired outcomes [13].

From reactive to proactive

Healthy, resilient and biodiverse ecosystems are fundamental to human health and societal wellbeing, yet broad environmental changes are increasingly altering ecosystem services and vector-borne disease dynamics. To maintain benefits from urban green spaces around climate adaptation, biodiversity conservation and enhancement, and human wellbeing while minimising unintended health costs and wider societal risks, proactive planning is required now.

Acknowledgments

The authors would like to thank Sarah Ashton (UoE) and Amrita Sharma (UoE) for their support with administration and organisation of the event; Peter Lefort (UoE) for facilitating the workshop; and to everyone who attended the workshop. The order of all other authors was determined by a random number generator. This piece is based on discussions at a workshop organised by Dr Joanne Garrett and Dr Mark Ferguson at the University of Exeter, March 2026.