Page - 20 - in Biodiversity and Health in the Face of Climate Change

20 (Linton et  al. 2016). In the summary, we primarily draw on existing reviews con- ducted in the past five  years supplemented with review evidence on additional themes such as diet. The chapter also covers three sub-aims. First, we consider the evidence for nature’s contributions to physical health from the broad perspective of the natural environment (see Sect. 2.2). We look at direct and indirect ways that natural systems influence human health and well-being with reference to the 11 body systems. Given that the body’s systems are highly interconnected, the discus- sion inevitably connects with material presented in other chapters in this volume (e.g. Cook et  al. Chap. 11, this volume). Within the scope of this review and synthe- sis, it is also inevitable that not all of the evidence can be covered. Nevertheless, the section shows some of the key mechanisms through which human physical health is influenced, according to the most recent literature. Second, we aim to take a closer look at the importance of different forms of ‘nature’, but with a particular focus on biodiversity (see Sect. 2.3). In cities, nature is often thought of as essential urban green infrastructure  – the means through which vital ecological and biodiversity- related functions (e.g. habitat provision and landscape connectivity) and most nature-derived human benefits are delivered (Benedict and McMahon 2002). However, cities and their populations cannot be considered in isolation. Therefore, the chapter touches on how the protective role of biodiversity operates through diverse pathways, how it functions at different human and geographical scales and when it is most significant during the life course. The protective role includes, but is not limited to, the regulation of disease emergence, micro-nutrient availability for human sustenance and the promotion of contact with symbiotic bacteria necessary for building up tolerances to environmental allergens (Ruokolainen et  al. 2017; Rogalski et  al. 2017). Thirdly, we provide an overview of some of the important ways that climate change impacts physical health and the natural environment, including through biodiversity (see Sect. 2.4). A particular emphasis is given to how climate change increases potential poor health burdens (including for example in terms of high temperatures and air pollution in urban areas) and also how extreme climate-related events and long-term climatic trends can erode the beneficial physi- cal health effects of nature, green spaces and biodiversity (LWEC 2015; European Environment Agency 2017). Before concluding on emerging research agendas, the chapter ends with a detailed case study example, focused on urban climate, climate change and biodiversity, primarily from the perspective of how the regulating func- tions of different plant species vary (see Sect. 2.5). Much of the focus of this chapter is on urban areas. Urban areas are where the majority of the population now resides  – nearly three quarters in Europe, with 41% in the most densely populated centres (European Environment Agency 2018)  – where stressors on human health and well-being tend to be most extreme. Evidence is drawn primarily from a European context, supplemented with evidence from else- where, where possible. It is recognized that this focus gives a particular perspective on connections and the challenges faced that may not be echoed in all contexts. S. J. Lindley et al.