Seite - 257 - in Biodiversity and Health in the Face of Climate Change

257 and health outcomes (the column on the right of Fig.  11.2) is less clear since the evi- dence of a causal relationship is less well established. However, there are plausible indirect links via the provision of the basic needs of life, which links to well-being and mental and physical health outcomes. There are also plausible (but unproven) direct relationships between exposure to biodiversity and mental and physical health out- comes. The following subheadings take each public health domain in turn and provide some selected examples to illustrate a public health viewpoint. A comprehensive review is beyond the scope of this chapter. 11.2.1 Food, Nutrition and  Clean Water Supply Biodiversity at all levels is linked to access to clean water and food of good nutritional value, which are fundamental for healthy populations. Urbanisation increases the dis- tances that food travels and increases the challenges of maintaining clean water sup- plies. Public and environmental health initiatives are important in mitigating such problems. Increasing urbanisation has been followed by agricultural intensification to supply growing populations, which often leads to a reduction in biodiversity (e.g. Fahrig et  al. 2015). However, conserving and enhancing the biodiversity of agricul- tural areas need not reduce crop productivity; for example, enhanced biodiversity reduces pest infestation, thus reducing the necessity for the use of pesticides (Petit et  al. 2015). In addition, providing food across different environmental conditions (including those resulting from climate change) means that maintaining genetic and species diversity may be important in the development of food crops for the future (e.g. Bernstein 2014). There is a growing movement of urban-based food production and the biodiversity of such systems is often greater than those of other areas of greenspace (Lin et  al. 2015). The supply of clean water for many cities worldwide relies on (often highly biodiverse) forest environments within the watershed (Dudley and Stolton 2003), although some land uses (including for livestock) may increase the likelihood of microbial contamination of water supplies, for example, with Giardia lamblia and Cryptosporidium species (Schreiber et  al. 2015). 11.2.2 Environmental Stress Urban environments tend to have poorer air and water quality, increased noise, decreased thermal comfort and increased stress (World Health Organisation 2016; Wheater 1999). Extreme temperatures in cities via the ‘urban heat island’ effect is a substantial threat to public health (World Health Organisation 2016). The most vul- nerable in society (i.e. with the lowest SES) suffer disproportionately from these stresses (Diaz et  al. 2006). Biodiversity can provide ecosystem services that buffer communities from environmental stress (Haines-Young and Potschin 2010), which may become especially important in the context of climate change. For example, 11 Biodiversity and  Health in  the  Face of  Climate Change: Implications for  Public…