They also benefit human health by reducing the incidence of infectious diseases and several other disorders, and by allowing space for physical exercise.

In and around cities, even major cities, these same benefits are available, permitting billions of dollars in cost savings to health services. Evidence of the reduced costs for health services from these benefits is increasing. An assessment of London’s green spaces found that they saved £370 million per year from improved mental health and £580 million per year due to better physical health.

Some concrete examples of these benefits are:

• One in five people in the developing world lack a reliable water supply and water-borne diseases cause millions of deaths each year. Functioning natural ecosystems are an efficient and cost-effective way of supplying clean water
• One third of the world’s 100 largest cities rely on forest-protected areas for their water supply.
• Risks of cardiovascular disease are reduced, while mental health and children’s cognitive development are improved with access to green space, including in urban areas.

To enhance the health benefits of urban nature and protected areas, many cities are launching programmes based on the Healthy Parks, Healthy People model by Parks Victoria, Australia. This Programme involves developing park-based activities for people, building awareness of parks, producing evidence of their benefits and informing cross-sector policies and plans.

Parks Canada’s collaboration with community groups on health initiatives produced the Mood Walks programme, designed to improve symptoms of anxiety and depression through guided walks in Rouge National Urban Park, Canada’s first national urban park.

The British Trust for Conservation Volunteers promotes Green Gyms as a way to combine physical exercise with nature conservation action, boosting participants’ mental health, social integration and activity levels.

Mobilising new partnerships is key to ensuring these types of programmes are effective, bringing together conservationists, health practitioners, scientists, planners and others in recognition of the health and wellbeing benefits of ecosystems and protected areas. Integrating biodiversity, health and urban policy requires that data from all relevant disciplines are considered in impact assessments and economic evaluations of policy proposals, and the integration enables policy action to meet a wide-range of international commitments, including the Convention on Biological Diversity and the New Urban Agenda.

Article based on the chapter "Nature-Based Solutions and Protected Areas to Improve Urban Biodiversity and Health" by Kathy MacKinnon, Chantal van Ham, Kate Reilly and Jo Hopkins in "Biodiversity and Health in the Face of Climate Change".