This report synthesizes the findings from the Millennium Ecosystem Assessment (MA) global and sub-global assessments of how ecosystem changes do or could affect human health and well-being. Over the past 50 years humans have changed natural ecosystems more rapidly and extensively than any comparable period in human history. The findings provide the strongest evidence so far of the ways in which pressures on ecosystems have resulted in the loss of vital ecosystem services which purify and replenish water soil and air resources essential to health and also keep many diseases in check. Loss of these ecosystem services in turn affect patterns of communicable and non-communicable disease distribution and transmission. In the future, still-increasing pressures on ecosystems could impact public health in a variety of ways that are unpredictable and potentially severe. Human exploitation of ecosystem services has indeed contributed to substantial net gains in well-being and development across much of the planet. Still not all regions and groups of people have benefited from this process and many have been harmed. Moreover the full costs associated with these gains are only now becoming apparent. Approximately 60% of the ecosystem services examined, from regulation of air quality to purification of water, are being degraded or used unsustainably. The Millennium Ecosystem Assessment has worked to assess the consequences of ecosystem change for human well-being and establish the scientific basis for actions needed to enhance the conservation and sustainable use of those systems so that they can continue to supply the services that underpin all aspects of human life. The assessment exercise has involved more than 1 300 experts worldwide and started in 2001.