Two major underlying sets of problems that challenge us in our efforts to preserve healthy environments, maintain the ecosystem services associated with them, and limit inequities associated with unhealthier environmental conditions among poor and marginalized populations. One set of problems is typified by greenhouse gas accumulation in the atmosphere. It is a problem at the global level: both the causes and the effects are global. The second set of problems relates to inequity: High-income countries make a much larger contribution to the problem, both historically and currently. At the same time, low-income countries and poor people within countries are more likely to suffer the consequence. The poor are more likely to live in more precarious environments (semi-arid areas, low-lying islands etc.). They are also less resilient to the anticipated climate changes due to limited technical capacity in local institutions and organizations, and fewer resources to devote to local adaptation.
Preserving healthy environments must encompass efforts to protect land, air, water and biodiversity that depends on different ecosystems. A major threat to healthy environments is the global demand for extraction of resources (mining, and industrial production, local population pressures with resultant demands on land, water and other resources. The 2005 Millennium Ecosystem Assessment found that 60% of the world’s ecosystem resources were degraded or used in unsustainable ways (Hassan et al 2005). Local and regional environment degradation may take many forms: chemical and microbiological contamination of water, particulates in the air from forest fires, coal-burning power plants, factories, erosion and contamination of soil, depletion of aquifers, loss of forests and wetlands and many others. Each of these can have effects on agricultural production and nutrition, and also directly on the occurrence of infectious and/or non-communicable diseases.