Large-scale and global environmental hazards to human health include climate change, stratospheric ozone depletion, changes in ecosystems due to loss of biodiversity, changes in hydrological systems and the supplies of freshwater, land degradation, urbanization, and stresses on food-producing systems.
Appreciation of this scale and type of influence on human health requires a new perspective which focuses on ecosystems and on the recognition that the foundations of long-term good health in populations rely in great part on the continued stability and functioning of the biosphere's life-supporting systems. It also brings an appreciation of the complexity of the systems upon which we depend.
Harmful effects of environmental change and ecosystem impairment on human health.
Protecting health from global environmental change requires management at many levels, from the social and economic drivers of environmental change, to the resulting hazards and exposures for human populations. WHO supports this linkage of environmental and health agendas, for example by providing health expertise into the UN Conventions on Climate Change, Biological Diversity and Desertification, and by advising the health sector on the necessary responses to address the health risks posed by large-scale environmental change.