Sixty percent of the benefits that the global ecosystem provides to support life on Earth - fresh water, clean air, abundant wildlife, and a relatively stable climate - are being degraded or used unsustainably with negative effects on human health, finds a new report released today by the World Health Organization.
"Ecosystems and Human Well-being: Health Synthesis," explores the complex links between the preservation of healthy and biodiverse natural ecosystems and human health.
"Over the past 50 years, humans have changed natural ecosystems more rapidly and extensively than in any comparable period in human history," said Dr. Lee Jong-wook, director-general of the World Health Organization. "This transformation of the planet has contributed to substantial net gains in health, well-being and economic development," said Dr. Lee, adding that not all regions and groups of people have benefited equally from this process.
In the report, scientists warn that harmful consequences of ecosystem degradation to human health are already being felt and could grow worse over the next 50 years.
"The benefits should be acknowledged," said Dr. of Purdue University, WHO's lead author on the report. "But these benefits are not enjoyed equally. And the risks we face now from ecosystem degradation, particularly among poor populations directly dependent on natural ecosystems for many basic needs, has to be addressed."
Many serious human diseases have originated in animals, and so changes in the habitats of animal populations that are disease vectors or reservoirs, may affect human health, sometimes positively and sometimes negatively, the report explains.
Sometimes the environmental circumstances leading to disease transmission are complex. For example, the Nipah virus is believed to have emerged after forest clearance fires in Indonesia drove carrier bats to neighboring Malaysia, where the virus infected intensively farmed pigs, and then crossed to humans.
Intensive livestock production, while providing benefits to health in terms of improved nutrition, has also created environments favorable to the emergence of diseases, the report points out.
Increased human contact with wild species and "bush meat" as a result of encroachment in forests and changes in diet also create opportunities for disease transmission.
Trends ranging from forest clearance to climate-induced habitat changes also appear to have impacted certain populations of mosquitoes, ticks and midges, altering transmission patterns for diseases like malaria and Lyme disease.
Deforestation also endangers health by intensifying the effects of natural disasters such as floods and landslides, resulting in reduced crop yields. This impairs the nutritional status of households and diet deficiencies harm children's physical and mental development. In turn, this can impair the livelihoods of farmers and limit the options open to their children.
Pressures on ecosystems could have unpredictable and potentially severe future impacts on health, the report states.