What is an ecosystem?
The term ecosystem refers to the combined physical and biological components of an environment. These organisms form complex sets of relationships and function as a unit as they interact with their physical environment.
Millennium Ecosystem Assessment Synthesis Report
Why do ecosystems matter for human health?
Ecosystem services are the benefits that people obtain from ecosystems. Ecosystem services are indispensable to the wellbeing of all people, everywhere in the world. They include provisioning, regulating, and cultural services that directly affect people, and supporting services needed to maintain the other services. From the availability of adequate food and water, to disease regulation of vectors, pests, and pathogens, human health and well-being depends on these services and conditions from the natural environment. Biodiversity underlies all ecosystem services.
The causal links between environmental change and human health are complex because they are often indirect, displaced in space and time, and dependent on a number of modifying forces. Human health ultimately depends upon ecosystem products and services (such as availability of fresh water, food and fuel sources) which are requisite for good human health and productive livelihoods. Significant direct human health impacts can occur if ecosystem services are no longer adequate to meet social needs. Indirectly, changes in ecosystem services affect livelihoods, income, local migration and, on occasion, may even cause political conflict. The resultant impacts on economic and physical security, freedom, choice and social relations have wide-ranging impacts on well-being and health, and the availability and access to health services and medicines.
Threats to ecosystems and health
Human interventions are altering the capacity of ecosystems to provide their goods (e.g. freshwater, food, pharmaceutical products, etc) and services (e.g. purification of air, water, soil, sequestration of pollutants, etc).
Ecosystem disruption can impact on health in a variety of ways and through complex pathways. The types of health effects experienced are determined by the degree to which local population’s depend on ecosystem services, and factors such as poverty which affect vulnerability to changes in elements like access to food and water.
UN Millennium Ecosystem Assessment
The Millennium Ecosystem Assessment (MA) was called for by the UN Secretary General in 2000, to assess the consequences of ecosystem change for human well-being. The MA was a multi-agency initiative and involved the work of over 1,360 experts worldwide. The five volumes assessment published in 2005 provides decision-makers and the public with relevant scientific information on the conditions of ecosystems, consequences of its change and options for response.
What did the MA tell us about the state of ecosystems in the world?
- Over the past 50 years, humans have changed ecosystems more rapidly and extensively than in any comparable period of time in human history, largely to meet rapidly growing demands for food, fresh water, timber, fiber and fuel. This has resulted in a substantial and largely irreversible loss in the diversity of life on Earth.
- The changes that have been made to ecosystems have contributed to substantial net gains in human well-being and economic development, but these gains have been achieved at growing costs in the form of the degradation of many ecosystem services, increased risks of nonlinear changes, and the exacerbation of poverty for some groups of people. These problems, unless addressed, will substantially diminish the benefits that future generations obtain from ecosystems.
- The degradation of ecosystem services could grow significantly worse during the first half of this century and is a barrier to achieving the Millennium Development Goals.
- The challenge of reversing the degradation of ecosystem while meeting increasing demands for services can be partially met under some scenarios considered by the MA, but will involve significant changes in policies, institutions and practices that are not currently under way. Many options exist to conserve or enhance specific ecosystem services in ways that reduce negative trade-offs or that provide positive synergies with other ecosystem services.
The bottom line of the MA findings is that human actions are depleting Earth’s natural capital, putting such strain on the environment that the ability of the planet’s ecosystems to sustain future generations can no longer be taken for granted. The assessment also showed that with appropriate actions it is possible to reverse the degradation of many ecosystem services over the next 50 years, but the changes in policy and practice required are substantial and not currently underway.
Conceptual Framework of how human well being and health is impacted by changes in ecosystems, at local, regional, and global scales