Prof. Moses Amweelo
Global biodiversity degradation significantly impacts the key components of human health and well-being. Ecosystem services, i.e. the benefits people obtain from ecosystems, are indispensable for the health and wellbeing of people around the world.
Biodiversity degradation leads to changes in the supply and flow of these goods and services.
The resulting impacts on economic and physical security, freedom and social relations have wide ranging consequences on human well-being and health.
When animal and plant species go locally extinct, genetic diversity is reduced, biological communities become altered, and ecosystems begin to lose their key functions.
Services provided by genetic building blocks, species and ecosystem processes may become compromised, diminish in effectiveness or even shift from being positive influences on health to having negative consequences.
Systems with lower genetic diversity are less buffered against degradation due to human activities or natural disasters.
They potentially provide fewer direct resources e.g. foods and medicines. The provision of food and medicines provides the main link between biodiversity and human health.
All food species, whether hunted or gathered in the wild, or grown in the most intensive production systems, occur within ecosystems whose productivity is impacted by the activity of other elements that exist within those ecosystems.
The current decline in dietary diversity that ensures essential components such as proteins, fatty acids and vitamins, in both rural and urban populations, may lead to serious deficiencies of minerals, vitamins and trace elements with negative effects on human health.
Impacts of climate change on disease emergence. Climate change is expected to affect disease incidence and emergence by: shifting the geographic locations of hosts, vectors and disease-causing parasites into new regions; altering the abilities of parasite species to survive, reproduce, and be transmitted from hosts to humans; increasing the frequency and intensity of floods and draughts that create health threats by disrupting sanitation and drinkable water supplies.
On the other hand, historically affected areas might become uninhabitable by the parasite and its mosquito vectors and thus malaria-free. The linkages between environmental change, health and biodiversity are highly complex. Changes to the environment that benefit our health can be viewed as trade-offs against biodiversity.
Gains in one domain can come at the expense of losses in another: drainage of the swamps in the Great Lakes Area of North America, while reducing biodiversity (i.e. biota that thrived in swamps) improved human health through elimination of malaria-carrying mosquitoes; elimination of vampire bats, which spread rabies to cattle in Latin America increased cattle productivity and thus improved human health via better nutrition.
But also in Africa, the presence of tsetse flies and their host species over large regions has prevented the colonization of some grazing areas by people and cattle thus preserving biodiversity and other ecosystem services in those areas. Main challenges: As global populations rise towards nine billion in 2050, trade-offs between human well-being and competing uses of resources and physical space for food supply and energy production will make it more difficult to maintain functioning levels of biodiversity.
Much of future global population growth will occur in areas where human health is at greatest risk because of poverty and natural resource scarcity. Simultaneously, this is where there is significant potential for disease transmission from the wild into human populations. Climate change adds uncertainty. It becomes more difficult to predict which biotic resources and ecosystem functions may be needed for human adaptation to projected food supply disruptions and ecosystem alterations. There will also be shifts in disease patterns and risks, as well as more direct health threats.
WHO estimates that half of childhood deaths in low-come countries are caused by malnutrition. Large-scale conversion of cropland to other forms of production, including non-food energy production coupled with inadequate pricing of agricultural goods and services might increase the risk of deaths from malnutrition in the future. Conflicts can arise between short-term benefits versus long-term costs.
There are trade-offs between positive and negative impacts of local biodiversity. For example, malaria can be reduced in the short term by draining wetlands, but in the long term this loss of wetlands causes major shortages in traditional foods and livelihoods (e.g. local fisheries collapse). Shifts to irrigated agriculture increase food production and improve nutrition but, conversely, also expand habitat for mosquitoes. In tropical and sub-tropical regions, this raises the local incidence of mosquito-borne diseases such as malaria, dengue fever and dengue haemorrhagic fever. While there are multiple benefits of biodiversity, biodiversity can also pose a risk to human health and quality of life.
For example, in the case of HIV and SARS, there is evidence pointing to the shift of these diseases from animal populations to humans being sparked by increased hunting and consumption of bush meat.
The way forward, management of biodiversity to benefit human health and well-being will require specific policies and at appropriate levels (e.g. regional, national, sub-national) that address health needs and criteria for good quality of life of the particular cultures that are affected.
Local policies need to strike a balance between biodiversity conservation, economic pressures, maintenance of cultural integrity, and immediate crisis abatement (e.g. disease epidemics, water shortages or floods, electric system overloads, or housing shortages).
The Namibia government promotes the conservation and sustainable use of Namibia’s biodiversity and effective management of ecosystems, as well as the equitable sharing of benefits arising thereof for the well-being of the nation (National Policy on Climate Change for Namibia 2011). Responses that mitigate the impacts of ecosystem changes on human health often involve policies and actions outside the health sector. Action to mitigate impacts of climate change will similarly require cooperation across multiple sectors.