ECOSYSTEM CHANGE AND THE FUTURE OF CIVILISATION

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Ecological changes can have many effects to human society and thus to human health. From a human-centred perspective, most human induced ecosystem changes have been beneficial, but past success and current techniques do not guarantee this trend will continue idefinitely. Several past ecosystem changes, including deforestation, soil degradation, climate change, and plant disease, are well-documented contributory causes for severe damage to human societies in regions and times as distinct as ancient Sumeria, mediaeval Greenland, Polynesian Easter Island and Victorian Ireland. This paper argues that, despite the promises of new technologies, the apparent guarantee against regional scarcity provided by trade, and growing public awareness of ecosystem damage–and thus self-organised attempts at ecosystem repair-a non-trivial threat exists to future civilisation from the deterioration of linked social-ecological systems. At the worst case, the-scale involved could be global. Methods The literature examining ecosystem change, human health and past civilisation failure was reviewed. As well, future scenarios theory, stimulated by participation in the scenarios working group of the Millennium Ecosystem Assessment, was used to construct and explore the interaction of plausible ecosystem changes over the next century with public health. Results A classification of four kinds of adverse effects to human health and well-being, due to adverse ecosystem change was developed. The first two kinds of changes, called “direct” and “mediated” have comparatively modest adverse public health impact. Largely borne by poor populations, the adverse health effects from such changes may be perceived as undesirable but temporary, acceptable trade-offs in exchange for net benefits to wider human well-being. However, we also identified two larger-scale risks, which we called “modulated” and “multi-systems failure”. Though putative, these threats represent serious issues for current epidemiologists. This is not only because of their scale, but because the lagged, inertial factors involved with their unfolding give a high premium to prevention. Causation in all four causal models, but particularly the two largest-scale was identified as multi-factorial, involving complex interaction between ecosystems and many social, political and non-living environmental factors. For example, reduced productivity of the global agro-ecosystem, caused by intensified droughts and floods, soil degradation and inadequate capital to develop virgin agricultural lands at high latitudes, even though made theoretically arable by global warming, could lead to regional food scarcity of unprecedented scale. This could interact with inequality, human rights violations, and economic malaise to create downward spirals that threaten the fabric of global civilisation. Conclusions Scenario construction is a fascinating exercise with a serous side. It is an accepted tool for environmental scientists (e.g. in climate change) but less known among epidemiologists. The complex-and contested-causation of adverse scenarios for global public health potentially undermines engagement by epidemiologists in their study but this reticence may be overcome. If so, epidemiologists, well-versed in adjusting for confounders, may also shed light on the intractable nature of similar problems, whose remedies are unlikely to be well-characterised without multi-disciplinary insights.