The relationship between human beings and the ecosystems of which they are a part is profound. The links between health and the environment are as old as human culture. Human evolution takes place within ecosystems, and there are deep psy- chological, social and cultural connections to ecosystems that go well beyond mere physiological needs.
In the late 20th and early 21st centuries, myriad threats to the health of the Earth’s environment have become apparent. There is a growing recognition that the Earth is itself a living system and that the ultimate determinant of human health (and that of all other species) is the health of the Earth’s life-supporting systems. The ecosystem-based ‘goods and services’ that we get from nature are the ecological determinants of health. Among the most important of these are oxygen, water, food, fuel, various natural resources, detoxifying processes, the ozone layer and a reasonably stable and habitable climate.
Public health in the 21st century must augment its scope to address the natural world; encompass concepts such as One Health and Ecohealth; and specifically target the health challenges of human-induced global climate change, resource deple- tion, ecotoxicity and loss of biodiversity.
Our knowledge of the health impacts of global ecological change is surprisingly limited. What we know is imprecise, pre- liminary and often speculative; we have some idea of the big picture, but the details are lacking. Even in the case of climate change, we have only a modest sense of the potential health impacts, although this has been the focus of some well-resourced research over the past few decades, both globally and in Canada.
We do know that the indirect health effects of global ecological change – those mediated through natural and human systems – are likely to be much greater than the direct effects (such as heat waves), although they are harder to quantify and attribute directly to a specific global change. This difficulty in quantifying the indirect health effects is part of the uncertainty with which we must deal.
The key human forces driving changes in ecosystem functioning are population growth and urbanization, economic growth and development, technological changes and advances, and social changes and movements aligned to these forces. Under- lying and shaping these drivers are societal and cultural values, which for the past 200 to 300 years have emphasized ‘progress’ or modernization, transforming human societies from rural and agrarian to secular, urban and industrial. The long history of modernization helps us to understand our current social, political, economic and cultural conditions, and, perhaps, to anticipate a post-modern society that enables us to stabilize and reverse these harmful ecological changes.
We will need some fundamental shifts in societal values, and with that new principles, and new ways of knowing, measuring and governing. Fortunately, we do not have to invent these from scratch as we have precedents and newly-emerging practices that can help provide a foundation for the new future we need to create. The fields of health promotion and Ecohealth offer conceptual and procedural guidance to catalyze a transformation toward public health equity for future populations.
If we understand the forces that shape us and the future we face, we are better equipped to make choices, express our values in a vision and then work to create it. Within public health, we need to explore scenarios of plausible futures, and help people create visions describing their preferred future.
CPHA’s vision of healthier, more sustainable, more just societies and communities will not be achieved in isolation from wider social processes. Realizing any such vision will demand transitions both within and outside public health and the larger health sector, including an explicit re-engagement with the values of public health.