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Trevor Hancock: Our health depends upon a healthy planet

In the world of population and public health in which I work, we have paid great attention in recent years to what are termed the “social determinants of health.

In the world of population and public health in which I work, we have paid great attention in recent years to what are termed the “social determinants of health.”

Poverty and all its attendant ills — food insecurity, poor and insecure housing, low levels of education, marginal, tenuous and unhealthy jobs and others — have been our focus.

But in focusing on these issues, we have neglected the most important determinants of our health, because like all other animal species we need air, water and food to survive, as well as other vital ecosystem “services.” In addition, we depend on nature for fuel and materials and a relatively stable climate system.

Functioning ecosystems are the most fundamental determinants of health, without which human societies and perhaps even humanity itself will fail. In which case, we are in trouble, as several recent reports have reminded us.

• The World Wide Fund for Nature released its bi-annual Living Planet Report in the fall of 2014. It found that the Living Planet Index, “which measures more than 10,000 representative populations of mammals, birds, reptiles, amphibians and fish, has declined by 52 per cent since 1970.”

• The same publication, using the Ecological Footprint, reported that the global footprint has more than doubled in the past 50 years and that “we would need the regenerative capacity of 1.5 Earths to provide the ecological services we currently use.”

If the whole world lived at the same level of consumption as we do in rich countries, we would need several more planets to meet our needs.

• Last week, a group of ocean scientists published a report in Science in which they examined the extent of damage to marine species globally.

A combination of overfishing, destruction of habitat, global warming, ocean acidification and pollution has already had a dramatic impact on sea life. They caution that if we continue as we are, we risk “a major extinction pulse, similar to that observed on land during the industrial revolution, as the footprint of human ocean use widens.”

• Also this past week, the U.S. National Oceanic and Atmospheric Administration reported that 2014 was the hottest year in the 135 years of recording; December was the hottest on record, and that was the case for five other months in 2014.

In short, four great human-created driving forces are converging, threatening the stability of our ecosystems: climate and atmospheric change, pollution and ecotoxicity, depletion of renewable and non-renewable resources, and the loss of habitat, species and biodiversity.

The ecological changes that we are creating are threatening our health and the stability of societies around the world.

For example, we can expect to see health impacts due to climate change. These will result from rising sea levels flooding low-lying land, changes in the distribution of insects that transmit diseases such as malaria, changes in water supply and agricultural ecosystems, and also in oceans, affecting food supply, and more extreme weather events.

All this will also result in large-scale migration of eco-refugees, with all the associated health concerns that raises.

That is why there has been growing attention to the ecological determinants of health in recent years. I am leading a two-and-a-half-year project for the Canadian Public Health Association to document the threats to health posed by these human-induced ecological changes, and to suggest the actions we need to take to address them. Our report will be out this spring.

More recently, at a global level, The Lancet, one of the world’s leading medical journals, published a manifesto for planetary health, noting our responsibility as health professionals to “respond to the fragility of our planet and our obligation to safeguard the physical and human environments within which we exist.” Now an international commission, supported by the Rockefeller Foundation, is developing a report on planetary health that will be released this summer.

When you come right down to it, we can’t have healthy people on an unhealthy planet. But we are making our planet sick, and it can’t go on.

Dr. Trevor Hancock is a professor and senior scholar at the University of Victoria’s school of public health and social policy.