True toll still to be uncovered

Canberra Times
Monday 19/10/2009 Page: 15

Discovering and attributing all of the health-related consequences of climate change will become easier in time, Tony McMichael writes

As governments haggle over emissions targets, timetables, trading, taxes and technical fixes, the Nero-fiddling-while-Rome-burns analogy looms ever larger. Meanwhile, human-induced climate change proceeds faster than before. Scientists met this month in Oxford to discuss what it would mean to live in a plus-four-degrees world. That's way beyond the assessed "safe" temperature limit.

A decade ago we would not have seriously foreseen such a world - one which, on the temperature scale, would take its nearly half way back to the late dinosaur era. The widely supported judgment from matey scientific disciplines is that a two degree increase represents "danger" territory. Current trends, plus the recent actual and latent warming, now suggest we will easily exceed a two-degree rise.

Nero presumably knew the impact of the great urban conflagration. We, however, have not yet comprehended the full consequences of climate change. We worry about impacts on GDP growth, property safety, job security, and iconic species. Those legitimate and important worries fall well short of understanding what is ultimately at stake.

We are playing for much higher stakes. Over aeons, natural changes in the planet's climate have driven great shifts in the conditions of life on Earth. Today, remarkably, we are the change-makers. And, as we weaken and disrupt the natural world's life-support systems and ecological processes, the risks to human well-being, health and survival escalate.

Yet, during most of this great modern discourse, the formal health sector has been a marginal participant. This, despite the fact that the UN Framework Convention on Climate Change (1992) states explicitly that the prime reason for averting "dangerous interference with the climate system" is to avoid serious damage to the environment, economic development and population health.

During this past year, the World Health Organisation, some regional development banks, enlightened national governmental development-aid agencies (like Denmark and Britain) and various health professional bodies have engaged more actively. They must still contend, though, with the prevailing popular misunderstanding of what determines health and disease. That popular view confuses the role of individual responsibility for personal health with the fundamental long-term dependence of the population's health on sustainable life-support from nature.

We readily apply whole population thinking to the health of livestock: the herd needs feed, water infection-free surroundings, and shelter from extremes. However, for our species, in modern urban settings, we assume that good health comes from individuals choosing sensibly in the supermarket, not smoking, wearing seat-belts, inheriting good genes, and having personal access to medical care.

Yes, those individual-level factors largely determine who among us gets sick. But the much bigger issue is to understand what limits the overall health of the population. Those limits are set by the conditions of the wider natural environment. And that is what is now being threatened. The risks to human health from climate change are many and great.

Our collective actions are jeopardising the foundations of population health: food yields, fresh water supplies, natural constraints on infectious disease agents, protection against extreme weather events, relative climatic stability, and social stability. Such systemic changes contributed historically to the decline of many regional societies, accompanied by undernutrition, starvation, epidemic outbreaks and conflict.

The Global Humanitarian Forum, chaired by Kofi Annan, estimates that at least 300,000 additional deaths now occur annually from several climate-related health impacts: under-nutrition, malaria, diarrhoeal diseases and flooding. Nearly all those deaths occur in poor and vulnerable countries. (Australia's past cumulative emissions account for about 2% of current human-induced warming - or 6000 of those deaths each year.) The complexity of human culture limits the exact study and quantification of most Health impacts of climate change.

When sea ice melts, the cause is clear. When, along with climatic changes, birds nest earlier and insects change their migration patterns, then it's pretty clearly due to climate. In humans, though, as the annual death toll from heat waves edges upwards with rising frequency of very hot days, might it be due to population ageing and the spread of dense heat-trapping suburbs? As malaria edges upwards on the warming eastern African slopes, is it due to changes in land use, people movement or mosquito spraying? Attributable impacts on health will, regrettably, become clearer as climate change progresses.

Meanwhile, much of the difficulty in attributing and quantifying those impacts reflects the inherent complexity of these systemic environmental changes. Counting road-deaths due to speeding is much easier than counting cases of undernutrition due to climate change in Africa, or climate related mental health problems in Australian rural communities undergoing warming, drying and declining production.

The systemic nature of climate change, as a fundamental long-term threat to the health of whole communities, mast be understood. This is more than an inconvenient truth; the risk to health from the disruption of physical and ecological processes is the real "bottom line" indicator of the dangers posed by climate change.

Tony McMichael, a National Health and Medical Research Council Australia Fellow at the Australian National University, has contributed to the Intergovernmental Panel on Climate Change, advises the World Health Organisation on climate change and health, and is a board member of The Climate Institute Australia.