2014 Theo Murphy High Flyers Think Tank – Climate change challenges to health: risks and opportunities

Introduction

The world’s climate is changing. General global warming has been observed over the past several decades. Associated with it are changes to the general circulation of the atmosphere and oceans, including to the vertical distribution of temperatures, atmospheric water vapour concentration, the incidence of extreme weather events, and sea-level rise, and concomitant changes to global biology as observed in shifts in the distribution of species and behavioural changes of both plants and animals.

Observed global warming today is rapid compared with palaeoclimate warming and warming in geologic times, and is consistent with expectations based on the infra-red absorption properties of greenhouse gases such as carbon dioxide, methane and nitrous oxide, and the way they affect the energy budget of Earth and other planets of our Universe. Strong evidence indicates that current atmospheric levels of greenhouse gases are the highest of any in at least the past million years and are caused by the effects of human activities on the gases’ natural biogeochemical cycles.

Understanding of this association gives us capacity to anticipate the future warming likely in response to continuing emissions of greenhouse gases. However, climate is a complex physical and dynamical system, so predictions of future change are not perfect. In particular, regionally, where individual human societies or ecosystems operate, uncertainty remains, not only as to how humans will respond to the challenge of reducing greenhouse gas emissions, but how general warming will manifest in change to local rainfall seasonality, sea level, storm frequency and intensity and so on, and thus affect human and plant and animal ecosystems.

Knowledge of these systems, however, is sufficient to cause concern that climate change impacts will be important. We cannot afford to wait until we have complete knowledge of future climate change and its impacts before acting to reduce the risk by working as a global community to reduce emissions. Nor can we delay anticipating as accurately as possible impacts in our geographic region, and planning adaptive responses to them. This imperative is all the greater given that once initiated these changes will persist for centuries, and that humankind’s mitigation responses to the emissions have been very slow. With each year’s delay, we commit the planet to climate change of greater seriousness and risk.

Climate affects natural systems in many and diverse ways. This Theo Murphy Think Tank will examine effects on human health and wellbeing and propose ways of reducing the now inevitable harm that some will cause. We will start with the guidance of Chapter 25 of the Intergovernmental Panel on Climate Change’s Fifth Assessment Report of the Second Working Group, which deals with the impacts, adaptation and vulnerability related to Australasia. It provides a carefully considered analysis and summary of Australia’s exposure to climate change, including the best projections of likely geographic changes to the physical climate for different levels of future greenhouse gas emissions.

Climate and its changes affect human health in many ways. In the first instance, temperature levels, in particular extremes of temperatures, affect human health and capacity to function. These impacts may be exacerbated by changes to humidity levels, both day-night variation and seasonal extremes. They interact with housing, emergency and health services, employment, age and existing health status. In Australia the potential impacts of bush fires on the physical and mental health of communities are of particular importance. Thus our first working group will target Temperature and extreme weather events.

Climate change alters the environment in which disease vectors live and reproduce and disease-causing organisms are incubated and transferred to humans. It is likely that the geographic range of particular vectors and diseases will change with climate change, exposing populations to change in the incidence of infectious diseases and medical facilities to change in disease patterns, increasing the demand for specialised services, and demanding vector control efforts in regions where they were not previously needed. Thus the second working group will target Infectious disease ecology and epidemiology.

Human health is strongly influenced by the quality and quantity of available food and water. The geographic range of food production and the food species cultivated are likely to change with ongoing climate change. Perhaps the most important effect of climate change on Australia, at least in its southern parts, will be a generally lower availability of water, which is likely to have effects on food production, increase costs of supply of potable water and decrease its quality, with possible flow-on health effects. The third working group will thus target issues related to Food and water supplies.

Climate change will affect the liveability of regions, potentially rendering existing infrastructure and social services ill-adapted to serve and protect citizens unless modified. Both will be sorely tested by increases in severe weather events. Some such impacts may also occur indirectly through requirements to change energy sourcing and use. This is likely to change employment associated with these sectors, threaten the viability of communities, change the price of energy, and create the potential for loss of livelihood and economic stress. The poor and disadvantaged are more likely to be affected than others in the community; thus raising challenges for the provision of social services and maintenance of social equity. The fourth working group will explore issues of Livelihood and disadvantage.

Climate change has the potential to seriously disrupt existing social structures, through the displacement of habitation by previously unexperienced levels of inundation, bush fires and storm damage, desertification and sea-level rise. Such displacements may be regional, national or even international, creating pressures on the security of settlements, employment and expectations, and conflict within and between communities. Such changes create the potential for both physical and mental ill health, resulting from uncertainty, anxiety and unavailability of food, water and shelter. Thus our fifth working group will explore Security, social instability and conflict issues consequent on climate change.

© 2018 Australian Academy of Science

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