Issues Magazine

Climate Change and Health: Impacts and Adaptation

By Peter Thomas and Tony Capon

The inevitable and continued warming of the Earth’s surface will have both direct and indirect negative impacts on human health. Reducing the effect of climate change on health rests on effective mitigation and adaptation strategies.

There is now little doubt among the scientific community that increasing atmospheric concentrations of greenhouse gases are causing climatic change. The average land temperature in Australia has risen by 0.9ºC since 1950, and modelling shows us that by 2100 there will be an average increase in global temperature of somewhere between 1.4ºC and 5.8ºC.

Direct Impacts on Health
The warming of the Earth’s surface will cause established weather patterns to change. Extreme weather events like the storms and floods experienced recently in Queensland, New South Wales and Victoria, and heatwaves, bushfires and droughts, will increase.

Such events are expected to increase in both frequency and severity. This increase and the growing trend for building on or near floodplains may expose a greater number of people to the effects of flooding and its associated health risks. Such health risks include physical injuries, communicable diseases and exposure to toxic pollutants.

Climate change models predict a likely increase in heatwaves and a decrease in cold spells. Exposure to heatwaves – prolonged periods of temperatures above 35–40ºC – causes both morbidity and mortality, particularly in urban areas. Cities may act like large “heat islands”, with buildings and pavements retaining heat and slowing down cooling at night.

In the summer of 2009, south-eastern Australia experienced an extreme heatwave, leading to the deaths of about 500 people. During the 2003 heatwave across Europe, mortality excess reached about 30,000 deaths. Many of those that died suffered from a pre-existing condition that was aggravated by the heat – particularly cardiovascular diseases or chronic respiratory diseases. Indeed, the number of people that died could be higher as the official cause of death is not always directly attributed to the heatwave within official statistics.

When such heatwave-induced mortality can be attributed to prolonged periods of hot temperatures, the primary causes tend to be stroke, hypothermia or dehydration. Those identified at being at greatest risk of suffering from the effects of heatwaves are those with pre-existing medical conditions, people aged over 65 years, and those living in urban areas.

We can also expect that higher temperatures will increase the incidence of food poisoning. Pathogens grow and spread at an increased rate if food is not stored at sufficiently cold temperatures. The number of reported cases of food poisoning, such as diarrhoeal disease, gastroenteritis and salmonellosis, rises in line with temperature increases.

Indirect Impacts on Health
Climate change will also affect health indirectly. Storms can damage infrastructure such as water, sewerage and power systems, creating health hazards. If sewerage systems are damaged there is potential for effluent to contaminate water systems, including drinking water. Without clean water, food can more easily become contaminated. Combined with the accelerated growth and spread of food-borne bacteria in warmer conditions (e.g. due to power supply failure), there is potential for an increase in the prevalence of food poisoning.

Heatwaves can cause the failure of electrical infrastructure. During these events, high demand for power (e.g. for air conditioning) over a prolonged period places significant pressure on power generation, distribution and supply systems. Interruptions to power supplies during a heatwave can have serious implications for health.

Higher urban air pollution levels increase both mortality rates and hospital admissions for respiratory and cardiovascular conditions. Motor vehicles are a leading cause of such pollution. Research has shown that warmer temperatures and strong sunlight intensify the amount of ozone that forms from exhaust emissions. Therefore we can expect warmer temperatures associated with climate change to bring about increases in air pollution, and hence escalating morbidity.

Climate change is set to change the established patterns of rainfall across Australia and in doing so may affect patterns of infectious diseases. The distribution of Ross River and Barmah Forest viruses may change. Some climate change modelling has predicted that in the future the dengue virus might be found as far south as Sydney.

All of these potential harmful health effects of climate change, particularly those associated with catastrophic events, have the potential to indirectly lead to an increase in mental health problems. Some people will struggle to cope with the enormity of loss that such events can bring about – the mental health impact of long-term drought on farming communities has been well-documented. Others will suffer from mental health problems associated with a decline in their physical health.

Adapting to Climate Change
The Australian community and the healthcare system need to be adequately prepared for the diverse health risks that climate change is set to bring. Increases in disease burden and morbidity will place greater strain on healthcare services. It is essential to start developing strategies that will reduce the severity of climate change impacts on health.

Modelling suggests that reducing emissions can reduce expected warming, and in doing so reduce the severity of the associated health impacts. However, reductions will not prevent all of the health problems associated with climate change.

Whatever strategies we use, human-induced global warming will still occur. We do not know how successful our attempts to mitigate global warming are going to be. We need to find ways of adapting to a changing climate. Putting into place considered climate change adaptation strategies can help to make communities that are more resilient and thus less susceptible to increased health risks.

Finding and implementing successful ways to adapt to climate change requires a coordinated approach by federal, state and local government, the health sector, planners and builders, emergency services and infrastructure providers. Such an approach needs to engage the entire community to achieve its maximum effect and target action towards those most at risk.

What to Adapt?
Healthcare providers such as hospitals, primary care providers, ambulance services and residential care homes will be put under strain by the health effects of climate change. Hospitals are already equipped to deal with surges resulting from catastrophic events, but the frequency and intensity of future surges will place pressure on health care. Identification of likely future needs is now essential so that the healthcare system is able to cope.

The role of health professionals in climate-change-induced events is not limited to treatment. Some health professionals can take preventative action to reduce the effect of events on human health. During heatwaves, for example, they can identify vulnerable groups, and give advice about how to avoid heat stress by changing behaviour and work practices.

In the aftermath of a catastrophic event such as flooding or a bushfire, community services are an important complement to health services, such as the Australian Red Cross and the Salvation Army, in helping people deal with mental health consequences. These services need to be well-prepared for such events.

Where infrastructure is unable to cope with the consequences of climate change, particularly during catastrophic events, more severe health effects can be expected. Successfully planning and adapting infrastructure to cope with events such as heatwaves, storms, floods and bushfires can help to reduce the impact such an event has on population health.

Future adaptation strategies will need to ensure that the systems supporting our key infrastructure, such as power and water supplies and sewerage systems, are less susceptible to failure. Where problems do occur they need to be able to be remedied quickly and other response plans readily put in place, such as prioritising needs and using backup supplies.

Most people in Australia live in urban areas. We can make changes to our cities to better equip them for the impacts of climate change. Building design is crucial to both mitigating and adapting to climate change. Improved insulation and more efficient natural cooling systems not only have the potential to reduce carbon emissions from air conditioning but can also protect people from heat stress.

Because cities are likely to continue to grow, how we adapt cities to cope with an increased population will affect our health in many ways. More parks, trees and greenery can reduce the impact of the urban heat island, as well as offsetting carbon emissions. Cities that make best use of the natural environment by creating wind tunnels between buildings and avoiding west-facing vistas will help to make cities more liveable during extreme heat events. This will lessen the impact of heat stress.

Mitigation, Adaptation and Health
Although the impacts of climate change on human health are mostly negative, choosing a low-carbon way of living can bring many positive health benefits. Making our cities less car-dependent can provide more opportunities for active travel. Fewer cars mean less fossil fuel use, lower carbon emissions and reduced health impacts from air pollution.

Walking and cycling where possible not only reduces carbon emissions but also has a number of health co-benefits. For example, such exercise reduces the risk of obesity and cardiovascular disease, and healthier people will be less susceptible to the adverse health effects of climate change.

Grazing animals are important contributors to greenhouse gas emissions of carbon dioxide and methane in Australia. Reducing the amount of red meat we eat, and substituting fruit and vegetables, will reduce carbon emissions and improve health at the same time.

Adapting buildings and how we use them to make them more carbon-efficient has the potential to bring real health benefits. For example, better insulation in buildings can reduce over-reliance on air-conditioning systems, which studies have shown may have adverse negative health consequences such as increased risk of respiratory health consequences including asthma. Designing high-rise buildings so that there is easy access to stairs rather than just to lifts increases exercise levels among the building’s occupants as well as reducing carbon emissions.

Conclusion
The many negative health impacts of climate change require a variety of adaptation strategies. Adaptation and the health co-benefits of reducing carbon emissions will help us to manage the expected health effects of climate change.

Further information about climate change and health can be found at the World Health Organization’s website: http://www.who.int/topics/climate/en

The National Climate Change Adaptation Research Network for Human Health is based at The Australian National University. The network comprises researchers from various disciplines (including epidemiology, climate science, environment, rural science, sociology, economics, mental health, infectious diseases, physiology, ergonomics, health promotion, health services) and research users (policy-makers, practitioners, industry, community). For more information see http://www.nccarf.edu.au/humanhealth