Changes in temperature and precipitation, and extreme events trigger indirect effects of climate change on the environment, affecting economic and social processes and systems, and natural ecosystems. Australia’s sixth national communication on climate change to the United Nations Framework Convention on Climate Change summarises the wide range of indirect effects of climate change for Australia (DIICCSRTE 2013):
- Water—decreased rainfall in southern Australia and south-western Western Australia, increased evaporation, and reduced run-off to streams and recharge to groundwater systems will result in decreased water availability and decreased water security (see the Inland water report).
- Coasts—sea level rise will result in greater coastal inundation, loss of wetlands, salt water mixing into freshwater sources, and erosion affecting coastal infrastructure and resources. Changes to weather patterns, ocean currents, ocean temperature, storm surges and ocean acidification could also affect coasts (see the Coasts report).
- Infrastructure—climate change will result in damage to energy, water, communications and built infrastructure. The interdependencies between critical infrastructure sectors complicate the likely effects of climate change on infrastructure. For example, extreme event damage to the electricity network would affect telecommunications and transportation infrastructure (see the Built environment report).
- Agriculture—climate change will result in a decrease in agricultural activity. Drought disrupts cropping, reduces stock numbers and erodes the resource base of farms. Severe storms, hailstorms, cyclones and floods destroy crops, damage infrastructure and interfere with activities such as harvesting and planting. Managing climate variability will become increasingly difficult for Australian primary producers, given the projected changes in mean temperature and precipitation that will be superimposed on large climate variability.
- Iconic natural systems—climate change is likely to intensify the effects of existing threats and enhance the cumulative impacts on iconic natural systems. For example, for Kakadu National Park, likely climate change impacts include rising sea levels, saltwater intrusion, changing fire patterns, and invasive flora and fauna. In the near term, increasing sea temperatures will damage coral systems on the Great Barrier Reef, and, in the long term, ocean acidification will damage oceanic calcifying organisms on the Reef.
- Human health—climate change will have some direct impacts on human health, such as the effects of heatwaves. Other effects could occur indirectly through disturbances of natural ecological systems, such as changes in the range and activity of mosquito populations (Bambrick et al. 2008, Åström et al. 2012), or increased fire activity that could result in the degradation of air quality in rural and urban centres (Keywood et al. 2013). The psychological impacts of climate change are likely to grow. Studies based on impacts of recent climate variability and extremes are being documented (Doherty & Clayton 2011); they indicate significant mental health risks associated with climate-related disasters—in particular, persistent and severe drought, floods and storms. These impacts are most acute in rural communities where climate change places additional stresses on livelihoods (Edwards et al. 2009).