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Cause & Effect

Australia’s climate has warmed by about 0.9°C since 1910.  Most of this warming can be attributed to increases in concentrations of atmospheric greenhouse gases, such as carbon dioxide, due to human activities.  Warming has been accompanied by changes to the frequency and severity of extreme weather, with more extreme heat and fewer cool extremes.  Global and Australian temperatures are expected to continue to increase, with further changes to extremes.

Sea level rise

Global mean sea level has increased throughout the 20th century, caused by thermal expansion of warming oceans and the loss of mass from glaciers and ice sheets. Sea levels are rising faster in northern Australian than southern Australia. Rates of sea level rise are increasing, with sea levels projected to rise by up to 1 metre by the end of this century.

Heatwaves

The majority of weather related deaths in Australia are caused by heatwaves. The duration, frequency and intensity of heatwaves have already increased across many parts of Australia. Rising global average temperatures in the future are projected to be accompanied by further substantial increases in heatwaves.

Extreme rainfall

There are no clear trends yet in the frequency of extreme rainfall in Australia. However, climate change projections indicate that rainfall is likely to become more intense in the future.  Projections for the Western Port region of Victoria, for example, indicate that maximum rainfall intensity could increase by 20 to 50% by 2070 for 24 hour events.

Drought

Southern Australia generally receives most of its rainfall during the cooler months of the year. In recent decades a decline in rainfall in the cooler months has been observed in southern Australia.  The reduction in rainfall is amplified in reduced flows in rivers and streams.  Average rainfall in southern Australia is projected to continue to decrease.  This decrease, combined with higher average temperatures, is likely to contribute to an increase in drought frequency and severity.

Effects

Increasing temperatures, rainfall changes and sea level rise due to climate change, are likely to contribute to increases in second order effects such as floods, bushfires and coastal impacts.  These changes will in turn impact on human health and infrastructure.

Coastal impacts

Approximately 85% of Australians live in the coastal zone, with up to 200,000 households living low lying areas. Sea level rise will bring significant risks to the coastal zone including inundation, more frequent flooding and coastal erosion. These risks have the potential to cause major damage to infrastructure and to disrupt services as well as threatening beaches, estuaries and dunes.

flood

Flood events represent the costliest natural disaster in Victoria and Australia as a whole. Projected increases in extreme rainfall, combined with greater intensity of development, is likely to increase the risk of flooding in the future.

human health

Climate change has the potential to impact on human health in many ways.  Well understood are the direct impacts of extreme weather, such as heat waves and storms, on human life and associated demands on public health and emergency services.  Less apparent are the indirect health effects of climate extremes, such as the impacts of droughts on the wellbeing of communities and changes in temperature and rainfall on the distribution and transmission of diseases.

bush fires

Some of Australia’s costliest natural disasters in terms of loss of life and infrastructure have been caused by bushfires in southern Australia. In recent decades there has been an increase in the number of extreme fire weather days in southern and eastern Australia. A further increase in extreme fire-weather is expected in the future, with a longer fire season in these regions.

infrastructure damage

Water and wastewater, power, transport, telecommunications and buildings infrastructure are all essential to the functioning of modern societies. Most of this infrastructure has been built based on historical climate information. Climate change brings major poses major direct and indirect risks to this infrastructure, posing challenges to the ways in which it is planned and managed in the future.

Biodiversity

Biodiversity is one of the most vulnerable sectors to climate change. Many of Australia’s most valued natural areas, and the rich biodiversity they support, are threatened by climate change. These include coastal and marine ecosystems, wetlands and other freshwater ecosystems wetlands and alpine biodiversity.

Adaptation Response

Many of the impacts of climate change are unavoidable, even if global efforts to reduce greenhouse gas emissions are successful. Climate change adaptation refers to strategies and actions to better manage the impacts of climate change. Good management will have significant economic, social and environmental benefits.

It is relevant to a wide range of policy and program areas including land use planning, infrastructure planning, emergency management, social services and financial management. Effective adaptation will encourage flexible, no-regrets responses, which build on existing plans and engage all of the community.