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Globally, climate change is recognised as one of the most serious environmental issues faced today. It is predicted to bring rising sea levels, shifting rainfall patterns and altered frequency and size of extreme climate events.

It is thought to be accelerated by the burning of fossil fuels by humans and increases in greenhouse gas levels, which results in escalating atmospheric temperatures. This affects cloud cover, rainfall, wind patterns, ocean currents and the distribution of plant and animal species.

Managing impacts

Parks and Wildlife recognises that the potential impacts of climate change will alter the ecological function of the Swan and Canning rivers and the way people interact with them. Rising water levels, changes in biodiversity and reduced stream flow are among the impacts of climate change predicted for the Swan Canning Riverpark.

Perth’s riverside location means management practices in the Swan Canning Catchment will need to accommodate understanding of climate change impacts throughout the region.

In 2007 a Technical Advisory Panel published a comprehensive paper on the potential impacts of climate change on the Swan and Canning rivers. This provides an overview of climate change impacts and potential adaptation strategies for the Swan Canning Catchment. A summary paper is also available.

 Further reading

Responding to climate change

We are already seeing localised effects of climate change:

  • average annual surface temperatures have increased approximately 0.6ºC from 1900 to 1990
  • an increase in storm surge activity has been observed since 1990 - this is reflected in elevated maximum water levels recorded in 2003 and 2004
  • Fremantle sea level records indicate average sea level has risen at a rate of 1.54mm a year between 1897 and 2007
  • autumn and winter rainfall and the frequency of large winter storms has steeply decreased since the early 1970s
  • river flow has decreased as a result of lower rainfall
  • marine water moves further upstream in summer and autumn

The Swan Canning river system is responding and will continue to respond to a series of drivers:

  • increased atmospheric and water temperatures
  • more frequent warm spells and heat waves potentially leading to more algal blooms
  • accelerated sea and estuary water level rise
  • decreased winter rainfall and streamflow
  • decreased groundwater levels leading to reduced flows to drains and streams

The Technical Advisory panel has predicted the changes that might occur in the river system:

  • Water, sediment, salt loads and nutrients from the Avon Catchment to the Swan River are expected to reduce with a drier climate.
  • Community use and perception of the rivers may change if loss of beaches, wetlands and vegetation reduces recreational facilities, changed aesthetic values or public perception of the health of the system if algal blooms and fish kills increase, and increased development of infrastructure to mitigate sea level rise
  • Sea level rise and decreased streamflow will impact the river’s ecology. This is predicted to:
    - increase stratification of saline water and penetration of marine water upstream
    - affect biological processes such as oxygen demand, nutrient cycling and sediment retention
    - alter distribution and abundance of species along with seasonal patterns of productivity and food-web dynamics
    - cause ongoing problems associated with eutrophication such as algal blooms and fish kills, particularly in the upper Swan River 

Parks and Wildlife’s response to climate change effects is based on an adaptive management approach. This is a systematic process of continually improving management policies and practices to reduce or accommodate the adverse impacts of climate change.

Adaption and mitigation strategies identified for the Swan Canning Riverpark include:

  • assessing foreshore vulnerability (vegetation and shoreline)
  • improving water quality through oxygenating water, trapping nutrients and ensuring adequate river flow
  • using monitoring and modelling to predict future changes
  • managing biodiversity
  • protecting infrastructure

Climate Change Risk Assessment Project

In 2010, a Climate Change Risk Assessment Project was developed to enable local government to assess the vulnerability of foreshore assets in the Riverpark to climate change-induced sea level rise. This project produced a risk assessment methodology to give local government the ability to plan, prioritise and manage the risks to the Riverpark’s economic, social and ecological assets. It can also be used by other foreshore land managers. The methodology includes a checklist of infrastructure, social and environmental assets. The project area spans from Fremantle traffic bridge to Windan Bridge on the Swan River and Riverton Bridge on the Canning River. A case study was also developed with support from the City of Perth to look at the potential effects of climate change at Point Fraser in the Swan River.