Easing the Coastal Squeeze

Among the more enduring images of climate change are scenes of lavish oceanfront homes surrendering to rising sea levels and falling into the ocean. This is a huge problem for people in urban areas but what about other species that also rely on the unique habitats that fringe our coasts? As sea levels continue to rise, where are species that depend on coastal fringes, like the critically endangered Orange-bellied Parrot, going to go if the sea eventually meets the farm fence or highway and their coastal habitat is gone?     

How can we ease the squeeze between where the ocean ends and where our coastal land uses begin? A team of scientists from The Nature Conservancy (TNC) set about reviewing the options. Their findings are published today in the journal Ocean and Coastal Management.    

“Our work found that there are a range of viable solutions for coastal landholders and managers to protect coastal fringe habitats and allow them space to ‘move’ as sea levels rise”, said co-author and Director of Conservation at TNC Australia, Dr James Fitzsimons. “Erosion and flooding are not new issues in these locations, however, the frequency and intensity of these impacts will increase dramatically with sea level rises and climate change. There are a range of planning options for addressing these threats but we can also use these and other financial mechanisms to benefit critical habitats such as saltmarshes and mangrove forests.”

The team describes how ‘natural infrastructure’, which enables both coastal habitat protection and coastal risk reduction, can be a cost-effective solution compared to the more frequently used ‘grey infrastructure’ such as weirs, levees and seawalls. For example, a common response to advancing shorelines is the installation of sea walls or bunds. While these can provide temporary protection for coastal assets, over the longer-term they cause changes in sediment, current and wave dynamics that accelerate erosion, often resulting in the loss of the very beaches and coastal habitats they were intended to protect. This results in any wildlife habitat being squeezed between advancing sea levels and existing hard infrastructure. The removal of bunds and seawalls and their replacement with living shorelines can reverse this trend for the protection of property and wildlife.

In rural green field sites, preplanning that allows sufficient buffers between the shoreline and the farm fence to protect important habitats such as saltmarshes and mangrove forests, offers the best solution for protecting these habitats while also reducing the impacts of rising sea levels for people and nature.     

The team’s findings summarise a range of coastal management options including managed retreat (the surrender of coastal zones to the ocean), intertidal habitat restoration, living shorelines and easements.