Relocating Australian Communities at Risk

Vulnerable Coastlines

With over 85% of Australia’s population residing within 50km from the coast, sea-level rise has emerged as a significant concern, the magnitude of which is anticipated to escalate in the years ahead. Continuing sea level rise is now unavoidable due to ongoing deep ocean warming and ice sheet melt, with sea levels expected to remain elevated for thousands of years. Relative to 1995–2014, the likely scenario for global mean sea level rise by 2100 is 0.28–0.55 meters, with the potential for much higher levels. Current 1-in-100-year (or, 1% probability in any given year) extreme sea level events are projected to occur at least annually in over half of all tide gauge locations by 2100, while risks to coastal ecosystems, populations, and infrastructure will continue to escalate beyond 2100. Over the next 2000 years, global mean sea level is projected to rise by about 2–3 meters if warming is limited to 1.5°C and 2–6 meters if limited to 2°C. Due to uncertainty associated with ice-sheet processes, global mean sea level rise of 2 meters by 2100 and in excess of 15 meters by 2300 (under the very high GHG emissions scenario) cannot be dismissed. Additionally, the IPCC could not rule out sea level rise of 5 meters by 2150.

Ocean currents, weather patterns (most notably El Nino and La Nina), and storms are all influenced by water temperatures. Flooding and storm surge in coastal and low-lying regions is further compounded by complex scenarios in river deltas - the location of some of the world’s largest cities. High rainfall, rapid water runoff, riverine and coastal flooding, and storm surge contribute to major flooding events. Coupled with the removal of vegetation and environmental degradation, these conditions further escalate coastal erosion and landslides. Back pressure from river flows and increased silt saturation can result in higher water levels, while groundwater extraction coupled with construction weight can lead to sinking cities.

In Australia, natural disasters are estimated to cost the economy an average of $38 billion per year, projected to increase to $73 billion per year by 2060, factoring in population growth, climate change, and rising property values. The 2022 South East Queensland floods alone incurred social, financial, and economic costs estimated at $7.7 billion. The stark reality is that numerous villages, towns and cities across Australia may no longer be viable for human habitation in the future.