Climate Change May Increase Risk Of Erosion, Flooding Along Pacific Coasts

ABC Science - Anna Salleh

Erosion at Wetherill St, Collaroy Beach. Andrew Short

Climate change will put coastal areas from Sydney to California at increased risk from erosion and flooding, independent of sea-level rise, a new study suggests.The research, published today in Nature Geoscience, is the first to link a pattern of beach erosion around the Pacific with the El Nino-Southern Oscillation (ENSO) climate cycle."Most people, when they talk about climate change and the coast, just talk about sea level," said co-author marine scientist, Professor Andrew Short from the University of Sydney.

"But whether sea level rises or not, we will still be getting shoreline changes taking place because of intensified cycles of El Nino and La Nina."
Storms generate waves and a temporary increase in the sea level, known as a storm surge, due to strong onshore winds and low atmospheric pressure.
The more intense a storm, the bigger the waves and the bigger the storm surge, and together these can have a devastating effect.
In areas with a long shallow continental shelf, for example, this can add metres to water levels during storms, Professor Short said.
"You get a double whammy," he said.
"You not only get big waves but you get higher sea levels so the waves can penetrate further inland and create greater damage."
Professor Short said recent evidence has suggested that the ENSO climate cycle will intensify with climate change, bringing more extreme El Nino and La Nina events, which will bring more stronger storms to the Pacific.

Erosion at Jimmy's Beach, NSW (Supplied: Andrew Short)

In a study designed to look at the impact of climate cycles, Professor Short and his colleagues found ENSO most strongly correlated with beach erosion.
They analysed records on wave conditions and shoreline position from 48 beaches around the Pacific including Australia, New Zealand, Hawaii, North America and Japan.
The data, collected between 1979 and 2012, revealed a pattern of change that matched the ENSO cycle.
The pattern was "synchronised, but out of phase", Professor Short said.

Beaches in the western Pacific, including Australia, would suffer inundation and erosion during a La Nina phase.
At the very same time, beaches in the eastern Pacific, including North America, would experience a relatively calm period, during which they could at least partially recover.
"One side erodes while the other builds up," Professor Short said.
"Anecdotally we've known things are different on either side of the Pacific, but no-one has ever done any study to verify this."
Professor Short said understanding how climate cycles like ENSO drive coastal change is important for predicting what may happen in the future, including the risk posed to coastal development.
"On the New South Wales coast, for example, we have 15 hotspots where development is already at risk," he said.
The erosion hotspots include Kingscliff, Byron Bay, and Jimmy's Beach in the state's north, Stockton Beach near Newcastle, Collaroy in Sydney and Surfside near Bateman's Bay in the state's south.
"If the climate models, which are predicting more intense El Ninos and La Ninas, are right, then we can expect even more extreme changes on our beaches," Professor Short said.
"We expect a significant increase in the amount of property at risk along the east coast of Australia."

Be Prepared: Climate Change, Security and Australia’s Defence Force

Climate Council - Admiral Chris Barrie (Ret.) and Will Steffen

Climate change is a significant and growing national security threat that is undermining the preparedness of the Australian Defence Force, our new report authored by Australia’s former Defence Chief found.
Be Prepared: Climate Change, Security and Australia’s Defence Force report reveals Australia is lagging behind its UK and US allies in preparing its militaries for climate change, with Australian Defence Force resources already under strain from the increased need for humanitarian assistance in response to climate-induced disasters.

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Key Findings

1. Climate change is a security threat. Climate change poses a significant and growing threat to human and societal wellbeing, threatening food, water, health and national security.

• Food security. The 2008 food crisis increased the number of undernourished people worldwide by 75 million. The cost of wheat increased by 127%, rice by 170% and maize by 300%. By increasing the frequency and severity of droughts in important food producing regions, climate change was a key factor in the crisis.
• Water security. Climate change will significantly affect the accessibility and availability of freshwater resources. Rising sea-levels can result in saltwater intrusion of coastal acquifers, while rainfall patterns are changing worldwide.
• Extreme weather. Climate change is increasing the frequency and severity of many extreme weather events. These events affect individuals and societies through the displacement of people, damage to critical infrastructure, and damage to health and livelihoods.

2. Global military forces are labelling climate change a “threat multiplier”.

• The impacts of climate change can exacerbate other stresses, like poverty, economic shocks and unstable institutions, to make crises worse. For instance, increasing extreme weather events can reduce the availability of food. Extreme weather and water scarcity contributed to soaring food prices, which saw food riots erupt across Africa and the Middle East in 2008. Rising food prices in 2011 have also been identified as one of the factors that destabilised the Middle East, leading, for example, to the “Arab Spring”.
• Climate change can worsen tensions and increase the risk of conflict between states as sea-level rises, coastlines retreat and the eventual submergence of small low-lying islands affect maritime boundaries and exclusive economic zones where natural resources are located.
• Leading international organisations and defence forces around the world, from the Pentagon to NATO member states and now the G7, have all identified climate change as a significant threat to national security.

3. Climate change puts the Australian Defence Force under pressure.

• Australia and the Asia-Pacific region are vulnerable to climate change with over half of the world’s natural disasters occurring in the Asia-Pacific region last year. The ADF will increasingly be called upon to deliver humanitarian assistance in response to extreme weather and its impacts both at home and overseas. In serious cases the ADF may need to coordinate with other countries to provide assistance.
• Extreme weather could also affect the ADF’s readiness and capability by disabling critical military and civilian infrastructure at times when rapid mobilisation is needed. Defence property (military bases) are also at risk from sea level rise and extreme weather.
• Rising temperatures and more frequent and intense heatwaves will have implications for the health of Australia’s military personnel when undertaking training and conducting military exercises.

4. The UK and US militaries are rapidly preparing for climate change while Australia lags behind.

• Governments in the UK and US have taken significant legislative and strategic steps to ensure that climate change is integrated into defence planning. The US has mandated that their military forces address the risks of climate change as a routine part of all mission planning.
• In Australia, comparatively less action is being taken by the Government to ensure the Australian Defence Force is prepared for the security risks posed by climate change.
• Increasingly, Australia is out of step with its allies in preparing for climate change, exposing Australian soldiers, sailors and airforce personnel, as well as Australia more broadly, to the considerable strategic risk and uncertainty climate change brings.

5. Strong action to reduce greenhouse gas emissions is critical for limiting the security implications of a changing climate.

• Global emissions must start tracking downward this decade if there is to be a chance of keeping the warming of the planet to below 2°C, and limiting the severity of climate change and its implications for security.
• We must adapt to the inevitable changes that are already occurring while working hard to minimise the long-term changes, some of which could be massive, abrupt and disruptive. 

Audio: Chris Barrie speaks to AM


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