News_

Shore break

22 September 2015
Coastal erosion of Australia's beaches could be worse than previously predicted.

The projected upsurge of El Niño and La Niña events will lead to extreme flooding and erosion in populated regions across the Pacific including Australia, according to a new study.

Increased El Niño and La Niña events are likely to cause more erosion in the southern corners at beaches like Narrabeen.

The impact of these storms is not presently included in most studies on future coastal vulnerability, which look primarily at sea level rise. New research data, from 48 beaches across three continents and five countries bordering the Pacific Ocean, suggest the predicted increase will exacerbate coastal erosion irrespective of sea level rise affecting the region.

Researchers from 13 different institutions, including the University of Sydney, analysed coastal data from across the Pacific Ocean basin from 1979 to 2012. The scientists sought to determine if patterns in coastal change could be connected to major climate cycles. Data came from beaches in the mainland United States and Canada, Japan, Australia, New Zealand and Hawaii.

The research was published in Nature Geoscience today.

Although previous studies have analyzed coastal impacts at local and regional levels, this is the first to pull together data from across the Pacific to determine basin-wide patterns. The research group determined all Pacific Ocean regions investigated were affected during either an El Niño or La Niña year. When the west coast of the U.S. mainland and Canada, Hawaii, and northern Japan felt the coastal impacts of El Niño, characterized by bigger waves, different wave direction, higher water levels and/or erosion, the opposite region in the Southern Hemisphere of New Zealand and Australia experienced “suppression,” such as smaller waves and less erosion. The pattern then generally flips: during La Niña, the Southern Hemisphere experienced more severe conditions.

Co-author Professor Andrew Short from the School of Geosciences says forecast increases in the strength of El Niño and La Niña weather events driven by global climate change means coastal erosion on many Australian beaches could be worse than currently predicted based on sea level rise alone.

“During enhanced La Niñas we can expect more tropical cyclones and east coast lows off the coast, leading to damaging cyclones and storm surges along the Queensland coast and severe beach erosion along the New South Wales coast. The more benign El Niños will bring fewer cyclones and long periods of lower southerly waves. These will rotate the beaches to the north, building out the northern ends, while severely eroding the southern corners of the beaches, where most development usually occurs. These impacts will take place irrespective of the amount of sea level rise.

“This study significantly advances the scientific knowledge of the impacts of El Niño and La Niña,” said Patrick Barnard, USGS coastal geologist and the lead author of the study. “Understanding the effects of severe storms fuelled by El Niño or La Niña helps coastal managers prepare communities for the expected erosion and flooding associated with this climate cycle.”

We can expect more tropical cyclones and more East Coast lows off the coast.
Professor Andrew Short, School of Geosciences

The study also investigated the coastal response of other climate cycles, such as the Southern Annular Mode, which has impacts at the same time in both hemispheres of the Pacific. The data revealed that when the Southern Annular Mode trended towards Antarctica, culminating in more powerful storms in the Southern Ocean, wave energy and coastal erosion in New Zealand and Australia increased, as did the wave energy along the west coast of North America. Other modes of climate variability, such as the Pacific North American pattern, which relates to atmospheric circulation in the North Pacific, are linked to coastal impacts that are more tightly restricted to the northern hemisphere.

Linking coastal erosion to natural climate patterns, such as El Niño/Southern Oscillation and the Southern Annular Mode, can be challenging.

“Shoreline behavior can be controlled by so many different factors, both locally and regionally, that it’s been difficult to isolate the signal until now. However, utilizing the many years of data we were able pull together in this study enabled us to definitively identify how the major climate drivers affect coastal hazards across the Pacific,” said Patrick Barnard. “This will greatly enhance our ability to predict the broader impacts of climate change at the coast.”

“Coastlines of the Pacific are particularly dynamic as they are exposed to storm waves generated often thousands of miles away. This research is of particular importance as it can help Pacific coastal communities prepare for the effects of changing storm regimes driven by climate oscillations like El Niño and La Niña. To help us complete the puzzle, for the next step we would like to look at regions of the Pacific like South America and the Pacific Islands where very limited shoreline data currently exists,” said Mitchell Harley of UNSW Australia, and a coauthor of the paper.

“It's not just El Niño we should be concerned about," said Ian Walker, professor of Geography at the University of Victoria and coauthor of the study. “Our research shows that severe coastal erosion and flooding can occur along the British Columbia coast during both El Niño and La Niña storm seasons unlike further south in California. We need to prepare not only for this winter, but also what could follow when La Niña comes.”

The published paper, “Coastal vulnerability across the Pacific dominated by El Niño/Southern Oscillation” is available online

Jocelyn Prasad

Media and Public Relations Advisor
Phone
  • + 61 434 605018
Mobile
Email
Address
  • Level 7 Jane Foss Russell Building G02

Related articles

28 September 2016

Discover the future at Innovation Week

For a week this October, we’ll be bringing together some of our brightest minds with industry and community partners to collaborate on how research and innovation can help us overcome some of the greatest health challenges facing our planet.

12 July 2016

Long distance links inspire innovation

Working with Professor Yasuyuki Todo (Waseda University) and Dr Hiroyasu Inoue (Hyogo University), Dr Petr Matous from the University of Sydney’s Faculty of Engineering and IT found that supply chains can work as important channels for the flow of information, innovation, and productivity between individual firms.

29 July 2016

University of Sydney joins Sydney Science Festival

Our researchers are involved in a range of public events to celebrate National Science Week from 11 to 21 August.

19 May 2016

Social brain refreshed

While we connect with hundreds – even thousands – of others via social media, our brain’s ability to build and maintain long-term stable relationships remains as limited as that of our hunter-gatherer ancestors.

06 February 2016

Study explains elastin's remarkable movements

New research likens the flexibility of elastin in a blood vessel to the dynamics of a ballet.

10 May 2012

Study exposes secret world of porn addiction

A major study from the University of Sydney has shed light on the secret world of excessive porn viewing and the devastating effect it has on viewers and their families.
14 February 2012

Human 'shock absorbers' discovered

An international team of scientists, led by the University of Sydney, has found the molecular structure in the body which functions as our 'shock absorber'.
29 March 2019

Sydney excels in national research engagement and impact assessment

The University of Sydney has performed strongly in the Australian Research Council's first Engagement and Impact Assessment of research at Australian universities.
29 August 2019

Sydney researchers secure $38 million in NHMRC funding

University of Sydney researchers have excelled in the latest National Health and Medical Research Council (NHMRC) funding round, attracting more than $38 million for our projects extending from Sydney to rural NSW.
25 September 2019

Professor Nalini Joshi named as Bragg Member of RiAus

Professor Joshi from the School of Mathematics and Statistics has been recognised as one of Australia's most outstanding contributors to science.