Waves are forecast to become larger and more powerful and to shift direction if the climate continues to warm at its current rate, with southern Australia among the regions to be hardest hit globally, new research says.
The study, led by scientists from Griffith University and published in Nature Climate Change on Tuesday, comes as meteorologists forecast a "quite rare event" later this week as a potentially damaging swell hits eastern Australia.
A monster wave in January 2015 that washed a woman off Nobbys breakwall in Newcastle. Credit: Cordelia Troy |
The wave changes, driven primarily by strengthening winds "might potentially exacerbate or even exceed in some coastal regions, impacts of future sea-level rise", the paper said.
Widespread ocean
regions can expect annual mean significant wave height - the average
difference between trough to crest of the highest third of waves - to
increase between 5 and 15 per cent compared with a 1979-2004 baseline.
The mean period between waves was projected to increase by a similar range of 5 to 15 per cent, implying increased forces to pound beaches and infrastructure when the waves reach the coast.
The mean period between waves was projected to increase by a similar range of 5 to 15 per cent, implying increased forces to pound beaches and infrastructure when the waves reach the coast.
Wave
direction would also shift between 5 and 15 degrees, potentially
shifting sand and hammering some areas now typically sheltered by
headlands and other coastal formations.
"For Australia, the south
coast and Victoria especially are really going to be impacted by the
Southern Ocean changes," Joao Morim, a PhD candidate at Griffith
University and lead author of the paper, said.
The
expected impact from swells for Australia's coastline would be driven
by an intensification and poleward shift of storm activity.
The west coast of South America was another region facing more damaging waves while the North Atlantic would most likely see a reduction because of a decrease mid-latitude storm activity in that basin, Mr Morim said.
However,
should emissions be limited sufficiently to contain global warming to
within the Paris climate target of 2 degrees compared with
pre-industrial levels, the projected wave changes "are not standing out
from the natural variability", Mr Morim said. His work was part of a
six-year project also involving the CSIRO.
Mitchell Harley, a
lecturer at the University of NSW's School of Civil and Environmental
Engineering who was not among the paper's authors, said the work was a
"nice step forward and presents a nice summary of what we do know and
importantly what we don't know".The west coast of South America was another region facing more damaging waves while the North Atlantic would most likely see a reduction because of a decrease mid-latitude storm activity in that basin, Mr Morim said.
Surfers ride big waves along the Sydney coastline in November 2015. Credit: Nick Moir |
Dr Harley said his interest was that waves would change over the next decade or so at a more local level.
"What this paper shows is there is still a lot of uncertainty in these projections," he said.
"Storms
are changing, the wind fields are changing around the world, and that's
going to have inevitable consequences on how our waves are striking the
coast and consequently how our coastline is going to respond," he said,
adding that satellites had identified an increase of about 3 per cent
in wave energy over the past half century.
Even small changes in
the direction of waves "can cause large-scale reorientations" of the
coastline, as sand gets scoured from some beaches and dumped on others,
Dr Harley said. Clarkes Beach near Byron Bay was one recent example
where dunes had been eroded by shifting conditions.Beach erosion has lately been a pressing issue for parts of Perth. Credit: WA Today |
Beaches
in Australia south of about the Sunshine Coast tended to be shaped
primarily by waves while those further north are dominated by tropical
cyclones and tidal changes, he said.
Coastal residents might get to experience some relatively severe wave activity this week, with significant wave heights expected to reach about six metres along parts of the NSW coast on Thursday.
In the future, though, direction changes of the waves in extreme events - as predicted by the research paper - "really causes huge effects on the wave-exposure of the coastline", he said.
Links
Coastal residents might get to experience some relatively severe wave activity this week, with significant wave heights expected to reach about six metres along parts of the NSW coast on Thursday.
Jordan
Notara, a forecaster at the Bureau of Meteorology, described the
predicted swell as "quite a rare event" for August, and said waves could
be damaging. The bureau has also issued a warning about the surf conditions.
Dr Harley said this week's swell would be coming from "the dead south", a typical direction for such big waves.#NSW beach conditions will be dangerous from Wednesday to Friday this week due to a large and powerful southerly #swell. Take care with #marine activities: https://t.co/tKd3s7dsyO @slsnsw @MarineRescueNSW pic.twitter.com/MAe4yBTchj— Bureau of Meteorology, New South Wales (@BOM_NSW) August 19, 2019
In the future, though, direction changes of the waves in extreme events - as predicted by the research paper - "really causes huge effects on the wave-exposure of the coastline", he said.
Links
- Robustness and uncertainties in global multivariate wind-wave climate projections
- Developers forced to plan for new coastal suburb shorelines... 170 metres inland
- 'Quite rare': Potentially damaging surf to pummel NSW coast this week
- 'Quite rare': Potentially damaging surf to pummel NSW coast this week
- Extreme Weather Caused By Climate Change Has Damaged 45% Of Australia’s Coastal Habitat
- Ocean Waves And Winds Are Getting Higher And Stronger
- Climate Change: We Need To Start Moving People Away From Some Coastal Areas, Warns Scientist
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