Satellite Images Reveal How Beaches Around The Pacific Vanish During La Niña

Stu Nettle picture
Stu Nettle (stunet)
Swellnet Analysis

Surfers, particularly those living on Australia’s East Coast, are well aware of the surf conditions wrought by La Niña. Three consecutive summers have shown just what the climate driver known as ‘the little girl’ is capable of.

The causal chain goes something like this: During La Niña stronger than normal tradewinds blow across the Pacific towards Australia, warm water piles up on our eastern shore, this creates an increase in tropical activity including easterly winds, which in turn leads to a surfeit of easterly swell across the whole Eastern Seaboard.

However, the causal chain doesn’t end there. It may not be quite as exciting to surfers, but all that La Niña swell energy then leaves its mark on the coast. To wit, the shoreline erodes. Without time to recover, the coast’s natural buffer - i.e beach sand - is transported from the beaches to the ocean.

Wamberal, July 2020 (Darren Pateman/AAP)

When it happens, the media usually focuses on erosion hotspots such as Wamberal and Collaroy, however a recent study by four Sydney scientists has shown that almost all beaches become thinner during La Niña. Meanwhile, on the other side of the Pacific, beaches in California and South America expand as sand piles up under ideal conditions.

Flick the switch to El Nino and the opposite becomes true: Beaches in Australia recover and expand in width, while those on the Pacific’s eastern rim begin to erode under sustained storm activity. It’s no coincidence that the very best Hawaiian seasons have been shown to coincide with El Nino.

At the heart of the research, which was led by Kilian Vos, was access to millions of satellite images taken over the last forty years. The scientists created a timeline of aerial imagery, and then set it against the ENSO (El Nino Southern Oscillation) cycle over the past four decades to confirm their suspicions.

To date, scientists have relied on either anecdotal evidence or a hodgepodge of sources to understand coastal cycles. Access to satellite imagery provides them with a consistent, long term source of information, which is necessary for scientific confirmation.

The scientists concerned have both released a paper on their findings, and also created a website, CoastSat, which tracks coastal changes across thousands of beaches in the Pacific Rim.

ENSO outlook for February 2023 (Australian Bureau of Meteorology)

According to Dr Mitchell Harley, one of the four scientists who worked on the project, the findings are “a very powerful tool for coastal councils and State Governments.”

With the current level of knowledge, La Niña can be predicted with a high degree of confidence from six to twelve months out. Rather than being reactive, “they [councils and governments] can now see how the coastline will respond,” says Dr Harley, “and be proactive by taking early measures to protect the coast.”

“This might mean boosting their staff levels,” adds Dr Harley, “shifting their resources, or protecting equipment assets.”

There’s also a project planning perspective, whereby existing or planned projects will have to be considered in the context of a soon-to-be altered coastline.

Even sand nourishment, which has been the classic last ditch effort by councils having their coastline battered, can be organised in advance. Perhaps dumped early as a preventative measure, rather than later as a cure.

Though such planning springboards off the back of Dr Harley’s work, there are other more compelling - read: scientific - aspects of the research. “In the scientific community,” says Dr Harley, “there’s conjecture that the cyclical nature of ENSO may be changing.”

And this is the big thing. Now that the scientists have a solid database to work off, all future ENSO cycles can be compared against the past.

“It gives us the power to understand what’s happening with the ENSO cycles, “ says Dr Harley.


Stephanie Check's picture
Stephanie Check's picture
Stephanie Check Wednesday, 15 Feb 2023 at 3:18pm

If they did no see that on the cards?

Ganzho Manh's picture
Ganzho Manh's picture
Ganzho Manh Wednesday, 15 Feb 2023 at 3:24pm

Total BS. It's a La Nina year and has been neutral for awhile and here in SoCal I've never in my 5+ decades of living and surfing N San Diego seen the reefs stripped of so much sand. Last summer the sand was minimal. The proof in the pudding will be if the littoral drift can replenish the beaches this summer....I'd love to see the "data" they're working with.

crg's picture
crg's picture
crg Wednesday, 15 Feb 2023 at 5:06pm

Not sure it is correlated to La Niña, but I passed through the SW coastline of Sri Lanka along the Hikkaduwa stretch in Oct/Nov and the locals were calling it the worst erosion in 50 years. Multiple beachfront hotels/homestays losing parts of their buildings.

frog's picture
frog's picture
frog Wednesday, 15 Feb 2023 at 6:59pm

Looks like super soft sedimentary rock or mud stone they have built on. Whether climate shifts or just unusual years causing the problems that is not safe and sound long term.

Nice views of course.

Distracted's picture
Distracted's picture
Distracted Thursday, 16 Feb 2023 at 3:56pm

No rock at Wamberal Frog, that’s all sand where the erosion is occurring in that image.

truebluebasher's picture
truebluebasher's picture
truebluebasher Wednesday, 15 Feb 2023 at 8:29pm

Not that many years back ... Palm Beach never looked healthier!
13 Jan 2017 Palm Beach (9:00 am ~ small-moderate wind / swell)
King Tide [1.84m] (Ample space for Footy fields running whole length of Southern Goldie beach)

Govt / GCCC > $Gazillion Palm Beach reclamation to rubber stamp Hi Rise Timeshare Trolley sales.

Just add...
Com Games Supa Dupa Rainbow
Annual Currumbin Ck Pumping
Near Shore Artificial Rock Reef
Record Tweed combo Dredge / Pump

Plus, throw in a pinch of 3 peat La Nina

Now stand back...bit further...might wanna retreat above the dunes...

21 Jan 2023 Palm Beach (8:00 am running a small-moderate wind / swell)
King Tide [1.87m] (Now, not enough room for a Beach volleyball court along what's left of Palm Beach)

Leave it to the experts to argue how Quarry / Reef / La Nina robbed Palm Beach of precious sand!
tbb has earlier reported that Cam images verify Palm Beach eroded in that above sequence.
Another 6 years of Expert Govt beach reclamation will see Palm Beach Hi rise topple into the sea.

Experts : "Reef doubles as a handy Rock Pile to extend the nearby groynes to address Reef Erosion."
Experts : "Hey! Did we think of that!"

Now the crew know why they built a rock reef between 2 rock groynes...(Plan B)
That's so cool...ya can't lose. (Take note Gromz!)

PS : New science argues Dredging extends 2x tidal range & height > 2x sediment runoff > 2x storm surge.
Palmy Locals might wanna consider their annual dredge'n'pump program is accelerating their local tidal regime.
Exampling Palm Beach as being gutted by 2 Bowling Lanes...Reef or anything in it's path only ramps the chaos.
GCCC may need to concede, they themselves, are accelerating their local sea change erosion.

Roystein's picture
Roystein's picture
Roystein Thursday, 16 Feb 2023 at 6:43am

Was interested in photos of rainbow recently.
Climate induced Sea level rise or three peat la Nina or both?

mick-free's picture
mick-free's picture
mick-free Thursday, 16 Feb 2023 at 8:47am

Time to go North Pac

yvdreh's picture
yvdreh's picture
yvdreh Thursday, 16 Feb 2023 at 10:45am

Coastal councils and state governments already have a plethora of data and tools to assist them in this area. Fat load of good it's done so far, literally the only thing that is the catalyst for any action is the $$$$.

radiationrules's picture
radiationrules's picture
radiationrules Thursday, 16 Feb 2023 at 12:13pm

Q for Craig > I don't want to sound selfish but is La Nina finished, in so far as normal trades are expected in indo from April/May this year?

Sam2609's picture
Sam2609's picture
Sam2609 Tuesday, 21 Feb 2023 at 8:14am

Seconded. I’m on the edge of my seat waiting for one of those amazing long range climate signal reports

Craig's picture
Craig's picture
Craig Tuesday, 21 Feb 2023 at 10:15am

Yep, looking like it.

radiationrules's picture
radiationrules's picture
radiationrules Tuesday, 21 Feb 2023 at 10:54am

thanks > any update is appreciated. I don't want to get skunked again.

Distracted's picture
Distracted's picture
Distracted Thursday, 16 Feb 2023 at 3:59pm

Different weather/ erosion processes in France but interesting that they have taken to demolition of this coastal hotel rather than try and defend it.

Logical's picture
Logical's picture
Logical Thursday, 23 Feb 2023 at 3:21pm

CLIMATE CHANGE HOAX cover story again.

North Curl Curl in SYdney - northern car park. - OPPOSITE happening MASSIVE MORE SAND.
The walk up from car park onto sand - the fence line horizontal posts were for years at shoulder height.
Now they are ankle height from 4 foot of extra sand.
The dunes are clearly building and moving back onto land.

Dr Tim Flannery - our ex Labor Left Wing Socilaist Climate Czar under Prime Minister Julia Gillard.
Send 10+ years ago that Pitt Water from Manly to Palm Beach would be knee high in sea water by 2020s.

THIS CLOWN only a few years ago bought a property near the Beach AT MANLY.

Climate Change is global hoax by the elite to distract the world from a exponentially increasing human population that is the root cause of pollution, oceans full of plastic bags, animal and Species extinction, cause of most 3rd world wars and more.

Logical's picture
Logical's picture
Logical Thursday, 23 Feb 2023 at 3:31pm

Dr Harley, “and be proactive by taking early measures to protect the coast.”

What a crock - not true, only demolishing those homes is the only answer.
You can't fortify thousands of miles of coastline.

Govts made a masisve mistake allowing developemnt so close to the water edge.
Same in Sydney - people own homes with land right to the harbour water edge.

These all should have had a 200 meter exclusion zone from high tide mark.
THese propties are all worth > $10 Million dollars.

But expect Councils to RAPE BLUE COLLAR workers through rates to pay for their "sea walls".

See folks what happens when you buy into the Climate Change Bullshit,

SeaHealing's picture
SeaHealing's picture
SeaHealing Tuesday, 28 Feb 2023 at 10:18pm

too true Logical. "The rich get richer, the poor get the picture, the bombs never hit ya when ya down so low" Midnight Oil - Hercules i think.
smarmy back room deals between the rich and the local council et al so they can block the public access to the shore line right around every city, thereby making it easier to control 'the plebs' as they are in smaller areas of packed beaches nowadays.
it is insurance co's doing the raping mostly though. these foolish house builders right on the beaches make premiums higher for us all no matter where we live or what we drive or own.