The Times Australia
The Times World News

.
The Times Real Estate

.

What does climate change mean for extreme waves? In 80% of the world, we don't really know

  • Written by Ian Young, Kernot Professor of Engineering, The University of Melbourne
What does climate change mean for extreme waves? In 80% of the world, we don't really know

Across much of the world’s oceans, waves are getting bigger. In the Southern Ocean, where storm-driven swell can propagate halfway across the world to California, the average wave has grown about 20cm in the past 30 years.

These changes are part of climate change, and are likely to continue well into the future. If you’re making long-term plans near the sea – like building ships, or constructing flood defences in coastal cities – you need more detail about how big those waves are going to get.

In a study[1] published today in Science Advances, we looked at the projected changes in the size of the very biggest waves around the globe. We found the uncertainties in the projections could be larger than the projected future changes themselves in about 80% of the world’s oceans and coastlines.

The ‘wave climate’

My group and I study the world’s “wave climate”: the size and distribution of ocean waves in different places, and how that has changed in the past and will change in the future.

We’re interested in the heights of average waves, but also the extreme conditions. As with floods or heatwaves, extreme waves are the ones that cause problems – so they’re often the ones we need to know about when we’re building near the sea.

From floating buoys and satellite radar, we have records of wave heights extending back 30 to 40 years. These data don’t cover the whole world, but we feed them into computer models that fill in the gaps.

An aerial photo of waves rolling in to shore.
Waves are driven by winds over the surface of the ocean. Dan Grinwis

Waves are created by the wind, so our models of waves are also tied to what we know about wind conditions. Taken all together, we have about 40 years of model data giving wave conditions for the whole world’s oceans (broken up into “pixels” about 25 kilometres across).

We also use a branch of statistics called extreme value analysis to calculate things like the biggest wave you can expect at a given location once in 100 years (the 100-year event).

Why waves are changing

As the climate changes, we expect that global wind patterns will change – so the world’s waves will change as well.

One change we are already seeing is that many low-pressure systems, which create high winds, are becoming more intense and moving away from the equator and towards the poles.

Read more: Climate change may change the way ocean waves impact 50% of the world’s coastlines[2]

In the southern hemisphere, this means more high winds over the Southern Ocean, driving bigger waves. This swell in the Southern Ocean propagates out into the Pacific, Atlantic and Indian oceans – which means bigger waves across the southern hemisphere.

Indeed, we have observed that average wave heights in the Southern Ocean have increased by around 20cm over the past 30 years.

In the northern hemisphere, there is more land closer to the pole. So the high winds are now more often happening over land, and ocean waves are actually losing some height.

A blurry future

So what does all this mean for the future? In our new study, we tried to figure that out.

To get an idea of the future of waves, we start with wind projections from major climate models that are used to project future temperatures as carbon dioxide levels in the atmosphere increase. We then feed these winds into our wave models, and see what they predict.

There are many wind and wave models, all with slight differences in their assumptions and the way they model the physics, so they all produce somewhat different projections. We combined the results from an ensemble of a dozen models to get a clearer picture of the differences.

An aerial photo of waves crashing on a coastline. Waves shape coastlines through erosion. Dan Grinwis

On average, we found extreme wave heights in many places are likely to grow by between 5% and 8% by 2100.

However, there is a lot of uncertainty in those estimates. One source of uncertainty is how much carbon dioxide humans pump into the atmosphere over the coming decades.

Another source is the uncertainty in the models themselves. We found that in many cases the difference in estimates between different models was about the same size as the projected changes in wave height.

A note of caution

The upshot of our research is that there is still a lot of uncertainty in what will happen to the size of extreme waves in the coming decades. That means there is also a lot of uncertainty in our projections of coastal flooding and the erosion of beaches.

These uncertainties may not seem huge – perhaps 30-40cm by 2100 – but they’re big enough to determine whether or not a particular coastal property ends up underwater.

Read more: Curious Kids: why are there waves?[3]

So for anyone making plans near the sea – like engineers designing coastal structures, governments building flood defences, or local councils making development decisions – the message is that you should err on the side of caution in your decision-making.

For the rest of us, it’s a reminder that climate change doesn’t just mean rising temperatures: it means a transformation of the whole global climate system, in ways we still don’t fully understand.

Read more https://theconversation.com/what-does-climate-change-mean-for-extreme-waves-in-80-of-the-world-we-dont-really-know-197526

The Times Features

Best Deals on Home Furniture Online

Key Highlights Discover the best deals on high-quality outdoor furniture online. Transform your outdoor space into a stylish and comfortable oasis. Explore a wide range of d...

Discover the Best Women's Jumpers for Every Season

Key Highlights Explore lightweight jumpers for spring and summer, ensuring breathability and ease. Wrap up warm with cozy wool jumpers for the chilly autumn and winter season...

Uncover the Elegance of Gorgeous Diamond Tennis Necklaces

Key Highlights Diamond tennis necklaces are a timeless piece of jewelry that exudes elegance and sophistication. They feature a continuous line of brilliant-cut diamonds, cre...

Dental Implants vs. Dentures: Which Is Better for You?

When it comes to replacing missing teeth, two of the most common options are dental implants and dentures. Both have their advantages and disadvantages, so choosing between them ...

What Neck Pain Really Means (And Why It’s More Than Just Poor Posture)

Neck pain is often brushed off as something temporary — a tight spot after a long day at the desk or a poor night’s sleep. But when the discomfort keeps returning, it could be a ...

The Work of Gosha Rubchinskiy: Fashion, Culture, and Youth

From Designer to Cultural Architect Gosha Rubchinskiy is not just a fashion designer—he's a cultural force. Born in Moscow in 1984, Rubchinskiy began his career in fashion in t...

Times Magazine

The Essential Guide to Transforming Office Spaces for Maximum Efficiency

Why Office Fitouts MatterA well-designed office can make all the difference in productivity, employee satisfaction, and client impressions. Businesses of all sizes are investing in updated office spaces to create environments that foster collaborat...

The A/B Testing Revolution: How AI Optimized Landing Pages Without Human Input

A/B testing was always integral to the web-based marketing world. Was there a button that converted better? Marketing could pit one against the other and see which option worked better. This was always through human observation, and over time, as d...

Using Countdown Timers in Email: Do They Really Increase Conversions?

In a world that's always on, where marketers are attempting to entice a subscriber and get them to convert on the same screen with one email, the power of urgency is sometimes the essential element needed. One of the most popular ways to create urg...

Types of Software Consultants

In today's technology-driven world, businesses often seek the expertise of software consultants to navigate complex software needs. There are several types of software consultants, including solution architects, project managers, and user experienc...

CWU Assistive Tech Hub is Changing Lives: Win a Free Rollator Walker This Easter!

🌟 Mobility. Independence. Community. All in One. This Easter, the CWU Assistive Tech Hub is pleased to support the Banyule community by giving away a rollator walker. The giveaway will take place during the Macleod Village Easter Egg Hunt & Ma...

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

LayBy Shopping