The Times Australia
The Times World News

.
The Times Real Estate

.

La Niña just raised sea levels in the western Pacific by up to 20cm. This height will be normal by 2050

  • Written by Shayne McGregor, Associate Professor, and Associate Investigator for the ARC Centre of Excellence for Climate Extremes, Monash University
La Niña just raised sea levels in the western Pacific by up to 20cm. This height will be normal by 2050

Severe coastal flooding[1] inundated islands and atolls across the western equatorial Pacific last week, with widespread damage to buildings and food crops in the Federated States of Micronesia, Marshall Islands, Papua New Guinea and Solomon Islands.

On one level, very high tides are normal at this time of year in the western Pacific, and are known as “spring tides”. But why is the damage so bad this time? The primary reason is these nations are enduring a flooding trifecta: a combination of spring tides, climate change and La Niña.

La Niña[2] is a natural climate phenomenon over the Pacific Ocean known for bringing wet weather, including in eastern Australia. A less-known impact is that La Niña also raises sea levels in the western tropical Pacific.

In a terrifying glimpse of things to come, this current La Niña is raising sea levels by 15-20 centimetres in some western Pacific regions – the same sea level rise projected to occur globally by 2050, regardless of how much we cut global emissions between now and then. So let’s look at this phenomena in more detail, and why we can expect more flooding over the summer.

These spring tides aren’t unusual

Low-lying islands in the Pacific are considered the frontline of climate change, where sea level rise poses an existential threat that could force millions of people to find new homes[3] in the coming decades.

Last week’s tidal floods show what will be the new normal by 2050. In the Marshall Islands, for example, waves were washing over boulder[4] barriers, causing flooding on roads half a metre deep.

This flooding has coincided with the recent spring tides. But while there is year to year variability in the magnitude of these tides that vary from location to location, this year’s spring tides aren’t actually unusually higher than those seen in previous years.

For instance, tidal analysis[5] shows annual maximum sea levels at stations[6] in Lombrom (Manus, Papua New Guinea) and Dekehtik (Pohnpei, Federated States of Micronesia) are roughly 1-3cm higher than last year. Meanwhile, those at Betio (Tarawa, Kiribati) and Uliga (Majuro, Marshall Islands) are roughly 3-6cm lower.

This means the combined impacts of sea level rise from climate change and the ongoing La Niña event are largely responsible for this year’s increased flooding.

A double whammy

The latest assessment report[7] from the Intergovernmental Panel on Climate Change finds global average sea levels rose by about 20cm between 1901 and 2018.

This sea level rise would, of course, lead to more coastal inundation in low-lying regions during spring tides, like those in the western tropical Pacific. However, sea level rise increases at a relatively small rate – around 3 millimetres per year. So while this can create large differences over decades and longer, year to year differences are small.

Read more: Do La Niña's rains mean boom or bust for Australian farmers?[8]

This means while global mean sea level rise has likely contributed to last week’s floods, there is relatively small differences between this year and the previous few years.

This is where La Niña makes a crucial difference. We know La Nina events impact the climate of nations across the Pacific, bringing an increased chance of high rainfall[9] and tropical cyclone landfall in some locations.

But the easterly trade winds, which blow across the Pacific Ocean from east to west, are stronger in La Niña years. This leads to a larger build up of warm water in the western Pacific.

Warm water is generally thicker than cool water (due to thermal expansion), meaning the high heat in the western equatorial Pacific and Indonesian Seas during La Niña events is often accompanied by higher sea levels.

Read more: Back so soon, La Niña? Here's why we're copping two soggy summers in a row[10]

This year is certainly no different, as can be seen in sea surface height anomaly maps here[11] and here[12].

From these maps, along with past studies[13], it’s clear Pacific islands west of the date line (180⁰E) and between Fiji and the Marshall Islands (15⁰N-15⁰S) are those most at risk of high sea levels during La Niña events.

What could the future hold?

We can expect to see more coastal flooding for these western Pacific islands and atolls over the coming summer months. This is because the La Niña-induced sea level rise is normally maintained throughout this period, along with more periods with high spring tides.

Interestingly, the high sea levels related to La Niña events in the northern hemisphere tend to peak in November-December, while they do not peak in the southern hemisphere[14] until the following February-March.

This means many western Pacific locations on both sides of the equator will experience further coastal inundation in the short term. But the severity of these impacts is likely to increase in the southern hemisphere (such as the Solomon islands, Tuvalu and Samoa) and decrease in the northern hemisphere (such as the Marshall Islands and the Federated States of Micronesia).

Looking forward towards 2050, a further 15-25cm of global average sea level rise is expected[15]. La Niña events typically cause sea levels in these regions to rise 10-15cm above average, though some regions can bring sea levels up to 20cm.

Given the projected sea level rise in 2050 is similar to the La Niña-induced rise in the western Pacific, this current event provides an important insight into what will become “normal” inundation during spring tides.

Read more: The seas are coming for us in Kiribati. Will Australia rehome us?[16]

Unfortunately, climate projections show this level of sea level rise by 2050 is all but locked in, largely due to the greenhouse gas emissions we’ve already released.

Beyond 2050, we know sea levels will continue to rise for the next several centuries, and this will largely depend on our future emissions. To give low-lying island nations a fighting chance at surviving the coming floods, all nations (including Australia) must drastically and urgently cut emissions.

References

  1. ^ Severe coastal flooding (asiapacificreport.nz)
  2. ^ La Niña (www.bom.gov.au)
  3. ^ find new homes (theconversation.com)
  4. ^ washing over boulder (asiapacificreport.nz)
  5. ^ tidal analysis (agupubs.onlinelibrary.wiley.com)
  6. ^ sea levels at stations (www.bom.gov.au)
  7. ^ assessment report (www.ipcc.ch)
  8. ^ Do La Niña's rains mean boom or bust for Australian farmers? (theconversation.com)
  9. ^ increased chance of high rainfall (theconversation.com)
  10. ^ Back so soon, La Niña? Here's why we're copping two soggy summers in a row (theconversation.com)
  11. ^ here (sealevel.jpl.nasa.gov)
  12. ^ here (aviso.altimetry.fr)
  13. ^ past studies (agupubs.onlinelibrary.wiley.com)
  14. ^ southern hemisphere (journals.ametsoc.org)
  15. ^ 15-25cm of global average sea level rise is expected (www.ipcc.ch)
  16. ^ The seas are coming for us in Kiribati. Will Australia rehome us? (theconversation.com)

Read more https://theconversation.com/la-nina-just-raised-sea-levels-in-the-western-pacific-by-up-to-20cm-this-height-will-be-normal-by-2050-173504

The Times Features

From Classic to Contemporary: 5 Timeless Costumes for Any Party

When it comes to dressing up for a costume party, you want to choose something that is not only fun but also memorable. Whether you're attending a Halloween event, a themed gathe...

Action Figures as Art: The Growing Trend of Custom Figures and Modding

Action figures have long been regarded as collectible items, valued by enthusiasts and fans for their connection to popular culture. However, in recent years, a growing trend has...

The Ultimate Guide to Securing Grants for Your Small Business in Australia

Running a small business in Australia comes with both opportunities and challenges. While it can be rewarding, funding your business through the early stages or periods of growth...

Men’s Guide to Styling Suits with Sweaters for the Ultimate Winter Look

Winter brings a unique set of challenges when it comes to maintaining a sharp and stylish wardrobe. While suits are a staple of a well-dressed man’s closet, staying warm during t...

Discover the Charm of a Girl's White Dress

Key Highlights Timeless elegance: White dresses feel pure and have classic charm. They are perfect for many types of events. Versatile styles: You can pick from lace, embroid...

Top Medical Grade Red Light Therapy Devices in Australia

Key Highlights Lumitter™ has advanced red light therapy devices that combine new ideas with wellness. Red light therapy helps lower pain and swelling and boosts skin health. ...

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