Why it might soon be time to say goodbye to beach holidays

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Shutterstock John Church, UNSW

For many coastal regions, sea-level rise is a looming crisis threatening our coastal society, livelihoods and coastal ecosystems. A new study, published in Nature Climate Change, has reported that the world will lose almost half of its valuable sandy beaches by 2100 as the ocean moves landward with rising sea levels.

Sandy beaches comprise about a third of the world’s coastline. And Australia, with nearly 12,000 kilometres at risk, could be hit hard.


Read more: Ancient Antarctic ice melt caused extreme sea level rise 129,000 years ago – and it could happen again


This is the first truly global study to attempt to quantify beach erosion. The results for the highest greenhouse gas emission scenario are alarming, but reducing emissions lead to lower rates of coastal erosion.

Our best hope for the future of the world’s coastlines and for Australia’s iconic beaches is to keep global warming as low as possible by urgently reducing greenhouse gas emissions.

sign showing area prone to coastal erosion

Losing sand in coastal erosion
Two of the largest problems resulting from rising sea levels are coastal erosion and an already-observed increase in the frequency of coastal flooding events.

Erosion during storms can have dramatic consequences, particularly for coastal infrastructure. We saw this in 2016, when wild storms removed sand from beaches and damaged houses in Sydney.

After storms like this, beaches often gradually recover, because sand from deeper waters washes back to the shore over months to years and in some cases decades. These dramatic storms and the long-term sand supply make it difficult to identify any beach movement in the recent past from sea-level rise.

What we do know is that the rate of sea-level rise has accelerated. It has increased by half since 1993, and is continuing to accelerate from ongoing greenhouse gas emissions.

If we continue to emit high levels of greenhouse gases, this acceleration will continue through the 21st century and beyond. As a result, the supply of sand may not be able to keep pace with rapidly rising sea levels.

Projections for the worst-case scenario
In the most recent Intergovernmental Panel on Climate Change (IPCC) report, released last year, the highest greenhouse gas emissions scenario resulted in global warming of more than 4°C (relative to pre-industrial temperatures) and a likely range of sea-level rise between 0.6 and 1.1 metres by 2100.

For this scenario, this new study projects a global average landward movement of the coastline in the range of 40 to 250 metres if there were no physical limits to shoreline movement, such as those imposed by sea walls or other coastal infrastructure.


Read more: What does the science really say about sea-level rise?


Sea-level rise is responsible for the vast majority of this beach loss, with faster loss during the latter decades of the 21st century when the rate of rise is larger. And sea levels will continue to rise for centuries, so beach erosion would continue well after 2100.

For southern Australia, the landward movement of the shoreline is projected to be more than 100 metres. This would damage many of Australia’s iconic tourist beaches such as Bondi, Manly and the Gold Coast. The movement in northern Australia is projected to be even larger, but more uncertain because of ongoing historical shoreline trends.

What happens if we mitigate our emissions
The above results are from a worst-case scenario. If greenhouse gas emissions were reduced such that the 2100 global temperature rose by about 2.5°C, instead of more than 4°C, then we’d reduce beach erosion by about a third of what’s projected in this worst-case scenario.

Current global policies would result in about 3°C of global warming. That’s between the 4°C and the 2.5°C scenarios considered in this beach erosion study, implying our current policies will lead to significant beach erosion, including in Australia.

Mitigating our emissions even further to achieving the Paris goal of keeping temperature rise to well below 2°C would be a major step in reducing beach loss.

Why coastal erosion is hard to predict
Projecting sea-level rise and resulting beach erosion are particularly difficult as both depend on many factors.

For sea level, the major problems are estimating the contribution of melting Antarctic ice flowing into the ocean, how sea level will change on a regional scale, and the amount of global warming.

The beach erosion calculated in this new study depends on several new databases. The databases of recent shoreline movement used to project ongoing natural factors might already be influenced by rising sea levels, possibly leading to an overestimate in the final calculations.


Read more: Sea level rise is inevitable – but what we do today can still prevent catastrophe for coastal regions


The implications
Regardless of the exact numbers reported in this study, it’s clear we will have to adapt to the beach erosion that we can no longer prevent, if we are to continue enjoying our beaches.

This means we need appropriate planning, such as beach nourishment (adding sand to beaches to combat erosion) and other soft and hard engineering solutions. In some cases, we’ll even need to retreat from the coast to allow the beach to migrate landward.

And if we are to continue to enjoy our sandy beaches into the future, we cannot allow ongoing and increasing greenhouse gas emissions. The world needs urgent, significant and sustained global mitigation of greenhouse gas emissions.The Conversation

John Church, Chair Professor, Climate Change Research Centre, UNSW

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

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Written by The Conversation

10 Comments

Total Comments: 10
  1. 0
    0

    What a disgusting bit of tripe this article is.

    Do try to catch up with the latest scientific publications, rather than this tripe.

  2. 0
    0

    So what the article says is what exactly? That we have no idea whether or if there will be beach erosion and if there is we don’t know by how much or what the possible effect will be.
    RIIIIGHT!

    Step 1. Stop building adjacent to any waterway and immediately stop insurance claims for flooding!
    Step 2. See step 1.

  3. 0
    0

    The problem with Climate change zealots and those whose income is derived from building up public opinion to support their income is that they use Coral sand islands that are continually building up with sand then washing away, as a normal pattern of life, nothing to do with any rising sea level. Erosion has always occurred both coastal and riverine (e.g. Grand Canyon), even the erosion that is continually being evidenced with the twelve apostles. Anyone put forward only the facts that support their argument, instead putting ALL the facts to give a balanced assessment of any issue. Rising sea levels must be measured where there is rocks or rock shelves, such as the areas on the East coast of Australia. There have have been swimming pools carved from the rock headlands forever one hundred years. They were built so that would fill each high tide using calculations to establish the height they needed to be. It would be interesting obtain those calculations and to see if there an increase in the water level, or not, or by how much. This would be a scientific assessment rather than a emotional, ideological one. I do believe that there is man made climate change, the 50% CO2 increase over the last 50 years, however one of the main causes is being ignored in that there has been over the same period a 100% increase in the human population all breathing out CO2. With changing weather patterns we also need to consider many other factors including the changing location of the magnetic poles, the tilting of the Earth on its axis relative to the Sun, and so on. There so many factors that are not even mentioned by so called environmental experts. There not enough room here to discuss all the issues related to changing conditions on Earth which have been occurring since the beginning, ask any real
    scientist about that

  4. 0
    0

    there are two issues here
    1. water expands when the temperature rises
    2. massive glacial melt in the arctic and antarctic regions
    if the rednecks on here don’t understand these things stay where you are until the water level gets up to your neck then maybe you’ll take notice of the scientific evidence

  5. 0
    0

    Obviously tiggr55 has not been watching the increase in Arctic ice.

  6. 0
    0

    Watch the film 2040 by Damon Gameu or read the same book. We can do a lot to change our course, seeing the erosion and the beach sand shifting on our local beach dramatically in the last few years is alarming.

  7. 0
    0

    What happens to people with their “head in the sand” when the water washes in?

  8. 0
    0

    Jesus was a surfer, and he is coming on a wave too.

  9. 0
    0

    Musicveg, I haven’t seen 2040,I hope it is not using the same ASSUMPTIONS as the Al Gore Incovenient Truth, which have now been found to be false. Unfortunately many of the things put forward are based on incorrect, and or selected data, without taking into account all factors..


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