The world may lose half its sandy beaches by 2100. It’s not too late to save most of them



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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 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 leads 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.

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 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 achieve 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 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 license. Read the original article.

Climate change may change the way ocean waves impact 50% of the world’s coastlines


Mark Hemer, CSIRO; Ian Young, University of Melbourne; Joao Morim Nascimento, Griffith University, and Nobuhito Mori, Kyoto University

The rise in sea levels is not the only way climate change will affect the coasts. Our research, published today in Nature Climate Change, found a warming planet will also alter ocean waves along more than 50% of the world’s coastlines.

If the climate warms by more than 2℃ beyond pre-industrial levels, southern Australia is likely to see longer, more southerly waves that could alter the stability of the coastline.

Scientists look at the way waves have shaped our coasts – forming beaches, spits, lagoons and sea caves – to work out how the coast looked in the past. This is our guide to understanding past sea levels.




Read more:
Rising seas threaten Australia’s major airports – and it may be happening faster than we think


But often this research assumes that while sea levels might change, wave conditions have stayed the same. This same assumption is used when considering how climate change will influence future coastlines – future sea-level rise is considered, but the effect of future change on waves, which shape the coastline, is overlooked.

Changing waves

Waves are generated by surface winds. Our changing climate will drive changes in wind patterns around the globe (and in turn alter rain patterns, for example by changing El Niño and La Niña patterns). Similarly, these changes in winds will alter global ocean wave conditions.




Read more:
Curious Kids: why are there waves?


Further to these “weather-driven” changes in waves, sea level rise can change how waves travel from deep to shallow water, as can other changes in coastal depths, such as affected reef systems.

Recent research analysed 33 years of wind and wave records from satellite measurements, and found average wind speeds have risen by 1.5 metres per second, and wave heights are up by 30cm – an 8% and 5% increase, respectively, over this relatively short historical record.

These changes were most pronounced in the Southern Ocean, which is important as waves generated in the Southern Ocean travel into all ocean basins as long swells, as far north as the latitude of San Francisco.

Sea level rise is only half the story

Given these historical changes in ocean wave conditions, we were interested in how projected future changes in atmospheric circulation, in a warmer climate, would alter wave conditions around the world.

As part of the Coordinated Ocean Wave Climate Project, ten research organisations combined to look at a range of different global wave models in a variety of future climate scenarios, to determine how waves might change in the future.

While we identified some differences between different studies, we found if the 2℃ Paris agreement target is kept, changes in wave patterns are likely to stay inside natural climate variability.

However in a business-as-usual climate, where warming continues in line with current trends, the models agreed we’re likely to see significant changes in wave conditions along 50% of the world’s coasts. These changes varied by region.

Less than 5% of the global coastline is at risk of seeing increasing wave heights. These include the southern coasts of Australia, and segments of the Pacific coast of South and Central America.

On the other hand decreases in wave heights, forecast for about 15% of the world’s coasts, can also alter coastal systems.

But describing waves by height only is the equivalent of describing an orchestra simply by the volume at which it plays.

Some areas will see the height of waves remain the same, but their length or frequency change. This can result in more force exerted on the coast (or coastal infrastructure), perhaps seeing waves run further up a beach and increasing wave-driven flooding.

Similarly, waves travelling from a slightly altered direction (suggested to occur over 20% of global coasts) can change how much sand they shunt along the coast – important considerations for how the coast might respond. Infrastructure built on the coast, or offshore, is sensitive to these many characteristics of waves.

While each of these wave characteristics is important on its own, our research identified that about 40% of the world’s coastlines are likely to see changes in wave height, period and direction happening simultaneously.

While some readers may see intense waves offering some benefit to their next surf holiday, there are much greater implications for our coastal and offshore environments. Flooding from rising sea levels could cost US$14 trillion worldwide annually by 2100 if we miss the target of 2℃ warming.




Read more:
Droughts and flooding rains already more likely as climate change plays havoc with Pacific weather


How coastlines respond to future climate change will be a response to a complex interplay of many processes, many of which respond to variable and changing climate. To focus on sea level rise alone, and overlooking the role waves play in shaping our coasts, is a simplification which has great potential to be costly.


The authors would like to acknowledge the contribution of Xiaolan Wang, Senior Research Scientist at Environment and Climate Change, Canada, to this article.The Conversation

Mark Hemer, Principal Research Scientist, Oceans and Atmosphere, CSIRO; Ian Young, Kernot Professor of Engineering, University of Melbourne; Joao Morim Nascimento, PhD Candidate, Griffith University, and Nobuhito Mori, Professor, Kyoto University

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

Coastal communities, including 24 federal seats at risk, demand action on climate threats


Barbara Norman, University of Canberra

Representatives of Australian coastal communities have gathered this week to discuss the major challenges they face. Delegates at the conference in Rockingham, Western Australia, represent 40 councils around Australia, some falling within the 24 federal electorates held by a margin of 5% or less. In contrast to the federal budget, climate change is at the top of their agenda.

At the coming federal election, 24 coastal electorates are held by a margin of 5% or less.
Compiled with NATSEM, University of Canberra and the Australian Coastal Councils, Author provided

Sea-level rise, floods, storms and bushfire were common concerns. The Australian Coastal Councils Conference’s May 6 communique demands national action:

Coastal councils and their communities call on the Australian Government to play a leadership role in developing a co-ordinated national approach to coastal management by adopting a set of policy initiatives based on the recommendations of the bipartisan Australian Parliamentary Coastal Inquiry.

Challenges of growth and change

Australia’s population is set to grow from 24 million to 40 million people by 2050. On present trends, this growth is likely to be concentrated in coastal regions, mostly along the eastern seaboard.

Australian Coastal Councils Association chair Barry Sammels, the mayor of Rockingham, observed:

Coastal seats are among the most vulnerable at the forthcoming election. Some of them are growing very rapidly, and others are changing demographically as ‘sea-changers’ migrate to coastal areas and people with young families are relocating from the cities in search of a better quality of life. This invariably means these regional coastal electorates, which have traditionally elected conservative political candidates, are becoming politically more volatile.

These communities are “at the forefront of climate vulnerability”, Sammels said. They are already dealing with coastal erosion and the prospect of rising sea levels and more frequent and extreme weather events.

Coastal communities, in particular those which are changing in character, are demanding these risks be taken seriously. … They currently feel there is a lack of commitment from both major parties to deal with these threats.

Lack of urgency at the top

Population growth is concentrated in coastal centres vulnerable to climate change.
p.16 State of Australian Cities 2014-15, Australian Government

While bipartisan interest in cities policies is growing, this needs to be extended to coastal regions experiencing big changes on several fronts – demographic, economic and environmental.

The lack of long-term strategic coastal planning puts both communities and environments at risk. The bleaching of the Great Barrier Reef illustrates the impacts of environmental change on tourism, jobs and long-term economic security.

We need a national plan to support local councils to better manage coastal urban development, climate change and the consequences for their communities. We have had over 25 national reports leading to largely no action.

In the communique, coastal councils reasonably call for action on key recommendations of the comprehensive 2009 parliamentary inquiry:

We propose that the following recommendations of the coastal inquiry be adopted:
That the Australian Government, in co-operation with state, territory and local governments, and in consultation with coastal stakeholders, develop an Intergovernmental Agreement on the Coastal Zone to be endorsed by the Council of Australian Governments.

And that:

The Australian Government ensure that [the agreement] forms the basis for a National Coastal Zone Policy and Strategy, which should set out the principles, objectives and actions that must be taken to address the challenges of integrated coastal zone management for Australia.

Despite much-reduced federal funding, the National Climate Change Adaptation Facility continues to help inform action by local government. Clearly, however, better long-term planning is required. This requires deeper institutional support, including a national perspective on urban growth in the context of climate change.

Mandurah, WA, epitomises both the pace of growth of coastal communities and their vulnerability to climate change.
Rexness/flickr, CC BY-SA

Action has begun locally

Finally, not all coastal planning and management is achieved through law and policy. A great deal of activity occurs locally through goodwill and collaboration. To highlight three examples:

Such collaboration and innovation deserves long-term funding from higher levels of government.

We may have got this far without an integrated approach to coastal planning and management, but without it there is no way we will be able to manage coastal growth with the projected demographic, economic and climate changes.

That’s why local councils are demanding immediate action on a national coastal policy to meet the needs of our coastal communities and environment. To ignore their call is a very significant political risk indeed.

The Conversation

Barbara Norman, Chair of Urban & Regional Planning & Director of Canberra Urban & Regional Futures, University of Canberra

This article was originally published on The Conversation. Read the original article.

Coral Reefs and Shoreline Protection


The link below is to an article that takes a look at coral reefs and the part they play in protection shorelines from surf erosion.

For more visit:
http://thinkprogress.org/climate/2014/05/16/3438478/coral-reefs-protect-shorelines/

The Six Big Environment Issues of Our Day


The link below is to an article that takes a look at the six big environmental issues of our day – climate change, loss of biodiversity, erosion, water scarcity, deforestation and pollution.

For more visit:
http://inhabitat.com/top-6-environmental-issues-for-earth-day-and-what-you-can-do-to-solve-them/

Article: Australia – Old Bar Under Threat


The link below is to an article reporting on coastal erosion at Old Bar, New South Wales, Australia. This town is just up the coast from where I live. It is a similar situation to Winda Woppa, which is only a suburb away from me. During intense storms the ocean erodes the sandy coastline rapidly and homes are increasingly at threat from storm surges.

The article below suggests that the situation at Old Bar is being caused by sea level rises as a consequence of climate change. This is the sort of reporting that is bringing a lot of discredit to climate change advocates, as it is not an honest report on the actual situation being reported on. I would not dispute that climate change is bringing us more severe weather events and this is certainly increasing pressure on coastal areas like Old Bar and Winda Woppa – but it is not sea level rises that is the problem. Factual and honest reporting is what is needed.

To view the article visit:
http://www.mmail.com.my/story/sea-rise-threatens-paradise-down-under-23507