Rising seas allow coastal wetlands to store more carbon



File 20190306 48417 1mvzgzg.jpg?ixlib=rb 1.1
Carbon storage in Australian mangroves can help mitigate climate change.
Shutterstock

Kerrylee Rogers, University of Wollongong; Jeffrey Kelleway, Macquarie University, and Neil Saintilan, Macquarie University

Coastal wetlands don’t cover much global area but they punch well above their carbon weight by sequestering the most atmospheric carbon dioxide of all natural ecosystems.

Termed “blue carbon ecosystems” by virtue of their connection to the sea, the salty, oxygen-depleted soils in which wetlands grow are ideal for burying and storing organic carbon.

In our research, published today in Nature, we found that carbon storage by coastal wetlands is linked to sea-level rise. Our findings suggest as sea levels rise, these wetlands can help mitigate climate change.

Sea-level rise benefits coastal wetlands

We looked at how changing sea levels over the past few millennia has affected coastal wetlands (mostly mangroves and saltmarshes). We found they adapt to rising sea levels by increasing the height of their soil layers, capturing mineral sediment and accumulating dense root material. Much of this is carbon-rich material, which means rising sea levels prompt the wetlands to store even more carbon.

We investigated how saltmarshes have responded to variations in “relative sea level” over the past few millennia. (Relative sea level is the position of the water’s edge in relation to the land rather than the total volume of water within the ocean, which is called the eustatic sea level.)




Read more:
Mangrove forests can rebound thanks to climate change – it’s an opportunity we must take


What does past sea-level rise tell us?

Global variation in the rate of sea-level rise over the past 6,000 years is largely related to the proximity of coastlines to ice sheets that extended over high northern latitudes during the last glacial period, some 26,000 years ago.

As ice sheets melted, northern continents slowly adjusted elevation in relation to the ocean due to flexure of the Earth’s mantle.

Karaaf Wetlands in Victoria, Australia.
Boobook48/flickr, CC BY-NC-SA

For much of North America and Europe, this has resulted in a gradual rise in relative sea level over the past few thousand years. By contrast, the southern continents of Australia, South America and Africa were less affected by glacial ice sheets, and sea-level history on these coastlines more closely reflects ocean surface “eustatic” trends, which stabilised over this period.

Our analysis of carbon stored in more than 300 saltmarshes across six continents showed that coastlines subject to consistent relative sea-level rise over the past 6,000 years had, on average, two to four times more carbon in the upper 20cm of sediment, and five to nine times more carbon in the lower 50-100cm of sediment, compared with saltmarshes on coastlines where sea level was more stable over the same period.

In other words, on coastlines where sea level is rising, organic carbon is more efficiently buried as the wetland grows and carbon is stored safely below the surface.

Give wetlands more space

We propose that the difference in saltmarsh carbon storage in wetlands of the southern hemisphere and the North Atlantic is related to “accommodation space”: the space available for a wetland to store mineral and organic sediments.

Coastal wetlands live within the upper portion of the intertidal zone, roughly between mean sea level and the upper limit of high tide.

These tidal boundaries define where coastal wetlands can store mineral and organic material. As mineral and organic material accumulates within this zone it creates layers, raising the ground of the wetlands.

The coastal wetlands of Broome, Western Australia.
Shutterstock

New accommodation space for storage of carbon is therefore created when the sea is rising, as has happened on many shorelines of the North Atlantic Ocean over the past 6,000 years.

To confirm this theory we analysed changes in carbon storage within a unique wetland that has experienced rapid relative sea-level rise over the past 30 years.




Read more:
Without wetlands, what will protect the Great Barrier Reef?


When underground mine supports were removed from a coal mine under Lake Macquarie in southeastern Australia in the 1980s, the shoreline subsided a metre in a matter of months, causing a relative rise in sea level.

Following this the rate of mineral accumulation doubled, and the rate of organic accumulation increased fourfold, with much of the organic material being carbon. The result suggests that sea-level rise over the coming decades might transform our relatively low-carbon southern hemisphere marshes into carbon sequestration hot-spots.

How to help coastal wetlands

The coastlines of Africa, Australia, China and South America, where stable sea levels over the past few millennia have constrained accommodation space, contain about half of the world’s saltmarshes.

Saltmarsh on the shores of Westernport Bay in Victoria.
Author provided

A doubling of carbon sequestration in these wetlands, we’ve estimated, could remove an extra 5 million tonnes of CO₂ from the atmosphere per year. However, this potential benefit is compromised by the ongoing clearance and reclamation of these wetlands.

Preserving coastal wetlands is critical. Some coastal areas around the world have been cut off from tides to lessen floods, but restoring this connection will promote coastal wetlands – which also reduce the effects of floods – and carbon capture, as well as increase biodiversity and fisheries production.




Read more:
As communities rebuild after hurricanes, study shows wetlands can significantly reduce property damage


In some cases, planning for future wetland expansion will mean restricting coastal developments, however these decisions will provide returns in terms of avoided nuisance flooding as the sea rises.

Finally, the increased carbon storage will help mitigate climate change. Wetlands store flood water, buffer the coast from storms, cycle nutrients through the ecosystem and provided vital sea and land habitat. They are precious, and worth protecting.


The authors would like to acknowledge the contribution of their colleagues, Janine Adams, Lisa Schile-Beers and Colin Woodroffe.The Conversation

Kerrylee Rogers, Associate Professor, University of Wollongong; Jeffrey Kelleway, Postdoctoral Research Fellow in Environmental Sciences, Macquarie University, and Neil Saintilan, Head, Department of Environmental Science, Macquarie University

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

Advertisements

For Pacific Island nations, rising sea levels are a bigger security concern than rising Chinese influence



File 20180830 195328 caziun.jpg?ixlib=rb 1.1
Malcolm Turnbull promised to ‘step up’ Australian engagement with the Pacific last year. Will it continue now that he’s gone?
Lukas Coch/AAP

Michael O’Keefe, La Trobe University

When the Pacific Islands Forum is held in Nauru from September 1, one of the main objectives will be signing a wide-ranging security agreement that covers everything from defence and law and order concerns to humanitarian assistance and disaster relief.

The key question heading into the forum is: can the agreement find a balance between the security priorities of Australia and New Zealand and the needs of the Pacific Island nations?

Even though new Prime Minister Scott Morrison is not attending the forum, sending Foreign Minister Marise Payne instead, the Biketawa Plus security agreement remains a key aim for Canberra.




Read more:
Why China’s ‘debt-book diplomacy’ in the Pacific shouldn’t ring alarm bells just yet


The original Biketawa Declaration was developed as a response to the 2000 coup in Fiji. It has served Australia and the region well, providing a framework for collective action when political tensions and crises occur. However, in the face of rapid change, it looks narrow and dated.

Why act now? The rationale is clear. Much has happened to alter the security landscape in the Pacific since 2000. But despite the commentary in Australia, security in the Pacific is not all about geopolitics. While Australia may be most worried about China’s rising influence in the region, it would be a mistake to think this is the primary preoccupation of Pacific leaders, too.

A focus on climate change as a security issue

One key reason for updating Biketawa is to realign Australia’s security interests with those of Pacific Island countries that have grown more aware of their shared interests and confident in expressing them in international relations. This growing confidence is clear in the lobbying of Pacific nations for climate change action at the United Nations and in Fiji’s role as president of the UN’s COP23 climate talks.

In the absence of direct military threats, the Pacific Island nations are most concerned about security of a different kind. Key issues for the region are sustainable growth along a “blue-green” model, climate change (especially the increasing frequency and intensity of natural disasters and rising sea levels), illegal fishing and over-fishing, non-communicable diseases (NCDs), transnational crime, money laundering and human trafficking.




Read more:
Pacific pariah: how Australia’s love of coal has left it out in the diplomatic cold


Some of these security issues can be addressed by redirecting more Australian military forces to the region. Indeed, “disaster diplomacy” has been an effective method of connecting Australia’s security interests with those of Pacific Island nations in the past.

However, other priorities for the Pacific seem to run counter to Australia’s current policies toward the region. For example, the Pacific’s sustainable “blue-green” development agenda seems incompatible with an export-oriented growth model that is often touted by Australia as an “aid for trade” solution to Pacific “problems”.

Climate change adaptation and mitigation must also be elevated to the top of the agenda in Australia’s relations with the region. It is the most pressing problem in the Pacific, but for political and economic reasons, it hasn’t resonated to the same extent with Canberra.

In fact, Australia has recently been identified as the worst-performing country in the world on climate action. This has not gone unnoticed in the Pacific. Fiji’s prime minister, in particular, has been clear in highlighting that Australia’s “selfish” stance on climate change undermines its credibility in the region.

These shifting priorities in the Pacific present a greater challenge for Australia, especially now that there are more players in the region, such as China, Russia and Indonesia. Australia may see these “outsiders” as potential threats, but Pacific nations are just as likely to view them as alternative development partners able to provide opportunities.

New Coalition team on the Pacific

Making matters even trickier is the leadership shake-up in Canberra. What’s perhaps most problematic is Julie Bishop’s departure as foreign minister. Bishop did more to engage with Pacific countries than any foreign minister in recent memory. The [2017 Foreign Policy White Paper], for example, prioritised increased Pacific engagement and led to the region receiving the lion’s share of Australia’s latest aid budget.

Payne will attend the Pacific Islands Forum on her first overseas visit as foreign minister. As the former defence minister, she lobbied for Australia to be seen as a “security partner of choice” in the Pacific. What remains to be seen is whether she can maintain the momentum on Biketawa Plus.




Read more:
Response to rumours of a Chinese military base in Vanuatu speaks volumes about Australian foreign policy


So the challenge for the new Coalition leadership is to find a way to push through a new Pacific security agreement that caters to both Australia’s security concerns about Chinese influence in the region and the Pacific Island countries’ focus on climate change and sustainable growth.

There are lessons that can be drawn from the decade-long negotiations between Australia, New Zealand and the Pacific Island nations over the Pacer Plus free-trade agreement, which was finally signed last year (without the region’s two largest economies, Papua New Guinea and Fiji). Australia must not underestimate the diplomatic skills of Pacific leaders or offer benefits that are perceived as being more attractive to it than the Pacific states.

Australia must also avoid allowing the leadership spill to impact its Pacific agenda at this sensitive time. Bishop’s focus on labour mobility between the Pacific islands and Australia has been most welcome, but there can be no authentic engagement with the region without addressing climate insecurity as well.The Conversation

Michael O’Keefe, Head of Department, Politics and Philosophy, La Trobe University

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

King tides and rising seas are predictable, and we’re not doing enough about it


Mark Gibbs, Queensland University of Technology

Recent king tides have again caused significant damage to coastal assets in Australia and New Zealand. This time the combination of large tides and coastal storms damaged properties on Torres Strait islands and in Nelson and other coastal areas of New Zealand. It is increasingly recognised worldwide that, despite many coastal adaptation plans being developed, the implementation of these plans is lagging.

King tides occur several times a year when the Moon is slightly closer to the Earth (so they’re sometimes called perigean spring tides). This means king tides are predictable, as are rising sea levels. The combination, along with sporadic storm events, will lead to increasing flooding of our coastal cities.




Read more:
Hurt by sea: how storm surges and sea-level rise make coastal life risky


Higher sea levels, whether creeping (associated with anthropogenic climate change) or transient (episodic storm events), have impacts on both private and public property and assets. What is now mostly nuisance flooding will become more problematic, and the ever-increasing global damage bill from disaster will continue to mount.

According to the global re-insurer Munich Re, losses from natural disasters in 2017 totalled US$330 billion, the second highest on record. Almost half of these losses (41%) were uninsured.

Who’s responsible for adaptation plans?

In keeping with the theory that risk is best managed by those closest to the risk, local government in Australia is the level of government best suited to managing such local risks. In response to the increasing threat from rising sea levels, many local government councils around Australia have developed coastal climate adaptation plans.

Federal and state governments clearly also have roles to play in managing coastal inundation. The federal government is often the insurer of last resort, especially for public infrastructure.


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

Read more: Coastal law shift from property rights to climate adaptation is a landmark reform


In Queensland, the state government has implemented the successful QCoast2100 program. This is helping local governments to develop adaptation plans all along the state’s coastline.

It is increasingly recognised that many of the plans developed in the past contain overcomplicated analyses of oversimplified adaptation options. Instead, we need less complicated ways of determining the most suitable adaptation option and assessments that consider more tailored and considered options, which will then be more readily implementable.

What are the options?

Coastal climate adaptation options tend to fall into one of three categories:

  • retreat – relocate assets and structures inland or to higher ground
  • protect – mostly by building engineered seawalls, although green infrastructure can also be implemented
  • accommodate – live with the hazard but reduce the vulnerability of structures and assets.

Retreat makes intuitive sense: relocating assets out of harm’s way reduces their vulnerability. However, this approach has proved politically problematic, especially for private buildings.

Most communities are familiar with seawalls and other forms of coastal protection. Others fundamentally disagree with the principle of hard coastal protection measures.




Read more:
Contested spaces: conflict behind the sand dunes takes a new turn


The third adaptation option, accommodating sea-level rise, is becoming the most popular approach in many nations, including the low-lying Netherlands. However, this approach is probably the least understood in Australia and rarely appears as the preferred option in Australian coastal adaptation plans.

This option includes making existing structures less vulnerable. This might involve relocating electrical and air-conditioning services and switchboards higher in existing buildings. Over time, vulnerable sites can be repurposed with less vulnerable land uses and structures.

This is different from pre-emptively evicting and relocating entire communities from vulnerable locations – the retreat option. The retreat option is most easily implemented immediately after major flooding that has led to significant damage.

Plans must consider the politics

Early coastal adaptation plans commonly advocated mass pre-emptive coastal retreat, but local government often ended up shelving or rejecting such recommendations. Instead, councils simply commissioned the construction of small local seawalls in areas at risk of erosion.

More developed and recent coastal adaptation plans consider finer spatial scales. What they still often don’t do is consider more sophisticated and politically informed adaptation options and approaches.

Hence adaptation planning is still often best characterised as the “plan and forget” approach. These plans typically lack monitoring and evaluation and a realistic implementation strategy.

The ConversationIncreased flooding of our coastline is inevitable and happening. Therefore, adaptation planning needs to consider more nuanced options that are likely to be more politically palatable and implementable.

Mark Gibbs, Director, Knowledge to Innovation; Chair, Green Cross Australia, Queensland University of Technology

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

Australia’s coastal living is at risk from sea level rise, but it’s happened before



File 20171220 5004 xd79ws.jpg?ixlib=rb 1.1
Australia’s coastline has moved before thanks to changes in sea level.
Flickr/Travellers travel photobook, CC BY

Sean Ulm, James Cook University; Alan N Williams, UNSW; Chris Turney, UNSW, and Stephen Lewis, James Cook University

With global sea levels expected to rise by up to a metre by 2100 we can learn much from archaeology about how people coped in the past with changes in sea level.

In a study published this week in Quaternary Science Reviews, we looked at how changes in sea level affected different parts of Australia and the impact on people living around the coast.

The study casts new light on how people adapt to rising sea levels of the scale projected to happen in our near future.


Read more: Cave dig shows the earliest Australians enjoyed a coastal lifestyle


Coastal living

More than eight out of every ten Australians live within 50km of the coast.

The Intergovernmental Panel on Climate Change says global sea levels are set to increase by the equivalent of 12mm/year, four times the average of the last century.

A major challenge for managing such a large increase in sea level is our limited understanding of what impact this scale of change might have on humanity.

While there are excellent online resources to model the local physical impacts of sea level rise, the recent geological past can provide important insights into how humans responded to dramatic increases in sea level.

The last ice age

At the height of the last ice age some 21,000 years ago, not only were the Greenland and Antarctic ice sheets larger than they are today, but 3km-high ice sheets covered large parts of North America and northern Europe.

This sucked vast amounts of water out of our planet’s oceans. The practical upshot was sea level was around 125m lower, making the shape of the world’s coastlines distinctly different to today.

As the world lurched out of the last ice age with increasing temperatures, the melting ice returned to the ocean as freshwater, dramatically increasing sea levels and altering the surface of our planet.

Arguably nowhere experienced greater changes than Australia, a continent with a broad continental shelf and a rich archaeological record spanning tens of millennia.

A bigger landmass

For most of human history in Australia, lower sea levels joined mainland Australia to both Tasmania and New Guinea, forming a supercontinent called Sahul. The Gulf of Carpentaria hosted a freshwater lake more than twice the size of Tasmania (about 190,000km2).

Our study shows that lower sea levels resulted in Australia growing by almost 40% during this time – from the current landmass of 7.2 million km2 to 9.8 million km2.

The coastlines also looked very different, with steep profiles off the edge of the exposed continental shelf in many areas forming precipitous slopes and cliffs.

Imagine the current coastline where the Twelve Apostles are on Victoria’s Great Ocean Road and then extend them around much of the continent. Many rivers flowed across the exposed shelf to the then distant coast.

The steep cliffs at the Apostles, off Victoria’s Great Ocean Road, look like parts of the ancient coastline of Australia.
Flickr/portengaround, CC BY-SA

When things warmed up

Then between 18,000 and 8,000 years ago, global climate warmed, leading to rapid melting of the ice sheets, and seeing sea levels in the Australian region rising from 125m below to 2m above modern sea levels.

Tasmania was cut off with the flooding of Bass Strait around 11,000 years ago. New Guinea was separated from Australia with the flooding of Torres Strait and creation of the Gulf of Carpentaria around 8,000 years ago.

We found that 2.12 million square km, or 20-29% of the landmass – a size comparable to the state of Queensland – was lost during this inundation. The location of coastlines changed on average by 139km inland. In some areas the change was more than 300km.

Much of this inundation occurred over a 4,000-year period (between 14,600 and 10,600 years ago) initiated by what is called Meltwater Pulse 1A, a period of substantial ice sheet collapse releasing millions of cubic litres of water back into the oceans.

During this period, sea levels rose by 58m, equivalent to 14.5mm per year. On the ground, this would have seen movement of the sea’s edge at a pace of about 20-24m per year.

Impacts of past sea level rise

The potential impacts of these past sea-level changes on Aboriginal populations and societies have long been a subject of speculation by archaeologists and historians.

Map of Australia showing sea-level change and archaeological sites for selected periods between 35,000 and 8,000 years ago. PMSL=Present Mean Sea Level.
Sean Ulm, Author provided

In his 1970s book Triumph of the Nomads: A History of Aboriginal Australia, the Australian historian Geoffrey Blainey hypothesised that:

Most tribal groups on the coast 18,000 years ago must have slowly lost their entire territory […] a succession of retreats must have occurred. The slow exodus of refugees, the sorting out of peoples and the struggle for territories probably led to many deaths as well as new alliances.

Archaeologists have long recognised that Aboriginal people would have occupied the now-drowned continental shelves surrounding Australia, but opinions have been divided about the nature of occupation and the significance of sea-level rise. Most have suggested that the ancient coasts were little-used or underpopulated in the past.

Our data show that Aboriginal populations were severely disrupted by sea-level change in many areas. Perhaps surprisingly the initial decrease in sea level prior to the peak of the last ice age resulted in people largely abandoning the coastline, and heading inland, with a number of archaeological sites within the interior becoming established at this time.

Cross-section profiles of the continental shelf at Port Stephens, NSW (top) and Cape Otway, Vic (bottom). PMSL=Present Mean Sea Level.
Sean Ulm, Author provided

During the peak of the last ice age, there is evidence on the west coast that shows people continued to use marine resources (shellfish, fish etc) during this time, albeit at low levels.

A shrinking landmass

With the onset of the massive inundation after the end of the last ice age people evacuated the coasts causing markedly increased population densities across Australia (from around 1 person for every 355 square km 20,000 years ago, to 1 person every 147 square km 10,000 years ago).

Rising sea levels had such a profound impact on societies that Aboriginal oral histories from around the length of the Australian coastline preserve details of coastal flooding and the migration of populations.

We argue that this squeezing of people into a landmass 22% smaller – into inland areas that were already occupied – required people to adopt new social, settlement and subsistence strategies. This may have been an important element in the development of the complex geographical and religious landscape that European explorers observed in the 18th and 19th centuries.

Following the stabilisation of the sea level after 8,000 years ago, we start to see the onset of intensive technological investment and manipulation of the landscape (such as fish traps and landscape burning).

We also see the formation of territories (evident by marking of place through rock art) that continues to propagate up until the present time. All signs of more people trying to survive in less space.


Read more: Buried tools and pigments tell a new history of humans in Australia for 65,000 years


So what are the lessons of the past for today? Thankfully, we can show that past societies survived rapid sea level change at rates slightly greater than those projected in our near future, albeit with population densities far lower than today.

But we can also see that sea level rise resulted in drastic changes to where people lived, how they survived, what technology they used, and probable modifications to their social, religious and political ways of life.

The ConversationIn today’s world with substantially higher population densities, managing the relocation of people inland and outside Australia, potentially across national boundaries, may provide to be one of the great social challenges of the 21st century.

Sean Ulm, Deputy Director, ARC Centre of Excellence for Australian Biodiversity and Heritage, James Cook University; Alan N Williams, Associate Investigator, ARC Centre of Excellence for Australian Biodiversity and Heritage, UNSW; Chris Turney, ARC Centre of Excellence for Australian Biodiversity and Heritage, University of New South Wales, UNSW, and Stephen Lewis, Principal Research Officer, James Cook University

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

Don’t give up on Pacific Island nations yet


Jon Barnett, University of Melbourne

Fiji’s presidency of this year’s United Nations climate summit has put a renewed focus on the future of low-lying Pacific Islands. And while we should not ignore the plight of these nations, it is just as damaging to assume that their fate is already sealed.

Many people in Australia consider island nations such as Kiribati, Tuvalu and the Marshall Islands to be almost synonymous with impending climate catastrophe. After returning from Papua New Guinea in 2015, federal immigration minister Peter Dutton infamously joked that “time doesn’t mean anything when you’re about to have water lapping at your door”.

If influential and everyday Australians, and the rest of the world, hold the view that Pacific Island nations are doomed to succumb to climate change, the danger is that this will become a self-fulfilling prophecy.


Read more: Australia doesn’t ‘get’ the environmental challenges faced by Pacific Islanders


When we deny the possibility of a future for low-lying small islands, we are
admitting defeat. This in turn undermines the impetus to reduce greenhouse gas emissions and find ways to help communities carry on living in their island homes. It leaves us unable to discuss any options besides palliative responses for climate refugees.

There are other consequences of this pessimistic framing of islands. It may
undermine efforts to sustainably manage environments, because a finite future is
anathema to the sustaining resources in perpetuity. It can also manifest itself in harmful local narratives of denial or self-blame. And it can lead to climate change being blamed for environmental impacts that arise from local practices, which then remain unchanged.

We would do well to listen instead to what the leaders of low-lying island nations are saying, such as Tuvalu’s Prime Minister Enele Sopoaga, who told the 2013 Warsaw climate summit:

… some have suggested that the people of Tuvalu can move elsewhere. Let
me say in direct terms. We do not want to move. Such suggestions are
offensive to the people of Tuvalu. Our lives and culture are based on our
continued existence on the islands of Tuvalu. We will survive.

Those sentiments were echoed by the late Tony de Brum, former foreign minister of the Marshall Islands and described as the “voice of the Pacific Islands on climate change”, who said in 2015:

Displacement is not an option we relish or cherish and we will not operate on that basis. We will operate on the basis that we can in fact help to prevent this from happening.

Determined to survive

These leaders are determined for good reasons. Small islands are likely to respond in a host of different ways to climate change, depending on their geology, local wave patterns, regional differences in sea-level rise, and how their corals, mangroves and other wildlife respond to changing temperatures and weather patterns.

Evidence suggests that even seemingly very similar island types may respond very differently to one another. In many cases it is too early to say for sure that climate change will make a particular island uninhabitable.

But perhaps even more important in the future of low-lying small islands is the
way people adapt to climate change. There are all sorts of ways in which people can adapt their environments to changing conditions. Indeed, when the first migrants arrived in the low-lying atolls of Micronesia more than 3,000 years ago they found sand islands with no surface water and little soil, and settled them with only what they had in their small boats. Modern technologies and engineering systems can transform islands even more substantially, so that people can still live meaningful lives on them under changed climate conditions.

Adapting islands to climate change will not be easy. It will involve changes in where and how things are built, what people eat, how they get their water and energy, and what their islands look like.

It will also involve changes in institutions that are fundamental to island
societies, such as those concerned with land and marine tenure. But it can be done, with ingenuity, careful and long-term planning, technology transfer, and
meaningful partnerships between governments and international agencies.

Failure so far

Frustratingly, however, the international community is so far failing island states when it comes to this crucial adaptation. Despite their acute vulnerability having been recognised for at least 30 years, low-lying atoll countries such as Kiribati, the Marshall Islands and Tuvalu are attracting only low or moderate amounts of international adaptation funding. This is mostly as part of larger regional projects, and often focused on building capacity rather than implementing actual changes.

It is we who have failed to reduce greenhouse gas emissions and to help low-lying islands adapt, and it is we who cannot imagine any long-term future for them. It seems all we can do is talk about loss, migration, and waves of climate refugees. Having let them down twice, this defeatist thinking risks denying them an independent future for a third time. This is environmental neo-colonialism.


Read more: Islands lost to the waves: how rising seas washed away part of Micronesia’s 19th-century history


The international community has a moral responsibility to deliver a
comprehensive strategy to minimise the risks climate change poses to remote
low-lying islands. People living on these islands have a legal and moral right to lead dignified lives in their homelands, free from the interference of climate impacts. People who live in affluent countries high above sea level have several responsibilities here.

First, as most of us agree, we should reduce our greenhouse gas emissions. We have some control over that through how we consume, invest, vote and travel. Second, we should insist that our governments do more to help low-lying states to adapt to climate change. It is our pollution, after all. And we should argue for a reversal in our declining aid budgets.

The ConversationAnd finally, and perhaps most importantly, we should all stop talking down the future of low-lying small islands, because all this does is hasten their demise.

Jon Barnett, Professor, School of Geography, University of Melbourne

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

Islands lost to the waves: how rising seas washed away part of Micronesia’s 19th-century history



File 20170824 6594 1ussrse.jpg?ixlib=rb 1.1
Laiap, to the west of the site of the now-disappeared Nahlapenlohd.
Author provided

Patrick D. Nunn, University of the Sunshine Coast

At first glance it may not seem so, but the story of the now-vanished island of Nahlapenlohd, a couple of kilometres south of Pohnpei Island in Micronesia, holds some valuable lessons about recent climate change in the western Pacific.

In 1850, Nahlapenlohd was so large that not only did it support a sizeable coconut forest, but it was able to accommodate a memorable battle between the rival kingdoms of Kitti and Madolenihmw. The skirmish was the first in Pohnpeian history to involve the European sailor-mercenaries known as beachcombers and to be fought with imported weapons like cannons and muskets.

Today the island is no more. The oral histories tell that so much blood was spilled in this fierce battle that it stripped the island of all its vegetation, causing it to shrink and eventually disappear beneath the waves.


Read more: Sea level rise has claimed five whole islands in the Pacific: first scientific evidence


Like many oral tales, this one tries to explain island disappearance post-1850 by making reference to an historical event. But in light of what we know today, the more plausible cause of the island’s disappearance is the sea-level rise in the western Pacific since the early 19th century, which has accelerated significantly over the past few decades. The disappearance of islands in the Solomon Islands in the southwest Pacific has recently been attributed to sea level rise. Further north, the same is true of several reef islands off Pohnpei.

Pohnpei and its surrounding islands, both past and present.
CREDIT, Author provided

Surveys of 12 of these islands have shown that not only have some – like Nahlapenlohd – completely disappeared, but that most others have shrunk over the past decade. Islands such as Laiap and Ros, which have lost two-thirds of their land area over this time, are likely to disappear completely within the coming decade.

The island of Laiap has shrunk since 2007.
CREDIT, Author provided

Why are islands in the western Pacific becoming the earliest casualties of sea-level rise? Partly because sea levels in this region have risen at two to three times the global average over the past few decades.

In parts of Micronesia, sea level has risen by 10-12mm each year between 1993 and 2012, far outpacing the global average of 3.1mm a year. While this rate is unlikely to be sustained indefinitely, the current trend would raise sea levels by a further 30-40cm by mid-century if it were to continue.

What’s more, reef islands are particularly vulnerable to erosion by rising seas, being made almost entirely of sand and gravel. Whole islands – even some island nations with which we are familiar today – are likely to be rendered uninhabitable or even disappear within the next 30 years. These include islands in nations like Kiribati, the Marshall Islands, Tokelau and Tuvalu, as well as some in other island nations that comprise mostly larger islands, such as the Federated States of Micronesia, of which Pohnpei is one.

Armoured islands

Yet we should note that not all of Pohnpei’s reef islands are disappearing, at least not at the same rate, and some have fortuitously evolved protection that will likely help them outlive their neighbours.

The coasts of some islands – like Kehpara and Nahlap – are “armoured” by beaches of huge boulders left there by large storms, often along their most exposed coasts. Other reef islands off Pohnpei’s leeward coast, such as Dawahk, are becoming “skeletonized” as waves wash across the island removing the sand and leaving only rocks, held in place by a maze of giant mangrove roots.

Whether or not the islands themselves succumb or survive, sea-level rise is a clear threat to their habitability for humans. Short-term interventions – either natural fortifications such as boulder beaches, or human-built defences such as seawalls – are unlikely to change the long-term outcome.

This underscores the fact that low-lying reef islands are transient – most Pacific reef islands formed only in the past 4,000 years after sea levels fell and sediment began to pile up on exposed reef platforms. The sea will remove today’s islands, just as it has washed away countless others before.

But of course we cannot ignore the human dimension. While only a few dozen people today call the reef islands of Pohnpei home, they are similar to many larger reef islands in Micronesia from which people may well be involuntarily displaced during the next few decades. Where these people might go, and how they can be accommodated in ways that preserve their dignity as well as their unique cultures, are very real questions for community leaders.


Read more: Australia doesn’t ‘get’ the environmental challenges faced by Pacific islanders


People first reached the islands of Micronesia from the Philippines, about 3,500 years ago after an unbroken ocean crossing of 2,300km. It’s an extraordinary achievement when you consider that people in most other parts of the world at that time rarely sailed out of sight of land. To have survived on islands in the middle of the ocean for more than three millennia, Micronesians and other Pacific islanders must have developed considerable resilience.

On high islands in Micronesia, the evidence for this is manifest. Ancient stonework constructions line many parts of the coastline, testament to a long
history of resisting shoreline change, and sometimes of manipulating it for human advantage.

Perhaps nowhere is more evocative of this today than Nan Madol, a megalithic complex built 1,000 years ago on 93 artificial islands off southeast Pohnpei. There are many explanations about why Nan Madol was created. Perhaps the truth is that it is an expression of dogged human resilience – one of hundreds along Micronesian coasts – in the face of an unruly nature.


The ConversationI thank my co-researchers on the project focused on Pohnpei’s reef islands, Augustine Kohler from the Department of National Archives, Culture and Historic Preservation of the Government of the Federated States of Micronesia, and my colleague Roselyn Kumar from the University of the Sunshine Coast’s Sustainability Research Centre.

Patrick D. Nunn, Professor of Geography, Sustainability Research Centre, University of the Sunshine Coast

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

Coastal councils are already adapting to rising seas – we’ve built a website to help


Sarah Boulter, Griffith University

The wild storms that lashed eastern Australia earlier this year damaged property and eroded beaches, causing millions of dollars’ worth of damage. As sea levels rise, the impact of storms will threaten more and more homes, businesses and services along the coastline.

CSIRO projections suggest that seas may rise by as much 82cm by the end of the century. When added to high tides, and with the influence of winds and associated storms, this can mean inundation by waters as high as a couple of metres.

As a community, we have to start deciding what must be protected, and how and when; where we will let nature take its course; how and if we need to modify the way we live and work near the coast; and so on. Many of these decisions fall largely to local governments.

We have launched a website to help local councils and Australians prepare for a climate change future. CoastAdapt lets you find maps of your local area under future sea-level scenarios, read case studies, and make adaptation plans.

How will sea-level rise affect you?

Using sea-level rise modelling from John Church and his team at CSIRO, CoastAdapt provides sea-level projections for four greenhouse gas scenarios, for individual local government areas. This also provides a set of inundation maps for the selected local government area.

Sydney’s possible sea level in 2100 under a worst-case scenario. Inundated areas shown in pale blue.
NCCARF

The inundation maps (developed by the Cooperative Research Centre for Spatial Information) show the average projected sea-level rise for a particular climate change scenario, combined with the highest tide. The method provides an approximation of where flooding may occur.

Because water is simply filled onto the map according to elevation, it doesn’t account for things like estuary shapes and water movement, the behaviour of waves and so on.

Brisbane’s possible sea level in 2100 under a worst-case scenario. Inundated areas shown in pale blue.
NCCARF

But both the maps and the sea-level projections are a useful way to start thinking about where risks may lie in any given local government area.

CoastAdapt also looks at what we know about coastal processes in the present day. Understanding these characteristics helps us understand where and why the coast is vulnerable to inundation and erosion.

For instance, sandy coasts are much more vulnerable to erosion than rocky coasts. The information will help decision-makers understand the behaviour of their coasts and their susceptibility to erosion under sea-level rise.

Darwin’s possible sea level in 2100 under a worst-case scenario. Inundated areas shown in pale blue.
NCCARF

Local councils already adapting

Adaptation is already happening on the ground around Australian local councils. We have highlighted several of these on CoastAdapt.

In the small seaside town of Port Fairy in southeast Victoria, for example, an active community group is monitoring the accelerated erosion of dunes on one of their beaches. The council and community have worked together to prioritise protecting dune areas with decommissioned landfill to prevent this rubbish tip being exposed to the beach.

Other councils have already undertaken the process of assessing their risks and drafting adaptation plans.

Low-lying areas in the City of Lake Macquarie already experience occasional flooding from high seas. This is expected to become more common and more severe.

Lake Macquarie Council has successfully worked with the local community to come up with 39 possible management actions, which the community then assessed against social, economic and environmental criteria. The area now has a strategy for dealing with current flooding and for gradually building protection for future sea-level rise.

This approach has engaged community members and given them the opportunity to help decide the future of their community.

Melbourne’s possible sea level in 2100 under a worst-case scenario. Inundated areas shown in pale blue.
NCCARF

Getting prepared

What stumps councils and other coastal decision-makers is the scale and complexity of the problem. Each decision-maker needs to have some sense of the risk of future climate change to their interests, then develop plans that will help them to cope or adapt to these risks. Planners and adaptors must navigate uncertainty in where, when and how much change they must consider, and how these changes interact with other issues that must be managed.

To better understand the risk, decision-makers need access to timely, authoritative advice presented in ways and levels that are useful for their needs. This is particularly true for an issue such as climate science, which is technically complex.

Climate projections, particularly at the local level, come with a level of certainty and probability. The further we look into the future, the more extraneous factors are unknown – for example, will global policy succeed in bringing down greenhouse emissions? Or will these keep increasing, which will necessitate planning for worst-case scenarios?

Add to this the questions around legal risk, financing adaptation measures, accommodating community views and so on, and the task is daunting.

That’s the thinking behind CoastAdapt – the first national attempt to create a platform that brings together a range of data, tools and research that have been developing and growing over the last decade. As well as maps and case studies, we’ve also built an adaptation planning framework (Coastal Climate Adaptation Decision Support) and set up an online forum for people to ask questions, exchange ideas and even pose questions to our panel of experts.

The author would like to acknowledge the work of staff of the National Climate Change Adaptation Research Facility. CoastAdapt is in beta version and is seeking feedback. The final version will be released in early 2017.

The Conversation

Sarah Boulter, Research Fellow, National Climate Change Adaptation Research Facility, Griffith University

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