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.

Rising seas will displace millions of people – and Australia must be ready


Jane McAdam, UNSW and John Church, UNSW

Sea-level rise is already threatening some communities around the world, particularly small island states, as it exacerbates disasters resulting from storm surges and flooding.

If greenhouse gas emissions continue unabated, by 2100 the world could see sea-level rise of a metre – or even more if there is a larger contribution from the Antarctic ice sheet, as some recent findings suggest.

Even without a larger Antarctic response, the rate of rise at the end of the 21st century for unmitigated emissions is likely to be equivalent to the rate of rise during the last deglaciation of the Earth, when sea level rose at more than a metre per century for many millennia. For all scenarios, sea-level rise will continue for centuries to come.




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


Without significantly more effective mitigation than currently planned, the rise will ultimately be many metres, or even tens of metres – the question is not if there will be large rises, but how quickly they will happen.

Forcing people from their homes

As well as causing seas to rise, climate change may also increase the severity of events like cyclones and rainfall, which may force people from their homes in many regions.




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


Global statistics on the risk of disaster displacement were not systematically collected until 2008, but already they offer stark figures. In 2017, 18.8 million people were internally displaced by natural disasters, with floods accounting for 8.6 million. By contrast, 11.8 million were displaced by conflict. Many more people are displaced each year by disasters than by conflict. Climate change intensifies this risk.

Roughly 100 million people live within about a metre of current high tide level. (Double these numbers for a five-metre sea-level rise, and triple them for 10 metres.)

Many of the world’s megacities are on the coast and vulnerable to sea-level change. Without adaption, it is estimated that by 2100 some of these areas will flood, displacing in the order of 100 million people.

While the vast majority of those people will never cross an international border, some will – and their legal status will be precarious because they will not qualify as refugees under the UN Refugee Convention (people with a well-founded fear of being persecuted for reasons of race, religion, nationality, political opinion or membership of a particular social group).




Read more:
Regionalism, human rights and migration in relation to climate change


In the current political climate, governments are reticent to create a new legal status for such people, and it would be difficult to encapsulate the complexity of climate change and disaster-related movement in a treaty definition anyway. Many factors drive people to leave their homes – such as poverty, resource scarcity and lack of livelihood opportunities – but climate change becomes the straw that breaks the camel’s back.

Good policy is essential

The most effective way to reduce the number of displaced people is strong global mitigation of emissions. In Australia, a successful NEG policy that included emissions reduction would cover about a third of Australia’s emissions. Mitigation policies also need to be developed to cover all emission sectors.

However, even with strong mitigation, adaptation will be essential. The evidence tells us that most people want to remain in their homes for as long as they can, and to return as quickly as possible. We therefore need laws and policies that permit people to remain in their homes where possible and desirable; that enable them to move elsewhere, before disaster strikes, if they wish; and to receive assistance and protection if they are displaced.

Coastal communities could live more effectively with rising sea levels by developing infrastructure, adopting and enforcing appropriate planning and building codes, and controlling flooding to allow sediment deposition. Storm-surge shelters and storm-surge warnings have already saved thousands of lives in countries like Bangladesh.

Good policy is essential. Studies of floods in Bangladesh showed that when people received prompt and adequate assistance, they were more likely to stay and rebuild than to move on in search of work to survive. By contrast, a year after Typhoon Haiyan struck the Philippines, tens of thousands of people remained displaced because the authorities said it was unsafe to go home but could not offer any alternative. This is likely to be a growing challenge with on-going climate change.




Read more:
Building housing on flood plains another sign of growing inequality


We are going to see more and more climate related disasters. We can do better in the way we prepare for and respond to them. The nature and timing of policy interventions will be crucial in determining outcomes after a disaster, because together they affect people’s ability to cope and be resilient. We need a broad, complementary set of policy strategies to assist people and give them choices.


<!– Below is The Conversation's page counter tag. Please DO NOT REMOVE. –>
The Conversation

On Thursday 24 August Jane McAdam and John Church will join Walter Kaelin to talk on Good Evidence, Bad Politics. This event is free to the public.

Jane McAdam, Scientia Professor and Director of the Kaldor Centre for International Refugee Law, UNSW and John Church, Chair professor, UNSW

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

Antarctica has lost 3 trillion tonnes of ice in 25 years. Time is running out for the frozen continent



File 20180613 110178 4dith6.jpg?ixlib=rb 1.1
As the world prevaricates over climate action, Antarctica’s future is shrouded in uncertainty.
Hamish Pritchard/British Antarctic Survey

Steve Rintoul, CSIRO and Steven Chown, Monash University

Antarctica lost 3 trillion tonnes of ice between 1992 and 2017, according to a new analysis of satellite observations. In vulnerable West Antarctica, the annual rate of ice loss has tripled during that period, reaching 159 billion tonnes a year. Overall, enough ice has been lost from Antarctica over the past quarter-century to raise global seas by 8 millimetres.

What will Antarctica look like in the year 2070, and how will changes in Antarctica impact the rest of the globe? The answer to these questions depends on choices we make in the next decade, as outlined in our accompanying paper, also published today in Nature.




Read more:
Ocean waves and lack of sea ice can trigger Antarctic ice shelves to disintegrate


Our research contrasts two potential narratives for Antarctica over the coming half-century – a story that will play out within the lifetimes of today’s children and young adults.

While the two scenarios are necessarily speculative, two things are certain. The first is that once significant changes occur in Antarctica, we are committed to centuries of further, irreversible change on global scales. The second is that we don’t have much time – the narrative that eventually plays out will depend on choices made in the coming decade.

Change in Antarctica has global impacts

Despite being the most remote region on Earth, changes in Antarctica and the Southern Ocean will have global consequences for the planet and humanity.

For example, the rate of sea-level rise depends on the response of the Antarctic ice sheet to warming of the atmosphere and ocean, while the speed of climate change depends on how much heat and carbon dioxide is taken up by the Southern Ocean. What’s more, marine ecosystems all over the world are sustained by the nutrients exported from the Southern Ocean to lower latitudes.

From a political perspective, Antarctica and the Southern Ocean are among the largest shared spaces on Earth, regulated by a unique governance regime known as the Antarctic Treaty System. So far this regime has been successful at managing the environment and avoiding discord.

However, just as the physical and biological systems of Antarctica face challenges from rapid environmental change driven by human activities, so too does the management of the continent.

Antarctica in 2070

We considered two narratives of the next 50 years for Antarctica, each describing a plausible future based on the latest science.

In the first scenario, global greenhouse gas emissions remain unchecked, the climate continues to warm, and little policy action is taken to respond to environmental factors and human activities that affect the Antarctic.

Under this scenario, Antarctica and the Southern Ocean undergo widespread and rapid change, with global consequences. Warming of the ocean and atmosphere result in dramatic loss of major ice shelves. This causes increased loss of ice from the Antarctic ice sheet and acceleration of sea-level rise to rates not seen since the end of the last glacial period more than 10,000 years ago.

Warming, sea-ice retreat and ocean acidification significantly change marine ecosystems. And unrestricted growth in human use of Antarctica degrades the environment and results in the establishment of invasive species.

Under the high-emissions scenario, widespread changes occur by 2070 in Antarctica and the Southern Ocean, with global impacts.
Rintoul et al. 2018. Click image to enlarge.

In the second scenario, ambitious action is taken to limit greenhouse gas emissions and to establish policies that reduce human pressure on Antarctica’s environment.

Under this scenario, Antarctica in 2070 looks much like it does today. The ice shelves remain largely intact, reducing loss of ice from the Antarctic ice sheet and therefore limiting sea-level rise.

An increasingly collaborative and effective governance regime helps to alleviate human pressures on Antarctica and the Southern Ocean. Marine ecosystems remain largely intact as warming and acidification are held in check. On land, biological invasions remain rare. Antarctica’s unique invertebrates and microbes continue to flourish.

Antarctica and the Southern Ocean in 2070, under the low-emissions (left) and high-emissions (right) scenarios. Each of these systems will continue to change after 2070, with the magnitude of the change to which we are committed being generally much larger than the change realised by 2070.
Rintoul et al. 2018. Click image to enlarge.

The choice is ours

We can choose which of these trajectories we follow over the coming half-century. But the window of opportunity is closing fast.

Global warming is determined by global greenhouse emissions, which continue to grow. This will commit us to further unavoidable climate impacts, some of which will take decades or centuries to play out. Greenhouse gas emissions must peak and start falling within the coming decade if our second narrative is to stand a chance of coming true.

If our more optimistic scenario for Antarctica plays out, there is a good chance that the continent’s buttressing ice shelves will survive and that Antarctica’s contribution to sea-level rise will remain below 1 metre. A rise of 1m or more would displace millions of people and cause substantial economic hardship.

Under the more damaging of our potential scenarios, many Antarctic ice shelves will likely be lost and the Antarctic ice sheet will contribute as much as 3m of sea level rise by 2300, with an irreversible commitment of 5-15m in the coming millennia.

The ConversationWhile challenging, we can take action now to prevent Antarctica and the world from suffering out-of-control climate consequences. Success will demonstrate the power of peaceful international collaboration and show that, when it comes to the crunch, we can use scientific evidence to take decisions that are in our long-term best interest.

The choice is ours.

Steve Rintoul, Research Team Leader, Marine & Atmospheric Research, CSIRO and Steven Chown, Professor of Biological Sciences, Monash University

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

Ocean waves and lack of sea ice can trigger Antarctic ice shelves to disintegrate


Luke Bennetts, University of Adelaide; Rob Massom, and Vernon Squire

Large waves after the loss of sea ice can trigger Antarctic ice shelf disintegration over a period of just days, according to our new research.

With other research also published today in Nature showing that the rate of annual ice loss from the vulnerable Antarctic Peninsula has quadrupled since 1992, our study of catastrophic ice shelf collapses during that time shows how the lack of a protective buffer of sea ice can leave ice shelves, already weakened by climate warming, wide open to attack by waves.




Read more:
Antarctica has lost 3 trillion tonnes of ice in 25 years. Time is running out for the frozen continent


Antarctica is covered by an ice sheet that is several kilometres thick in places. It covers an area of 14 million square kilometres – roughly twice the size of Australia. This ice sheet holds more than 90% of the world’s ice, which is enough to raise global mean sea level by 57 metres.

As snow falls and compacts on the ice sheet, the sheet thickens and flows out towards the coast, and then onto the ocean surface. The resulting “ice shelves” (and glacier tongues) buttress three-quarters of the Antarctic coastline. Ice shelves act as a crucial braking system for fast-flowing glaciers on the land, and thus moderate the ice sheet’s contribution to sea-level rise.

In the southern summer of 2002, scientists monitoring the Antarctic Peninsula (the northernmost part of mainland Antarctica) by satellite witnessed a dramatic ice shelf disintegration that was stunning in its abruptness and scale. In just 35 days, 3,250 square km of the Larsen B Ice Shelf (twice the size of Queensland’s Fraser Island) shattered, releasing an estimated 720 billion tonnes of icebergs into the Weddell Sea.

This wasn’t the first such recorded event. In January 1995, roughly 1,500 square km of the nearby Larsen A Ice Shelf suddenly disintegrated after several decades of warming and years of gradual retreat. To the southwest, the Wilkins Ice Shelf suffered a series of strikingly similar disintegration events in 1998, 2008 and 2009 — not only in summer but also in two of the Southern Hemisphere’s coldest months, May and July.

These sudden, large-scale fracturing events removed features that had been stable for centuries – up to 11,500 years in the case of Larsen B. While ice shelf disintegrations don’t directly raise sea level (because the ice shelves are already floating), the removal of shelf ice allows the glaciers behind them to accelerate their discharge of land-based ice into the ocean – and this does raise sea levels. Previous research has shown that the removal of Larsen B caused its tributary glaciers to flow eight times faster in the year following its disintegration.




Read more:
Cold and calculating: what the two different types of ice do to sea levels


The ocean around ice shelves is typically covered by a very different (but equally important) type of ice, called sea ice. This is formed from frozen seawater and is generally no more than a few metres thick. But it stretches far out into the ocean, doubling the area of the Antarctic ice cap when at its maximum extent in winter, and varying in extent throughout the year.

The response of Antarctic sea ice to climate change and variability is complex, and differs between regions. Around the Antarctic Peninsula, in the Bellingshausen and northwestern Weddell seas, it has clearly declined in extent and annual duration since satellite monitoring began in 1979, at a similar rate to the Arctic’s rapidly receding sea ice.

The Southern Ocean is also host to the largest waves on the planet, and these waves are becoming more extreme. Our new study focuses on “long-period” swell waves (with swells that last up to about 20 seconds). These are generated by distant storms and carry huge amounts of energy across the oceans, and can potentially flex the vulnerable outer margins of ice shelves.

The earliest whalers and polar pioneers knew that sea ice can damp these waves — Sir Ernest Shackleton reported it in his iconic book South!. Sea ice thus acts as a “buffer” that protects the Antarctic coastline, and its ice shelves, from destructive ocean swells.

Strikingly, all five of the sudden major ice shelf disintegrations listed above happened during periods when sea ice was abnormally low or even absent in these regions. This means that intense swell waves crashed directly onto the vulnerable ice shelf fronts.

The straw that broke the camel’s back

The Antarctic Peninsula has experienced particularly strong climate warming (roughly 0.5℃ per decade since the late 1940s), which has caused intense surface melting on its ice shelves and exacerbated their structural weaknesses such as fractures. These destabilising processes are the underlying drivers of ice shelf collapse. But they do not explain why the observed disintegrations were so abrupt.

Our new study suggests that the trigger mechanism was swell waves flexing and working weaknesses at the shelf fronts in the absence of sea ice, to the point where they calved away the shelf fronts in the form of long, thin “sliver-bergs”. The removal of these “keystone blocks” in turn led to the catastrophic breakup of the ice shelf interior, which was weakened by years of melt.

Our research thus underlines the complex and interdependent nature of the various types of Antarctic ice – particularly the important role of sea ice in forming a protective “buffer” for shelf ice. While much of the focus so far has been on the possibility of ice shelves melting from below as the sea beneath them warms, our research suggests an important role for sea ice and ocean swells too.

The edge of an ice shelf off the Antarctic Peninsula, with floating sea ice beyond (to the left in this image).
NASA/Maria Jose Vinas

In July 2017 an immense iceberg broke away from the Larsen C Ice Shelf, just south of Larsen B, prompting fears that it could disintegrate like its neighbours.

Our research suggests that four key factors will determine whether it does: extensive flooding and fracturing across the ice shelf; reduced sea ice coverage offshore; extensive fracturing of the ice shelf front; and calving of sliver-bergs.




Read more:
Don’t worry about the huge Antarctic iceberg – worry about the glaciers behind it


If temperatures continue to rise around the Antarctic, ice shelves will become weaker and sea ice less extensive, which would imply an increased likelihood of future disintegrations.

However, the picture is not that clear-cut, as not all remaining ice shelves are likely to respond in the same way to sea ice loss and swell wave impacts. Their response will also depend on their glaciological characteristics, physical setting, and the degree and nature of surface flooding. Some ice shelves may well be capable of surviving prolonged absences of sea ice.

The ConversationIrrespective of these differences, we need to include sea ice and ocean waves in our models of ice sheet behaviour. This will be a key step towards better forecasting the fate of Antarctica’s remaining ice shelves, and how much our seas will rise in response to projected climate change over coming decades. In parallel, our new findings underline the need to better understand and model the mechanisms responsible for recent sea ice trends around Antarctica, to enable prediction of likely future change in the exposure of ice shelves to ocean swells.

Luke Bennetts, Lecturer in applied mathematics, University of Adelaide; Rob Massom, Leader, Sea Ice Group, Antarctica & the Global System program, Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, and Vernon Squire, Deputy Vice-Chancellor Academic, Professor of Applied Mathematics

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

Senate report: climate change is a clear and present danger to Australia’s security


Matt McDonald, The University of Queensland

The Senate Committee on Foreign Affairs, Defence and Trade yesterday presented its report on the national security implications of climate change.

The report makes several findings and recommendations, noting at the outset that climate change has a range of important security implications, both domestically and internationally.

Tellingly, none of the expert submissions questioned the rationale for this inquiry, nor the claim that climate change challenges Australian national security.




Read more:
US military strategists warn that climate is a ‘catalyst for conflict’



The report concludes that:

the consensus from the evidence (is) that climate change is exacerbating threats and risks to Australia’s national security.

Significantly, it also notes that climate change threatens both state and human security in the Australian context. Here are some of the key security implications.

Sea-level rises and natural disasters are key challenges

The report emphasises the risks posed by rising sea levels and an increase in the frequency and intensity of environmental stress (droughts and floods, for example) and natural disasters such as cyclones. In turn, it notes that these could trigger population movements, with people displaced by extreme weather events or rising seas.

This, the report argues, would have significant implications for the Australian Defence Force (ADF). Humanitarian assistance and disaster relief missions involving the ADF have increased significantly in Australia and our region in recent years. The report predicts that the ADF will face even more pressure to carry out this type of mission in the future.

In its submission, the Department of Defence pointed out that the ADF was not established to provide these roles. The report recommends the creation of a senior leadership position within Defence to plan and manage disaster relief missions both here and abroad.

Australia, and its backyard, are particularly vulnerable

The report notes that Australia and its region are particularly vulnerable to the impacts of climate change.

Australia’s population is largely clustered in coastal areas, and this is also true of the Asian region generally and the Pacific specifically. Pacific island nations – as low-lying and with limited resources for implementing adaptive measures – are acutely vulnerable to sea-level rises. In the Asian region 40 million people were displaced by natural disasters in 2010-11 alone.

The report argues that Australia’s obligation to its neighbours in the region, acknowledged in recent statements on the Pacific, will create significant pressure on Australia and its defence force to manage the implications of climate change. It recommends sending even more aid to the Pacific region to help build climate resilience.

Defence needs to plan ahead

While the report acknowledges Defence efforts, a key finding is the urgent need for Defence to plan for a climate-affected world.

Future deployments associated with disaster relief and population movement, for example, will require urgent Defence planning to ensure personnel have the right training, resources and equipment. Australia’s forces will need to be trained and equipped for the likely ever-increasing number of humanitarian assistance and disaster relief missions in particular.

The report notes that Defence acquisition will need to account for temperature rises in future decades. This includes ensuring that equipment is fit for purpose in the long term. It will need to be able to withstand higher temperatures and potentially to run on different types of fuel.

The committee also recommends that Defence establish its own emissions reduction targets regarding energy use.

While more mundane, the management of existing infrastructure and real estate in the context of climate change, already the subject of Defence assessments, is also crucial. Defence is Australia’s largest land owner, and much of its infrastructure and resources will be exposed to higher temperatures and sea levels. The report recommends that Defence release existing risk assessments of assets’ exposure to climate change.




Read more:
Defence white paper shows Australian forces must safeguard nature too


The issue cuts right across the government

While many of the recommendations are specifically for the Department of Defence, a core theme of the report is the need for a “whole of government” response. Besides adapting to climate change, the government needs to take action to limit the extent of the problem in the first place. This means that all departments, all levels of government, and society as a whole need to work together to reduce greenhouse gas emissions. The need to commit to mitigation efforts is a surprising, but welcome, finding of the consensus report.

As the report points out, to deal with future disruption both here and abroad, Australia will need to build resilient societies that can adapt to change. This poses challenges to urban planning, aid programs and health services as much as to Defence.

The report makes several recommendations aimed at fostering this type of across-the-board response from the government. Among these are the development of a Climate Security White Paper and the creation of a Climate Security role within the Home Affairs portfolio to oversee domestic responses to climate change. In both cases, these are responses to suggestions in expert submissions that existing measures and responses were partial and uncoordinated.

What does all this mean?

Potentially, not much. Recommendations of Senate inquiries are just that, and governments have the right to politely ignore or dismiss them. This is more likely to happen to reports proposed by the opposition or, as in this case, by the Greens.

When the inquiry was announced in mid-2017, the government described it as unnecessary. In its response to the report, Coalition senators generally indicated that they felt existing arrangements were sufficient.




Read more:
Climate change and security: a wake-up call for Australia


It is nevertheless telling that Australia’s Defence establishment – on the face of it a bastion of conservatism – is worried about climate change. In my conversations with Defence officials, two things are apparent.

First, they are increasingly aware of the need to plan ahead to meet the challenges of climate change, including many of those noted above. This reflects the fact that Defence is an area in which long-term planning and threat assessment have always been central.

Second, they are also acutely aware of the toxic politics of climate change in Australia. Given its recent history, even those in Defence who are most convinced of the need to act are concerned about putting their heads above the parapet, so to speak.

The ConversationViewed in this light, it may be that these recommendations – in a consensus report, arising from a Senate inquiry and based on expert advice – provide just the basis for mainstreaming climate consciousness into defence and security planning. In the process, it is possible it’s just this sort of intervention that encourages changes in public debate and broader climate policy orientations. In Australia’s rancorous history of climate politics, stranger things have happened.

Matt McDonald, Associate Professor of International Relations, The University of Queensland

This article was originally published on The Conversation. 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.