Managed retreat of settlements remains a tough call even as homes flood and coasts erode


Tayanah O’Donnell, Australian National UniversityIt is no joke that New South Wales residents are in the midst of their fourth “one in 100 year” event since January 2020. Much of the Australian east coast continues to experience heavy rainfall, strong winds and abnormally high tides. All will make the current floods worse.

As climate tipping points are reached and the Earth’s systems begin to buckle under the strain, the need for considered adaptation strategies is overwhelmingly clear. One of these strategies is for human settlements to retreat from areas most at risk, whether from floods or bushfires. While something needs to be done to ensure future generations do not suffer catastrophic consequences, managed retreat is a complex tool.

These strategic decisions in the next five to ten years will be challenging. And these decisions really matter: where and how do we build residential areas that can cope with a climate-changed world?




Read more:
Yes, Australia is a land of flooding rains. But climate change could be making it worse


What is managed retreat?

Managed retreat can be defined as “purposeful, co-ordinated movement of people and assets out of harm’s way”. Managed retreat more often refers to the retreat of existing development out of harm’s way. Planned retreat is usually the preferred phrasing for new development that is planned for possible future relocation.

Both planned and managed retreat are focused on the permanent relocation of people and assets, as opposed to the evacuations we are seeing now.

Managed retreat is experiencing a resurgence in scientific literature as the impacts of climate change become increasingly frequent, severe and more obvious. These impacts bring with them a recognition of the need for adaptation even as we urgently reduce greenhouse gas emissions.

Of course, relocating away from high-risk locations is not an entirely new concept. However, managed retreat in response to a changing climate is not only complex, but also has a lot of political baggage. The complexity spans legal, financial, cultural and logistical factors among others: the political baggage seemingly associated with effective climate action in Australia often hinders governments’ abilities to respond properly.

Societies around the world need to grapple with the reality that managed retreat will become a suite of tools to respond to crisis. Insurers will not always be available, and the costs to governments (and therefore to you, the taxpayer) of responding to increasing rates of disasters, irrespective of insurance, will continue to grow exponentially.




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How insurers can get better at responding to natural disasters


Responding to events after the fact is an unsustainable model of adaptation. There is, too, a need to acknowledge settlement needs and historical built environment legacies that have put significant state infrastructure in harm’s way.

Managing difficult trade-offs

We know trade-offs need to be made between what we protect and what we let go in suburban floodplain areas.

Legal machanisms to force people and assets to move can and must be thoughtful. The implementation of managed retreat in urbanised areas faces multiple hurdles. These include:




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


It is wrong to see managed retreat as the panacea for climate risk and development in vulnerable locations. In many cases, once development is in place, it can be more appealing to some to protect an at-risk area rather than work towards managed retreat. Even where managed retreat has been successful, as in the case of the flood-prone township of Grantham, it was not without pain.

There are also other, more basic needs, such as having land available where people can relocate.

Working out highest and best use of land

There are ways that land can be used for its highest and best use at a point in time. For example, tools like easements can enable vulnerable land to be used, subject to event-based or time-based trigger-point thresholds. Once these thresholds are reached, the land is put to some other use. The advantage of these machanisms, especially for new development, is that owners are clear about the risks from the start.

This still leaves us with hard decisions about responding to at-risk current developments. Putting off these hard decisions and leaving them for future decision-makers will result in a huge injustice, because there will be catastrophe as Earth’s tipping points are passed. Development decisions made now will determine the impacts on our children and grandchildren.

Urban development decisions for both new and existing development in this coming decade demand courage and leadership. If we accept that Australian cities will continue to expand and increase in density, then we have some serious questions to ask ourselves. What kind of future do we want?

Some areas should simply not be developed.




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‘Climigration’: when communities must move because of climate change


There is a risk that an over-reliance on managed retreat will over-simplify the challenge of working out what to do about development in at-risk locations. There is a clear need to separate out what to do about current and past developments, and how to approach new developments.

The latter is easy – do not rebuild residential homes in at-risk areas. Governments should repurpose these zones for uses that permit nature-based solutions to the need to adapt to climate change.

Current development is much more complex. In some cases, managed retreat – done thoughtfully and considerately – will be the only option.The Conversation

Tayanah O’Donnell, Honorary Senior Lecturer, Australian National University

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

Worried about Earth’s future? Well, the outlook is worse than even scientists can grasp



Daniel Mariuz/AAP

Corey J. A. Bradshaw, Flinders University; Daniel T. Blumstein, University of California, Los Angeles, and Paul Ehrlich, Stanford University

Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.

The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.

The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.

Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.

Girl in breathing mask attached ot plant in container
Humanity must come to terms with the future we and future generations face.
Shutterstock

Getting to grips with the problem

First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe.

This is largely because academics tend to specialise in one discipline, which means they’re in many cases unfamiliar with the complex system in which planetary-scale problems — and their potential solutions — exist.

What’s more, positive change can be impeded by governments rejecting or ignoring scientific advice, and ignorance of human behaviour by both technical experts and policymakers.

More broadly, the human optimism bias – thinking bad things are more likely to befall others than yourself – means many people underestimate the environmental crisis.

Numbers don’t lie

Our research also reviewed the current state of the global environment. While the problems are too numerous to cover in full here, they include:

  • a halving of vegetation biomass since the agricultural revolution around 11,000 years ago. Overall, humans have altered almost two-thirds of Earth’s land surface

  • About 1,300 documented species extinctions over the past 500 years, with many more unrecorded. More broadly, population sizes of animal species have declined by more than two-thirds over the last 50 years, suggesting more extinctions are imminent




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What is a ‘mass extinction’ and are we in one now?


  • about one million plant and animal species globally threatened with extinction. The combined mass of wild mammals today is less than one-quarter the mass before humans started colonising the planet. Insects are also disappearing rapidly in many regions

  • 85% of the global wetland area lost in 300 years, and more than 65% of the oceans compromised to some extent by humans

  • a halving of live coral cover on reefs in less than 200 years and a decrease in seagrass extent by 10% per decade over the last century. About 40% of kelp forests have declined in abundance, and the number of large predatory fishes is fewer than 30% of that a century ago.

State of the Earth's environment
Major environmental-change categories expressed as a percentage relative to intact baseline. Red indicates percentage of category damaged, lost or otherwise affected; blue indicates percentage intact, remaining or unaffected.
Frontiers in Conservation Science

A bad situation only getting worse

The human population has reached 7.8 billion – double what it was in 1970 – and is set to reach about 10 billion by 2050. More people equals more food insecurity, soil degradation, plastic pollution and biodiversity loss.

High population densities make pandemics more likely. They also drive overcrowding, unemployment, housing shortages and deteriorating infrastructure, and can spark conflicts leading to insurrections, terrorism, and war.




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Climate explained: why we need to focus on increased consumption as much as population growth


Essentially, humans have created an ecological Ponzi scheme. Consumption, as a percentage of Earth’s capacity to regenerate itself, has grown from 73% in 1960 to more than 170% today.

High-consuming countries like Australia, Canada and the US use multiple units of fossil-fuel energy to produce one energy unit of food. Energy consumption will therefore increase in the near future, especially as the global middle class grows.

Then there’s climate change. Humanity has already exceeded global warming of 1°C this century, and will almost assuredly exceed 1.5 °C between 2030 and 2052. Even if all nations party to the Paris Agreement ratify their commitments, warming would still reach between 2.6°C and 3.1°C by 2100.

people walking on a crowded street
The human population is set to reach 10 billion by 2050.
Shutterstock

The danger of political impotence

Our paper found global policymaking falls far short of addressing these existential threats. Securing Earth’s future requires prudent, long-term decisions. However this is impeded by short-term interests, and an economic system that concentrates wealth among a few individuals.

Right-wing populist leaders with anti-environment agendas are on the rise, and in many countries, environmental protest groups have been labelled “terrorists”. Environmentalism has become weaponised as a political ideology, rather than properly viewed as a universal mode of self-preservation.

Financed disinformation campaigns against climate action and forest protection, for example, protect short-term profits and claim meaningful environmental action is too costly – while ignoring the broader cost of not acting. By and large, it appears unlikely business investments will shift at sufficient scale to avoid environmental catastrophe.

Changing course

Fundamental change is required to avoid this ghastly future. Specifically, we and many others suggest:

  • abolishing the goal of perpetual economic growth

  • revealing the true cost of products and activities by forcing those who damage the environment to pay for its restoration, such as through carbon pricing

  • rapidly eliminating fossil fuels

  • regulating markets by curtailing monopolisation and limiting undue corporate influence on policy

  • reigning in corporate lobbying of political representatives

  • educating and empowering women across the globe, including giving them control over family planning.

A coal plant
The true cost of environmental damage should be borne by those responsible.
Shutterstock

Don’t look away

Many organisations and individuals are devoted to achieving these aims. However their messages have not sufficiently penetrated the policy, economic, political and academic realms to make much difference.

Failing to acknowledge the magnitude and gravity of problems facing humanity is not just naïve, it’s dangerous. And science has a big role to play here.

Scientists must not sugarcoat the overwhelming challenges ahead. Instead, they should tell it like it is. Anything else is at best misleading, and at worst potentially lethal for the human enterprise.




Read more:
Mass extinctions and climate change: why the speed of rising greenhouse gases matters


The Conversation


Corey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University; Daniel T. Blumstein, Professor in the Department of Ecology and Evolutionary Biology and the Institute of the Environment and Sustainability, University of California, Los Angeles, and Paul Ehrlich, President, Center for Conservation Biology, Bing Professor of Population Studies, Stanford University

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

Pacific Islands must stop relying on foreign aid to adapt to climate change, because the money won’t last



Patrick Nunn, Author provided

Patrick D. Nunn, University of the Sunshine Coast and Roselyn Kumar, University of the Sunshine Coast

The storm of climate change is approaching the Pacific Islands. Its likely impact has been hugely amplified by decades of global inertia and the islands’ growing dependency on developed countries.

The background to this situation is straightforward. For a long time, richer developed countries have been underwriting the costs of climate change in poorer developing countries, leaving them reliant on Western solutions to their climate-related issues.




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Their fate isn’t sealed: Pacific nations can survive climate change – if locals take the lead


But as rising sea water continues to encroach on these low-lying Pacific islands, inundating infrastructure and even cemeteries, it’s clear almost every externally sponsored attempt at climate adaptation has failed here.

And as the costs of adaptation in richer countries escalate, this funding support to developing countries will likely taper out in future.

We’ve researched climate change adaptation in the Pacific for more than 50 years. We argue this trend is not merely unsustainable, but also dangerous. Pacific Island nations must start drawing from traditional knowledge to adapt to climate change, rather than continue to rely on foreign funds.

The ruins of a sea wall on a coastline.
High waves destroyed this sea wall on Majuro Atoll (Marshall Islands).
Patrick Nunn, Author provided

Western solutions don’t always work

On a global scale, climate adaptation strategies have largely been either ineffective or unsustainable.

This is especially the case in non-Western contexts, where Western science continues to be privileged. In the Pacific Islands, this is often because these Western strategies invariably subordinate, even ignore, funding recipients’ culturally grounded worldviews.

A good example is the desire of foreign donors to build hard structures, such as sea walls, to protect eroding coasts. This is the preferred strategy in richer nations.

However it does not embrace nature-based solutions such as replanting coastal mangroves, which can be more readily sustained in poorer contexts.

A likely scenario

The availability of external financial assistance means developing countries have become more dependent on their richer counterparts for climate change adaptation.

For example, between 2016 and 2019, Australia provided A$300 million to help Pacific Island nations adapt to climate change, committing to a further $500 million to 2025. This left little need or incentive for these countries to fund their own adaptation needs.




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But imagine this climate change scenario. Ten years from now, unprecedented rainfall is dumped on Australia’s east coast over a prolonged period. Several cities become flooded and remain so for weeks.

In the aftermath, the Australian government scrambles to make recently flooded areas liveable once more. They build a series of massive coastal dikes – structures to prevent the rising sea from flooding populated areas.

The cost is exorbitant and unanticipated – like COVID-19 – so the government will look for ways to shuffle money around. This may well include reducing financial aid for climate change adaptation in poorer countries.

Plunging international aid

Economic modelling shows nations will incur massive costs this century to adapt to climate change within their own borders. So it’s almost inevitable wealthier countries will rethink the extent of their assistance to the developing world.

A chart showing the projected adaptation aid to the Pacific Islands.
Recent and projected Australian GDP and adaptation aid to Pacific Island.
countries.

Patrick Nunn, Author provided

In fact, even before the pandemic, Australia’s foreign aid budget was projected to decrease in real terms by nearly 12% from 2020 to 2023.

These factors do not bode well for developing countries, which will be facing higher climate adaptation costs and dwindling foreign aid assistance.




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Australia is spending less on diplomacy than ever before – and its influence is suffering as a result


Building autonomy with ‘cashless adaptation’

Leaders of developing countries should anticipate this situation now, and reverse their growing dependence on outside assistance.

For example, rural communities in regions like the Pacific Islands could revive their use of “cashless adaptation”. This means developing ways of adapting livelihoods to climate change that cost nothing.

These methods include the intentional planting of surplus crops, the use of traditional methods of food preservation and water storage, the use of free locally-available materials and labour for constructing sea defences. And it perhaps even includes the recognition that living along coastal fringes exposes you unnecessarily to weather-related change.

Prior to globalisation, this is how it was for decades, even centuries, in places like the rural Pacific islands. Then, adaptation to a changing environment was sustained by cooperation with one another and the use of freely available materials, not with cash.

Researchers have also argued for such “looking forward to the past” strategies regarding Hawaii’s climate adaptation.

And research from last year in Fiji showed more rural communities still have and use a stock of traditional methods for anticipating and withstanding disasters, such as flood and drought.




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We can take this argument further. Perhaps it’s time for Pacific Island nations to rediscover traditional medicines, at least for primary health care, to supplement western medicine.

Greater production and consumption of locally grown foods, over imported foods, is also an important and valuable transformation.

The future of the developing world

A hut with a large pointed roof, built with local materials.
Dirak faluw (‘men’s house’) at Wanyaan Village on Yap (Micronesia) was.
constructed by community labour using local-available materials.

Roselyn Kumar, Author provided

The need for nations to adapt to unanticipated phenomena like climate change and COVID-19 encourages de-globalisation – including that countries depend less on cross-border aid and economic activity. So it seems inevitable that under current global circumstances, smaller economies will be forced to become more efficient and self-reliant.

Restoring traditional adaptation strategies would not only drive effective and sustainable climate change adaptation, but also would restore residents’ beliefs in their own time-honoured ways of coping with environmental shocks.

This not only means finding ways to reduce costs through cashless adaptation, but also to explore radical ways of reducing dependency and increasing autonomy. An appeal to past practice, and traditional ways of coping, is well worth considering.The Conversation

Patrick D. Nunn, Professor of Geography, School of Social Sciences, University of the Sunshine Coast and Roselyn Kumar, , University of the Sunshine Coast

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

Unwelcome sea change: new research finds coastal flooding may cost up to 20% of global economy by 2100



Darren Pateman/AAP

Ebru Kirezci, University of Melbourne and Ian Young, University of Melbourne

Over the past two weeks, storms pummelling the New South Wales coast have left beachfront homes at Wamberal on the verge of collapse. It’s stark proof of the risks climate change and sea level rise pose to coastal areas.

Our new research published today puts a potential price on the future destruction. Coastal land affected by flooding – including high tides and extreme seas – could increase by 48% by 2100. Exposed human population and assets are also estimated to increase by about half in that time.

Under a scenario of high greenhouse gas emissions and no flood defences, the cost of asset damage could equate up to 20% of the global economy in 2100.

Without a dramatic reduction in greenhouse gas emissions, or a huge investment in sea walls and other structures, it’s clear coastal erosion will devastate the global economy and much of the world’s population.

In Australia, we predict the areas to be worst-affected by flooding are concentrated in the north and northeast of the continent, including around Darwin and Townsville.

Man cleans up after Townsville flood
A clean-up after flooding last year in Townsville, an Australian city highly exposed to future sea level rise.
Dan Peled/AAP

Our exposed coasts

Sea levels are rising at an increasing rate for two main reasons. As global temperatures increase, glaciers and ice sheets melt. At the same time, the oceans absorb heat from the atmosphere, causing the water to expand. Seas are rising by about 3-4 millimetres a year and the rate is expected to accelerate.

These higher sea levels, combined with potentially more extreme weather under climate change, will bring damaging flooding to coasts. Our study set out to determine the extent of flooding, how many people this would affect and the economic damage caused.




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


We combined data on global sea levels during extreme storms with projections of sea level rises under moderate and high-end greenhouse gas emission scenarios. We used the data to model extreme sea levels that may occur by 2100.

We combined this model with topographic data (showing the shape and features of the land surface) to identify areas at risk of coastal flooding. We then estimated the population and assets at risk from flooding, using data on global population distribution and gross domestic product in affected areas.

Homes at Collaroy in Sydney damaged by storm surge
Many coastal homes, such as these at Sydney’s Collaroy beach, are exposed to storm surge damage.
David Moir/AAP

Alarming findings

So what did we find? One outstanding result is that due to sea level rise, what is now considered a once-a-century extreme sea level event could occur as frequently as every ten years or less for most coastal locations.

Under a scenario of high greenhouse gas emissions and assuming no flood defences, such as sea walls, we estimate that the land area affected by coastal flooding could increase by 48% by 2100.




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This could mean by 2100, the global population exposed to coastal flooding could be up to 287 million (4.1% of the world’s population).

Under the same scenario, coastal assets such as buildings, roads and other infrastructure worth up to US$14.2 trillion (A$19.82 trillion) could be threatened by flooding.

This equates to 20% of global gross domestic product (GDP) in 2100. However this worst-case scenario assumes no flood defences are in place globally. This is unlikely, as sea walls and other structures have already been built in some coastal locations.

In Australia, areas where coastal flooding might be extensive include the Northern Territory, and the northern coasts of Queensland and Western Australia.

Elsewhere, extensive coastal flooding is also projected in:
– southeast China
– Bangladesh, and India’s states of West Bengal and Gujurat
– US states of North Carolina, Virginia and Maryland
– northwest Europe including the UK, northern France and northern Germany.

A woman struggles through floodwaters in Bangladesh
Bangladesh is among the nations most exposed to coastal flooding this century.
SOPA

Keeping the sea at bay

Our large-scale global analysis has some limitations, and our results at specific locations might differ from local findings. But we believe our analysis provides a basis for more detailed investigations of climate change impacts at the most vulnerable coastal locations.

It’s clear the world must ramp up measures to adapt to coastal flooding and offset associated social and economic impacts.

This adaptation will include building and enhancing coastal protection structures such as dykes or sea walls. It will also include coastal retreat – allowing low-lying coastal areas to flood, and moving human development inland to safer ground. It will also require deploying coastal warning systems and increasing flooding preparedness of coastal communities. This will require careful long-term planning.

All this might seem challenging – and it is. But done correctly, coastal adaptation can protect hundreds of millions of people and save the global economy billions of dollars this century.




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The Conversation


Ebru Kirezci, PhD candidate, University of Melbourne and Ian Young, Kernot Professor of Engineering, University of Melbourne

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

Their fate isn’t sealed: Pacific nations can survive climate change – if locals take the lead


Rachel Clissold, The University of Queensland; Annah Piggott-McKellar, University of Melbourne; Karen E McNamara, The University of Queensland; Patrick D. Nunn, University of the Sunshine Coast; Roselyn Kumar, University of the Sunshine Coast, and Ross Westoby, Griffith University

They contribute only 0.03% of global carbon emissions, but small island developing states, particularly in the Pacific, are at extreme risk to the threats of climate change.

Our study, published today in the journal Nature Climate Change, provides the first mega-assessment on the progress of community-based adaptation in four Pacific Island countries: the Federated States of Micronesia, Fiji, Kiribati and Vanuatu.




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Pacific Island nation communities have always been resilient, surviving on islands in the middle of oceans for more than 3,000 years. We can learn a lot from their adaptation methods, but climate change is an unprecedented challenge.

Effective adaptation is critical for ensuring Pacific Islanders continue living fulfilling lives in their homelands. For Australia’s part, we must ensure we’re supporting their diverse abilities and aspirations.

Short-sighted adaptation responses

Climate change brings wild, fierce and potentially more frequent hazards. In recent months, Cyclone Harold tore a strip through multiple Pacific countries, killing dozens of people, levelling homes and cutting communication lines. It may take Vanuatu a year to recover.

Expert commentary from 2019 highlighted that many adaptation responses in the Pacific have been short-sighted and, at times, even inadequate. The remains of failed seawalls, for example, litter the shorelines of many island countries, yet remain a popular adaptive solution. We cannot afford another few decades of this.




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International climate aid commitments from rich western countries barely scratch the surface of what’s needed, yet it’s likely funding will dry up for regions like the Pacific as governments scramble together money for their own countries’ escalating adaptation costs.

This includes Australia, that has long been, and continues to be, the leading donor to the region. Our government contributed about 40% of total aid between 2011 and 2017 and yet refuses to take meaningful action on climate change.

Understanding what successful adaptation should look like in developing island states is urgent to ensure existing funding creates the best outcomes.

Success stories

Our findings are based on community perspectives. We documented what factors lead to success and failure and what “best practice” might really look like.

We asked locals about the appropriateness, effectiveness, equity, impact and sustainability of the adaptation initiatives, and used this feedback to determine their success.




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The results were mixed. While our success stories illustrate what “best practice” involves, issues still emerged.

Our top two success stories centred on community efforts to protect local marine ecosystems in the Federated States of Micronesia and Vanuatu. Nearby communities rely on these ecosystems for food, income and for supporting cultural practice.

One initiative focused on establishing a marine park with protected areas while the other involved training in crown-of-thorns starfish control. As one person told us:

we think it’s great […] we see the results and know it’s our responsibility.

Initiatives that focus on both the community and the ecosystem support self-sufficiency, so the community can maintain the initiatives even after external bodies leave and funding ceases.

Pele Island, Vanuatu. Can you see coral in the water? The community initiative was aiming to protect this coral ecosystem from crown-of-thorns starfish.
Karen McNamara, Author provided

In these two instances, the “community” was expanded to the whole island and to anyone who utilised local ecosystems, such as fishers and tourism operators.

Through this, benefits were accessible to all: “all men, all women, all pikinini [children],” we were told.

Standing the test of time

In Vanuatu, the locals deemed two initiatives on raising climate change awareness as successful, with new scientific knowledge complementing traditional knowledge.

And in the Federated States of Micronesia, locals rated two initiatives on providing tanks for water security highly. This initiative addressed the communities’ primary concerns around clean water, but also had impact beyond merely climate-related vulnerabilities.

This was a relatively simple solution that also improved financial security and minimised pollution because people no longer needed to travel to other islands to buy bottled water.

Aniwa, Vanuatu. A communal building in the village has a noticeboard, put up as part of one of the climate-awareness raising initiatives.
Rachel Clissold, Author provided

But even among success stories, standing the test of time was a challenge.

For example, while these water security initiatives boosted short-term coping capacities, they weren’t flexible for coping with likely future changes in drought severity and duration.




Read more:
Pacific islands are not passive victims of climate change, but will need help


Adaptation needs better future planning, especially by those who understand local processes best: the community.

Listening to locals

For an adaptation initiative to be successful, our research found it must include:

  1. local approval and ownership

  2. shared access and benefit for community members

  3. integration of local context and livelihoods

  4. big picture thinking and forward planning.

To achieve these, practitioners and researchers need to rethink community-based adaptation as more than being simply “based” in communities where ideas are imposed on them, but rather as something they wholly lead.

Communities must acknowledge and build on their strengths and traditional values, and drive their own adaptation agendas – even if this means questioning well-intentioned foreign agencies.

Being good neighbours

Pacific Islands are not passive, helpless victims, but they’ll still need help to deal with climate change.

Pacific Island leaders need more than kind words from Australian leaders.




Read more:
Pacific Island nations will no longer stand for Australia’s inaction on climate change


Last year, Fijian prime minister, Frank Bainimarama, took to Facebook to remind Australia:

by working closely together, we can turn the tides in this battle – the most urgent crisis facing not only the Pacific, but the world.

Together, we can ensure that we are earthly stewards of Fiji, Australia, and the ocean that unites us.

Together, we can pass down a planet that our children are proud to inherit.The Conversation

Rachel Clissold, Researcher, The University of Queensland; Annah Piggott-McKellar, Postdoctoral research fellow, University of Melbourne; Karen E McNamara, Associate professor, The University of Queensland; Patrick D. Nunn, Professor of Geography, School of Social Sciences, University of the Sunshine Coast; Roselyn Kumar, , University of the Sunshine Coast, and Ross Westoby, Research Fellow, Griffith University

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

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



Shutterstock

John Church, UNSW

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

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




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

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

Losing sand in coastal erosion

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

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

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

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

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

Projections for the worst-case scenario

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

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




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


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

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

What happens if we mitigate our emissions

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

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

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

Why coastal erosion is hard to predict

Projecting sea-level rise and resulting beach erosion are particularly difficult, as both depend on many factors.

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

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




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


The implications

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

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

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

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

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

Climate explained: why coastal floods are becoming more frequent as seas rise



As sea levels rise, it becomes easier for ocean waves to spill further onto land.
from http://www.shutterstock.com, CC BY-ND

James Renwick, Victoria University of Wellington


CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

I saw an article claiming that “king tides” will increase in frequency as sea level rises. I am sceptical. What is the physics behind such a claim and how is it related to climate change? My understanding is that a king tide is a purely tidal effect, related to Moon, Sun and Earth axis tilt, and is quite different from a storm surge.

This is a good question, and you are right about the tides themselves. The twice-daily tides are caused by the gravitational forces of the Moon and the Sun, and the rotation of the Earth, none of which is changing.

A “king” tide occurs around the time when the Moon is at its closest to the Earth and Earth is at its closest to the Sun, and the combined gravitational effects are strongest. They are the highest of the high tides we experience.

But the article you refer to was not really talking about king tides. It was discussing coastal inundation events.




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


When tides, storms and sea levels combine

During a king tide, houses and roads close to the coast can be flooded. The article referred to the effects of coastal flooding generally, using “king tide” as a shorthand expression. We know that king tides are not increasing in frequency, but we also know that coastal flooding and coastal erosion events are happening more frequently.

As sea levels rise, it becomes easier for ocean waves to penetrate on to the shore. The biggest problem arises when storms combine with a high tide, and ride on top of higher sea levels.

The low air pressure near the centre of a storm pulls up the sea surface below. Then, onshore winds can pile water up against the coast, allowing waves to run further inshore. Add a high or king tide and the waves can come yet further inshore. Add a bit of sea level rise and the waves penetrate even further.

The background sea level rise has been only 20cm around New Zealand’s coasts so far, but even that makes a noticeable difference. An apparently small rise in overall sea level allows waves generated by a storm to come on shore much more easily. Coastal engineers use the rule of thumb that every 10cm of sea level rise increases the frequency of a given coastal flood by a factor of three.

This means that 10cm of sea level rise will turn a one-in-100-year coastal flood into a one-in-33-year event. With another 10cm of sea level rise, it becomes a one-in-11-year event, and so on.

Retreating from the coast

The occurrence rates change so quickly because in most places, beaches are fairly flat. A 10cm rise in sea levels might translate to 30 or 40 metres of inland movement of the high tide line, depending on the slope of the beach. So when the tide is high and the waves are rolling in, the sea can come inland tens of metres further than it used to, unless something like a coastal cliff or a sea wall blocks its way.

The worry is that beaches are likely to remain fairly flat, so anything within 40 metres of the current high tide mark is likely to be eroded away as storms occur and we experience another 10cm of sea level rise. If a road or a house is on an erodible coast (such as a line of sand dunes), it is not the height above sea level that matters but the distance from the high tide mark.

Another 30cm of sea level rise is already “baked in”, guaranteed over the next 40 years, regardless of what happens with greenhouse gas emissions and action on climate change. By the end of the century, at least another 20cm on top of that is virtually certain.




Read more:
Our shameful legacy: just 15 years’ worth of emissions will raise sea level in 2300


The 30cm rise multiplies the chances of coastal flooding by a factor of around 27 (3x3x3) and 50cm by the end of the century increases coastal flooding frequency by a factor of around 250. That would make the one-in-100-year coastal flood likely every few months, and roads, properties and all kinds of built infrastructure within 200 metres of the current coastline would be vulnerable to inundation and damage.

These are round numbers, and local changes depend on coastal shape and composition, but they give the sense of how quickly things can change. Already, key roads in Auckland (such as Tamaki Drive) are inundated when storms combine with high tides. Such events are set to become much more common as sea levels continue to rise, to the point where they will become part of the background state of the coastal zone.

To ensure cities such as Auckland (and others around the world) are resilient to such challenges, we’ll need to retreat from the coast where possible (move dwellings and roads inland) and to build coastal defences where that makes sense. The coast is coming inland, and we need to move with it.The Conversation

James Renwick, Professor, Physical Geography (climate science), Victoria University of Wellington

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

Our shameful legacy: just 15 years’ worth of emissions will raise sea level in 2300



Indonesian residents wade through flood water near the Ciliwung river in Jakarta in February 2018. Our emissions in the near future will lock in sea level rise over centuries.

Bill Hare, Potsdam Institute for Climate Impact Research

Greenhouse gas emissions released over the first 15 years of the Paris Agreement would alone lock in 20cm of sea-level rise in centuries to come, according to new research published today.

The paper shows that what the world pumps into the atmosphere today has grave long-term consequences. It underscores the need for governments to dramatically scale up their emission reduction ambition – including Australia, where climate action efforts have been paltry.

The report is the first to quantify the sea-level rise contribution of human-caused greenhouse gas emissions that countries would release if they met their current Paris pledges.

The 20cm sea-level rise is equal to that observed over the entire 20th century. It would comprise one-fifth of the 1m sea level rise projected for 2300.

A satellite image showing meltwater ponding in northwest Greenland near the ice sheet’s edge.
EPA/NASA EARTH OBSERVATORY

The picture is bleak

The study was led by researchers at Climate Analytics and the Potsdam Institute for Climate Impact Research, and was published today by the Proceedings of the National Academy of Sciences. It estimated the sea level rise to be locked in by 2300 due to greenhouse gas emissions between 2016 and 2030 – the first pledge period on the Paris treaty.

During those 15 years, emissions would cause sea levels to rise by 20cm by 2300. Even if the world cut all emissions to zero in 2030, sea levels would still rise in 2300. These estimates do not take into account the irreversible melting of parts of the Antarctic ice sheet.




Read more:
The good, the bad and the ugly: the nations leading and failing on climate action


The researchers found that just over half of the sea level rise can be attributed to the top five polluters: China, the US, the European Union, India and Russia.

The emissions of these jurisdictions under will cause seas to rise by 12cm by 2300, the study shows.

The important takeaway message is that what the world does now will take years to play out – it is a stark warning of the long-term consequences of our actions.

Severe storms at Collaroy on Sydney’s northern beaches caused major damage to beachfront homes.
UNSW WATER RESEARCH

It’s worse than we thought

Last week a separate paper in Nature Communications showed sea-level rise could affect many more people than previously thought. The authors produced a new digital elevation model that showed many of the world’s coastlines are far lower than estimated with standard methods.

In low-lying parts of coastal Australia, for example, the previous data has
overestimated elevation by an average of 2.5m.

Their projections for the millions of people to be affected by sea-level rise are frightening. Within three decades, rising sea levels could push chronic floods higher than land currently home to 300 million people. By 2100, areas home to 200 million people could be permanently below the high tide line.

But what of Australia, girt by sea?

Australia is a coastal nation: the vast majority of our population lives within 50km of the sea, and will be heavily impacted by sea-level rise. Already, we’re seeing severe coastal erosion and inundation during king tides – and that’s without factoring in the impact of storm surges.

Clearly the world needs strong climate action to reduce greenhouse gas emissions as fast as possible. The Intergovernmental Panel on Climate Change has said emissions must be lowered to 45% below 2010 levels by 2030 and to zero by mid-century.

We also know that unless the world achieves this, we will not just lose parts of our coasts but also iconic ecosystems such as the Great Barrier Reef.



Australia’s emissions comprise a relatively small proportion of the global total – 1.4% or around 5% if we count coal and liquified natural gas exports. However, we have a much bigger diplomatic and political influence on the international stage.




Read more:
Australia’s hidden opportunity to cut carbon emissions, and make money in the process


Australia should use its position to push for urgent action internationally. But the federal government’s appalling record on emissions reduction – despite its efforts to claim otherwise – puts us in a very weak position on the global stage. We cannot point fingers at other nations while our emissions rise and we sell as much coal as possible to the rest of the world, while also burning as much as we can.



All the while, Australia is becoming the poster child for extreme sea-level events, more frequent and severe bushfires and other devastating climate impacts.

Governments, including Australia’s, must put forward much stronger 2030 emission reduction pledges by 2020. There should seek to decarbonise at a pace in line with the Paris Agreement’s 1.5°C temperature goal.

Otherwise, our emissions today will cause seas to rise far into the future. This process cannot be reversed – it will be our legacy to future generations.


Climate Analytics researcher Alexander Nauels was lead author of the study.The Conversation

Bill Hare, Director, Climate Analytics, Adjunct Professor, Murdoch University (Perth), Visiting scientist, Potsdam Institute for Climate Impact Research

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