02/08/2020

(AU) Unwelcome Sea Change: New Research Finds Coastal Flooding May Cost Up To 20% Of Global Economy By 2100

The Conversation -  | 

Darren Pateman/AAP

Authors
  • Ebru Kirezci, PhD candidate, University of Melbourne
  • Ian Young, Kernot Professor of Engineering, 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.

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.

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.

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.

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.

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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(AU) We Can't Beat The Planet Into Submission. We Can Retreat

Sydney Morning Herald - Elizabeth Farrelly

Author

Elizabeth Farrelly is a Sydney-based columnist, essayist and award winning author with a PhD in architecture.
The floods have gone but the storm images remain, burned onto our collective retina. Up and down the NSW coast, clifftop mansions teeter beside the abyss. Living rooms are torn open, decks and stairs sail vainly into space and concrete foundations dangle like bloodied stumps. It looks so wrong. What was hidden is now exposed, what was support is now a liability, what was enviable, an object of pity. Above all, like some emblem of our times, what was certain is now precarious.

On the beach ... the scene at Wamberal. Credit: James Brickwood

The old beachcomber in the news clip has seen it all. “Like the Bible says,” he notes drily, “build on rock, not sand.” It’s solid practical advice. But this is no simple practical question. The biblical injunction is meant as a parable, a learning opportunity. And so, perhaps, is this. Sure, storms happen. But in a year that has seen unprecedented catastrophes pile up faster than bodies in a cheap crime novel, it may be time to ask: Are we doing something wrong?

In any relationship, you can respond to crisis by trying to change the other, or by trying to change yourself. Usually it’s a power thing. The dominant partner gets to carry on regardless. The subservient one gets to work on themselves. The ironic effect of this dynamic is that the powerful remain unenlightened while the underdogs are forced, however painfully, into wisdom.

Our relationship with the planet is no exception. For centuries, humans have regarded themselves as dominant. We routinely assume that nature should change to accommodate us, not vice versa. But how sure are we that this is still valid? More disturbingly, has our cumulative unwisdom reached such depths we can now no longer even ask the question?

In Australia, the pandemic has killed 189. The Christmas bushfires, if you include the 445 smoke-related deaths, killed more than twice that, plus 11 million hectares of bush and, it is now estimated, almost three billion animals. Both events, like the recent storms, were intensified by a presumption of dominion reminiscent of Tony Abbott’s 2017 climate policy speech which cited our biblical task of “subduing the earth and all its creatures”.

So when the residents of Narrabeen or Wamberal insist on being allowed to build seawalls and revetments to protect their houses against huge surging waves, the question is, should they? When bush communities are determined to rebuild after cataclysmic fire, when the NSW government allows development in the notorious floodplains of the Hawkesbury – envisaging a doubling of that population by 2050 – then proposes to mitigate this flood risk by raising the level of the Warragamba Dam by 12 metres, the same question applies: should they?

The kneejerk response is understandable. We all want to protect ourselves from nature. We all want to protect our property. And we all want to do it, if possible, by changing nature, not ourselves. But is it, on the evidence, wise? Or is it time we all, as a species, pulled our heads in?

The standard terminology puts this as a choice between “armouring” the shore or “planned retreat,” as if our relationship with the oceans were some kind of high-risk military campaign. And perhaps it is but, if so, who do we expect to win? Cnut?

These risks – storm erosion, bushfire and flood - are voluntary at two levels. One, we don’t have to live there. Two, living there may feel as though it’s about loving nature – the sea view, the bush, the river. In fact, though, it can only exacerbate both the power imbalance between us and nature, and the destructive impact on, first, her, then us.

You live in the bush, you end up felling trees to reduce fire danger. You live on a floodplain, you end up building massive dams which, like the Warragamba project, will cost $700 million and threaten indigenous heritage, threatened species and 65 kilometres of wild river. You live on a coastal cliff, you end up wanting to armour the coastline with seawalls and revetments that change local currents, diminish biodiversity and merely shift the erosion to either end of the new wall.

One answer is just to keep building, create a wall without end, armour the entire inhabited coast. But even if that made sense – in a nutty way like Trump’s wall – it doesn’t deal with the fact that just living in such places exacerbates the problem.

When you live close to nature you’re necessarily remote. Not Tibooburra-type remote. Remote as in spread out, incapable of public transit, eternally car-dependent and wasteful of other resources such as roads, sewers and reticulated services. This all hastens climate change, increasing the likelihood, frequency, duration and intensity of fire, flood and storm. It can only get worse.

My purpose here is not to apportion individual blame. Admittedly, I’ve long regarded the Australian coastline as a repository for its ugliest buildings and greediest culture and look with some nostalgia upon New Zealand’s habit (since 1892) of reserving the 20-metre “Queen’s chain” for public health and access.

But this does seem an opportune moment to dwell less on individual rights and more on collective responsibilities. We need to select the greater good for the greater number, and governments prepared to deploy carrot and stick in that direction. Because if we really love nature the best we can do for her is stay right away.

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(AU) Local Community Needs Must Not Be Overlooked As We Adapt To Climate Change

Australian Academy of Science

Retrofitting existing housing and preparing for coastal inundation and storms are just a few of the issues that need to be considered in community-led approaches to climate change adaptation in Australia. Photo: Pixabay

The needs of local communities are at risk of being overlooked as Australia grapples with how to adapt to climate change, according to leading climate change adaptation experts.

The finding follows a series of recent meetings of national leaders hosted by Future Earth Australia, a program of the Australian Academy of Science.

Leaders from across the private and finance sectors, all levels of government, Indigenous communities, land management, social services and universities in all states and territories gathered from 13 to 16 July 2020 for ‘Securing Australia’s Future: Reimagining Climate Adaptation’.

The meetings, which come ahead of a planned National Adaptation Summit in 2021, took stock of Australia’s successes, failures, opportunities and pathways for adapting to a changing climate, with a focus on the role of community-led approaches to adaptation.

Australian National University Emeritus Professor Stephen Dovers said there has long been a national focus on climate science, when what was needed was a shift to also prioritise the social adaptation needs for local communities.

“One example is the need to retrofit housing for variable climates,” said Emeritus Professor Dovers, who is past Chair of the Steering Committee of Future Earth Australia.

“Some local communities feel resilient and well-adapted to looming climate change shocks, but not others. We know that there is a desire among local communities to engage in the planning that is underway to adapt to a future that will see a drastically different climate and environment.”

University of Sydney Professor David Schlosberg said meeting participants found that a forward-looking approach to adaptation requires engaging community values and vulnerabilities, in addition to climate risks, and to be working towards an actionable and tangible agenda that benefits local communities.

“Good adaptation policy requires recognition of both the variety of knowledge types necessary to build adaptation pathways, and the role of different sectors—economic, social, environmental and cultural—in developing and implementing policy and action,” said Professor Schlosberg.

Meeting participants also found:
  • there is a clear role for top down leadership from the Australian Government, in conjunction with well supported and financed local or regional ‘bottom up’ initiatives
  • a strong policy framework is necessary from governments at all levels, to enable the necessary and broader social and community engagement.
Future Earth Australia Director, Dr Tayanah O’Donnell, said adaptation had come into sharp focus in the wake of the unprecedented bushfire season experienced in the summer of 2019–20, and now the COVID-19 pandemic, with both having ongoing, profound impacts on our wellbeing and economy.

“Effective adaptation in Australia acknowledges that increasing bushfire risk is only one dimension of climate change adaptation. Coastal inundation, storms, drought, heatwaves, business viability in a low carbon economy, biosecurity issues, and increased threats to human health, also demand coordinated attention,” Dr O’Donnell said.

“The bushfires and COVID-19 are major disruptions which have presented an unusual opportunity to consider how Australian society can prepare and act to adapt to these complex challenges.

“These roundtables are the start of a longer conversation and national agenda setting strategy being led by Future Earth Australia at the Australian Academy of Science.”

The National Adaptation Summit in 2021 will be hosted by the University of Sydney, Western Sydney University and Future Earth Australia.

Future Earth Australia has opened public submissions on this topic. The consultation, which is open until 30 October 2020, seeks contributions on the successes, failures, opportunities and pathways for adaptation, with a particular interest in learning about community-led approaches taking place.

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