Victoria’s wild storms show how easily disasters can threaten our water supply


Ian Wright, Western Sydney UniversityThe wild storms that recently raged across eastern Victoria caused major property and environmental damage, and loss of lives. They’ve also triggered serious water contamination incidents.

Yarra Valley Water issued an urgent health warning to not to drink tap water — not even if it’s boiled — in three affected suburbs: Kalista, Sherbrooke and The Patch.

So what caused this incident? Yarra Valley Water says the severe weather led to an equipment failure, with potentially unsafe water entering the drinking water system.

I spoke to the water authority about the nature of the contamination, and they did not provide any more detail. But based on my three decades of experience in the water industry, I can offer some insight into how disasters create contamination crises, and Australia’s vulnerabilities.

Does boiling water help?

Despite recent health warnings, it’s worth pointing out that Australia’s water supply is generally safe and reliable, with few exceptions. Still, this is hardly the first time disasters have disrupted water supply, whether from droughts, storms and floods, or bushfires.

For example, the Black Summer bushfires damaged water supply infrastructure for many communities, such as in Eden and Boydtown on the south coast of New South Wales. The Bega Valley Shire Council issued a boil water notice, as the loss of electricity stopped chlorinating the water supply, which is needed to maintain safe disinfection levels.

Boil water alerts indicate harmful pathogens may be present in the water, and you should boil water for at least one minute to kill them.




Read more:
Better boil ya billy: when Australian water goes bad


In inland and remote communities, drinking water contamination can be more common and very difficult to resolve.

For example, many remote Western Australian towns have chronic water quality problems, with drinking water often failing to meet Australian standards. And in 2015, the WA Auditor General reported the water in many Indigenous communities contains harmful contaminants, such as uranium and nitrates.

The source of this contamination is often naturally occurring chemical compounds in the local geology of ground water supplies.

One of the biggest contamination incidents in Australia occurred in August and September in 1998. A series of extreme wet weather events after a long drought triggered the contamination of Sydney’s drinking water with high levels of protozoan parasites, which can cause serious diseases such as gastroenteritis or cryptosporidiosis. It resulted in boil water alerts across much of the Sydney metropolitan area.

But what makes this latest incident in Victoria so concerning is that authorities have warned even boiling will not reduce contamination. This suggests contamination may be due to the presence of a harmful chemical, or high levels of sediment particles.

Sediment in water — measured as “turbidity” — can be hazardous because these particles can hold other contaminants, or even shield pathogens from disinfection.

Yarra Valley Water’s advice for the affected suburbs is to avoid using water in any cooking, making ice, brushing teeth or mixing baby formula, and for people to take care not to ingest water in the shower or bath. Emergency drinking water is being supplied by Yarra Valley Water in some locations.

So why do disasters threaten our drinking water?

This latest incident is another reminder that our drinking water is vulnerable to disruption from extreme weather.

This is almost certain to continue, and worsen, as the the Bureau of Meterology’s State of the Climate 2020 report predicts more extreme weather — including drought, heatwaves, bushfires, storms, and floods — in Australia’s future.

As these disasters become more frequent and extreme under climate change, impacts on water supplies across Australia are likely to become more destructive.

A good example of how this can unfold was the impact on Canberra’s water supply after the destructive 2003 bushfires.

Fire burned most of the region’s Cotter River catchments, which hold three dams. After fires went out, massive storms eroded the weakened ground, and washed ash, soil and organic debris into the storage reservoirs. It took years for the water supply system to fully recover.

Physical damage to water infrastructure is also a big risk, as modern water supplies are large and complex. For example, a fallen tree could break open the roof of a sealed water storage tank, exposing water to the elements.

Interruptions of electrical supplies after extreme weather are also common, leading to failures of water supply technology. This, for instance, could stop a water pump from operating, or break down the telemetry system which helps control operations.

As difficult as these hits to Australia’s water security are, and will be in future, it’s even more problematic in the developing world, which may not have the resources to recover.

How can we withstand these challenges?

To maintain optimal water quality, we must protect the integrity of water catchments — areas where water is collected by the natural landscape.

For example, damaging logging operations along steep slopes in Melbourne’s biggest water catchment threatens to pollute the city’s drinking water because it increases the risk of erosion during storms.




Read more:
Logging must stop in Melbourne’s biggest water supply catchment


There’s also merit in Australian cities investing in advanced treatment of wastewater for reuse, rather than build infrequently used desalination plants for when there’s drought.

Australia could follow the US state of California which has ambitious targets to reuse more than 60% of its sewage effluent.

And it’s completely safe — Australia has developed guidelines to ensure recycled water is treated and managed to operate reliably and protect public health.




Read more:
Why does some tap water taste weird?


If you’re concerned about water quality from the tap and haven’t received any alerts, you might just not like its taste. If in doubt, contact you local water supplier.


This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. It is supported by a philanthropic grant from the Paul Ramsay foundation. You can read the rest of the stories here.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University

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

Three weeks without electricity? That’s the reality facing thousands of Victorians, and it will happen again


James Ross/AAP

Anthony Richardson, RMIT UniversityLast week’s storm system wreaked havoc across Victoria. Some 220,000 households and businesses lost power, and residents in the hills on Melbourne’s fringe were warned yesterday it might not be restored for three weeks.

The extreme weather severely damaged the poles and powerlines that distribute electricity, particularly in the Mount Dandenong area. Senior AusNet official Steven Neave said of the region this week, “we basically have no network left, the overhead infrastructure is pretty much gone. It requires a complete rebuild”.

That leaves about 3,000 customers without electricity for weeks, in the heart of winter. The loss of power also cut mobile phone and internet services and reportedly allowed untreated water to enter drinking supplies.

So, could this disaster have been avoided? And under climate change, how can we prepare for more events like this?

fallen tree on powerlines
Fallen trees brought down power lines across Melbourne.
Daniel Pockett/AAP

An uncertain future

The Mount Dandenong area is heavily forested, and the chance of above-ground power infrastructure being hit by falling trees is obviously high.

Without electricity, people cannot turn on lights, refrigerate food or medications, cook on electric stoves or use electric heaters. Electronic banking, schooling and business activities are also badly disrupted. For vulnerable residents, in particular, the implications are profound.

Such disruptions are hard to avoid, at least while the electricity network is above ground. Good management, however, can prevent some trees coming down in storms.

The more pertinent question is: how can we prepare for such an event in the future?

Scientists warn such extreme weather will increase in both frequency and severity as climate change accelerates. The Australian Energy Market Operator is acutely aware of this, warning climate change poses “material risks to individual assets, the integrated energy system, and society”.

However, it’s challenging to predict exactly how future heatwaves, storms, bushfires and floods will affect the power network. As AEMO notes, many climate models related to storms and cyclones involve an element of unpredictability. So, plans to make the electricity system more resilient must address this uncertainty.

As researchers have noted, there is no “one future” to prepare for – we must be ready for many potential eventualities.




Read more:
Victoria’s wild storms show how easily disasters can threaten our water supply


tree fallen on house
Under climate change, extreme weather is predicted to become more severe.
Daniel Pockett/AAP

Yallourn – the bigger problem?

Meanwhile, in Victoria’s LaTrobe Valley, a situation at the Yallourn coal-fired power station which may have even greater consequences for electricity supplies.

A coal mine wall adjacent to the station is at risk of collapse after flooding in the Morwell River caused it to crack. If the wall is breached and the mine is flooded, as happened in 2012, there will be no coal to power the station and almost a quarter of Victoria’s power supply could be out for months.

Victoria’s energy needs are increasingly supplied by renewables. However, losing Yallourn’s generation capacity would reduce the capacity of the network to adapt to other possible disruptions.

If further disruptions seem unlikely, it’s worth noting the Callide Power Station in Queensland is still operating at reduced capacity after a recent fire.




Read more:
An act of God, or just bad management? Why trees fall and how to prevent it


power plant with chimneys
A wall adjacent to the Yallourn power plant may collapse.
Julian Smith/AAP

Look beyond the immediate crisis

The Victorian government has offered up to A$1,680 per week, for up to three weeks, to help families without power buy supplies and find alternative accommodation.

Welfare groups say the assistance could be improved. They have called for changes to make it quicker and easier for people to access money, cash injections to frontline charities and more temporary accommodation facilities for displaced people and their pets.

While no doubt needed, these are all reactive responses targeted at those without electricity. When any system is disrupted, however, the effects can be widespread and felt long after the initial problem has been addressed.

Take dairy farmers in Gippsland, for example, who could not milk their cows without electricity. Cows must be milked regularly or else they stop producing milk – they cannot be “switched back on” when electricity is restored. Longer-term assistance may well be required for farmers facing such ripple effects.

And as welfare groups have noted, power companies should support affected customers over the long-term, with electricity discounts, deferrals and payment plans.




Read more:
No food, no fuel, no phones: bushfires showed we’re only ever one step from system collapse


Sign reading 'power and shower'
Relief centres offer affected residents a hot shower and electricity access, but longer-term solutions are also needed.
Daniel Pockett/AAP

A call for backup

So, what else can be done to prepare for future power disruptions? Those with backup options, such as portable fuel-powered generators, or off-grid household batteries connected to solar panels, will undoubtedly be more resilient in such events.

These are examples of “system redundancy”, providing alternative electricity until the network is restored.

But it costs money to invest in household batteries or a generator that may never be used. Resilience is often a function of wealth, and the less well-off risk being left behind.

Certainly, governments can act to make society as a whole more resilient to power outages. For example, mobile phone towers have backup battery life of just 24 hours. As Victoria’s Emergency Management Commissioner Andrew Crisp said this week, extending that is something authorities “need to look at”.

Power and communications infrastructure could be moved underground to protect it from storms. While such a move would be expensive, it has been argued not doing so will lead to greater long-term costs under a changing climate.

The recent challenges at Yallourn and Callide show the risks inherent in a centralised electricity network dominated by coal.

Certainly, integrating renewable energy sources into the power network comes with its own challenges. However, expanding energy storage such as batteries, or shifting to small, community-level microgrids will go a long way to improving the resilience of the system.

This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. It is supported by a philanthropic grant from the Paul Ramsay Foundation. Find the series here.The Conversation

Anthony Richardson, Researcher and Teacher, Centre for Urban Research, RMIT University

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

Wetlands have saved Australia $27 billion in storm damage over the past five decades



Shutterstock

Obadiah Mulder, University of Southern California and Ida Kubiszewski, Crawford School of Public Policy, Australian National University

Australia is in the midst of tropical cyclone season. As we write, a cyclone is forming off Western Australia’s Pilbara coast, and earlier in the week Queenslanders were bracing for a cyclone in the state’s far north (which thankfully, didn’t hit).

Australia has always experienced cyclones. But here and around the world, climate change means the cyclone threat is growing – and so too is the potential damage bill. Disadvantaged populations are often most at risk.

Our recent research shows 54 cyclones struck Australia in the 50 years between 1967 and 2016, causing about A$3 billion in damage. We found the damages would have totalled approximately A$30 billion, if not for coastal wetlands.

Wetlands such as mangroves, swamps, lakes and lagoons bear the brunt of much storm damage to coast, helping protect us and our infrastructure. But over the past 300 years, 85% of the world’s wetland area has been destroyed. It’s clear we must urgently preserve the precious little wetland area we have left.

A wetland close to coastal development.
Wetland areas provide important protection from cyclones.
Shutterstock

A critical buffer

National disasters cost Australia as much as A$18 billion each year on average. About one-quarter of this is due to cyclone damage.

Wetlands can mitigate cyclone and hurricane damage, by absorbing storm surges and slowing winds. For example in August 2020, Hurricane Laura hit the United States’ midwest. Massive damage was predicted, including a 6.5-metre storm surge extending 65 kilometres inland.

However the surge was one metre at most – largely because the storm drove straight into a massive wetland that absorbed most of the predicted flood.

In Australia, wetlands are lost through intentional infilling or drainage for mosquito control, or to create land for infrastructure and agriculture. They’re also lost due to pollution and upstream changes to water flows.

Caley Valley Wetlands,  next to Adani's Abbot Point coal terminal.
Australia’s wetlands are at risk. Pictured is the Caley Valley Wetlands, next to Adani’s Abbot Point coal terminal. Adani was fined for releasing polluted water into the wetland.
Gary Farr/ACF

Putting a price on cyclone protection

Our research set out to determine the financial value of the storm protection provided by Australia’s wetlands.

We examined the 54 cyclones that struck Australia in the five decades to 2016. We gathered data including:

  • physical damage wrought in each storm swath (or storm path)
  • gross domestic product (GDP) in the storm’s path
  • maximum windspeed during each storm, which helps predict damage
  • total area of wetlands in each swath.

Using a powerful type of statistics called Bayesian analysis, we estimated the extent to which GDP, windspeed and wetland area affected total damage. This allowed us to estimate damage caused in the absence of wetlands.

We found for every hectare of wetland, about A$4,200 per year in cyclone damage was avoided. This means the A$3 billion in cyclone damage over the past 50 years would have totalled approximately A$30 billion, if not for coastal wetlands.




Read more:
Restoring a gem in the Murray-Darling Basin: the success story of the Winton Wetlands


Importantly, the percentage of damage averted falls rapidly as wetland area decreases. And the protection afforded by a single hectare of wetland increases drastically if there are fewer other wetlands in the path of the storm. This makes protecting remaining wetland even more critical.

If the average cyclone path in Australia were to contain around 30,000 hectares of wetlands, it would avert about 90% of potential storm damage. If the wetland area dropped to 3,000 hectares, only about 30% of damage would be averted.

Climate change is making cyclones worse. By 2050, Australia’s annual damage bill could be as high as A$39 billion, assuming current levels of wetlands are maintained.

Seawalls and other artificial structures can be built along the coast to protect from storms. However, research in China has found wetlands are more cost-effective and efficient than man-made structures at preventing cyclone damage.

Unlike man-made structures, wetlands maintain themselves. Their only “cost” is the opportunity cost of not being able to use the land for something else.

People inspect cyclone damage
Wetlands can help prevent cyclone damage, such as this wrought in Queensland during Cyclone Debbie in 2017.
Dan Peled/AAP

Keeping wetlands safe

According to recent analysis by the authors, which is currently under peer review, global wetlands provide US$447 billion (A$657 billion) worth of protection from storms each year.

Of course, wetlands provide benefits beyond storm protection. They store carbon, regulate our climate and control flooding. They also absorb waste including pollutants and carbon, provide animal habitat and places for human recreation.

Wetlands are an incredibly important resource. It’s critical we protect them from development and keep them healthy, so they can continue to provide vital services.




Read more:
Our new model shows Australia can expect 11 tropical cyclones this season


This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. You can read the rest of the stories here.The Conversation

Obadiah Mulder, PhD Candidate in Computational Biology, University of Southern California and Ida Kubiszewski, Associate Professor, Crawford School of Public Policy, Australian National University

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

Winter storms are speeding up the loss of Arctic sea ice



A scientist checks cracks in the Arctic sea ice after a storm (April 2015, N-ICE2015 expedition).
Amelie Meyer/NPI, Author provided

Amelie Meyer, University of Tasmania

Arctic sea ice is already disappearing rapidly but our research shows winter storms are now further accelerating sea ice loss.




Read more:
Arctic breakdown: what climate change in the far north means for the rest of us


The research is based on data we gathered during an expedition on a small Norwegian research vessel, the Lance, that was left to drift in the Arctic sea ice for five months in 2015.

Time series of air temperature anomalies in the Arctic for the period 1981-2010: Temperatures in the Arctic in May and June 2019 period were the warmest in the satellite records.
Zack Labe (@ZLabe)

The expedition was intense and felt more like going to the Moon than going on a typical research cruise. What took us by surprise were the many winter storms that battered the ice (and our ship and ice camp).

It has taken us years to collate these data but now we know the winter storms play a key role in the fate of Arctic sea ice, particularly in the Atlantic sector of the Arctic.

Norwegian research vessel ‘Lance’ frozen in the Arctic sea ice in February 2015 during the N-ICE2015 expedition.
Paul Dodd (NPI)

How winter storms amplify climate change

On average, about 10 extreme storms will reach all the way to the North Pole each winter. While these winter storms are short (they last on average 6-48 hours), they can be incredibly intense.

During a storm in winter 2015 we saw the air temperature rise from -40℃ (-40℉) to 0℃ (32℉) in just a day, and then fall back to -30℃ (-22℉) the next day, when cold Arctic air returned after the storm.

These storms bring heat, moisture and strong winds into the Arctic, and next we look at how they impact sea ice and its surroundings.

Warming and weakening the ice

The heat from the storms warms up the air, snow and ice, slowing down the growth of the ice. Moisture from the storms falls as snow on the ice. After the storm, the blanket of snow insulates the ice from the cold air, further slowing the growth of the ice for the remainder of winter.

The strong winds during the storms push the ice around and break it into pieces, making it more fragile and deforming it, more like a boulder field.

The strong winds also stir the ocean below the ice, mixing up warmer water from deeper waters to the surface where it melts the ice from below. This melting of the ice in the middle of winter can happen for several days after the storms when the air is already back to well below freezing.

Processes related to Arctic winter storms. In the first storm phase, strong southerly winds compress the ice cover and transport warm air, moisture, and bring strong winds. In the second phase, northerly winds transport ice southwards. After the storm has passed, cold and calm conditions return, allowing new ice to grow in leads. When the next winter storm arrives, it further drives the ice cover into a relatively thin-ice, snow-covered mosaic of strongly deformed ice floes. These new conditions impact surrounding ecosystems by shaping habitats and light conditions.
Graham et al., 2019 (Scientific Reports)

Thinner ice, shelter for life and accelerated melting

The breakup of the ice opens big passages of open water between ice floes, called leads. In winter these passages end up refreezing rapidly, generating new super-thin ice.

These thinner refrozen patches of ice let more light through in the following spring, allowing ocean plants (phytoplankton) to bloom earlier.

The rougher sea ice landscape becomes a shelter for many ice-associated Arctic organisms, including ice algae, becoming biological hot spots in the following spring.

The broken up and deformed ice drifts faster, reaching warmer waters where it melts sooner and faster.

So really, winter storms precondition the ice to a faster melt in the following spring with an impact that continues well into the following season.

Why is Arctic sea ice declining?

Winter sea ice cover in the Atlantic sector of the Arctic has been retreating at a record breaking pace, especially in the Barents Sea off Norway and Russia.

Average September Arctic sea ice extent from 1979 to 2018. Black line shows monthly average for each year; blue line shows the trend.
National Snow and Ice Data Center

The Arctic is particularly sensitive to human driven climate change. We know the decrease in sea ice is due to both the warming of the Arctic (air and ocean) and changing wind patterns that break up the ice cover.

But there are also amplifying mechanisms or “feedback” mechanisms, in which one natural process reinforces another. Their role in the decrease of sea ice is hard to predict. We now know winter storms in the Arctic contribute to these feedback mechanisms.

More storms ahead

Arctic winter storms are increasing in frequency and this is likely due to climate change.

With the thinner Arctic sea ice cover and shallower warmer water in the Arctic Ocean, the mechanisms we observed during the winter storms will likely strengthen and the overall impact of winter storms on Arctic ice is likely to increase in the future.

Two weeks ago, the Arctic sea ice reached its minimum extent for 2019, after another winter of intense winter storms. The minimum ice extent was effectively tied for second lowest since modern record-keeping began in the late 1970s, along with 2007 and 2016, reinforcing the long-term downward trend in Arctic ice extent. Arctic sea ice has been declining for at least 40 years, and amplifying mechanisms such as the winter storms are accelerating this retreat.

Arctic sea ice extent just reached its annual minimum extent for 2019 on September 18. This season was a tie for the 2nd lowest on record, along with 2007 and 2016 and behind 2012, which holds the overall record minimum.
Zack Labe (@ZLabe)

As highlighted in the recent IPCC Ocean and Cryopshere report, these changes in September sea ice are likely unprecedented for at least 1,000 years.

Remember also that changes in the Arctic don’t just affect the immediate region: Arctic warming has been linked to the polar vortex, and weather extremes across central Europe and north America.




Read more:
Microplastics may affect how Arctic sea ice forms and melts


As we start taking into account feedback mechanisms like the winter storms, our predictions for the first Arctic sea ice free summer are indicating it will likely happen before 2050.The Conversation

Amelie Meyer, Research fellow, University of Tasmania

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

Protecting wetlands helps communities reduce damage from hurricanes and storms



File 20181009 72133 1o1hr7u.jpg?ixlib=rb 1.1
Protecting coastal wetlands, like this slough in Florida’s Everglades National Park, is a cost-effective way to reduce flooding and storm damage.
NPS/C. Rivas

Siddharth Narayan, University of California, Santa Cruz and Michael Beck, University of California, Santa Cruz

2017 was the worst year on record for hurricane damage in Texas, Florida and the Caribbean from Harvey, Irma and Maria. We had hoped for a reprieve this year, but less than a month after Hurricane Florence devastated communities across the Carolinas, Hurricane Michael has struck Florida.

Coastlines are being developed rapidly and intensely in the United States and worldwide. The population of central and south Florida, for example, has grown by 6 million since 1990. Many of these cities and towns face the brunt of damage from hurricanes. In addition, rapid coastal development is destroying natural ecosystems like marshes, mangroves, oyster reefs and coral reefs – resources that help protect us from catastrophes.

In a unique partnership funded by Lloyd’s of London, we worked with colleagues in academia, environmental organizations and the insurance industry to calculate the financial benefits that coastal wetlands provide by reducing storm surge damages from hurricanes. Our study, published in 2017, found that this function is enormously valuable to local communities. It offers new evidence that protecting natural ecosystems is an effective way to reduce risks from coastal storms and flooding.

Coastal wetlands and flood damage reduction: A collaboration between academia, conservation and the risk industry.

The economic value of flood protection from wetlands

Although there is broad understanding that wetlands can protect coastlines, researchers have not explicitly measured how and where these benefits translate into dollar values in terms of reduced risks to people and property. To answer this question, our group worked with experts who understand risk best: insurers and risk modelers.

Using the industry’s storm surge models, we compared the flooding and property damages that occurred with wetlands present during Hurricane Sandy to the damages that would have occurred if these wetlands were lost. First we compared the extent and severity of flooding during Sandy to the flooding that would have happened in a scenario where all coastal wetlands were lost. Then, using high-resolution data on assets in the flooded locations, we measured the property damages for both simulations. The difference in damages – with wetlands and without – gave us an estimate of damages avoided due to the presence of these ecosystems.

Our paper shows that during Hurricane Sandy in 2012, coastal wetlands prevented more than US$625 million in direct property damages by buffering coasts against its storm surge. Across 12 coastal states from Maine to North Carolina, wetlands and marshes reduced damages by an average of 11 percent.

These benefits varied widely by location at the local and state level. In Maryland, wetlands reduced damages by 30 percent. In highly urban areas like New York and New Jersey, they provided hundreds of millions of dollars in flood protection.

Wetland benefits for flood damage reduction during Sandy (redder areas benefited more from having wetlands).
Narayan et al., Nature Scientific Reports 7, 9463 (2017)., CC BY

Wetlands reduced damages in most locations, but not everywhere. In some parts of North Carolina and the Chesapeake Bay, wetlands redirected the surge in ways that protected properties directly behind them, but caused greater flooding to other properties, mainly in front of the marshes. Just as we would not build in front of a seawall or a levee, it is important to be aware of the impacts of building near wetlands.

Wetlands reduce flood losses from storms every year, not just during single catastrophic events. We examined the effects of marshes across 2,000 storms in Barnegat Bay, New Jersey. These marshes reduced flood losses annually by an average of 16 percent, and up to 70 percent in some locations.

Reductions in annual flood losses to properties that have a marsh in front (blue) versus properties that have lost the marshes in front (orange).
Narayan et al., Nature Scientific Reports 7, 9463 (2017)., CC BY

In related research, our team has also shown that coastal ecosystems can be highly cost-effective for risk reduction and adaptation along the U.S. Gulf Coast, particularly as part of a portfolio of green (natural) and gray (engineered) solutions.

Reducing risk through conservation

Our research shows that we can measure the reduction in flood risks that coastal ecosystems provide. This is a central concern for the risk and insurance industry and for coastal managers. We have shown that these risk reduction benefits are significant, and that there is a strong case for conserving and protecting our coastal ecosystems.

The next step is to use these benefits to create incentives for wetland conservation and restoration. Homeowners and municipalities could receive reductions on insurance premiums for managing wetlands. Post-storm spending should include more support for this natural infrastructure. And new financial tools such as resilience bonds, which provide incentives for investing in measures that reduce risk, could support wetland restoration efforts too.

The dense vegetation and shallow waters within wetlands can slow the advance of storm surge and dissipate wave energy.
USACE

Improving long-term resilience

Increasingly, communities are also beginning to consider ways to improve long-term resilience as they assess their recovery options.

There is often a strong desire to return to the status quo after a disaster. More often than not, this means rebuilding seawalls and concrete barriers. But these structures are expensive, will need constant upgrades as as sea levels rise, and can damage coastal ecosystems.

Even after suffering years of damage, Florida’s mangrove wetlands and coral reefs play crucial roles in protecting the state from hurricane surges and waves. And yet, over the last six decades urban development has eliminated half of Florida’s historic mangrove habitat. Losses are still occurring across the state from the Keys to Tampa Bay and Miami.

Protecting and nurturing these natural first lines of defense could help Florida homeowners reduce property damage during future storms. In the past two years our team has worked with the private sector and government agencies to help translate these risk reduction benefits into action for rebuilding natural defenses.

Across the United States, the Caribbean and Southeast Asia, coastal communities face a crucial question: Can they rebuild in ways that make them better prepared for the next storm, while also conserving the natural resources that make these locations so valuable? Our work shows that the answer is yes.

This is an updated version of an article originally published on Sept. 25, 2017.The Conversation

Siddharth Narayan, Postdoctoral Fellow, Coastal Flood Risk, University of California, Santa Cruz and Michael Beck, Research professor, University of California, Santa Cruz

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

The Sydney Barrier Reef: engineering a natural defence against future storms


Rob Roggema, University of Technology Sydney

The risk of more severe storms and cyclones in the highly urbanised coastal areas of Newcastle, Sydney and Wollongong might not be acute, but it is a real future threat with the further warming of the southern Pacific Ocean. One day a major storm – whether an East Coast Low or even a cyclone – could hit Sydney. The Conversation

With higher ocean temperatures killing and bleaching coral along the Great Barrier Reef to the north, we could also imagine where the right temperatures for a coral reef would be in a warmer climate. Most probably, this would be closer to the limits of the low latitudes, hence in front of the Sydney metro area.

We should then consider whether it is possible to help engineer a natural defence against storms, a barrier reef, should warming oceans make conditions suitable here.

Ocean warming trend is clear

The oceans are clearly warming at an alarming rate, with the unprecedented extent and intensity of coral bleaching events a marker of rising temperatures. After the 2016-2017 summer, coral bleaching affected two-thirds of the Great Barrier Reef.

On the other side of the Pacific, sea surface temperatures off Peru’s northern coast have risen 5-6℃ degrees above normal. Beneath the ocean surface, the warming trend is consistent too.

The East Australian Current keeps the waters around Lord Howe Island warm enough to sustain Australia’s southernmost coral reef. The waters off Sydney are just a degree or two cooler.

With the East Australian Current now extending further south, the warming of these south-eastern coastal waters might be enough in a couple of decades for Nemo to swim in reality under Sydney Harbour Bridge.

This shift in ocean temperatures is expected to drive strong storms and inland floods, according to meteorologists.

On top of this, when we plot a series of maps since 1997 of cyclone tracks across the Pacific, it shows a slight shift to more southern routes. These cyclones occur only in the Tasman Sea and way out from the coast, but, still, there is a tendency to move further south. The northern part of New Zealand recently experienced the impacts this could have.

Think big to prepare for a big storm

If we would like to prevent what Sandy did to New York, we need to think big.

If we don’t want a storm surge entering Parramatta River, flooding the low-lying areas along the peninsulas, if we don’t want flash-flooding events as result of river discharges, if we don’t want our beaches to be washed away, if we want to keep our property along the water, and if we want to save lives, we’d better prepare to counter these potential events through anticipating their occurrence.

The coast is the first point where a storm impacts the city. Building higher and stronger dams have proven to be counterproductive. Once the dam breaks or overflows the damage is huge. Instead we should use the self-regenerating defensive powers nature offers us.

Thinking big, we could design a “Sydney Barrier Reef”, which allows nature to regenerate and create a strong and valuable coast.

The first 30-40 kilometres of the Pacific plateau is shallow enough to establish an artificial reef. The foundations of this new Sydney Barrier Reef could consist of a series of concrete, iron or wooden structures, placed on the continental shelf, just beneath the water surface. Intelligently composed to allow the ocean to bring plants, fish and sand to attach to those structures, it would then start to grow as the base for new coral.

This idea has not been tested for the Sydney continental flat yet. But in other parts of the world experiments with artificial reefs seem promising. At various sites, ships, metro carriages and trains seem to be working as the basis for marine life to create a new underworld habitat

The Sydney Barrier Reef will have the following advantages:

  1. Over decades a natural reef will grow. Coral will develop and a new ecosystem will emerge.

  2. This reef will protect the coast and create new sandbanks, shallow areas and eventually barrier islands, as the Great Barrier Reef has done.

  3. It will increase the beach area, because the conditions behind the reef will allow sediments to settle.

  4. It creates new surfing conditions as a result of the sandbanks.

  5. It will protect Sydney from the most severe storm surges as it breaks the surge.

  6. It will present a new tourist attraction of international allure.

Let’s create a pilot project as a test. Let’s start to design and model the pilot to investigate what happens in this particular location. Let’s simulate the increase of temperature over time and model the impact of a cyclone.

Let’s create, so when Sandy hits Sydney, we will be better protected.

Rob Roggema, Professor of Sustainable Urban Environments, University of Technology Sydney

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

Election FactCheck: are larger, more frequent storms predicted due to climate change?


Kevin Walsh, University of Melbourne

Certainly larger and more frequent storms are one of the consequences that the climate models and climate scientists predict from global warming. But you cannot attribute any particular storm to global warming, so let’s be quite clear about that. – Prime Minister Malcolm Turnbull, speaking to reporters in Tasmania on June 9, 2016.

In the aftermath of the deadly East Coast Low that swamped eastern Australia, dumping massive amounts of rain in early June, the prime minister toured flood-affected Launceston and announced emergency relief funding.

Turnbull told reporters that larger and more frequent storms were forecast by climate scientists but cautioned that no individual storm could be attributed to global warming.

Is he right?

Checking the source

The Conversation asked the prime minister’s office for sources to support his statement but did not hear back before publication deadline. Nevertheless, we can test his statement against recent published and peer-reviewed research on this question.

The science shows that, just like real estate, climate change is all about location. Different parts of Australia will be affected in different ways by climate change.

And global warming will have different effects on different types of weather systems.

Let’s break Turnbull’s statement into two parts: is it true that we can expect larger and more frequent storms as a consequence of global warming? And is it possible to attribute a specific storm to global warming?

Can we expect larger and more frequent storms as a result of global warming?

Yes – but not for all regions or types of storms.

There are many types of storms that affect different parts of Australia, among them East Coast Lows, mid-latitude cyclones (a category that includes cyclones that happen in the latitudes between Australia and Antarctica), tropical cyclones, and associated extreme rainfall events. Each will be affected in a different way by climate change, and the effect will vary by region and by season.

On East Coast Lows: Acacia Pepler, who is studying extreme rainfall and East Coast Lows in relation to climate change, recently wrote in The Conversation that her research showed that:

… East Coast Lows are expected to become less frequent during the cool months May-October, which is when they currently happen most often. But there is no clear picture of what will happen during the warm season. Some models even suggest East Coast Lows may become more frequent in the warmer months. And increases are most likely for lows right next to the east coast – just the ones that have the biggest impacts where people live.

For all low-pressure systems near the coast, “most of the models we looked at had no significant change projected in the intensity of the most severe East Coast Low each year,” Pepler wrote.

On mid-latitude cyclones: Another study predicted that the overall wind hazard from mid-latitude cyclones in Australia will decrease – except in winter over Tasmania.

On tropical cyclones: Northern Australia is expected to get fewer cyclones in future – but their maximum wind speeds are expected to become stronger.

On rainfall: Scientists tend to be quite confident that climate change will be accompanied by an increase in extreme rainfall for most storms in future. One of the main reasons for this is that increased temperatures will cause increased evaporation. While the total amount of water held in the atmosphere will also increase slightly in future, the total amount of rain has to go up too.

Is it true you can’t attribute any particular storm to global warming?

Turnbull is correct. We cannot say for sure that a particular flooding rainfall event was solely “caused” by climate change, any more than we can say for certain that a particular car accident was solely caused by speeding (even if excessive speed was a likely or even major contributing factor).

Evidence for the effects of global warming on extreme rainfall events that have already occurred is currently equivocal for most regions.

According to a collection of studies published in 2015:

A number of this year’s studies indicate that human-caused climate change greatly increased the likelihood and intensity for extreme heat waves in 2014 over various regions. For other types of extreme events, such as droughts, heavy rains, and winter storms, a climate change influence was found in some instances and not in others.

One recent study in that report found:

evidence for a human-induced increase in extreme winter rainfall in the United Kingdom.

Verdict

Malcolm Turnbull was essentially correct on both points.

It’s true that scientists predict more frequent and intense storms for some parts of Australia as the climate changes. The evidence appears to be strong that extreme rainfall will increase. Some increases in extreme wind speeds are possible – but not in all regions or all seasons.

Turnbull was right to say you cannot attribute any particular storm to global warming. –Kevin Walsh


Review

This is a good FactCheck that summarises the broad conclusions from a range of studies examining the nature of current and likely future storms across Australia.

As the author points out, Australian storms range from tropical cyclones in the northern tropical regions to temperate east coast lows and mid-latitude cyclones.

The consensus regarding tropical cyclones is that they will generally decrease in frequency in the Australian region. In northeast Australia, they are forecast to experience the most dramatic decrease in frequency of any ocean basin globally. Some northern hemisphere ocean basins will see an increase in their frequency.

The intensity of these types of storms is expected to increase. This will not only involve higher wind speeds but also higher storm surges and floods. That will mean greater coastal impacts and damage to coastal developments and infrastructure.

So the prime minister’s statement about more frequent storms resulting from climate change does not apply to tropical cyclones – however, he was right to say that larger and more frequent storms are one of the predicted consequences of climate change. This consequence is predicted to apply to other storm categories, but not tropical cyclones.

And yes, climate scientists are hesitant to attribute the occurrence of any single storm to global warming. – Jonathan Nott


Have you ever seen a “fact” worth checking? The Conversation’s FactCheck asks academic experts to test claims and see how true they are. We then ask a second academic to review an anonymous copy of the article. You can request a check at checkit@theconversation.edu.au. Please include the statement you would like us to check, the date it was made, and a link if possible.

The Conversation

Kevin Walsh, Reader, School of Earth Sciences, University of Melbourne

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