Category Archives for Sydney
Sydney’s disastrous flood wasn’t unprecedented: we’re about to enter a 50-year period of frequent, major floods
Tom Hubble, University of SydneyLast month’s flood in the Hawkesbury-Nepean River region of western Sydney peaked at a staggering 12.9 metres, with water engulfing road signs and reaching the tops of many houses.
There hasn’t been a major flood on the Hawkesbury-Nepean for more than 30 years, with the last comparable one occurring in 1990. Long-term Sydneysiders, however, will remember that 12 major floods occurred during the 40 years before 1990. Five of these were larger than last month’s flood.
So what’s going on? The long-term rainfall pattern in the region and corresponding river flow is cyclic in nature. This means 40 to 50 years of dry weather with infrequent small floods are followed by 40 to 50 years of wet weather with frequent major floods.
As river and floodplain residents take stock of the recent damage to their homes and plan necessary repairs, it’s vital they recognise more floods are on the way. Large, frequent floods can be expected to occur again within 10 or 20 years if — as expected — the historical pattern of rainfall and flooding repeats itself.
Living in a bathtub
Many of the 18,000 people who were evacuated live in and around a region known as the “Sackville Bathtub”. As the name suggests, this flat, low-lying section of the floodplain region was spectacularly affected.
Digital Earth Australia Map, Geoscience Australia, Tom Hubble
The Sackville Bathtub is located between Richmond and Sackville. It’s part of the Cumberland Plain area of Western Sydney and formed very slowly over 100 million years due to plate tectonic processes. The bathtub’s mudstone rock layers are folded into a broad, shallow, basin-shaped depression, which is surrounded by steep terrain.
Downstream of Sackville, the Hawkesbury-Nepean River flows through sandstone gorges and narrows in width. This creates a pinch-point that partially blocks the river channel.
Just as a bath plug sitting half-way over a plughole slows an emptying bath, the Sackville pinch-point causes the bathtub to fill during floods.
Will raising the dam wall work?
The NSW state government is planning to raise the wall of the Warragamba Dam to help mitigate catastrophic floods in the region. But this may not be an effective solution.
Typically, somewhere between 40% and 60% of the floodwater that fills up the Sackville Bathtub comes from unimpeded, non-Warragamba sources. So, when the Hawkesbury-Nepean River floods, the bathtub is already quite full and causing significant problems before Warragamba begins to spill. The Warragamba water then raises the flood level, but often by only a couple of metres.
Raising Warragamba Dam’s wall as a mitigation measure will only control about half the floodwater, and won’t prevent major floods delivered by the Nepean and Grose rivers, which also feed into the region. This represents a small potential benefit for a very large cost.
Tom Hubble – Redrawn from data presented in Appendix One of the Hawkesbury-Nepean Flood Study; Infrastructure NSW 2019.
A long flooding period is on our doorstep
The idea of drought-dominated and flood-dominated periods for the Hawkesbury-Nepean River system was proposed in the mid-1970s by the University of Sydney’s Robin Warner. Since the late 1990’s, it hasn’t been the focus of much research.
Read more:
What is a 1 in 100 year weather event? And why do they keep happening so often?
He showed a century-long cycle of alternating periods of dry weather and small floods followed by wet weather and big floods is normal for Sydney. This means the March flood may not have come as a surprise to older residents of the Sackville Bathtub, who have a lived experience of the whole 40-50 year flooding cycle.
As a rough average, one major flood occurred every four years during the last wet-weather period between 1950 and 1990. The largest of this period occurred in November 1961. It filled the Sackville Bathtub to a depth of 15 metres and — like the June 1964 (14.6 metres) and March 1978 (14.5 metres) events — caused more widespread flooding than this year’s flood.
Sam Hood/NSW State Library/Flickr, CC BY
We’re currently 30 years into a dry period, which may be about to end. Conditions might stay dry for another 10 or 20 years.
These cycles are likely caused by natural, long-term “climate drivers” — long-term climatic fluctuations such as El Niño and La Niña, the Pacific Decadal Oscillation and the Indian Ocean Dipole, which are driven by oceanic current circulations. These global phenomena bring both benevolent weather and destructive weather to Australia.
Eastern Australia experiences decades-long periods of wetter weather when these climate drivers sync up with each other. When they’re out of sync, we get dry weather periods.
These long-term cycles are natural and have been operating for thousands of years, but climate change is amplifying and accelerating them. Dry periods are getting drier, wet periods are getting wetter.
The good news and bad news
The bad news is that 12-plus metre floods at Hawkesbury River (Windsor Bridge) are not all that unusual. There have been 24, 12-plus metre floods at Windsor Bridge since 1799.
The good news is meteorological forecasters are excellent at predicting when the storms that generate moderate, large and catastrophic floods are coming. We can expect several days’ to a week’s notice of the next big flood.
We can also prepare our individual and communal responses for more large and frequent floods on the Hawkesbury-Nepean. Residents of the area need to think about how they might live near the river as individuals. Decide what is precious and what you will fit into a car and trailer. Practice evacuating.
As a community, we must ensure the transport infrastructure and evacuation protocols minimise disruption to river and floodplain residents while maximising their safety. It’s particularly important we set up inclusive infrastructure to ensure disadvantaged people, who are disproportionately affected by disasters, also have a fighting chance to evacuate and survive.
Read more:
Not ‘if’, but ‘when’: city planners need to design for flooding. These examples show the way
Upgrading the escape routes that enable people to evacuate efficiently is absolutely vital. As is rethinking whether we should continue urban expansion in the Sackville Bathtub.
So remember, the next major flood is going to occur sooner than we would like. If you live in this region, you must start preparing. Or as a wise elder once said, “Live on a floodplain, own a boat!”
This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. Read the rest of the stories here.
Tom Hubble, Associate Professor, University of Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Not just hot air: turning Sydney’s wastewater into green gas could be a climate boon
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Bernadette McCabe, University of Southern Queensland
Biomethane technology is no longer on the backburner in Australia after an announcement this week that gas from Sydney’s Malabar wastewater plant will be used to power up to 24,000 homes.
Biomethane, also known as renewable natural gas, is produced when bacteria break down organic material such as human waste.
The demonstration project is the first of its kind in Australia. But many may soon follow: New South Wales’ gas pipelines are reportedly close to more than 30,000 terajoules (TJs) of potential biogas, enough to supply 1.4 million homes.
Critics say the project will do little to dent Australia’s greenhouse emissions. But if deployed at scale, gas captured from wastewater can help decarbonise our gas grid and bolster energy supplies. The trial represents the chance to demonstrate an internationally proven technology on Australian soil.
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What’s the project all about?
Biomethane is a clean form of biogas. Biogas is about 60% methane and 40% carbon dioxide (CO₂) and other contaminants. Turning biogas into biomethane requires technology that scrubs out the contaminants – a process called upgrading.
The resulting biomethane is 98% methane. While methane produces CO₂ when burned at the point of use, biomethane is considered “zero emissions” – it does not add to greenhouse gas emissions. This is because:
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it captures methane produced from anaerobic digestion, in which microorganisms break down organic material. This methane would otherwise have been released to the atmosphere
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it is used in place of fossil fuels, displacing those CO₂ emissions.
Biomethane can also produce negative emissions if the CO₂ produced from upgrading it is used in other processes, such as industry and manufacturing.
Biomethane is indistinguishable from natural gas, so can be used in existing gas infrastructure.
Read more:
Biogas: smells like a solution to our energy and waste problems
The Malabar project, in southeast Sydney, is a joint venture between gas infrastructure giant Jemena and utility company Sydney Water. The A$13.8 million trial is partly funded by the federal government’s Australian Renewable Energy Agency (ARENA).
Sydney Water, which runs the Malabar wastewater plant, will install gas-purifying equipment at the site. Biogas produced from sewage sludge will be cleaned and upgraded – removing contaminants such as CO₂ – then injected into Jemena’s gas pipelines.
Sydney Water will initially supply 95TJ of biomethane a year from early 2022, equivalent to the gas demand of about 13,300 homes. Production is expected to scale up to 200TJ a year.
Sydney Water
Biomethane: the benefits and challenges for Australia
A report by the International Energy Agency earlier this year said biogas and biomethane could cover 20% of global natural gas demand while reducing greenhouse emissions.
As well as creating zero-emissions energy from wastewater, biomethane can be produced from waste created by agriculture and food production, and from methane released at landfill sites.
The industry is a potential economic opportunity for regional areas, and would generate skilled jobs in planning, engineering, operating and maintenance of biogas and biomethane plants.
Methane emitted from organic waste at facilities such as Malabar is 28 times more potent than CO₂. So using it to replace fossil-fuel natural gas is a win for the environment.
Read more:
Emissions of methane – a greenhouse gas far more potent than carbon dioxide – are rising dangerously
It’s also a win for Jemena, and all energy users. Many of Jemena’s gas customers, such as the City of Sydney, want to decarbonise their existing energy supplies. Some say they will stop using gas if renewable alternatives are not found. Jemena calculates losing these customers would lose it A$2.1 million each year by 2050, and ultimately, lead to higher costs for remaining customers.
The challenge for Australia will be the large scale roll out of biomethane. Historically, this phase has been a costly exercise for renewable technologies entering the market.
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The global picture
Worldwide, the top biomethane-producers include Germany, the United Kingdom, Sweden, France and the United States.
The international market for biomethane is growing. Global clean energy policies, such as the European Green Deal, will help create extra demand for biomethane. The largest opportunities lie in the Asia-Pacific region, where natural gas consumption and imports have grown rapidly in recent years.
Australia is lagging behind the rest of the world on biomethane use. But more broadly, it does have a biogas sector, comprising than 240 plants associated with landfill gas power units and wastewater treatment.
In Australia, biogas is already used to produce electricity and heat. The step to grid injection is sensible, given the logistics of injecting biomethane into existing gas infrastructure works well overseas. But the industry needs government support.
Last year, a landmark report into biogas opportunities for Australia put potential production at 103 terawatt hours. This is equivalent to almost 9% of Australia’s total energy consumption, and comparable to current biogas production in Germany.
A clean way to a gas-led recovery
While the scale of the Malabar project will only reduce emissions in a small way initially, the trial will bring renewable gas into the Australia’s renewable energy family. Industry group Bioenergy Australia is now working to ensure gas standards and specifications are understood, to safeguard its smooth and safe introduction into the energy mix.
The Morrison government has been spruiking a gas-led recovery from the COVID-19 recession, which it says would make energy more affordable for families and businesses and support jobs. Using greenhouse gases produced by wastewater in Australia’s biggest city is an important – and green – first step.
Bernadette McCabe, Professor and Principal Scientist, University of Southern Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
After a storm, microplastics in Sydney’s Cooks River increased 40 fold
James HItchcock, Author provided
James Hitchcock, University of Canberra
Each year the ocean is inundated with 4.8 to 12.7 million tonnes of plastic washed in from land. A big proportion of this plastic is between 0.001 to 5 millimetres, and called “microplastic”.
But what happens during a storm, when lashings of rain funnel even more water from urban land into waterways? To date, no one has studied just how important storm events may be in polluting waterways with microplastics.
Read more:
Microplastic pollution is everywhere, but scientists are still learning how it harms wildlife
So to find out, I studied my local waterway in Sydney, the Cooks River estuary. I headed out daily to measure how many microplastics were in the water, before, during, and after a major storm event in October, 2018.
The results, published on Wednesday, were startling. Microplastic particles in the river had increased more than 40 fold from the storm.
Author provided
To inner west Sydneysiders, the Cooks River is known to be particularly polluted. But it’s largely similar to many urban catchments around the world.
If the relationship between storm events and microplastic I found in the Cooks River holds for other urban rivers, then the concentrations of microplastics we’re exposing aquatic animals to is far higher than previously thought.
14 million plastic particles
They may be tiny, but microplastics are a major concern for aquatic life and food webs. Animals such as small fish and zooplankton directly consume the particles, and ingesting microplastics has the potential to slow growth, interfere with reproduction, and cause death.
Determining exactly how much microplastic enters rivers during storms required the rather unglamorous task of standing in the rain to collect water samples, while watching streams of unwanted debris float by (highlights included a fire extinguisher, a two-piece suit, and a litany of tennis balls).
Back in the laboratory, a multi-stage process is used to separate microplastics. This includes floating, filtering, and using strong chemical solutions to dissolve non-plastic items, before identification and counting with specialised microscopes.
Author provided
In the days before the October 2018 storm, there were 0.4 particles of microplastic per litre of water in the Cooks River. That jumped to 17.4 microplastics per litre after the storm.
Overall, that number averages to a total of 13.8 million microplastic particles floating around in the Cooks River estuary in the days after the storm.
Read more:
Seafloor currents sweep microplastics into deep-sea hotspots of ocean life
In other urban waterways around the world scientists have found similarly high numbers of microplastic.
For example in China’s Pearl River, microplastic averages 19.9 particles per litre. In the Mississippi River in the US, microplastic ranges from 28 to 60 particles per litre.
Where do microplastics come from?
We know runoff during storms is one of the main ways pollutants such as sediments and heavy metals end up in waterways. But not much is known about how microplastic gets there.
However think about your street. Wherever you see litter, there are also probably microplastics you cannot see that will eventually work their way into waterways when it rains.
Read more:
Sustainable shopping: how to stop your bathers flooding the oceans with plastic
Many other sources of microplastics are less obvious. Car tyres, for example, which typically contain more plastic than rubber, are a major source of microplastics in our waterways. When your tyres lose tread over time, microscopic tyre fragments are left on roads.
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Microplastics may even build up on roads and rooftops from atmospheric deposition. Everyday, lightweight microplastics such as microfibres from synthetic clothing are carried in the wind, settling and accumulating before they’re washed into rivers and streams.
What’s more, during storms wastewater systems may overflow, contaminating waterways. Along with sewage, this can include high concentrations of synthetic microfibers from household washing machines.
And in regional areas, microplastics may be washing in from agricultural soils. Sewage sludge is often applied to soils as it is rich in nutrients, but the same sludge is also rich in microplastics.
What can be done?
There are many ways to mitigate the negative effects of stormwater on waterways.
Screens, traps, and booms can be fitted to outlets and rivers and catch large pieces of litter such as bottles and packaging. But how useful these approaches are for microplastics is unknown.
Raingardens and retention ponds are used to catch and slow stormwater down, allowing pollutants to drop to bottom rather than being transported into rivers. Artificial wetlands work in similar ways, diverting stormwater to allow natural processes to remove toxins from the water.
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But while mitigating the effects of stormwater carrying microplastics is important, the only way we’ll truly stop this pollution is to reduce our reliance on plastic. We must develop policies to reduce and regulate how much plastic material is produced and sold.
Plastic is ubiquitous, and its production around the world hasn’t slowed, reaching 359 million tonnes each year. Many countries now have or plan to introduce laws regulating the sale or production of some items such as plastic bags, single-use plastics and microbeads in cleaning products.
Read more:
We have no idea how much microplastic is in Australia’s soil (but it could be a lot)
In Australia, most state governments have committed to banning plastic bags, but there are still no laws banning the use of microplastics in cleaning or cosmetic products, or single-use plastics.
We’ve made a good start, but we’ll need deeper changes to what we produce and consume to stem the tide of microplastics in our waterways.
James Hitchcock, Post-Doctoral Research Fellow, University of Canberra
This article is republished from The Conversation under a Creative Commons license. Read the original article.
5 big environment stories you probably missed while you’ve been watching coronavirus
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Rod Lamberts, Australian National University and Will J Grant, Australian National University
Good news: COVID-19 is not the only thing going on right now!
Bad news: while we’ve all been deep in the corona-hole, the climate crisis has been ticking along in the background, and there are many things you may have missed.
Fair enough – it’s what people do. When we are faced with immediate, unambiguous threats, we all focus on what’s confronting us right now. The loss of winter snow in five or ten years looks trivial against images of hospitals pushed to breaking point now.
As humans, we also tend to prefer smaller, short-term rewards over larger long-term ones. It’s why some people would risk illness and possible prosecution (or worse, public shaming) to go to the beach with their friends even weeks after social distancing messages have become ubiquitous.
But while we might need to ignore climate change right now if only to save our sanity, it certainly hasn’t been ignoring us.
So here’s what you may have missed while coronavirus dominates the news cycle.
Heatwave in Antarctica
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On February 6 this year, the northernmost part of Antarctica set a new maximum temperature record of 18.4℃. That’s a pleasant temperature for an early autumn day in Canberra, but a record for Antarctica, beating the old record by nearly 1℃.
That’s alarming, but not as alarming as the 20.75℃ reported just three days later to the east of the Antarctic Peninsula at Marambio station on Seymour Island.
Read more:
Anatomy of a heatwave: how Antarctica recorded a 20.75°C day last month
Bleaching the reef
The Intergovernmental Panel on Climate Change has warned a global average temperature rise of 1.5℃ could wipe out 90% of the world’s coral.
As the world looks less likely to keep temperature rises to 1.5℃, in 2019 the five-year outlook for Australia’s Great Barrier Reef was downgraded from “poor” to “very poor”. The downgrading came in the wake of two mass bleaching events, one in 2016 and another in 2017, damaging two-thirds of the reef.
And now, in 2020, it has just experienced its third in five years.
Of course, extreme Antarctic temperatures and reef bleaching are the products of human-induced climate change writ large.
But in the short time since the COVID-19 crisis began, several examples of environmental vandalism have been deliberately and specifically set in motion as well.
Read more:
We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy
Coal mining under a Sydney water reservoir
The Berejiklian government in New South Wales has just approved the extension of coal mining by Peabody Energy – a significant funder of climate change denial – under one of Greater Sydney’s reservoirs. This is the first time such an approval has been granted in two decades.
While environmental groups have pointed to significant local environmental impacts – arguing mining like this can cause subsidence in the reservoir up to 25 years after the mining is finished – the mine also means more fossil carbon will be spewed into our atmosphere.
Peabody Energy argues this coal will be used in steel-making rather than energy production. But it’s still more coal that should be left in the ground. And despite what many argue, you don’t need to use coal to make steel.
Read more:
Albanese says we can’t replace steelmaking coal. But we already have green alternatives
Victoria green-lights onshore gas exploration
In Victoria, the Andrews government has announced it will introduce new laws into Parliament for what it calls the “orderly restart” of onshore gas exploration. In this legislation, conventional gas exploration will be permitted, but an existing temporary ban on fracking and coal seam gas drilling will be made permanent.
The announcement followed a three-year investigation led by Victoria’s lead scientist, Amanda Caples. It found gas reserves in Victoria “could be extracted without harming the environment”.
Sure, you could probably do that (though the word “could” is working pretty hard there, what with local environmental impacts and the problem of fugitive emissions). But extraction is only a fraction of the problem of natural gas. It’s the subsequent burning that matters.
Trump rolls back environmental rules
Meanwhile, in the United States, the Trump administration is taking the axe to some key pieces of environmental legislation.
One is an Obama-era car pollution standard, which required an average 5% reduction in greenhouse emissions annually from cars and light truck fleets. Instead, the Trump administration’s “Safer Affordable Fuel Efficient Vehicles” requires just 1.5%.
The health impact of this will be stark. According to the Environmental Defense Fund, the shift will mean 18,500 premature deaths, 250,000 more asthma attacks, 350,000 more other respiratory problems, and US$190 billion in additional health costs between now and 2050.
And then there are the climate costs: if manufacturers followed the Trump administration’s new looser guidelines it would add 1.5 billion tonnes of carbon dioxide to the atmosphere, the equivalent of 17 additional coal-fired power plants.
Read more:
When it comes to climate change, Australia’s mining giants are an accessory to the crime
And so…
The challenges COVID-19 presents right now are huge. But they will pass.
The challenges of climate change are not being met with anything like COVID-19 intensity. For now, that makes perfect sense. COVID-19 is unambiguously today. Against this imperative, climate change is still tomorrow.
But like hangovers after a large celebration, tomorrows come sooner than we expect, and they never forgive us for yesterday’s behaviour.
Rod Lamberts, Deputy Director, Australian National Centre for Public Awareness of Science, Australian National University and Will J Grant, Senior Lecturer, Australian National Centre for the Public Awareness of Science, Australian National University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Heavy rains are great news for Sydney’s dams, but they come with a big caveat
Ian Wright, Western Sydney University and Jason Reynolds, Western Sydney University
Throughout summer, Sydney’s water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.
But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.
This is great news for the city, but it comes with a big caveat. Floodwaters will undoubtedly wash bushfire debris into reservoirs – possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.
Reservoirs filled with rain
The water level of Sydney’s massive Lake Burragorang – the reservoir behind Warragamba Dam – rose by more than 11 meters this week. Warragamba supplies more than 80% of Sydney’s water.
Other Sydney water storages, including Nepean and Tallowa dams, are now at 100%.
WaterNSW report that 865,078 megalitres of extra water has been captured this week across all Greater Sydney’s dams.
This dwarfs the volume of water produced by Sydney’s desalination plant, which produces 250 megalitres a day when operating at full capacity. Even at this rate, it would take more than 3,400 days (or nine years) to match the volume of water to added to Sydney’s supply this week.
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But then comes the pollution
Thankfully, the rain appears to have extinguished bushfires burning in the Warragamba catchment for months.
But the water will also pick up bushfire debris and wash it into dams.
Over the summer, bushfires burnt about 30% of Warragamba Dam’s massive 905,000 hectare water catchment, reducing protective ground cover vegetation. This increases the risk of soil erosion. Rain will wash ash and sediment loads into waterways – adding more nitrogen, phosphorous and organic carbon into water storages.
Read more:
Bushfires threaten drinking water safety. The consequences could last for decades
Waterways and ecosystems require nutrients like phosphorous and nitrogen, but excess nutrients aren’t a good thing. They bring contamination risks, such as the rapid growth of toxic blue-green algae.
Drinking water catchments will always have some degree of contamination and water treatment consistently provides high quality drinking water. But poor water quality after catchment floods is not without precedent.
We’ve seen this before
In August 1998, extreme wet weather and flooding rivers filled the drought-affected Warragamba Dam in just a few days.
This triggered the Cryptosporidium crisis, when the protozoan parasite and the pathogen Giardia were detected in Sydney’s water supplies. It triggered health warnings, and Sydneysiders were instructed to boil water before drinking it. This event did not involve a bushfire.
Read more:
Better boil ya billy: when Australian water goes bad
The Canberra bushfires in January 2003 triggered multiple water quality problems. Most of the region’s Cotter River catchments, which hold three dams, were burned. Intense thunderstorms in the months after the bushfire washed enormous loads of ash, soil and debris into catchment rivers and water reservoirs.
This led to turbidity (murkiness), as well as iron, manganese, nitrogen, phosphorus and carbon in reservoir waters. The inflow of organic material also depleted dissolved oxygen which triggered the release of metals from reservoir sediment. At times, water quality was so poor it couldn’t be treated and supplied to consumers.
The ACT Government was forced to impose water restrictions, and built a A$38 million water treatment plant.
Have we come far enough?
Technology in water treatment plants has developed over the past 20 years, and water supply systems operates according to Australian drinking water guidelines.
Unlike the 1998 Sydney water crisis, WaterNSW, Sydney Water and NSW Health now have advanced tests and procedures to detect and manage water quality problems.
In December last year, WaterNSW said it was aware of the risk bushfires posed to water supplies, and it had a number of measures at its disposal, including using booms and curtains to isolate affected flows.
However at the time, bushfire ash had already reportedly entered the Warragamba system.
Author provided
Look to recycled water
Sydney’s water storages may have filled, but residents should not stop saving water. We recommend Level 2 water restrictions, which ban the use of garden hoses, be relaxed to Level 1 restrictions which ban most sprinklers and watering systems, and the hosing of hard surfaces.
While this measure is in place, longer term solutions can be explored. Expanding desalination is a popular but expensive option, however greater use of recycled wastewater is also needed.
Read more:
80% of household water goes to waste – we need to get it back
Highly treated recycled water including urban stormwater and even treated sewage should be purified and incorporated into the water supply. Singapore is a world leader and has proven the measure can gain community acceptance.
It’s too early to tell what impact the combination of bushfires and floods will have on water storages. But as extreme weather events increase in frequency and severity, all options should be on the table to shore up drinking water supplies.
Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University and Jason Reynolds, Senior Lecturer in Geochemistry, Western Sydney University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Trees can add $50,000 value to a Sydney house, so you might want to put down that chainsaw
Tom Casey/Shutterstock
Sara Wilkinson, University of Technology Sydney; Agnieszka Zalejska-Jonsson, KTH Royal Institute of Technology, and Sumita Ghosh, University of Technology Sydney
Sydney’s Inner West Council has a new policy that it is reported means “residents will no longer need to seek council approval to prune or remove trees within three metres of an existing home or structure”. Hold on, don’t reach for that chainsaw yet, because research shows good green infrastructure – trees, green roofs and walls – can add value to your home.
Green infrastructure offers significant, economic, social and environmental benefits. Urban greening is particularly important in dense urban areas like Sydney’s Inner West. Among its benefits, green infrastructure:
- improves air quality
- provides space for social interaction
- manages stormwater
- reduces the urban heat island effect
- provides space for urban food production
- improves biodiversity.
Some of these benefits accrue to owners/occupiers, whereas others provide wider societal benefits.
Read more:
Higher-density cities need greening to stay healthy and liveable
A 2017 study focusing on three Sydney suburbs found a 10% increase in street tree canopy could increase property values by A$50,000 on average. And the shading effect of trees can reduce energy bills by up to A$800 a year in Sydney. So retaining your green infrastructure – your trees, that is – can deliver direct financial gains.
On a larger scale, a collaborative project with Horticulture Innovation Australia Limited compared carbon and economic benefits from urban trees considering different landuses along sections of two roads in Sydney. Higher benefits were recorded for the Pacific Highway, with 106 trees per hectare and 58.6% residential land use, compared to Parramatta Road, with 70 trees per hectare and 15.8% residential.
For the Pacific Highway section, total carbon storage and the structural value of trees (the cost of replacing a tree with a similar tree) were estimated at A$1.64 million and A$640 million respectively. Trees were also valuable for carbon sequestration and removing air pollution.
Tree species, age, health and density, as well as land use, are key indicators for financial and wider ecosystem benefits. Specifically, urban trees in private yards in residential areas are vital in providing individual landowner and collective government/non-government benefits.
Graeme Bartlett/Wikipedia, CC BY-SA
Challenges of growth
As populations grow, cities increase density, with less green infrastructure. The loss of greenery affects the natural environment and both human and non-human well-being.
Read more:
We’re investing heavily in urban greening, so how are our cities doing?
© State of New South Wales through the Greater Sydney Commission. Data: SPOT5 Woody Extent and Foliage Projective Cover (FPH) 5-10m, 2011, NSW Office of Environment and Heritage
Trees and other green infrastructure reduce some impacts of urban density. However, policies, government incentives and national priorities can produce progress in urban greening or lead to setbacks. In the case of the Inner West Council, for instance, the inability to fund monitoring of changes in tree cover could lead to reductions at the very time when we need more canopy cover.
Key concerns include installation and maintenance costs of green infrastructure (trees, green roofs and walls) in property development, and tree root damage. Knowledge and skills are needed to maintain green infrastructure. As a result, developers often consider other options more feasible.
In the short and long term, multiple performance benefits and economic and environmental values are needed to establish the viability of green infrastructure.
Read more:
Australian cities are lagging behind in greening up their buildings
Learning from Stockholm
Stockholm shares many issues found in Australian cities. Stockholm houses over 20% of Sweden’s inhabitants, is increasing in density and redeveloping land to house a growing population. Aiming to be fossil-free by 2050, Stockholm acknowledges the built environment’s role in limiting climate change and its impacts.
In a research project we intend to use virtual reality (VR) and electroencephalogram (EEG) technology to assess perceptions of green infrastructure and reactions to it in various spaces.
Our project combines VR with EEG hardware, which measures human reactions to stimuli, to learn how people perceive and value green infrastructure in residential development.
Identifying all the value of green infrastructure
The many benefits of green infrastructure are both tangible and non-tangible. Economic benefits include:
- those that directly benefit owners, occupants or investors – stormwater, increased property values and energy savings
- other financial impacts – greenhouse gas savings, market-based savings and community benefits.
Read more:
If planners understand it’s cool to green cities, what’s stopping them?
The various approaches to evaluating net value present a challenge in quantifying the value of green infrastructure. The most common – cost-benefit analysis, triple bottom line, life cycle assessment and life cycle costing – are all inadequate for evaluating trade-offs between economic and environmental performance. Conventional cost-benefit analysis is insufficient for investment analysis, as it doesn’t include environmental costs and benefits.
This is salient for green infrastructure, as owners/investors incur substantial direct costs, whereas various shareholders share the value. Perhaps, in recognition of the shared value, a range of subsidies could be adopted to compensate investors. Discounted rates anyone?
Recent efforts to evaluate the business case for green infrastructure include attempts to identify and quantify the creation of economic, environment and community/social value. However, an approach that includes a more comprehensive set of value drivers is needed to do this. This is the gap we aim to fill.
The results of experiments using VR and EEG technology and semi-structured interviews will provide a comprehensive understanding of green infrastructure. This will be correlated with capital and rental values to determine various degrees of willingness to pay.
With this knowledge, property developers in Sweden and Australia will be able to make a more informed and holistic business case for increasing green infrastructure for more liveable, healthy cities.
Maybe we can then persuade more people, including those in the Inner West, to hang onto their trees and leave the chainsaws in the garage.
Sara Wilkinson, Professor, School of the Built Environment, University of Technology Sydney; Agnieszka Zalejska-Jonsson, Researcher, Division of Building and Real Estate Economics, KTH Royal Institute of Technology, and Sumita Ghosh, Associate Professor in Planning, School of the Built Environment, University of Technology Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Sydney declares a climate emergency – what does that mean in practice?
Late on Monday night, the City of Sydney became the first state capital in Australia to officially declare a climate emergency. With climate change considered a threat to human life, Sydney councillors unanimously supported a motion put forward by Lord Mayor Clover Moore to mobilise city resources to reduce carbon emissions and minimise the impact of future change.
The decision sees Sydney join a variety of local and national governments around the world, in a movement that is increasingly gaining momentum. In total, some 658 local governments around the world have made the same declaration, with the UK and Canada committing their national governments to the global movement in just the past two months.
An official declaration of climate emergency puts a government on a “wartime mobilisation” that places climate change at the centre of policy and planning decisions.
Read more:
UK becomes first country to declare a ‘climate emergency’
While interpretations differ on what a “climate emergency” means in practice, governments have established a range of measures to help meet the targets set by the Paris climate agreement. Under this agreement, 197 countries have pledged to limit global temperature rise to less than 2℃ above pre-industrial levels, and ideally no more than 1.5℃.
With 2018 having brought all manner of record-breaking climate extremes, and global average temperatures projected to reach 3.2℃ above the pre-industrial average based on current national pledges and targets for greenhouse emissions, Sydney’s recognition of a national emergency is both highly appropriate and also a major turning-point for Australia.
Although a signatory to the Paris Agreement, Australia’s greenhouse emissions have risen over the past four years since the repeal of the carbon price. With Australian emissions most notably increasing around transport, the United Nations climate discussions currently being held in Bonn have raised concerns over the nation’s ability to meet its Paris commitments.
Economic impacts
With the global cost of inaction on climate change projected to reach a staggering US$23 trillion a year by the end of the century (equivalent to around five 2008 global financial crises every year), several nations are already ramping up their Paris Agreement commitments ahead of schedule. The UK recently announced its intention to be carbon-neutral by 2050.
Australia is particularly vulnerable to the future financial costs of climate change, with economic models suggesting losses of A$159 billion a year through the impact of sea level rise and drought-driven collapses in agricultural productivity. The cost for each household has been put at about A$14,000.
Read more:
Cutting cities’ emissions does have economic benefits – and these ultimately outweigh the costs
After Sydney’s declaration, 150 faith leaders on Tuesday signed an open letter endorsing the decision, and describing the climate issue as a moral challenge that transcends religious belief. They have called for an urgent mobilisation to reach 100% renewable energy by the year 2030, and for an end to the approval of any new coal and gas projects, including Adani’s controversial Carmichael coal mine in Queensland.
The recent court ruling against the proposed Rocky Hill coal mine in the New South Wales Hunter Valley – a decision made partly on climate grounds – could mark a crucial turning point in the fortunes of future mining projects.
Read more:
Landmark Rocky Hill ruling could pave the way for more courts to choose climate over coal
As part of its emergency declaration, Sydney has also called on the federal government to establish a “just transition authority” to support Australians currently employed in fossil fuel industries. This is an urgent issue and a crucial part of the transition to a low-emissions economy.
A major nationwide training program will be needed to help re-skill the estimated 8,000 people who work in fossil-fuelled electricity production, and to help fill the tens of thousands of new jobs in renewable energy-related fields.
With the scale of change required to decarbonise the global economy and hopefully avoid a 2℃ warmer world, the need to support communities across Australia and overseas will likely become an increasing challenge for governments around the world. Putting ourselves on an emergency footing could help provide precisely the impetus we need.
Chris Turney, Professor of Earth Science and Climate Change, ARC Centre of Excellence for Australian Biodiversity and Heritage, UNSW
This article is republished from The Conversation under a Creative Commons license. Read the original article.
The backflip over Sydney’s marine park is a defiance of science
John Turnbull
David Booth, University of Technology Sydney and John Turnbull, UNSW
The New South Wales government’s decision to back away from establishing no-fishing zones in waters around Sydney leaves significant question marks over the plan, which is open for public consultation until September 27.
Fisheries Minister Niall Blair explained the apparent backflip by saying he was “confident that fishing is not the key threat to the sustainability of our marine environment”, after receiving what he described as “robust” feedback from local communities and anglers.
NSW government
The originally proposed Sydney Marine Park comprised 17 “sanctuary zones” (totalling 2.4% of the area, including estuaries), 3 “conservation zones” totalling 2.6%, and 21 “special purpose zones”, which would allow (and in some cases protect) fishing.
Sanctuary zones allow no fishing; conservation zones allow taking of lobster and abalone (see below); and special purpose zones have a range of restrictions or allowances, not necessarily of any conservation benefit. For instance, four offshore artificial reefs are classed as special purpose zones.
The plans cover the waters around Sydney, stretching from Newcastle in the north to Wollongong in the south. Formally known as the Hawkesbury Shelf marine bioregion, it is the only bioregion wholly in NSW that does not have a marine park. This is despite Sydney’s magnificent array of underwater and coastal habitats, which are home to more fish species than the entire British Isles.
Read more:
Recreational fishing in marine parks: you can’t be serious!
New zones and ranked threats
The original marine park proposal was far from ideal. A good marine park should have a string of closely connected sanctuary zones, but there was a large gap from southern Sydney to Wollongong where no sanctuary zones were proposed.
Instead, there was a new “conservation zone” to allow fishing for lobster and abalone. Yet lobster in particular are important to this ecosystem, because they protect kelp by preying on sea urchins.
NSW government
The NSW government based its earlier proposal on a principle called TARA, short for “threat and risk assessment”, in which all perceived factors are ranked according to their environmental, social and economic outcomes.
While other major threats such as climate change and pollution are ranked highly, fishing doesn’t appear until number 18 on the government’s list (see page 8 here. One reason for this is that fishing is split into eight categories (such as “recreational fishing by boat – line and trap”), masking its overall impact. Even 4WDs on beaches are ranked as a greater threat to the environment than many types of fishing.
Premier Gladys Berejiklian’s press release about the marine park public consultation didn’t mention the environmental threat posed by fishing at all. Yet there is clear evidence that fishing directly harms fish stocks.
One recent study shows that stocks of inshore fish species have declined in Australia by 30% in a decade, except in sanctuary zones. Worldwide, sanctuary zones (also called no-take zones) have been shown to help fish grow larger and more abundant. And recent studies in NSW coastal waters have reiterated the benefits of no-take zones for species such as morwong, bream, and snapper.
Partial protection doesn’t work
The latest proposals, which would allow recreational but not commercial fishing, would be much less effective than full protection. One recent study suggested that partial protection is no better than no protection at all.
According to a NSW government estimate, recreational fishing removes more than 3 million fish, crustaceans and molluscs from NSW coastal waters every year. But marine parks are primarily about conservation, and this requires us to face some stark realities. With more than 8 million people likely to call Sydney home in the next 40 years, pressures on our coasts will only increase.
Sanctuary zones are one of the best available conservation tools to guard against these impacts. These zones have also been shown to make wildlife more resilient to climate change.
Even before the government’s decision to rescind the proposed sanctuary zones, the original plan for no-take zones to cover just 2.4% of the region was a severe compromise. By comparison, the Great Barrier Reef Marine Park has 30% sanctuary zone coverage, and the rest of NSW has 7-8%. International best practice recommends at least 20%, and even the Commonwealth Marine Reserves Management Plan offers 6% no-take coverage.
But now, with no sanctuary zones, Sydney’s proposed “marine park” is not worthy of the name.
Wrong priorities
A peculiar contradiction is that despite one-quarter of the listed threats being fishing-related, the NSW government’s marine estate management strategy includes an initiative to encourage fishing. Pollution is also a high-priority threat, and fishing is the largest source of subtidal debris.
John Turnbull
If local-level threats such as fishing and litter are not dealt with, resilience to climate change suffers as a result. We must tackle all threats – overfishing, pollution, climate change – and not shy away from one because it’s politically unpalatable.
Read more:
Marine parks for fish and people: here’s how to do it
It is frustrating that the NSW government has opted to abolish these marine sanctuaries before the public consultation was complete. The wider public understands the value of sanctuary zones, as indicated in recent opinion polls showing clear support for the original plans among Sydneysiders – even many of those who fish.
Some fishers are now calling for sanctuary zones to be scrapped or wound back in other iconic NSW marine parks, such as Lord Howe Island and Solitary Islands. This move would be a defiance of the science. The evidence shows that sanctuary zones are essential for restoring and preserving our marine estate for future generations.
David Booth, Professor of Marine Ecology, University of Technology Sydney and John Turnbull, , UNSW
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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