It is once again time to have a bit of a break and this time I am aiming for a two-week break. I find it much better to be proactive when certain little signs begin to appear in my health than to wait for something more major to occur. So a little downtime and a little more sleep are what I require at the moment. So, I’ll be back in a couple of weeks.
Monthly Archives for May 2021
Native forest logging makes bushfires worse – and to say otherwise ignores the facts
Philip Zylstra, University of Wollongong; Grant Wardell-Johnson, Curtin University; James Watson, The University of Queensland, and Michelle Ward, The University of QueenslandThe Black Summer bushfires burned far more temperate forest than any other fire season recorded in Australia. The disaster was clearly a climate change event; however, other human activities also had consequences.
Taking timber from forests dramatically changes their structure, making them more vulnerable to bushfires. And, crucially for the Black Summer bushfires, logged forests are more likely to burn out of control.
Naturally, the drivers of the fires were widely debated during and after the disaster. Research published earlier this month, for example, claimed native forest logging did not make the fires worse.
We believe these findings are too narrowly focused and in fact, misleading. They overlook a vast body of evidence that crown fire – the most extreme type of bushfire behaviour, in which tree canopies burn – is more likely in logged native forests.
Australian National University
Crown fires vs scorch
The Black Summer fires occurred in the 2019-20 bushfire season and burned vast swathes of Australia’s southeast. In some cases, fire spread through forests with no recorded fire, including some of the last remnants of ancient Gondwanan rainforests.
Tragically, the fires directly killed 33 people, while an estimated 417 died due to the effects of smoke inhalation. A possible three billion vertebrate animals perished and the risk of species extinctions dramatically increased.
Much of the forest that burned during Black Summer experienced crown fires. These fires burn through the canopies of trees, as well as the undergrowth. They are the most extreme form of fire behaviour and are virtually impossible to control.
Crown fires pulse with such intense heat they can form thunderstorms which generate lightning and destructive winds. This sends burning bark streamers tens of kilometres ahead of the fire, spreading it further. The Black Summer bushfires included at least 18 such storms.
Various forest industry reports have recognised logging makes bushfires harder to control.
And to our knowledge, every empirical analysis so far shows logging eucalypt forests makes them far more likely to experience crown fire. The studies include:
- A 2009 paper suggesting changes in forest structure and moisture make severe fire more likely in logging regrowth compared to undisturbed forest
- 2012 research concluding the probability of crown fires was higher in recently logged areas than in areas logged decades before
- A 2013 study that showed the likelihood of crown fire halved as forests aged after a certain point
- 2014 findings that crown fire in the Black Saturday fires likely peaked in regrowth and fell in mature forests
- 2018 research into the 2003 Australian Alps fires, which found the same increase in the likelihood of crown fire during regrowth as was measured following logging.
The findings of these studies are represented in the image below. The lines a, b and c refer to the 2013, 2014 and 2018 studies respectively.
Author supplied
Crown fires take lives
The presence of crown fire is a key consideration in fire supression, because crown fires are very hard to control.
However, the study released last week – which argued that logging did not worsen the Black Summer fires – focused on crown “scorch”. Crown scorch is very different to crown fire. It is not a measure of how difficult it is to contain the fire, because even quite small flames can scorch a drought-stressed canopy.
Forestry studies tend to focus more on crown scorch, which damages timber and is far more common than crown fires.
But the question of whether logging made crown scorch worse is not relevant to whether a fire was uncontrollable, and thus was able to destroy homes and lives.
Importantly, when the study said logging had a very small influence on scorch, this was referring to the average scorch over the whole fire area, not just places that had been logged. That’s like asking how a drought in the small town of Mudgee affects the national rainfall total: it may not play a large role overall, but it’s pretty important to Mudgee.
The study examined trees in previously logged areas, or areas that had been logged and burned by fires of any source. It found they were as likely to scorch on the mildest bushfire days as trees in undisturbed forests on bad days. These results simply add to the body of evidence that logging increases fire damage.
Richard Wainwright/AAP
Managing forests for all
Research shows forests became dramatically less likely to burn when they mature after a few decades. Mature forests are also less likely to carry fire into the tree tops.
For example during the Black Saturday fires in 2009, the Kilmore East fire north of Melbourne consumed all before it as a crown fire. Then it reached the old, unlogged mountain ash forests on Mount Disappointment and dropped to the ground, spreading as a slow surface fire.
The trees were scorched. But they were too tall to ignite, and instead blocked the high winds and slowed the fire down. Meanwhile, logged ash forests drove flames high into the canopy.
Despite decades of opportunity to show otherwise, the only story for eucalypt forests remains this: logging increases the impact of bushfires. This fact should inform forest management decisions on how to reduce future fire risk.
We need timber, but it must be produced in ways that don’t endanger human lives or the environment.
Philip Zylstra, Adjunct Associate Professor at Curtin University, Honorary Fellow at University of Wollongong, University of Wollongong; Grant Wardell-Johnson, Associate Professor, Environmental Biology, Curtin University; James Watson, Professor, The University of Queensland, and Michelle Ward, PhD Candidate, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Mouse plague: bromadiolone will obliterate mice, but it’ll poison eagles, snakes and owls, too
Belinda Davis, Author provided
Robert Davis, Edith Cowan University; Bill Bateman, Curtin University; Damian Lettoof, Curtin University; Maggie J. Watson, Charles Sturt University, and Michael Lohr, Edith Cowan UniversityIt’s the smell that hits you first. The scent of urine and decomposing bodies. Then you notice other signs: scuttles and squeaks, small dead bodies leaking blood, tails sticking out of hubcaps.
If you’ve lived through a mouse plague, you’ve seen this, and smelled the stench of mice dying of poison baits.
As a desperate measure to help combat the mouse plague devastating rural communities across New South Wales, the state government yesterday secured 5,000 litres of bromadiolone. This is a bait that’s usually illegal to roll out at the proposed scale.
This is a bad idea. While bromadiolone effectively kills mice, it also travels up the food chain to poison predators who eat the mice, and other species. And these predators, from wedge-tailed eagles to goannas, are coming out in droves to feast on their abundant prey.
When your prey is everywhere
Animal plagues in Australia are fuelled by the “boom and bust” of rainfall.
We have natural, flood-driven population explosions of the native long-haired rat, with accompanying booms of letter-winged kites, their predator. We also have locust plagues when the conditions are right, leading to antechinus or mice plagues which eat the locusts.
Since at least the late 1800s, we’ve had terrible plagues of the introduced house mouse (Mus musculus). But rarely has it been this bad, with conditions currently seeming worse than the last plague in 2011, which caused over A$200 million in crop damage alone.
High numbers of birds of prey — nankeen kestrels, black-shouldered kites and barn owls — are often reported feasting on plague mice.
Snakes, goannas, native carnivores such as quolls, and feral cats and foxes, also take advantage of the abundant food. Pets, especially cats and some dogs, are highly likely to consume mice under these conditions, too.
Poisoning the food web
Laying out poison baits is one way people try to end mouse infestations and plagues. So-called “anticoagulant rodenticides” are divided into first and second generations, based on when they were first synthesised and the differences in potency.
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Second generation anticoagulant rodenticides have higher toxicities than first generation, and are lethal after a single feed. First generation rodenticides, on the other hand, require rodents to feed on them for consecutive days to be lethal.
But mouse-eating predators are highly exposed to second generation rodenticides. For most animal species, the lethal doses of rodenticide aren’t yet known.
A scientific review from 2018 documented the poisoning of 31 bird, five mammal and one reptile species. Second generation aniticoaugulant rodenticides were implicated in the death of these animals.
Our research from 2020 found urban reptiles are highly exposed to second generation rodenticides, too. This includes mouse-eating snakes, called dugites, which had up to five different rodent poisons in them.
We also found poisons in frog-eating tiger snakes, and in omnivorous bobtail skinks which eat fruit, vegetation and snails. This is even more concerning because it shows how second generation rodenticides can saturate the entire foodweb, affecting everything from slugs to fish.
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Bromadiolone is particularly dangerous, even to humans
The NSW government secured bromadiolone baits as part of its $50 million mouse plague support package for regional communities.
Five thousand litres of the poison can treat around 95 tonnes of grain, and the government will provide it for free to primary producers once federal authorities approve its use.
Bromadiolone is usually restricted to use in and around buildings. But given the widespread impacts on wildlife, using bromadiolone at the proposed scale will do more harm than good.
Past research on bromadiolone has shown residues persist for up to 135 days in the carcasses of voles (another rodent species). In international studies, bromadiolone has been found in the livers of a host of birds of prey, including a range of owl species, red kites, sparrowhawks and golden eagles.
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And it’s not just a problem for wildlife, humans are also at risk of exposure. For example, we can get exposed from eating eggs from chickens that feed on poisoned mice, or more directly from eating other animals that may have ingested poisoned mice.
A 2013 study looked at chicken eggs for human consumption, and detected bromadiolone in eggs between five and 14 days after the chicken ingested the poison. It’s not yet clear how many of these eggs we’d have to eat for us to get sick.
So what are the alternatives?
There are highly effective first generation rodenticides that provide viable solutions for managing mouse plagues. They may take a little longer to kill mice, but the upshot is they don’t stick around in the environment. A 2020 study found house mice in Perth didn’t have genetic resistance to first generation rodenticides, which suggests they’re effectively lethal.
Another approach has been to use zinc phosphide, a poison which is unlikely to secondarily poison other animals that eat the poisoned mice. However, zinc phosphide is still extremely toxic and will kill sheep, cows, pets and even humans if directly eaten.
Rolling out double-strength zinc phosphide may be the lesser of the evils in causing secondary poisoning, but only if used very carefully.
And another way to help control the mouse plague is to limit food resources for mice on farms. Farmers can minimise grain on ground, and Australia should invest in research for grain storage facilities that are less permeable to mice.
Mouse plagues are a regular cycle in Australia. Natural predators not only help create healthy, natural ecosystems, but also they help with mouse control. Second generation rodenticides will only destroy and weaken the predator populations we need to help us combat the next plague.
Robert Davis, Senior Lecturer in Wildlife Ecology, Edith Cowan University; Bill Bateman, Associate professor, Curtin University; Damian Lettoof, PhD Candidate, Curtin University; Maggie J. Watson, Lecturer in Ornithology, Ecology, Conservation and Parasitology, Charles Sturt University, and Michael Lohr, Adjunct Lecturer, Edith Cowan University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Government-owned firms like Snowy Hydro can do better than building $600 million gas plants
Arjuna Dibley, The University of MelbourneThe Morrison government today announced it’s building a new gas power plant in the Hunter Valley, committing up to A$600 million for the government-owned corporation Snowy Hydro to construct the project.
Critics argue the plant is inconsistent with the latest climate science. And a new report by the International Energy Agency has warned no new fossil fuel projects should be funded if we’re to avoid catastrophic climate change.
The move is also inconsistent with research showing government-owned companies can help drive clean energy innovation. Such companies are often branded as uncompetitive, stuck in the past and unable to innovate. But in fact, they’re sometimes better suited than private firms to take investment risks and test speculative technologies.
And if the investments are successful, taxpayers, the private sector and consumers share the benefits.
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Lead, not limit
Federal energy minister Angus Taylor announced the funding on Wednesday. He said the 660-megawatt open-cycle gas turbine at Kurri Kurri will “create jobs, keep energy prices low, keep the lights on and help reduce emissions”.
Experts insist the plan doesn’t stack up economically and may operate at less than 2% capacity.
But missing from the public debate is the question of how government-owned companies such as Snowy Hydro might be used to accelerate the clean energy transition.
Australian governments (of all persuasions) have not often used the companies they own to lead in clean energy innovation. Many, such as Hydro Tasmania, still rely on decades-old hydroelectric technologies. And others, such as Queensland’s Stanwell Corporation and Western Australia’s Synergy, rely heavily on older coal and gas assets.
Asking Snowy Hydro to build a gas-fired power plant is yet another example – but it needn’t be this way.
Read more:
A single mega-project exposes the Morrison government’s gas plan as staggering folly
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The burning question
Globally, more than 60% of electricity comes from wholly or partially state-owned companies. In Australia, despite the 20-year trend towards electricity privatisation, government-owned companies remain important power generators.
At the Commonwealth level, Snowy Hydro provides around 20% of capacity to New South Wales and Victoria. And most electricity in Queensland, Tasmania and Western Australia is generated by state government-owned businesses.
But political considerations mean government-owned electricity companies can struggle to navigate the clean energy path.
For example in April this year, the chief executive of Stanwell Corporation, Richard Van Breda, suggested the firm would mothball its coal-powered generators before the end of their technical life, because cheap renewables were driving down power prices.
Queensland’s Labor government was reportedly unhappy with the announcement, fearing voter backlash in coal regions. Breda has since stepped down and Stanwell is reportedly backtracking on its transition plans.
Such examples beg the question: can government-owned companies ever innovate on clean energy? A growing literature in economics, as well as several real-world examples, suggest that under the right conditions, the answer is yes.
Read more:
The 1.5℃ global warming limit is not impossible – but without political action it soon will be
Stanwell Corporation
Privatised is not always best
Economists have traditionally argued state-owned companies are not good innovators. As the argument goes, the absence of competitive market forces makes them less efficient than their private sector peers.
But recent research by academics and international policy institutions such as the OECD has shown government ownership in the electricity sector can be an asset, not a curse, for achieving technological change.
The reason runs contrary to orthodox economic thinking. While competition can lead to firm efficiency, some economists argue government-owned firms can take greater risks. Without the pressure for market-rate returns to shareholders, government enterprises may be freer to invest in more speculative technologies.
My ongoing research has shown the reality is even more complex. Whether state-owned electric companies can drive clean energy innovation depends a great deal on government interests and corporate governance rules.
For example, consider the New York Power Authority (NYPA) which, like Snowy Hydro, is wholly government owned.
New York Governor Andrew Cuomo has deliberately sought to use NYPA to decarbonise the state’s electricity grid. The government has managed the company in a way that enables it to take risks on new transmission and generation technologies that investor-owned peers cannot.
For instance, NYPA is investing in advanced sensors and computing systems so it can better manage distributed energy sources such as solar and wind. The technology will also simulate major catastrophic events, including those likely to ensue from climate change.
These investments are likely to contribute to greater grid stability and greater renewables use, benefiting not just NYPA but other electricity generators and ultimately, consumers.
Such innovation is nothing new. Also in the US, the state-owned Sacramento Municipal Utility District built one of the first utility-scale solar projects in the world in 1984.
Mary Altaffer/AP
The way forward
More could be done to ensure Australian government-owned corporations are clean energy catalysts.
Clean energy technologies can struggle to bridge the gap from invention to widespread adoption. Public investment can bring down the price of such technologies or demonstrate their efficacy.
In this regard, government-owned companies could work with private technology firms to invest in technologies in the early stages of development, and which could have significant public benefits. For instance, in 2020, the Western Australian government-owned company Synergy sought to build a 100 megawatt battery with private sector partners.
But many problems facing state-owned companies are the result of ever-changing government policy priorities. The firms should be reformed so they are owned by government, but operated at arm’s length and with other partners. This might better enable clean energy investment without the politics.
Arjuna Dibley, Visiting Researcher, Climate and Energy College, The University of Melbourne
This article is republished from The Conversation under a Creative Commons license. Read the original article.
International Energy Agency warns against new fossil fuel projects. Guess what Australia did next?
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Samantha Hepburn, Deakin UniversityEven if every country meets its current climate targets, Earth’s temperature will still rise by a dangerous 2.1℃ this century, according to sobering findings from a new International Energy Agency report.
The IEA found the route to net-zero greenhouse gas emissions by 2050 was “narrow and extremely challenging”, and electricity grids in developed economies such as Australia must be zero emissions by 2053. The IEA was abundantly clear: no new fossil fuel projects should be approved.
The report couldn’t come at a worse time for the Morrison government. This week, it announced A$600 million for a major new gas-fired power plant at Kurri Kurri in New South Wales, claiming it was needed to shore up electricity supplies.
The IEA’s findings cast serious doubt on this decision, and put even more pressure on Australia ahead of crucial international climate talks in Glasgow in November. So let’s take a look at the report in more detail, and see how Australia measures up.
What the report said
The IEA report sets out a comprehensive roadmap to achieve net-zero emissions by 2050. The good news is this is still achievable. But it’ll take a lot money and enormous effort.
There must be what the report describes as a “total transformation of the energy systems that underpin our economies”. Put simply, the world’s energy economy must be grounded in solar and wind — not coal, gas and oil.
The report works from a basic principle: even if the climate pledges countries have made under the Paris agreement are fully achieved, there will still be 22 billion tonnes of global carbon dioxide emissions in 2050.
This is well short of net zero.
So the IEA set out more than 400 milestones to achieve the global energy transformation. And these absolutely must be complied with if we’re to stop catastrophic global warming and limit temperature rise to 1.5℃.
The milestones include:
Massive investment in electricity networks
Enormous amounts of money are needed to shift away from fossil fuels and meet the global electricity demand doubling over the next 30 years. Existing networks took 130 years to build — we need to build the same again in about one-sixth the time. This includes investing in hydrogen and bio-energy (energy made from organic material), which the report calls a “pillar of decarbonisation”.
Read more:
The 1.5℃ global warming limit is not impossible – but without political action it soon will be
Transport
Electric vehicles need to rapidly expand to 65% of the global fleet by 2030, and 100% by 2050. This will require an enormous increase in public electric vehicle charging units and hydrogen refuelling units. To facilitate this shift, petrol and diesel will be phased out. Many countries around the world, including the United Kingdom and Japan, have already introduced a ban on new fossil fuel cars by 2030.
Building and industry
We need to urgently retrofit homes and buildings to make them more energy efficient. Steel, cement and chemical industries, primary emitters, must shift to carbon capture and sequestration and hydrogen.
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But the biggest take-home message for Australia is there must be no new development in fossil fuel beyond 2021.
No new fossil fuel development
The report states:
Beyond projects already committed as of 2021, there are no new oil and gas fields approved for development in our pathway, and no new coal mines or mine extensions are required.
Global demand for oil peaked in 2019, and has declined since then, largely due to COVID-19 lockdowns. Under the roadmap, this decline will continue and reach 75% by 2050. Any growth in demand during this period will be met by growing emergent markets in renewables, green hydrogen and bio-energy.
And of course, the report states no new coal plants should be financially supported unless equipped with carbon capture and sequestration. Inefficient coal plants must be phased out by 2030.
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If the roadmap is followed, renewable energy will overtake coal by 2026, and oil and gas by 2030.
For this to happen, annual additions of 630 gigawatts of solar and 390 gigawatts of wind power will be required by 2030. This means the world needs to install the equivalent of “the world’s largest solar park roughly every day”, according to the report.
Australia, are you listening?
Australia’s gas-fired recovery plans are directly inconsistent with the IEA roadmap. The government has argued expanding fossil fuel supply is critical for energy security.
Not only did the federal government just announce over a half a billion dollars for a new gas-fired power plant in NSW, it’s also spending a further $173 million to develop the Beetaloo basin in the Northern Territory, another gas reserve.
Read more:
Paying Australia’s coal-fired power stations to stay open longer is bad for consumers and the planet
Experts, advisers and Energy Security Board chair Kerry Schott have all disagreed with these moves. They argue, in line with the IEA report, that cheaper, cleaner alternatives to gas generation, such as wind and solar, can easily provide the dispatchable power required.
The government’s stubborn fossil fuel funding will make it more difficult than it already is to stop global warming beyond 1.5℃.
Australia must immediately stop investing in new fossil fuel projects. While this may be a difficult transition to accept given the enormous scope of gas reserves in Australia, there’s no point spending vast amounts of money on new infrastructure to extract a resource that will be commercially unviable in a decade.
Australia is ignoring the economic and environmental imperatives of transitioning to a low carbon framework. This is reckless, and unfair to other countries. We have the resource capacity and economic strength to transition our energy sector, unlike many developing countries. But we choose not to.
A national embarrassment
John Kerry, the US special presidential envoy for climate, says the next round of international climate talks in Scotland is the “last best chance the world has” to avoid a climate crisis.
But Australia’s investment in new gas development stands in stark contrast to the increasingly ambitious energy commitments of other developed countries. We shouldn’t come empty-handed, with no new targets, to yet another international climate summit.
US President Joe Biden has vowed to cut greenhouse gas emissions by 50-52% compared with 2005 levels. He has banned new oil and gas leases on federal land, removed fossil fuel subsidies and plans to double wind capacity by 2030.
Likewise, the European Commission seeks to stop funding oil and gas projects. Denmark recently implemented a ban on future gas extraction in the North Sea. And Spain has done the same.
Australia is ignoring its global responsibilities. As a result, we’ll be hit hard by the so-called “Carbon Border Adjustment” policies from the US and European Union, which tax imported goods according to their carbon footprint.
Ultimately, our actions will leave us economically and environmentally isolated in a rapidly emerging new energy world order.
Read more:
The EU is considering carbon tariffs on Australian exports. Is that legal?
Samantha Hepburn, Director of the Centre for Energy and Natural Resources Law, Deakin Law School, Deakin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
We sliced open radioactive particles from soil in South Australia and found they may be leaking plutonium
National Archives of Australia
Barbara Etschmann, Monash University; Joel Brugger, Monash University, and Vanessa Wong, Monash UniversityAlmost 60 years after British nuclear tests ended, radioactive particles containing plutonium and uranium still contaminate the landscape around Maralinga in outback South Australia.
These “hot particles” are not as stable as we once assumed. Our research shows they are likely releasing tiny chunks of plutonium and uranium which can be easily transported in dust and water, inhaled by humans and wildlife and taken up by plants.
A British nuclear playground
After the US atomic bombings of Hiroshima and Nagasaki in 1945, other nations raced to build their own nuclear weapons. Britain was looking for locations to conduct its tests. When it approached the Australian government in the early 1950s, Australia was only too eager to agree.
Between 1952 and 1963, Britain detonated 12 nuclear bombs in Australia. There were three in the Montebello Islands off Western Australia, but most were in outback South Australia: two at Emu Field and seven at Maralinga.
National Archives of Australia
Besides the full-scale nuclear detonations, there were hundreds of “subcritical” trials designed to test the performance and safety of nuclear weapons and their components. These trials usually involved blowing up nuclear devices with conventional explosives, or setting them on fire.
The subcritical tests released radioactive materials. The Vixen B trials alone (at the Taranaki test site at Maralinga) spread 22.2 kilograms of plutonium and more than 40 kilograms of uranium across the arid landscape. For comparison, the nuclear bomb dropped on Nagasaki contained 6.4 kilograms of plutonium, while the one dropped on Hiroshima held 64 kilograms of uranium.
These tests resulted in long-lasting radioactive contamination of the environment. The full extent of the contamination was only realised in 1984, before the land was returned to its traditional owners, the Maralinga Tjarutja people.
Hot potatoes
Despite numerous cleanup efforts, residual plutonium and uranium remains at Maralinga. Most is present in the form of “hot particles”. These are tiny radioactive grains (much smaller than a millimetre) dispersed in the soil.
Plutonium is a radioactive element mostly made by humans, and the weapons-grade plutonium used in the British nuclear tests has a half life of 24,100 years. This means even 24,100 years after the Vixen B trials that ended in 1963, there will still be almost two Nagasaki bombs worth of plutonium spread around the Taranaki test site.
Plutonium emits alpha radiation that can damage DNA if it enters a body through eating, drinking or breathing.
Read more:
Dig for secrets: the lesson of Maralinga’s Vixen B
In their original state, the plutonium and uranium particles are rather inactive. However, over time, when exposed to atmosphere, water, or microbes, they may weather and release plutonium and uranium in dust or rainstorms.
Until recently, we knew little about the internal makeup of these hot particles. This makes it very hard to accurately assess the environmental and health risks they pose.
Monash PhD student Megan Cook (the lead author on our new paper) took on this challenge. Her research aimed to identify how plutonium was deposited as it was carried by atmospheric currents following the nuclear tests (some of it travelled as far as Queensland!), the characteristics of the plutonium hot particles when they landed, and potential movement within the soil.
Nanotechnology to the rescue
Previous studies used the super intense X-rays generated by synchrotron light sources to map the distribution and oxidation state of plutonium inside the hot particles at the micrometre scale.
To get more detail, we used X-rays from the Diamond synchrotron near Oxford in the UK, a huge machine more than half a kilometre in circumference that produces light ten billion times brighter than the Sun in a particle accelerator.
Studying how the particles absorbed X-rays revealed they contained plutonium and uranium in several different states of oxidation – which affects how reactive and toxic they are. However, when we looked at the shadows the particles cast in X-ray light (or “X-ray diffraction”), we couldn’t interpret the results without knowing more about the different chemicals inside the particles.
To find out more, we used a machine at Monash University that can slice open tiny samples with a nanometre-wide beam of high-energy ions, then analyse the elements inside and make images of the interior. This is a bit like using a lightsaber to cut a rock, only at the tiniest of scales. This revealed in exquisite detail the complex array of materials and textures inside the particles.
Cook et al (2021), Scientific Reports, Author provided
Much of the plutonium and uranium is distributed in tiny particles sized between a few micrometres and a few nanometres, or dissolved in iron-aluminium alloys. We also discovered a plutonium-uranium-carbon compound that would be destroyed quickly in the presence of air, but which was held stable by the metallic alloy.
This complex physical and chemical structure of the particles suggests the particles formed by the cooling of droplets of molten metal from the explosion cloud.
In the end, it took a multidisciplinary team across three continents — including soil scientists, mineralogists, physicists, mineral engineers, synchrotron scientists, microscopists, and radiochemists — to reveal the nature of the Maralinga hot particles.
From fire to dust
Our results suggest natural chemical and physical processes in the outback environment may cause the slow release of plutonium from the hot particles over the long term. This release of plutonium is likely to be contributing to ongoing uptake of plutonium by wildlife at Maralinga.
Even under the semi-arid conditions of Maralinga, the hot particles slowly break down, liberating their deadly cargo. The lessons from the Maralinga particles are not limited to outback Australia. They are also useful in understanding particles generated from dirty bombs or released during subcritical nuclear incidents.
Read more:
Friday essay: the silence of Ediacara, the shadow of uranium
There have been a few documented instances of such incidents. These include the B-52 accidents that resulted in the conventional detonation of thermonuclear weapons near Palomares in Spain in 1966, and Thule in Greenland in 1968, and the explosion of an armed nuclear missile and subsequent fire at the McGuire Air Force Base in the USA in 1960.
Thousands of active nuclear weapons are still held by nations around the world today. The Maralinga legacy shows the world can ill afford incidents involving nuclear particles.
Barbara Etschmann, Research officer, Monash University; Joel Brugger, Professor of Synchrotron Geosciences, Monash University, and Vanessa Wong, Associate Professor, Monash University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Most people consider climate change a serious issue, but rank other problems as more important. That affects climate policy
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Sam Crawley, Te Herenga Waka — Victoria University of WellingtonStraight denial of climate change is now relatively rare. Most people believe it is happening and is a serious problem. But many rank other issues — healthcare and the economy — as more important.
This means people can’t be easily classified as either deniers or believers when it comes to climate change. In my research, I focused on understanding the complexity of climate opinion in light of the slow political response to climate change around the world.
I conducted an online survey in the UK and found 78% of respondents were extremely or fairly certain climate change is happening.
But when asked to rank eight issues (climate change, healthcare, education, crime, immigration, economy, terrorism and poverty) from most to least important to the country, 38% ranked climate change as least important, with a further 15% placing it seventh out of eight.
Recent pledges from a number of large countries to reach net zero in greenhouse gas emissions by 2050 have led Climate Action Tracker to project that limiting warming to 2℃ by 2100 may be possible.
Although this progress is heartening, it has taken many years to reach this point and the challenges in actually meeting these emission targets cannot be overstated.
Climate ranking in other countries
I found similar results in other countries. Based on a Eurobarometer survey of 27,901 European Union citizens, a majority of the populations in all EU member countries are concerned about climate change, but only 43% across the EU rank it in the top four most important issues for the world. There are some differences between countries — climate change tends to be ranked higher in Nordic countries and lower in Eastern Europe.
Fewer than 5% of 3,445 respondents in the 2017 New Zealand Election Study said the environment was the most important election issue and an even smaller number specifically mentioned climate change.
Read more:
NZ election 2020: survey shows voters are divided on climate policy and urgency of action
Why are some people more engaged with climate change than others? People’s worldview or ideology seem to be particularly important.
In many countries — including, as illustrated in my research, the UK and New Zealand — there are partisan and political divides in climate change with supporters of right-wing parties less likely to support climate change policies or to see it as an important issue.
People who support free-market economics, hold authoritarian attitudes or have exclusionary attitudes towards minorities are also less likely to engage with climate change.
Consequences for climate policy
In democracies, politicians often respond to public opinion; ignoring it risks being voted out at the next election. But the degree to which they do so depends on how important the issue is to the public relative to other issues.
If people are not thinking about an issue when they go to vote, politicians are less likely to give that issue much attention. As my research shows, people in most countries don’t give climate change a high importance ranking, and politicians are therefore not under enough public pressure to take the difficult steps required to combat climate change.
There are other reasons for the slow political response to climate change, besides the low importance of climate change among the public. Vested interests, such as fossil fuel companies, are undoubtedly involved in slowing the adoption of strong climate policies in many countries.
Read more:
Climate explained: Why are climate change skeptics often right-wing conservatives?
Although only a minority of the population, climate change deniers may also make some politicians hesitate to act. But, regardless of the influence of vested interests and deniers, it is difficult for politicians to act on climate change when the public believes other issues are more important.
Understanding the relationship between public opinion and climate policy can help focus the efforts of climate campaigners. Perhaps less attention could be paid to the influence of vested interests.
Given the deep ideological reasons climate change deniers have for their disbelief, it’s unlikely they will be convinced otherwise. Fortunately, this may not be required to move climate policy forward.
As my research reveals, the majority of the public want action on climate change but tend to be more concerned about other issues. Campaigners might find it useful to focus their attention on persuading this section of the population about the urgency of climate action.
Sam Crawley, Researcher, Te Herenga Waka — Victoria University of Wellington
This article is republished from The Conversation under a Creative Commons license. Read the original article.
‘One sip can kill’: why a highly toxic herbicide should be banned in Australia
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Nedeljka Rosic, Southern Cross University; Joanne Bradbury, Southern Cross University, and Sandra Grace, Southern Cross UniversityThere’s a weedkiller used in Australia that’s so toxic, one sip could kill you. It’s called paraquat and debate is brewing over whether it should be banned.
Paraquat is already outlawed in many places around the world. The Australian Pesticides and Veterinary Medicines Authority has been reviewing paraquat’s use here for more than two decades, and its final decision is due later this year.
We are medical and environmental scientists, and have researched the harmful effects of paraquat, even when it’s used within the recommended safety range. We strongly believe the highly toxic chemical should be banned in Australia.
The potentially lethal effects on humans are well known. In Australia in 2012, for example, a farmer died after a herbicide containing paraquat accidentally sprayed into his mouth. And our research has found paraquat also causes serious environmental damage.
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Paraquat: the story so far
Paraquat is the active ingredient in Gramoxone, among other products. It has been used since the 1950s, mostly to control grass and weeds around crops such as rice, cotton and soybeans.
Paraquat is registered as a schedule 7 poison on the national registration scheme, meaning its use is strictly regulated.
Suppliers of paraquat say it should not be banned, insisting herbicides containing it are safe for people and the environment when used for their intended purpose and according to label instructions.
Farmers have also argued against a ban, saying it would force them to use more expensive, less effective alternatives and reduce crop yield.
Paraquat has been banned in more than 50 countries, including the United Kingdom, China, Thailand and European Union nations. However, it’s still widely used by farmers in the developing world, and in Australia and the United States.
Read more:
Ban on toxic mercury looms in sugar cane farming, but Australia still has a way to go
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A chemical peril
Paraquat is a non-selective herbicide, which means it kills plants indiscriminately. It does so by inhibiting photosynthesis, the process by which plants convert sunlight into chemical energy.
Paraquat stays in the environment for a long time. It’s well known for causing collateral damage to plants and animals. For example, even at very low concentrations, paraquat has been found to harm the growth of honey bee eggs.
Exposure to living organisms can occur by spray drift or when paraquat is sprayed on crops then reaches surface and underground sources of drinking water.
Paraquat can have unintended consequences for biological organisms and the environment, particular in waterways. Our recent paper summarised the evidence of the harmful effects of paraquat at realistic field concentrations.
We found evidence that paraquat can severely inhibit healthy bacterial growth in aquatic environments, which in turn affects nutrient cycling and the decomposition of organic matter.
The research also shows paraquat can distort tropical freshwater plankton communities by negatively impacting metabolic diversity and reducing phytoplankton growth.
In fish, paraquat has been found to lead to a death rate of common carp three times higher than the weed it is used to control.
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‘One sip can kill’
In addition to the environmental effects, of course, paraquat is highly toxic to humans. A small accidental sip can be fatal and there is no antidote.
The US Centers for Disease Control and Prevention says paraquat is a leading cause of fatal poisoning in parts of Asia, the Pacific Islands, and South and Central Americas.
Paraquat enters the body through the skin, digestive system or lungs. If ingested in sufficient amounts, it causes lung damage, leading to pulmonary fibrosis and death through respiratory failure. The liver and kidney can also fail.
Several recent incidents in Australia demonstrate the risks of paraquat poisoning due to human error, even within the current strict regulations.
According to news reports, the Queensland farmer poisoned by paraquat in 2012 was filling a pressure pump to control weeds on his property. The unit cracked and paraquat sprayed over his body and face, entering his mouth.
In 2017, an adult with autism took a sip from a Coke bottle used to store paraquat. The bottle had been left in a disabled toilet at a sports ground in New South Wales. The man was initially given 12 hours to live, but fortunately recovered after two weeks in hospital.
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Pesticides and suicide prevention – why research needs to be put into practice
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Paraquat: not worth the risk
There’s a growing awareness of the threats posed by global chemical use. In fact, a paper released this week suggests the potential risk to humanity is on a scale equivalent to climate change.
Paraquat is no doubt an effective herbicide. However, in our view, the risks it poses to humans and the environment outweigh the agricultural benefits.
Current regulation in Australia has not prevented harm from paraquat. It’s time for Australia to join the movement towards a global ban on this toxic chemical.
Read more:
The real cost of pesticides in Australia’s food boom
Editor’s note: the article has been updated to reflect the fact products other than Gramoxone also contain paraquat.
Nedeljka Rosic, Senior Lecturer, Southern Cross University; Joanne Bradbury, Senior Lecturer, Evidence Based Healthcare, Faculty of Health, Southern Cross University, and Sandra Grace, Professor, Southern Cross University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
We found a secret history of megadroughts written in tree rings. The wheatbelt’s future may be drier than we thought
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Alison O’Donnell, The University of Western Australia; Edward Cook, Columbia University, and Pauline Grierson, The University of Western AustraliaDrought over the last two decades has dealt a heavy blow to the wheatbelt of Western Australia, the country’s most productive grain-growing region. Since 2000, winter rainfall has plummeted by almost 20% and shifted grain-growing areas towards the coast.
Our recent research, however, found these dry conditions are nothing out of the ordinary for the region.
In fact, after analysing rings in centuries-old tree trunks, we found the region has seen far worse “megadroughts” over the last 700 years. Australia’s instrumental climate records only cover the last 120 or so years (at best), which means these historic droughts may not have previously been known to science.
Our research also found the 20th century was the wettest of the last seven centuries in the wheatbelt. This is important, because it means scientists have likely been underestimating the actual risk of drought – and this will be exacerbated by climate change.
What we can learn from ancient trees
We estimate the risk of extreme climate events, such as droughts, cyclones and floods, based on what we know from instrumental climate records from weather stations. Extending climate records by hundreds or even thousands of years means scientists would be able to get a much better understanding of climate variability and the risk of extreme events.
Alison O’Donnell, Author provided
Thankfully we can do just that in many parts of the world using proxy records — things like tree rings, corals, stalagmites and ice cores in Antarctica. These record evidence of past climate conditions as they grow.
For example, trees typically create a new layer of growth (“growth ring”) around their trunks, just beneath the bark, each year. The amount of growth generally depends on how much rain falls in the year. The more it rains, the more growth and the wider the ring.
Alison O’Donnell, Author provided
We used growth rings of native cypress trees (Callitris columellaris) near a large salt lake at the eastern edge the wheatbelt region. These trees can live for up to 1,000 years, perhaps even longer.
We can examine the growth rings of living trees without cutting them down by carefully drilling a small hole into the trunk and extracting a column (“core”) of wood about the size of a drinking straw. By measuring the ring widths, we developed a timeline of tree growth and used this to work out how much rain fell in each year of a tree’s life.
This method allowed us to reconstruct the last 668 years of autumn-winter rainfall in the wheatbelt.
Alison O’Donnell, Author provided
A history of megadroughts
One of the most pressing questions for the wheatbelt is whether the decline in autumn-winter rainfall observed in recent decades is unusual or extreme. Our extended record of rainfall lets us answer this question.
Yes, rainfall since 2000 was below the 668-year average — but it was not extremely low.
The last two decades may seem particularly bad because our expectations of rainfall in the wheatbelt are likely based on memories of higher rainfall. But this frequent wet weather has actually been the anomaly. Our tree rings revealed the 20th century was wetter than any other in the last 700 years, with 12% more rain in the autumn-winter seasons on average than the 19th century.
Read more:
500 years of drought and flood: trees and corals reveal Australia’s climate history
Before the 20th century, the wheatbelt saw five droughts that were longer and more severe than any we’ve experienced in living memory, or have recorded in instrumental records. This includes two dry periods in the late 18th and 19th centuries that persisted for more than 30 years, making them “megadroughts”.
While the most recent dry period has persisted for almost two decades so far, rainfall during this period is at least 10% higher than it was in the two historical megadroughts.
This suggests prolonged droughts are a natural and relatively common feature of the wheatbelt’s climate.
Hannah Etchells, Author provided
So how does human-caused climate change play into this?
It’s likely both natural climate variability and human-caused climate change contributed to the wheatbelt’s recent decline in rainfall. Unfortunately, it’s also likely their combined influence will lead to even less rainfall in the near future.
What happens now?
Our findings have important implications for assessing the risk of drought. It’s now clear we need to look beyond these instrumental records to more accurately estimate the risk of droughts for the wheatbelt.
But currently, proxy climate records like tree rings aren’t generally used in drought risk models, as there aren’t many of them in the regions scientists want to research.
Improving risk estimates leads to better informed decisions around preparing for and managing the effects of droughts and future natural disasters.
Read more:
To help drought-affected farmers, we need to support them in good times as well as bad
Our findings are a confronting prospect for the future of farming in the wheatbelt.
Australian farmers have shown tremendous innovation in their ability to adapt in the face of drought, with many shifting from livestock to crops. This resilience will be critical as farmers face a drier, more difficult future.
Alison O’Donnell, Research Fellow in Dendroclimatology, The University of Western Australia; Edward Cook, Ewing Lamont Research Professor, Director Of Tree-Ring Lab, Columbia University, and Pauline Grierson, Director, West Australian Biogeochemistry Centre, The University of Western Australia
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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