Adelaide Street Circuit designer Bob Barnard estimates it could cost more than $100 million to remodel the track for the MotoGP, but the premier says that number has not been mentioned to him.
When major new climate change scenarios are released, there’s always strong interest. These scenarios lay out what our future climate will look like, depending on how fast we act to cut emissions.
But what was surprising about the seven new scenarios announced last week was that United States President Donald Trump took an interest.
Why? Because a high-emissions scenario – known as RCP8.5 and its successor SSP5-8.5 – had been removed. Under these worst-case scenarios, nations would make no effort to cut emissions and expand fossil fuel use. By 2100, carbon dioxide levels would almost triple, to 1,135 parts per million and the world would be around 4.5°C hotter than the pre-industrial period.
The climate scientists responsible for laying out the range of possible futures removed the RCP8.5 scenarios for a very good reason. Although often slow and incomplete, our efforts to tackle climate change have made a tangible difference. We have averted the worst climate future once thought possible.
The job is far from done. Emissions are at record highs and global warming is speeding up.
But the removal of this high-emissions scenario isn’t, as Trump and other climate sceptics have claimed, a sign of failed modelling, or that climate change was a hoax. It’s a sign the expansion of solar, wind, electric vehicles and batteries have slowed emissions growth.
Many climate impacts are becoming evident after about 1.4°C of warming – the level we’re roughly at now.
Because this period of extremely rapid climate change is due to human activities, it means we also have the opportunity to shape the future.
What will this look like? Will the world keep heating up, or will rapid action cut emissions and bring warming to a halt? The answer will make a big difference to the future humanity faces.
Predicting anything is difficult. But a group of scientists has created scenarios representing a range of possible climate futures.
Because the future is not set, scientists lay out a range of possible pathways for our future greenhouse gas emissions. They base them on what’s happened so far and what might happen in politics and technology over coming decades.
Then they select the emissions pathways deemed most plausible and then sample a range of different futures which are more or less optimistic about our fossil fuel use.
Scientific groups around the world then model these scenarios in depth using different climate models to ensure there’s a large amount of data available at global, regional and local levels.
These scenarios aren’t ranked by how likely they are. All are considered to be plausible futures. The huge range of temperature outcomes – approaching 2°C between the most and least optimistic scenarios by 2100 – points to how much of the future is in our hands.
The two previous releases included two closely related scenarios – RCP8.5 and SSP5-8.5 respectively.
Here, “8.5” refers to radiative forcing – the level of extra heat (in watts) trapped per square metre by 2100.
In these worst-case scenarios, the world sharply boosts fossil fuel use. Unsurprisingly, this leads to very high amounts of global warming. Scientists have long argued over whether this was plausible in the first place.
None of the new scenarios are as pessimistic as RCP8.5/SSP5-8.5. The worst possible scenario now envisions high emissions leading to warming of around 3.5°C by 2100. That would still be very, very bad.
Climate sceptics leapt on the removal of RCP8.5 as a sign the projections were wrong. These attacks were not made in good faith, but to cast doubt on climate science.
A clear eyed assessment is that RCP8.5 was removed because climate action is starting to work.
But while the worst outcome has been averted, we have also missed the window for the best future climate.
The new scenarios have no pathway as optimistic as the lowest emissions scenario from the last round of major climate projections. That scenario – SSP1-1.9 – envisaged strong climate action and rapid cuts to emissions, leading to global warming peaking at around 1.5°C.
Because global emissions haven’t yet begun to fall, the most optimistic new pathway would lead to warming peaking at about 1.9°C.
While we will definitely now pass 1.5°C, the hope is to only temporarily overshoot that level of warming while working to draw carbon dioxide back out of the atmosphere to get back to 1.5°C.
Our current emissions trajectory is somewhere in the middle – below the high emissions path but well above the most optimistic scenario. Based on current policies and countries’ actions, we’re looking at around 2.6°C warming by 2100.
You might wonder why we need to keep redoing these climate scenarios.
One reason: facts change on the ground. Solar keeps rolling out far faster than expected, but fracking has opened up large new fossil fuel deposits. Political shifts make climate action more or less likely.
Another is because our climate models are continually improving. The better the models get, the more accurate and detailed our projections of sea level rise and other climate impacts can be.
Taking RCP8.5 off the table is a sign of progress – we’ve avoided the worst-case scenario. But we have also missed the best case future.
The next five years could play out in many different ways, leading to better or worse future climates. We must understand and prepare for what we’re facing – and double down on our efforts to create the best future possible.
Andrew King receives funding from the Australian Research Council and the National Environmental Science Program.
Some 350,000 years ago, the centre of New Zealand’s North Island appeared much different than the mountainous, scrub-covered landscape it is today.
Amid a glacial period, temperatures were colder and conditions harsher. Vast beech and podocarp forests blanketed the region, providing habitat for abundant native birdlife.
It was against this tranquil backdrop that the one of the Earth’s most explosive eruptions violently unfolded, releasing enough material to carpet much of the country.
Now, colleagues and I have pieced together traces left by the event to provide an unprecedented picture of how it happened – while shedding important new light on the mechanics of those rare cataclysms that are known as supereruptions.
The Whakamaru supereruption was one of the largest ever recorded on Earth – and the greatest produced by New Zealand’s famous Taup? Volcanic Zone.
Stretching from Whakaari/White Island to Ruapehu, this dynamic area is the product of two powerful geological processes: the Pacific Plate sinking beneath the Australian Plate, and the central North Island simultaneously being pulled apart.
It is home to numerous volcanic features today, from geothermal fields with bubbling hot springs and mud pools, to caldera systems and active stratovolcanoes.
Throughout its 2-million-year history, the zone has experienced four known events of such immense scale that they are formally classified as supereruptions – or those that would score a maximum 8 on the Volcanic Explosivity Index.
Only a few dozen have ever been recorded worldwide – the most recent being the ?ruanui eruption that helped create Lake Taup? around 25,300 years ago.
For volcanologists, they pose some of the field’s greatest mysteries: how can so much magma build up below the surface, and then erupt all at once? And what happens to the surrounding landscapes?
To help answer these questions, we turn to preserved volcanic deposits that can be used to reconstruct the processes that play out during these rare events.
Two signature products of supereruptions are “flow” deposits – hot, dangerous masses of rock and gas that travel along the ground – and “fall” deposits, typically mixtures of crystals and volcanic glass that fall from the air.
The challenge for volcanologists is that typically only fragments of these deposits are preserved – and they are often scattered across great distances.
In the Whakamaru supereruption, massive pyroclastic flows left behind thick layers of dense volcanic rock across the Whakamaru and King Country regions. Ash and pumice spread much farther, blanketing much of the North Island and parts of the Pacific Ocean.
One of the first steps in our study was to build a database of these deposits by matching the unique chemical signature of volcanic glass produced during the eruption.
This process is similar to forensic science at a crime scene: fingerprints may suggest a suspect, but DNA evidence can confirm the match. In volcanology, deposits can offer clues as to how they got there, but it is their chemical composition which provides the definitive link.
Using this approach, we analysed more than 30 sites around New Zealand and the south Pacific Ocean. All were found to have come from the Whakamaru supereruption.
With these correlated, we were then able to reconstruct this extraordinary episode.
At the beginning of the eruption, a large lake likely lay within the central North Island, much like Lake Taup? today.
When the magma reached the surface, it erupted directly into this lake, triggering extremely violent interactions between magma and water, which drove the earliest phase of the eruption.
It appears this first phase was driven by the evacuation of a singular magma body.
As the eruption progressed, the lake was gradually destroyed and infilled. Eventually, the system transitioned into a much drier style of volcanism.
At the same time, the eruption evolved into a far larger and more complex event beneath the surface. Instead of being fed by one magma chamber, it appears to have triggered a cascading sequence involving at least five separate magma bodies erupting at once.
The amount of ash generated by the eruption is staggering.
Most of the North Island – and even far-away Chatham Island – would have been carpeted in around 30cm or more of material. Areas closer to the eruption were left buried under as much as 4.5m of ash.
Hot, dense pyroclastic flows also swept across the landscape, leaving deposits up to hundreds of metres thick closer to the eruption source.
Altogether, we estimate the eruption released around 2,300 cubic kilometres of volcanic material – enough to bury the entirety of New Zealand beneath roughly nine metres of debris if spread evenly from Cape Reinga to Invercargill.
Today, the Taup? Volcanic Zone remains one of the most active and powerful volcanic systems on Earth.
Although supereruptions like Whakamaru are rare, Taup? volcano has produced many smaller yet still devastating eruptions throughout its history, all of which would have had major impacts on both New Zealand and the wider world.
Understanding how these types of volcanoes operate is essential, both in preparing for future eruptions and for understanding how past events may have transformed the landscape we see today.
The author acknowledges the contributions of Simon Baker and Colin Wilson to this research.
Anna Miller does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Mining giant BHP has come under fire for spending hundreds of millions of dollars on new diesel trucks in the Pilbara, despite promising a transition to electric trucks in its climate strategy.
Like other mining companies, BHP’s diesel-driven fleet is eligible for fuel tax credits on diesel. The company’s controversial decision to shelve its plans raises the pressing issue of the diesel fuel rebate.
This rebate began as targeted support for a struggling agricultural sector in the 1980s, but has morphed into an almost $5 billion subsidy for some of the nation’s most profitable corporations.
So, what is the diesel fuel rebate? And is this fossil fuel subsidy still fit for purpose?
Since federation in 1901, diesel and petroleum products imported into Australia have been subject to import taxes. Since 1929, tax collected from the petrol pump has been earmarked to build and maintain the nation’s road network.
Australia’s diesel fuel rebate scheme was introduced in 1982. The Fuel Tax Credits Scheme, as it’s officially known, was designed to cushion farmers from rising fuel costs.
Farm and mine businesses buying diesel for off-road uses like tractors, harvesters and irrigation pumps could claim a rebate. At the time, Australia’s mining sector was far smaller.
Now, 44 years later, the rebate scheme still allows businesses like agriculture and mining to claim back the federal fuel tax paid on diesel used in eligible machinery, equipment and heavy vehicles.
Today, the mining industry receives about half of the diesel rebate.
Since 2010, Australia’s consumption of liquid fuel has changed dramatically, with official statistics showing falling petrol demand and rising diesel use over the past decade. Petrol use has gradually declined as vehicle efficiency has improved. In contrast, diesel consumption has nearly doubled.
This surge in diesel consumption reflects Australia’s growth in freight, heavy vehicles and, particularly, mining. The diesel rebate scheme is now one of Australia’s largest fossil fuel subsidies, alongside tax concessions for aviation fuel and a range of support measures for coal and gas production, with recent analysis putting its annual cost at around $11.2 billion by 2026–27.
Mining is by far the largest beneficiary, claiming about $5 billion a year in diesel rebates according to one analysis. This includes roughly $1.5 billion for coal mining alone. Agriculture receives only a fraction of the total.
What began as support for farmers using off-road fuel has become a standing subsidy for Australia’s most profitable miners.
Meanwhile, aviation fuel pays little excise – about 3 cents per litre – to fund the Civil Aviation Safety Authority. This compares to a fuel excise rate of 52c per litre on petrol and diesel, which the Australian government halved on April 1 this year in response to fuel price spikes from the US-Israeli war in Iran.
Since 1992, the formal link between petrol and diesel excise and road funding has ended, with fuel tax now flowing into general revenue rather than a dedicated roads fund. The rebate was originally justified on fairness grounds – off?road users were not meant to subsidise public roads – but once fuel tax stopped being a dedicated roads charge, that logic largely evaporated.
The May 2026 federal budget fuel package was worth more than $10 billion, centred on a permanent government-owned fuel reserve.
These are reminders Australia’s fuel security problem is immediate, not theoretical. The government’s response has been to buy and store more fuel, rather than reduce our structural dependence on imported oil and support a shift to electrification and renewable energy.
Australia’s fuel rebate entrenches higher diesel use. But the “we need more fuel” argument ignores the fact Australia’s economy is decisively decoupling from fossil energy consumption.
Uncoupling from oil is not a theoretical future possibility – it is slowly happening. Oil consumption in particular has plateaued since the early 2000s, even as GDP has roughly doubled. If Australia wants to meet its emissions-reduction commitments, it should hasten the shift away from fossil oil, not maintain a subsidy for it.
Australia has long failed to gain a fair share of revenue from our finite mineral wealth. Our petroleum resource rent tax is notoriously weak.
Mining companies argue tougher taxes will drive investment offshore. But Australia has some of the world’s highest-grade iron ore, coal and critical minerals. A tax regime would have to be extraordinarily high to make extraction unprofitable.
We are now in the fourth major oil crisis.
Unlike the others, this one arrives with cheaper renewable alternatives readily available. Wind, solar, batteries and electric vehicles are now cheaper than fossil alternatives and faster to deploy.
During a fuel crisis, we should scrutinise where our finite tax revenues are directed. The fuel rebate was designed mostly for farmers, when the mining industry was a fraction of its current size.
Does the policy need to return to its original aim? Or is a new form of road user tax required?
Whatever the mechanism, it makes sense to direct revenue towards electrification, not lock in another decade of diesel dependence.
In a statement, a spokesperson for BHP said it has net zero goal for reducing its scope 1 and 2 greenhouse gas emissions to net zero by 2050.
Despite this progress, many of the technologies the resources industry will need to achieve net zero are not yet ready to be deployed, BHP said.
“For example, no Australian mining operation is currently utilising critical 240-ton battery-electric haul trucks as the technology is not advanced enough to scale to an operational fleet,” the spokesperson said.
BHP is partnering with equipment producers to run trials of battery-electric equipment, including two 240-ton battery electric haul trucks, on a BHP site in the Pilbara, and four battery-electric locomotives which we plan to commence trialling in coming months.
Ray Wills does not work for, consult, own shares in or receive funding from any company or organisation that would directly benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Peter Newman receives funding from the federal government to attend IPCC meetings as a lead author on transport and cities, and receives funding for a research project on Net Zero Precincts from CRC RACE.
Property owners’ lack of motivation due to ‘split incentive’ is main reason rental properties are missing out on energy upgrades, research finds
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Renters make up nearly a third of Australian households yet many are missing out on energy upgrades – such as insulation, appliances and rooftop solar – that could slash their power bills and improve home comfort.
The problem, according to the Institute for Energy Economics and Financial Analysis (IEEFA), is landlords’ lack of motivation.