If Australia switched to EVs, we’d be more reliant on China’s car factories – but wean ourselves off foreign oil

by bpckle | Apr 8, 2025 | Media

Australia has huge reserves of coal and gas – but very little oil. Before the 20th century, this didn’t matter – trains ran on local coal. But as cars and trucks have come to dominate, Australia has become more and more reliant on imported oil.

Imports now account for around 80% of total refined fuel consumption, the highest level on record.

If the flow of oil stopped due to war or economic instability, Australia would have about 54 days worth in storage before we ran out. That would be a huge problem.

But as more drivers switch from petrol and diesel to electric cars, this equation will change. We can already see this in China, where a rapid uptake of electric vehicles has seen oil demand begin to fall.

On one level, ending Australia’s dependence on foreign oil makes sense at a time of great geopolitical uncertainty. But on the other, going electric would lead to more reliance on China, now the world’s largest manufacturer of EVs.

Reducing reliance on oil makes clear sense for climate and national security reasons. But going electric has to be done carefully, to ensure Australia isn’t reliant on just one country.

Importing oil makes us vulnerable

In recent years, almost all of Australia’s refineries have closed. The government spent billions keeping the Geelong and Brisbane refineries open, as well as other fuel security measures, such as boosting domestic fuel reserves and building more storage.

The last two refineries rely on imported crude oil, as Australian oil from the North-West Shelf largely isn’t suitable for local refining.

As a result, Australia is more reliant than ever on importing fuels from large refineries in Asia such as South Korea, Singapore and Malaysia. In 2023, around 45,000 megalitres of fuel were imported from these nations.

Almost three-quarters (74%) of these liquid fuels are used in transport, across road, rail, shipping and air transport. But road transport is the big one – our cars, trucks and other road vehicles use more than half (54%) of all liquid fuels.

This reliance presents clear energy security risks. If war, geopolitical tension, economic turmoil or price volatility slows or stops the flow of oil, Australia’s cities and towns would grind to a halt.

In January, Australia had 30 days worth of petrol. Our stores of all types of oil are a bit higher, at 54 days worth. But that’s still well short of the 90 days the International Energy Agency (IEA) requires of member nations.

Electricity made locally

Shifting to electric vehicles promises cleaner air and far lower ongoing costs for drivers, as electricity is much cheaper than petrol or diesel and maintenance is far less.

But there’s another factor – the energy source. Australia’s electricity is all produced and consumed inside its borders, using local resources (sun, wind, water, coal and gas).

In this respect, electric vehicles offer much greater energy security. A war in the Middle East or a trade war over tariffs would not bring Australia to a halt. This is one reason why China has so aggressively gone electric – to end its soaring dependence on foreign oil.

Mainstreaming EVs in Australia will mean accelerating production of renewable electricity further so we can power not just homes and industry but charge cars, trucks and buses, too.

Doing this would boost our energy security, break our dependency on imported oil and drive down emissions.

EV manufacturing is expanding rapidly with more models, lower purchase prices, improved battery charging times and increasing consumer adoption.

Globally, over 17 million EVs (battery and plug-in hybrids) were sold in 2024, including 91,000 battery and 23,000 plug-in hybrids in Australia.

IEA data shows electric vehicles are already reducing oil demand globally, as are electric bikes and mopeds.

Ending our dependence on oil will be slow. Australia Institute research estimates 8% of imported fuels could be replaced by local electricity once EVs make up 25% of the passenger car fleet. At 100% EVs, we would reduce oil demand by 33%.

The other two-thirds of demand is largely from trucks, planes and ships. Electric trucks are coming, but the sector isn’t as mature as electric cars. It’s a similar story for planes and cargo ships.

Energy security and EVs

Australia doesn’t manufacture EVs at scale. As a result, we import EVs from the top manufacturing nations. China is far and away the leader, building 80% of Australia’s new EVs.

Australia is a major producer of critical minerals essential to the manufacture of EVs, as well as other green technologies such as lithium, cobalt and nickel. But China dominates much of the global supply chain for refining these minerals and manufacturing batteries.

There’s a risk in relying largely on one country for EVs, especially given the present geopolitical instability.

Balancing security and sustainability

EVs unquestionably offer large benefits for Australia’s energy security by steadily reducing our reliance on imports from volatile global oil markets.

But this has to be balanced with other security concerns, such as a heightened reliance on China, as well as the privacy and security risks linked to data collection from digitally connected EVs.

A balanced approach would see authorities emphasise energy independence through renewables and strong support for vehicle electrification through legislative and regulatory frameworks.

Under this approach, policymakers would work to diversify supply chains, strengthen cybersecurity and encourage local manufacturing of EV components.

This approach would reduce new security risks while unlocking the environmental and economic benefits of widespread EV adoption.

Hussein Dia receives funding from the Australian Research Council, the iMOVE Australia Cooperative Research Centre, Transport for New South Wales, Queensland Department of Transport and Main Roads, Victorian Department of Transport and Planning, and Department of Infrastructure, Transport, Regional Development, Communications and the Arts.

The latest update on NZ’s state of the environment is sobering – but there are glimmers of progress

by bpckle | Apr 8, 2025 | Media

If left unaddressed, many environmental changes in Aotearoa New Zealand could threaten livelihoods, health, quality of life and infrastructure for generations to come, according to the latest update on the state of the environment.

The Ministry for the Environment and StatsNZ produce an environmental assessment every three years, collating data and trends on air quality, freshwater and marine environments, the land and climate.

The latest report shows that long-term drivers of change – including international influences, economic demands and climate change – mean many natural systems have become less resilient and are at risk of collapse. But it also highlights improvements in urban air quality and reduced waste flows to landfill.

Real risks to people, communities and places

Many environmental trends in New Zealand are sobering.

Soil erosion is increasing and continues to degrade downstream freshwater and marine ecosystems. Soils misplaced from land, including through landslides or gradual loss of topsoil, can threaten homes and infrastructure and reduce the potential for growing food or storing carbon.

Climate change is projected to increase erosion rates by up to 233%, depending on future emissions scenarios.

Native forests are most effective at reducing soil erosion, but exotic forests can also help. The report shows the area planted in exotic forest has increased by 12% (220,922 hectares) between 1996 and 2018, with most of this new area coming from exotic grassland.

Landfill contaminants, including leachates and microplastics, threaten soil health. New Zealand remains the highest producer of waste to landfill per capita among developed countries, but waste flows to landfill have dropped by 11% in 2023, compared with a 2018 peak.

The report offers another glimmer of progress. While air pollution still affects health, long-term air quality is gradually improving thanks to a shift away from cars with combustion engines.

Water quality and green spaces

What happens on land commonly flows into water, often affecting human health and recreation. The report shows that between 2019 and 2024, nearly half of all groundwater monitoring sites failed to meet drinking water standards for E. coli at least once. Nitrate concentrations also rose at around half of all sites.

Freshwater ecosystems are critically affected by the space we give them. Urban development can displace natural features such as wetlands and floodplains, which store water and provide a buffer against extreme weather events.

Four in five New Zealanders live in urban areas and the report shows green spaces have not kept up with population growth. Continued development near rivers and on floodplains, without maintaining natural buffers, increases risks to homes and infrastructure as flood extremes worsen with climate change.

Coastal areas face their own challenges. Rising seas and storm surges threaten not only homes and roads, but also culturally significant places. As many as 420 archaeological sites on public conservation land are at risk of coastal inundation and 191 marae are within one kilometre of the coast.

Livelihoods and biodiversity at risk

New Zealand is a globally significant biodiversity hotspot and natural landscapes are central to cultural identity. The land and waters, and species we share them with, are inseparable from M?ori identity. The economy, from agriculture to tourism, also depends on thriving ecosystems.

But many pressures on biodiversity are worsening, according to the report. About 94% of native reptiles and 78% of native birds are threatened or at risk of extinction.

Extreme weather events (expected to increase with climate change) threaten food and fibre crops. The report estimates the recovery of these sectors from Cyclone Gabrielle will cost up to NZ$1.1 billion.

Pest species continue to damage ecosystems at a cost of $9.2 billion in 2019–20, including primary-sector losses of $4.3 billion.

Wilding conifers are a particular concern, having invaded an estimated two million hectares of land, primarily on the conservation estate. Without careful management, the report projects they could cover up to 25% of New Zealand’s land within 30 years.

Stories behind the numbers

For the first time, the ministry has released a companion report to share stories of hope.

It highlights the links between environmental challenges and how nature-based approaches can benefit both people and the environment.

In Tair?whiti, for instance, a native forest restoration project is protecting Gisborne’s drinking water supply. A large block of commercial pine is being replaced with native forests to stabilise erodible land, filter water runoff before it reaches dams, and provide habitat for native flora and fauna.

In Auckland, the Making Space for Water program is restoring Te Auaunga (Oakley Creek), the city’s longest urban river. The work includes widening the river channel, removing restrictive structures and planting native vegetation to regenerate historical wetland habitats. Along with reducing flooding in the area, these changes provide improved recreational spaces for people.

The report notes the complexity of interactions between people and the natural environment, which means that many impacts cannot be seen straight away. For instance, nitrates move through groundwater very slowly and we may continue to see the effects of past decisions for some time yet. Furthermore, climate change can amplify many environmental stressors.

The state of our environment mirrors our collective decisions. This update offers an opportunity to guide those decisions towards a more resilient future.

Christina McCabe is affiliated with Te Whare W?nanga o Waitaha / The University of Canterbury, and Te P?naha Matatini, a Centre of Research Excellence.

Antarctica’s hidden threat: meltwater under the ice sheet amplifies sea-level rise

by bpckle | Apr 7, 2025 | Media

One of the biggest challenges in predicting Antarctica’s deeply uncertain future is understanding exactly what’s driving its ice loss.

A vast network of lakes and streams lies beneath the thick ice sheet. This water can lubricate the ice, allowing it to slide more rapidly toward the ocean.

Our new research shows “subglacial water” plays a far larger role in Antarctic ice loss than previously thought. If it’s not properly accounted for, future sea-level rise may be vastly underestimated.

Including the effects of evolving subglacial water in ice sheet models can triple the amount of ice flowing to the ocean. This adds more than two metres to global sea levels by 2300, with potentially enormous consequences for coastal communities worldwide.

Understanding the role of subglacial water

Subglacial water forms when the base of the ice sheet melts. This occurs either due to friction from the movement of the ice, or geothermal heat from the bedrock below.

The presence of subglacial water enables ice to slide over the bedrock more easily. It can also cause further melting under ice shelves, leading to even faster ice loss.

So it’s crucial to understand how much subglacial water is generated and where it goes, as well as its effect on ice flow and further melting.

But subglacial water is largely invisible. Being hidden underneath an ice sheet more than two kilometres deep makes it incredibly difficult to observe.

Scientists can drill boreholes through hundreds to thousands of metres of ice to get to it. But that’s an expensive and logistically challenging process.

Alternatively, they can use ice-penetrating radar to “see” through the ice. Another technique called laser altimetry examines changes in the height of the ice at the surface. Bulges might appear when lakes under the ice sheet fill, or disappear when they empty.

More than 140 active subglacial lakes have been identified beneath Antarctica over the past two decades. These discoveries provide valuable insights. But vast regions — especially in East Antarctica — remain unexplored. Little is known about the connections between these lakes.

What we did and what we found

We used computer simulations to predict the influence of subglacial water on ice sheet behaviour.

We used two computer models:

• an advanced ice sheet model that simulates how the ice sheet flows and responds to climate.
• a specialised hydrology model that predicts subglacial water production and flow.

Then we explored how different assumptions about subglacial water pressure affect ice sheet dynamics. Specifically, we compared scenarios where water pressure was allowed to change over time against scenarios where it remained constant.

When the effects of changing subglacial water pressure were included in the model, the amount of ice flowing into the ocean under future climate nearly tripled.

These findings suggest many existing sea-level rise projections may be too low, because they do not fully account for the dynamic influence of subglacial water.

Our research highlights the urgent need to incorporate subglacial water dynamics into these models. Otherwise we risk significantly underestimating the rate and magnitude of future sea-level rise.

In the video below, the moving dark lines show where grounded ice begins to float. The left panel is a scenario where subglacial water is not included in the ice sheet model and the right panel is a scenario that includes the effects of evolving subglacial water.

A looming threat

Failing to account for subglacial water means global sea-level rise projections are underestimated by up to two metres by 2300.

A two-metre rise would put many coastal cities in extreme danger and potentially displace millions of people. The economic damage could reach trillions of dollars, damaging vital infrastructure and reshaping coastlines worldwide.

It also means the timing of future tipping points are underestimated too. This is the point at which the ice sheet mass loss becomes much more rapid and likely irreversible. In our study, most regions cross this threshold much earlier, some as soon as 2050. This is deeply concerning.

The way forward

Understanding Antarctica’s hidden water system is challenging. The potential for rapid, catastrophic and irreversible ice loss remains.

More observations are needed to improve our models, particularly from remote regions such as East Antarctica. Continuing to gather information from boreholes, ice-penetrating radar and satellites will help us better understand how the underside of the ice sheet behaves. These techniques can then be combined with computer simulations to enable more accurate projections of future ice loss and sea-level rise.

Our new research shows integrating subglacial water dynamics into ice sheet models is a top priority. Understanding this hidden threat is crucial as the world grapples with the consequences of global warming especially rising seas.

Chen Zhao is the recipient of an Australian Research Council Discovery Early Career Researcher Award. Dr Zhao is affiliated with Australian Antarctic Program Partnership (AAPP), at the Institute of Marine and Antarctic Studies (IMAS), University of Tasmania, supported under the Antarctic Science Collaboration Initiative program.

Ben Galton-Fenzi is also affiliated with Australian Antarctic Program Partnership (AAPP), at the Institute of Marine and Antarctic Studies (IMAS), supported under the Antarctic Science Collaboration Initiative program, and the Australian Centre for Excellence in Antarctic Science, supported under the Australian Research Council Special Research Initiative, both based at the University of Tasmania.

Batteries for all, not just the rich? Labor’s home battery plan must be properly targeted to be fair

by bpckle | Apr 7, 2025 | Media

Over the weekend, Labor promised to subsidise home batteries by 30%. This would save about A$4,000 per household up front for an average battery. The scheme has a goal of one million batteries by 2030, costing an estimated $2.3 billion.

The promise was received broadly favourably as a measure to help with cost of living pressures and encourage the broader shift to clean energy. Labor’s policy has some similarity to an earlier Greens pledge. Last month, the Coalition hinted it was working on its own home battery plan. Opposition leader Peter Dutton has attacked Labor’s plan, claiming the subsidies would benefit the rich.

Dutton makes a good point. Upfront subsidies have to be well targeted. If they’re not, they could easily go to wealthier households and leave poorer ones behind.

To fix it, Labor should start with lower subsidies – and means test them.

What’s the fuss about home batteries?

Homes with batteries can use stored solar energy instead of grid energy, or charge from the grid when power is cheap and use it when grid power is expensive. They can reduce power bills by around $1,000 a year.

Over 300,000 Australian households already have a home battery. Uptake was already accelerating in Australia and overseas, as battery prices fall and power prices climb.

If this policy leads to 1 million batteries by 2030 as Labor hopes, they would boost grid stability, reduce demand for expensive peak power from gas generators and even avoid the need to build some new transmission lines. These would be positive – if the benefits can be spread fairly.

Subsidies must be properly targeted

Caution is necessary, because we have seen very similar issues with previous schemes.

When solar panels were expensive in the 2000s, many state governments offered subsidies to encourage more households to put them on their roofs. On one level, this worked well – one third of all Australian households now have solar. But on another, it failed – richer households took up solar subsidies much more than poorer, as my research has shown. As solar prices have fallen, this imbalance has partly been corrected.

Home batteries are now in a similar situation. Installing an average sized home battery of between 5 and 10 kilowatt hours can cost less than $10,000, without the proposed federal subsidy. But this upfront cost means it’s currently largely wealthy households doing it, as I have shown in other research.

If Labor’s policy isn’t properly targeted, wealthier households are more likely to take it up. This is because they can more easily afford to spend the remaining cost. Studies on electric and other vehicle subsidies in the United States show at least half of the subsidies went to people who would have bought the vehicle regardless. That’s good for wealthy households, but unfair to others.

Targeting has advantages for governments, too. Proper targeting would reduce the cost to the public purse.

So who should be eligible?

Wealthier households are likely to be able to afford home batteries without the subsidy – especially as costs fall.

The cost of living crisis has hit less wealthy households hardest. A home battery policy should focus heavily on giving these households a way to reduce their power bills.

How can governments do this? Largely by means-testing. To qualify for the subsidy, households should have to detail their financial assets.

To begin with, a policy like this should only be eligible for households outside the top 25% for wealth.

What about the 31% of Australians who rent their homes? This diverse group requires careful thought.

Governments may have to offer extra incentives to encourage landlords to install home batteries. The solar roll-out shows landlords do benefit, as they can charge slightly higher rent for properties with solar.

How much should subsidies be?

Labor’s election offering of a 30% subsidy is too generous.

While home batteries can cost more than $10,000, cheaper battery options are now available and state incentive schemes are also emerging. Western Australia, for instance, will have its own generous battery subsidy scheme running before July 1.

Some households might be able to get subsidies at both state and national levels, which would cover most of the cost of a smaller battery.

When governments offer high subsidies at the start of a new scheme, there’s a real risk of a cost blowout.

To avoid this, governments should begin with the lowest subsidy which still encourages household investment. If low subsidies lead to low uptake, the government could then raise subsidies after an annual review.

Another option is to vary how much the subsidy is based on household wealth. Lower wealth households get higher subsidies (say $2,500) while higher wealth households get a much lower subsidy (say $500).

Governments could even consider equitable reverse auctions, where households with similar wealth compete for subsidies. Governments can then choose lower bids in the interest of cost-effectiveness.

At present, Labor’s policy would give higher subsidies for larger batteries. This isn’t ideal. On solar, there’s a lack of evidence higher subsidies lead to larger solar systems, while households with more wealth tend to get larger solar systems.

Good start, improvement needed

Labor’s home battery policy has been welcomed by many in the energy sector. But as it stands, we cannot be sure it will fairly share the benefits of home batteries.

If Labor or the Coalition does offer a well-targeted home battery policy, it would be world leading. Over time, it would directly help with the rising cost of living and ensure less wealthy households benefit.

Rohan Best previously received funding from the Economic Research Institute for ASEAN and East Asia (ERIA).

98% of Queensland prawn areas at risk of inundation by rising seas this century

by bpckle | Apr 7, 2025 | Media

As climate change wreaks havoc with the world’s oceans, future production of fish, crustaceans and other aquatic organisms is under threat.

Our new research shows how this disturbance will play out for Australia’s prawn industry, which is concentrated in Queensland. We found by 2100, sea level rise threatens to flood 98% of the state’s approved prawn areas.

The problem is not confined to prawns – Queensland barramundi farming is also at risk from sea-level rise. Climate change also poses challenges for other major seafood industries in Australia, including salmon in Tasmania.

Australian seafood is vital to our culture and diets, and the national economy. We must take steps now to ensure the aquaculture industry thrives in a warmer world.

Spotlight on Queensland prawns

Aquaculture refers to breeding, rearing and harvesting fish, crustaceans, algae and other organisms in water. Australia’s aquaculture industry is expected to be worth A$2.2 billion by 2028–29.

Aquaculture can involve a variety of methods, from ponds and sea cages to indoor tank systems and even giant ships.

Aquaculture is one of Queensland’s fastest-growing primary industries – partly due to burgeoning production in prawn farming.

Queensland is also expected to experience a 0.8m sea-level rise by 2100, under a high-emissions scenario. Our research investigated how this could affect the state’s aquaculture industry.

We did this by examining existing data on coastal inundation and erosion from sea-level rise, combined with data on current and future aquaculture production areas.

We found 43% of sites where aquaculture production is currently occurring are at risk from sea-level rise. Prawn farming is the most vulnerable.

About 98% of areas approved for prawn farming in Queensland are expected to be inundated by seawater by 2100. The risk includes 88% of areas currently producing prawns. Prawns are grown in large ponds on land near the coast with access to saltwater, which makes them particularly vulnerable to inundation. Annual prawn production losses due to sea-level rise could reach up to A$127.6 million by century’s end.

Inundation and coastal erosion can cause breaches in pond walls compromising their structural integrity. These risks may be amplified when sea-level rise coincides with coastal flooding. Rising seas can also increase salinity in surrounding soils and groundwater, further affecting ponds. Other aquaculture infrastructure, such as hatcheries, buildings, and roads, may also be disrupted.

The Gold Coast region – a prawn production hub – is particularly vulnerable. Damage caused by ex-Tropical Cyclone Alfred highlights the vulnerability of coastal infrastructure to extreme weather. This will only worsen as the planet warms.

Queensland barramundi farms also face a serious threat. Some 44% of areas producing barramundi are likely to be exposed to inundation, causing up to A$22.6 million in annual production losses. Meanwhile, two of Queensland’s designated “Aquaculture Development Areas” – regions earmarked by the state government for industry expansion – may be unsuitable due to future sea levels. Both are located in the Hinchinbrook Shire Council area.

Beyond rising seas

Globally and in Australia, climate change is posing myriad challenges to seafood farmers.

Rising water temperatures stress animals such as salmon, lowering oxygen levels which slows growth rates and increases their risk of disease. Such depletion is a particular concern in already low-oxygen environments, such as Tasmania’s Macquarie Harbour.

Ocean heatwaves can cause mass fish deaths and devastate production. In Tasmania in February, more than 5,500 tonnes of dead fish were dumped at southern Tasmanian waste facilities – a problem linked to warmer water temperatures.

Dead and decomposing fish can further alter oxygen levels in water, spread disease to wild populations and attract scavengers. In the Tasmanian case, fish remains washed up on public beaches, angering the public and leading to calls for greater industry regulation.

Extreme weather further complicates aquaculture operations. Storms, flooding and abnormal rain patterns can affect water salinity which impacts species growth and survival. They can also damage vital infrastructure, which may allow animals to escape.

This occurred in 2022, when repeated flooding and disease outbreaks on oyster farms in New South Wales led to complete stock losses, prolonged farm closures and workers being laid off.

Surviving a warmer future

Not all aquaculture operations will suffer under climate change. Warming waters can lead to longer growing seasons in temperate regions. It can also expand suitable habitat for tropical species such as tilapia, mussels and oysters. Regions previously inhospitable to aquaculture may become viable production zones.

For the countries and producers that are expected to suffer, those that plan for and adapt to climate shifts can minimise losses.

Key steps industry and government can take include:

• planning farms in lower-risk areas and relocating vulnerable sites

• implementing climate-resilient infrastructure and restoring coastal ecosystems near farms to buffer against climate impacts

• expanding to include diverse species and selectively breeding stock that can tolerate the changing conditions

• strategic government policies and planning, financial incentives, and investment in resilient infrastructure to help the industry stay ahead of climate risks.

With the right strategies, Australia’s aquaculture industry can adapt to a changing climate and continue to contribute to food security and community wellbeing.

Caitie Kuempel receives funding from the Blue Economy Cooperative Research Centre. She is affiliated with BECRC Marine Spatial Planning project.

Marina receives Griffith University International Postgraduate Research Scholarship and Griffith University Postgraduate Research Scholarship as and HDR PhD Student

New satellite data shows NZ’s major cities are sinking – meaning rising seas will affect them sooner

by bpckle | Apr 7, 2025 | Media

Rising seas are already affecting coastal communities in Aotearoa New Zealand. On a global average, the sea level is now 18 centimetres higher than it was in 1900, and the annual rate of increase has been accelerating to currently 4.4 millimetres per year.

This may not seem much, but it is already amplifying the impact of storm and tidal surges. Over the coming decades and centuries, this will pose increasingly serious problems for all coastal communities.

But this is not the end of our troubles. Some parts of New Zealand’s coastline are also sinking. In many New Zealand cities, shorelines are steadily subsiding, with growing impacts on coastal infrastructure.

Our new research reveals where and how fast this is happening. We found the coastlines near all major cities in New Zealand are sinking a few millimetres each year, with some of the fastest rates in coastal suburbs of Christchurch, where the land is still adjusting to the impact of the 2011 earthquake.

Relative increase in sea level

Sea-level rise is happening globally because the ocean is expanding as it continues to warm and glaciers and polar ice sheets are melting.

Meanwhile, land subsidence operates on regional or local scales, but it can potentially double or triple the effects of sea-level rise in certain places. This dual effect of rising seas and sinking land is know as relative sea-level rise and it gives coastal communities a more accurate projection of what they need to prepare for.

To understand which parts of the coast are most at risk requires detailed and precise measurements of land subsidence. The key to this is to observe Earth from space.

We have used a technique known as interferometric synthetic aperture radar (InSAR). This involves the repeat acquisition of satellite radar images of the Earth’s surface, tied to very accurate global navigation satellite system measurements of ground stations.

This builds on earlier work by the NZSeaRise project, which measured vertical land movement for every two kilometres of New Zealand’s coastline. Our study uses a significantly higher resolution (every ten metres in most places) and more recent datasets, highlighting previously missed parts of urban coastlines.

Urban hotspots

For instance, in Christchurch the previous NZSeaRise dataset showed very little subsidence at Southshore and New Brighton. The big differences in the new data are not due to the increase in spatial resolution, but because the rate of vertical land movement is very different from the time prior to the 2011 earthquake.

Localised subsidence in these Christchurch suburbs is up to 8mm per year, among the fastest rates of urban subsidence we observed. These areas sit upon natural coastal sand dunes above the source area of the earthquake and the Earth’s crust is still responding to that sudden change in stress.

We have tracked vertical movement of the land with millimetre-scale precision for five major cities in New Zealand. The InSAR technique works particularly well in urban areas because the smooth surface of pavements, roads and buildings better reflects the satellite radar beam back into space where it is picked up by the orbiting satellite.

This means the estimates of relative sea-level rise for these cities are close to or above 7mm per year. If sustained, this amounts to around 70cm of sea-level rise per century – enough to seriously threaten most sea defences.

Our new satellite measurements provide a detailed picture of urban subsidence, even within single suburbs. It can vary by as much as 10mm per year between parts of a city, as this map of Dunedin and the Otago Harbour shows.

We found hotspots of very rapidly sinking regions. They tend to match areas of land that have been modified, particularly along the waterfront. During the 20th century, many acres of land were reclaimed from the ocean, and this new land is still compacting, creating an unstable base for the overlying infrastructure.

One example of this is in Porirua Harbour, where a section of reclaimed land near the mouth of Porirua Stream is sinking at 3–5mm per year. This is more than double the average rate for Porirua’s coast.

Paradoxically, perhaps, it is only by looking back on our planet from outer space that we can begin to see with sufficient detail what is happening to the land in our own backyard.

The good news is that we can use the results to identify coastlines that are particularly vulnerable to sea-level rise and plan accordingly for any future development. Our new measurements are just the first step in what must become a major effort to watch the ups and downs of our coastlines and urban areas.

Jesse Kearse 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.

Biosecurity policies can be annoying – but a century of Antarctic data shows they work  

by bpckle | Apr 7, 2025 | Media

Visitors to Australia are often shocked at having to declare an apple or wooden item under our biosecurity policies. Biosecurity policies are used to keep out pest species and diseases. But they’re expensive to uphold and people can question their worth.

The good news is, they work – and Antarctica’s strict biosecurity policies prove it.

Under the web of agreements governing Antarctica, cargo must be checked for any sign of plants, seeds, insects and rodents. Visitors must ensure the items they bring are clean.

In our new research, we analysed a century of data on how many species have been introduced to the icy continent and surrounding sub-Antarctic islands.

Though there’s little human presence here, many species have been introduced and several have established – including rodents, aphids, and weedy plants – in a surprisingly short time. But across most sub-Antarctic islands, we found the rate of introduced species has remained steady, or slowed, after biosecurity policies were introduced, even as more humans arrived.

The exception was the Antarctic continent itself, where species introductions are increasing. This is likely due to surging visitor numbers and inconsistent biosecurity efforts between different nations and tourist operators.

Our work shows biosecurity policies work – if they’re followed.

Biosecurity in the cold

Antartica and sub-Antarctic islands such as Heard and McDonald Islands have an exceptional richness of species. Wandering albatrosses and emperor penguins live nowhere else. Some islands are home to meadows of megaherbs.

Unfortunately, introduced species have had dramatic effects. Mice eat albatrosses alive. Midges entirely change the functioning of terrestrial systems. Weedy plants outcompete and displace unusual plants on several islands.

Antarctic environments are particularly susceptible to introduced species. New species tend to have faster life cycles and are more tolerant of disturbance. Most indigenous species evolved without predators or competitors.

As the climate heats up, introduced species get a boost. Warmer conditions make it easier for them to get their first foothold, and they do better with warmer climates than do the indigenous species.

These vulnerabilities are why nations responsible for sub-Antarctic islands and those who jointly govern Antarctica through the Antarctic Treaty put strict biosecurity protocols in place from the 1990s onwards.

These policies ban the deliberate introduction of new species and specify the measures visitors and cargo have to undergo to reduce the chance of new species being introduced accidentally.

These protocols include cleaning equipment, clothing and cargo. In many cases, these policies also require eradication of any potentially damaging species if found.

Is it worth it?

All this takes time and money. To do it properly requires many hours of inspections and specific facilities, among other things. Ongoing research is also needed, to ensure the policies keep working.

But eradication of species once established is often even more expensive. Costs are rising globally. Invasive species have cost Australia at least A$390 billion since the 1960s. Eradicating introduced rabbits, rats and mice from Australia’s Macquarie Island cost about A$25 million.

So, are our biosecurity efforts worth the cost?

Assessing the effectiveness of biosecurity policies is rare because it is difficult. To properly gauge effectiveness, you need data from before and after the policy came in. It’s also hard to pinpoint when a species made the jump to the cold; it’s harder to spot one new plant than a thriving population years after the first seeds took root.

We believe our work solves these problems. We collected data on species arrivals across the Antarctic region and corrected for biases using new mathematical approaches that account for differences in survey effort over time.

Most species introductions now happen by accident. Because introductions are closely tied to the numbers of visitors, we expected more species would arrive as visitor numbers grew. But on most sub-Antarctic islands, that didn’t happen. Species arrived at the same rate or more slowly than expected, even as more visitors came.

In other words, the policies are working.

Why is Antarctica the exception?

Since 1998, biosecurity policies for the Antarctic continent haven’t managed to slow the rates of introductions.

Newly introduced species are largely being found on the Antarctic Peninsula, where most tourists and scientists go. The peninsula has the mildest climate of the whole continent and is where Antarctica’s native flowering plants are found, as well as mosses, lichens and fungi.

The new arrivals include annual bluegrass which displaces native plants. Also arriving are invertebrates, such as midges and springtails which can alter how nutrients are cycled in soil and shift other ecosystem functions.

It’s not fully clear why biosecurity policies aren’t working as well on the continent as for the islands. Likely causes include inconsistencies in how biosecurity is policed by different nations, a rapidly warming climate and very rapidly growing numbers of people to the peninsula.

What does this mean for the world?

Introduced species are one of the largest environmental and economic challenges we face, according to an authoritative recent assessment.

This may seem surprising. But the unchecked impact of species such as red fire ants, varroa mite and feral pigs cost Australian farmers billions each year. Prevention is usually better – and cheaper – than the cure.

What our research shows is that biosecurity policies actually work to protect the environment and are likely to be cheaper than the cost of control or eradication. Introduced species now cost the global economy an estimated $423 billion annually.

Society and decision-makers can see environmental regulations as a cost without a benefit. Being able to show the real advantages of these regulations is vital.

Rachel Leihy works for the Arthur Rylah Institute for Environmental Research and Monash University, Melbourne, Australia. This research was done as a part of the Australian Research Council funded program Securing Antarctica’s Environmental Future.

Melodie McGeoch receives funding from the Australian Research Council – SRIEAS Grant SR200100005 Securing Antarctica’s Environmental Future.

Steven Chown receives funding from the Australian Research Council. He is an Honorary life member of the Scientific Committee on Antarctic Research.