Experts warn that some marine species are at risk of ‘mass mortality events’ in ever-warming oceans
UK waters are being hit with an “extreme” marine heatwave, the Met Office has said, as scientists warn that high ocean temperatures globally could result in “mass-mortality events” for some species.
The forecasters said these elevated temperatures have developed rapidly because of last month’s heat dome, during which most of Europe sweltered in its worst ever heatwave that scientists said would have been impossible without the climate crisis.
South Australia confirms its second H5 bird flu case while Western Australia investigates two more suspected detections, as authorities say the virus has not spread beyond isolated wild birds.
Every winter, millions of Australians are reminded how hard it is to live comfortably in older homes. Warm air constantly leaks out through poorly insulated ceilings, walls and floors, and through gaps in floors, windows and under doors. Heaters run day and night, sending energy bills soaring.
The gap between new and old homes is huge. Since 2004, new homes across most of Australia have to meet minimum energy performance standards. Homes now have to reach 7 stars on the national Home Energy Rating scheme, known as NatHERS (or the equivalent BASIX system in New South Wales). The higher the rating, the cheaper it is to get through winter or summer.
By contrast, homes built before 2004 get an average of just 2.1 stars. Many lack basic features such as insulation, draught proofing and energy efficient appliances. That’s according to new research we undertook assessing energy performance of almost 1,100 older homes in NSW. Across the state, this means about 850,000 homes would get zero or 1 star for energy performance.
Almost half (46%) the homes assessed got the worst rating for cold weather comfort, while 37% were rated as very difficult to keep cool in summer.UTS/DCCEEW
Why does this matter?
Requiring new homes to be more and more energy efficient over time is good policy. Energy efficient homes require less heating and cooling and keep residents comfortable.
But houses last a long time. In NSW, most homes were built before these standards were introduced over 20 years ago. Older homes make up 61% of the state’s housing stock, or just over two million homes.
The energy performance gap means most people in NSW live in homes which are harder and more expensive to keep comfortable during cold and hot weather.
These costs can be considerable. Of a home’s fixed energy use, 38% is used to heat air, 29% to heat water, and 16% to cool air. A 2-star home would typically need 4–6 times as much energy as a 7 star home to maintain a comfortable temperature.
Residents are forced to run their heaters and air conditioners more often to maintain comfortable temperatures or risk their wellbeing if they can’t afford to.
It’s not news that older homes aren’t as energy efficient. But much of what was known came from a 2015 study on 60 houses in Victoria, which found homes built before 2005 averaged 1.8 stars. Our new research analysed 1,091 homes across New South Wales, giving us a much larger and geographically diverse evidence base.
The homes in this research came from across the state. They were selected to be representative of older housing types, including single dwellings and townhouses built before 2004. Apartments were not included.
A small group of home energy assessors visited and assessed all 1,091 homes between July 2023 and June 2024. Each home was assessed using the Residential Efficiency Scorecard approach, and then converted into the equivalent NatHERS star rating.
Demand for heating and cooling differ depending on climatic zones in NSW.UTS/DCCEEW
Why is the gap so large?
The introduction of minimum energy standards has led to clear improvement in new homes. Builders and owners can choose how to meet energy performance requirements – it’s not one size fits all.
Typically, newer NSW homes have double the ceiling insulation of older homes, coupled with insulation in external walls and often under floors. Windows and doors with good air seals are now standard features.
By contrast, a typical older home has little or no insulation in the walls and floors. It’s common for warm air to leak out and draughts of cold air to blow in. Our research found only 22% of doors and 40% of windows were sealed.
Older homes also tend to have older, less energy-efficient methods of heating and cooling. We found 72% of fixed heating and 60% of cooling appliances had efficiency ratings of medium or below.
Older homes have much worse insulation than newer homes. The R value refers to how well insulation resists heat flow.UTS/DCCEEW/CSIRO
Renters have it worse
Our research shows renters have it worse. Older homes used as private rentals had significantly lower energy ratings (1.6 NatHERS stars) compared to the homes where owners lived there (2.1 stars).
Rental properties had lower levels of insulation in ceilings and walls, as well as less access to heating and cooling. Almost a quarter of rentals (24%) had no air conditioners.
Rental homes were more than twice as likely to have expensive-to-run electric radiators for winter heating (16% compared to 6–7% for owner-occupied).
What can be done?
Many older homes can be upgraded to make them more liveable and cheaper to live in. These include:
Lower cost
sealing gaps to prevent draughts
switching to water-efficient shower heads
Mid-range
upgrading insulation in ceilings, walls and potentially floors
improving internal window coverings
replacing inefficient appliances with energy-efficient reverse cycle air conditioners for heating and cooling
switching to efficient heat pumps for hot water or setting existing electric systems to heat in the middle of the day alongside new solar sharer plans if eligible
Combining improvements can cut energy consumption up to 39%.
Cheap upgrades include sealing gaps around windows, under doors and in walls to stop cold air getting in.NataKor/Getty
Scaling up
Upgrading older homes at scale would cut energy consumption while improving resident comfort and reducing energy bills.
But cost is a deterrent. Our research has informed the state government’s new Home Energy Saver scheme, intended to make this less of a barrier.
The scheme currently offers zero interest loans for home owners to upgrade energy performance. In the future, it will offer discounts of up to A$4,000 for owners and renters on lower incomes.
The government plans to introduce disclosure of home energy ratings when homes are sold or rented to give people more information about energy costs.
It’s too early to say whether these schemes will do what policymakers hope. But our research shows the problem is real – and it won’t fix itself.
Matthew Daly has received funding from the RACE for 2030 Cooperative Research Centre, the NSW Department of Climate Change, Energy, the Environment and Water, and the Australian Renewable Energy Agency for home energy upgrades and demand flexibility research.
Australia is racing to contain the spread of highly pathogenic avian influenza (HPAI), which is now believed to have infected seven seabirds.
There are currently five confirmed or suspected cases of the H5N1 clade 2.3.4.4b strain in Western Australia, alongside one in South Australia and one in New South Wales.
HPAI is still not established in Australia, and currently poses little risk to human health. But the H5N1 strain has already devastated wildlife populations globally.
We’re yet to see how this deadly virus will affect our country’s wildlife. But an urgent concern is the potential for scavenger animals to spread H5N1 further by eating infected carcasses.
The term carcass, which refers to the body of a dead animal, may make you queasy. But carcasses are a natural and vital part of our ecosystems.
They provide food for scavengers, who in turn ensure our landscapes aren’t littered with dead animal material. Vultures are the most well-known example.
But Australia has no vultures. Instead, our “clean up crew” is made up of a hodgepodge list of native and invasive species including dingoes, Tasmanian devils, red foxes, feral pigs, quolls, raptors such as kites and sea eagles, and corvids such as crows and ravens.
We now know 48 species of Australian vertebrate animals will, in certain conditions, feed on carcasses. But scavenging isn’t limited to carnivores. In fact, research shows almost all animals will scavenge if needed, including herbivores such as brushtail possums.
Infected carcasses are a risk
H5N1 in Australia poses a risk to any species that scavenges, or even touches, an infected carcass.
Raptors, corvids and gulls commonly scavenge along shorelines and are most vulnerable to the virus. Mammals that forage along coastlines, such as red foxes, may also be more at risk.
The H5N1 strain can survive in infected carcasses for up to 30 days at 20°C, and 240 days at 4°C. This creates a wide window during which scavengers can be exposed to the virus.
A scavenger that eats a contaminated carcass may get sick. But they can also spread the virus by moving infected carcass material or infecting other animals through their bodily fluids. Scavengers may also die from the virus and contaminate any other scavengers that feed on their carcass.
It’s difficult to predict how H5N1 may spread through Australia’s scavenger species, because we don’t have any detailed research looking at which species actually eat dead birds.
However, international research shows mammals can be infected after consuming infected bird carcasses. Scientists have also observed high rates of H5N1 infection and death in vultures in Europe and the US.
Scavenging may be seasonal
Whether scavengers actually feed on carcasses often depends on the season. Research suggests birds and mammals scavenge more in winter compared to summer. That’s because there is typically less live prey available in the colder months.
This is concerning, given the H5N1 strain has arrived in the middle of the Australian winter. However, summer may slow the spread of the virus. One reason is scavenging insects such as flies, ants and beetles can consume carcasses extremely quickly, sometimes even faster than mammals and birds. In doing so, they may reduce how many infected carcasses scavengers are exposed to.
There are several ways we can curb the spread of H5N1 through our scavenger species.
One is to immediately remove any infected carcasses, particularly from high-value conservation areas. We should also limit activities likely to cause the build-up of carcasses, such as recreational duck or quail hunting.
Where we can’t get rid of carcasses, we must track scavenger activity. This is possible through carcass monitoring, which can help identify which species are actually eating dead birds and whether they are native or introduced. We want to protect our native scavengers, while limiting the harm introduced scavengers may do to our ecosystems.
We must also monitor the scavengers themselves. As with wild birds, this allows us to notice any virus-related health problems and measure overall infection rates.
Our bird flu response must prioritise the health and management of scavenger animals. Only then can we protect our animals, ecosystems and communities from a wider H5N1 outbreak.
Michael Ward receives funding from the Australian Research Council via a Laureate Fellowship.
Thomas Newsome receives funding from the Australian Research Council. He is President of the Royal Zoological Society of New South Wales, and a member of the Australasian Wildlife Management Society (past President), Australian Mammal Society and Ecological Society of Australia.
Niraj Meisuria 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.
