Alpine ash (Eucalyptus delegatensis) is a tall eucalypt species that grows in the cool, wet mountains of south?eastern Australia.
These forests store large amounts of carbon in their wood and soils. They help regulate water flows into major rivers and dams, and provide habitat for a wide range of birds, mammals and insects.
Mainland alpine ash forests are now formally listed as endangered. This is because bushfires are becoming more frequent and severe due to climate change, which threatens to wipe out some of these forests.
In our new study, we examined how alpine ash forests would change under different climate scenarios, and found that difficult choices likely lie ahead.
Is it still possible to protect this unique species? We think so.
From the ashes
Alpine ash is what ecologists call an “obligate seeder”. This refers to plants that, after a major disturbance such as a bushfire, can only regenerate from seed.
If a mature forest burns, many adult trees die. However, the heat from the flames opens their seed capsules high in the canopy, releasing a flush of seed that allows the forest to regenerate. But this strategy only works if there is enough time between fires for young trees to mature and start to reproduce.
In recent decades, increasingly hot and dry conditions have sparked larger fires, including the devastating “Black Summer” fires of 2019-20. As a result, some regions have been repeatedly burnt within a matter of years.
When fire returns before the new generation of trees can produce seed of their own, alpine ash forests can fail to regenerate and may be replaced by other vegetation. This process, known as “immaturity risk”, is a major reason why alpine ash is now considered an endangered species.
In response, forest managers are increasingly turning to aerial resowing. Helicopters or planes are used to drop seed over burnt areas where young trees were killed before they could produce seed. The goal is to protect patches of alpine ash forest which could otherwise be replaced by other species, and turn into shrublands or grasslands.
Research has shown this active management approach helps protect smaller pockets of alpine ash affected by repeated severe fires. But it’s still unclear how effective aerial sowing can be at a landscape scale.
What we did
In our study, we used a powerful computer model to simulate these ecosystems over the next century and examined the forest changes that happened along the way. We focused on the Australian Alps, the country’s highest mountain range which stretches across southeast Australia.
We then tested how alpine ash forests will fare under different climate scenarios. This allowed us to consider three main questions:
what drives alpine ash decline in mainland Australia and how much loss can we expect?
in a warmer climate, how important is the reproductive age, meaning when the trees first produce seed, to the species’ survival?
how effective is aerial resowing after fires for protecting alpine ash at a landscape scale?
Finally, we examined how these combined factors – climate, fire, tree maturity and resowing – together may reshape the size, location and spread of alpine ash forests over the next century.
Across all scenarios, alpine ash forests shrank dramatically – by between 49% and 65% – over the next 100 years, even without taking extra warming from future climate change into account.
This means that even our current climate and fire patterns are enough to push alpine ash towards extinction. The main drivers of its decline were aridity (hot and dry conditions) and the frequency and severity of current bushfires. But what mattered in its survival?
The strongest factor was the age at which trees first produced seed. We examined trees at seven and 15 years of age. Scientists often treat 15 years as the “normal” age for this species to reach maturity. Work by colleagues and our own field observations, however, suggest that young alpine ash trees can start producing seed much earlier, at about seven years age.
When we assumed trees could produce seed earlier, our model predicted about 96,000 hectares more alpine ash forest would survive in a century’s time. compared to maturity at 15 years. That’s about 14% of existing alpine ash forests in mainland Australia.
Surprisingly, our study shows aerial resowing after fire would only boost alpine ash survival marginally, saving between 1% and 3% of alpine ash forest area over the next 100 years.
Hard decisions ahead
Our findings show even current climate and fire risk are enough to push Australia’s alpine ash forests towards long-term decline. Therefore, authorities have to make hard decisions about which areas can be saved – and which can’t.
It also means we can’t wait for the future to unfold. To protect this important species, we must make targeted decisions about which regions to prioritise now.
To guide these difficult decisions, authorities can use the resist–accept–direct framework to target management and conservation activities at large scales, relevant to species conservation.
Resist
In some high value areas, forest managers can “resist” change by focusing on fuel management to reduce the intensity of future fires and limit how quickly they spread.
In areas where fuel management works, managers can also use targeted resowing. Given our research shows this approach isn’t as effective across large scales however, resowing should be used selectively to to keep patches of alpine ash connected and protect forest edges that will burn more frequently.
Accept
In high-risk areas, managers may need to “accept” that alpine ash will be taken over by more fire-tolerant vegetation, such as resprouting eucalypts. These trees can survive fires and regenerate their crowns by growing fresh shoots from their bark or roots. Such vegetation types may provide different ecosystem values, but are more resilient to future fire and climate.
Direct
In the remaining areas, managers can actively “direct” change. For example, they could introduce these fire-resilient “resprouter” tree species, such as mountain gums (Eucalyptus dalrympleana), or snow gums (E. pauciflora). They could also sow or plant alpine ash in areas previously occupied by other species or used by humans, or test climate-resilient seed sources for regeneration.
The future for alpine ash is likely going to be a mixed bag.
Landscape-scale models like ours can be used to map and better understand which areas can be protected, which can’t, and what else can be done to help forest managers take the best course of action.
That’s crucial to protect our unique alpine ash forests in a warmer, drier and more fire-prone world.
Benjamin Wagner receives funding from the Victorian Department of Energy, Environment and Climate Action.
Craig Nitschke receives or has received funding from the the Victorian Department of Energy, Environment and Climate Action, Parks Victoria, the Australian Alps Liaison Office, Melbourne Water, VicForests, the City of Melbourne, Greening Australia, the Australian Research Council, Australian Forest and Wood Innovations, Natural Hazards Research Australia, the federal Department of Climate Change, Energy, the Environment and Water, the Australian Institute of Nuclear Science and Engineering, New South Wales Local Land Services, the New South Wales Natural Resources Commission, the North Central Catchment Management Authority, the Northeast Catchment Management Authority, the Goulburn Broken Catchment Management Authority, the Paddy Pallin Foundation, the Norman Wettenhall Foundation and the Foundation for Australia’s Most Endangered Species.
Kaitlyn Hammond has received funding from the Victorian Department of Energy, Environment and Climate Action, Parks Victoria and the Australian Alps Liaison Office.
Forecasters expect the El Niño now underway in the tropical Pacific to strengthen into a strong or very strong climate driver later this year.
When an El Niño arrives, it reorganises rainfall patterns around the world. Parts of the Americas and east Africa tend to get heavier rain, while monsoonal rains in Asia get weaker and drier conditions settle over eastern Australia, southeast Asia, India and southern Africa.
This mix of heat and disrupted water supplies could have real consequences for food supply, especially rice. El Niño doesn’t tend to hit wheat as hard, because a bad season in one region is often offset elsewhere. But rice is different. Production is concentrated in Asia and only a small share is traded.
Over half the world’s population relies on rice. India and China grow more than half of the world’s supply, and rice supplies more than half of all daily calories in countries such as Bangladesh, Vietnam and Cambodia.
Poorer households spend the largest share of income on food, so price spikes hit them first and hardest. In 2007-08, rice prices roughly tripled, food riots broke out in dozens of countries, and in Haiti, the unrest helped bring down the prime minister. Securing rice is about more than food – it underpins public order.
Rice is also a thirsty crop. Most high-yielding varieties are bred for flooded paddies, where water suppresses weeds, supports flowering and grain development, and helps keep plants cool. Hardier upland rice can grow with less water but usually yields less. Hence, breeders want to move the drought-tolerance of upland rice into lowland varieties that most farmers actually grow.
If this year’s El Niño is severe, it could hit the water supplies of several major producers at once, so shortfalls compound rather than cancel out.
Fertiliser prices have also spiked in 2026 due to the Iran war and disruption to the Strait of Hormuz, making a hard season even harder.
The issue with irrigation
Around three-quarters of the world’s rice comes from irrigated lowland paddies. Irrigation buffers rice against patchy rainfall in normal years, but it depends on water sources such as rivers, reservoirs and snowmelt which El Niño can affect.
Australia shows this clearly. The Riverina region of New South Wales grows some of the most water-efficient rice in the world. But rice competes for water with permanent plantings such as almonds, which must be watered regularly.
In the worst droughts, Australia’s rice crop has fallen to a small fraction of normal production.
A shock that travels
Rice is thinly traded. Most of what a country grows is eaten at home, and exports are often less than 10% of production. This means a disruption to a few big exporters can move prices fast.
In 2023, India clamped down on rice exports to protect domestic prices, resulting in global price surge. But the picture recently reversed. India now has record stocks and is exporting heavily after lifting its bans, easing prices.
This situation is not guaranteed to last. During the 2007-08 rice crisis, export bans and panic buying were the major factors driving up prices. If this year’s El Niño is severe, it could hit several regions at once, triggering bans and panic buying on a larger scale. Worst hit would be poorer nations dependent on rice imports, such as the Philippines and West African countries.
Some rice varieties can better tolerate hotter, drier conditions.Rio Susanto/Getty
Can we prepare?
Rice farmers in Indonesia are racing to plant their crop ahead of El Niño, and farmers elsewhere are trying to adapt too.
Researchers can play a key role. Before being domesticated, wild rice was a humble grass with much smaller grains and lower yields. Thousands of years of selective breeding have turned it into cultivated rice, with much larger yields.
Our recent work suggests some rice varieties can conserve water without an obvious yield and quality penalty even when water supplies are limited.
Farming methods can save water too: growers can let paddies dry between waterings, irrigate later in the season, or grow rice more like a dryland crop. Standing water also shields the crop from temperature extremes, cooling it in heat and buffering it against cold, so cutting it back too far can expose flowers to damage at the most vulnerable stage.
Beyond the farm, preparation means better forecasting, sustained research investment, and a shared resolve among rice-growing nations to keep trade open rather than hoard in a crisis.
We are not powerless against a strong El Niño. But this year’s rice supply faces a real test. The stakes are high, not just for food security, but also for global stability.
Vito Butardo Jr receives funding from AgriFutures Australia.
Many parts of Australia have already broken early winter maximum and minimum temperature records.
In southern Australia, Sydney and Melbourne had their warmest ever starts to winter. Daily observations show both cities experienced above-average June temperatures almost every day of the month.
Adelaide has also recorded above-average June temperatures in its first three weeks. Hobart and Canberra had mild starts to winter, with temperatures well above normal. So far, Perth is the only southern capital with typical June temperatures.
The world is experiencing a trend of unseasonably high temperatures driven by global heating, including the early summer heatwave in western Europe and parts of Asia.
So, what can we expect for the rest of the winter season? And does a warm winter have consequences for Australia’s next summer?
The months ahead
Abnormally warm conditions in Australia are likely to continue for at least the coming weeks, according to the Bureau of Meteorology’s seasonal outlooks. Long periods of dry weather are likely, especially in late winter and spring, following the recent El Niño development.
However, infrequent cold polar outbreaks still can impact southern Australia due to jet stream “waviness” south of Australia. Here, waviness is the meandering of the air currents as they form the jet stream. If this occurs in a north-south direction instead of west to east, this can affect the movement of cold air and low pressure systems.
A poor 2026 Australian ski season has just started, and the outlook for sufficiently deep snow cover is unfavourable. However, just one or two unexpected heavy snowstorms can produce a major season turnaround.
We’re part of a wider trend
The seasons underway in Australia exemplify a worldwide trend of unseasonably high temperatures, including the early summer heatwave in western Europe.
Previously, extreme summer temperatures occurred later in the European summer, during July or August. But the present heatwave has produced record June maximum temperatures throughout Europe.
On June 26, the United Kingdom’s hottest ever June day, temperatures reached 37.3°C. The previous all-time UK June record was 36.1°C in 1976. During the heatwave, much of France, Spain, Italy and Germany reached or exceeded 40°C. Humidity levels have also been high. This unusually early and intense heatwave confirms climate extremes are the new normal.
Many nations are facing their warmest winters on record. The extreme heat is due to accelerated global warming since the 1990s, caused by human-made climate change. The United Nations predicts hot and cold extremes in nearly all inhabited regions with increasing global warming.
Our research, published earlier this year, confirmed this unseasonable warmth is due to the warming of Earth’s atmosphere and oceans. Global warming causes changes in large-scale southern hemisphere atmospheric circulation patterns. It also amplifies the impacts of known “climate drivers”, which are large-scale processes in the atmosphere and ocean that dictate weather patterns and climate variability.
We know the southern hemisphere jet streams, the fast-flowing, narrow bands of wind in the upper atmosphere, and associated storm paths, have shifted poleward. Once-reliable winter and spring rain-producing systems now often pass south of Australia.
Hence, southern Australia has been experiencing more high pressure systems. The result is cloudless skies and higher daytime temperatures. This is similar to the current heat dome in western Europe.
Furthermore, Pacific Ocean temperatures off the Australian subtropical east coast are well above average. Consequently, Tasman Sea high-pressure systems are directing warm, humid air over southeast Australia. This airflow means daily minimum temperatures are warmer than average.
A record-setting Australian summer?
You might be wondering whether Australia’s next summer will break heat records. For now, the best answer can only be a firm “maybe”.
Accelerated global warming is continuing, and clearly not confined to Europe. Recently, the eastern half of the United States issued an early summer heat dome warning.
Forecasters are warning southeast Australia to expect hotter, drier conditions in this El Niño year – a frightening combination that suggests record heatwaves, droughts and extreme bushfire danger are likely.
Melbourne is particularly vulnerable to dry weather because of low dam levels. Its catchment level (64% and falling) is the lowest since the Tinderbox Drought of 2017–19. Daily observational data shows Melbourne missed the rain that replenished Australia’s other southern capital cities in autumn and spring. Melbourne and its catchment are in the rain shadow of the Great Dividing Range, drying out the warm, humid subtropical air.
There is still a possibility Australia’s summer won’t break records. After all, an El Niño does not always generate extreme temperatures, dry conditions and fire weather. Also, the Southern Annular Mode – a climate driver that can influence rainfall and temperature in Australia – might bring more cold fronts.
Therefore, it’s possible that extreme heat might not take place in late spring or early summer. But the way things are shaping up, it looks likely.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
Red warnings issued in Hungary, Poland, Romania and the Balkans, with authorities urging people to stay indoors
Parts of central, eastern and southern Europe sweltered on Monday as the “heat dome” behind last week’s record-breaking temperatures shifted east, bringing dangerous conditions to a new swathe of the continent.
Budapest is forecast to exceed 40C on Tuesday, according to models from the European Centre for Medium-Range Weather Forecasts.
Teams painstakingly combed endangered Atlantic habitat over several years, helping to grow 8m native trees
A small band of volunteers has helped to grow nearly 8m native trees in Scotland, crucial to efforts to restore lost parts of the Atlantic rainforest, after collecting 11m seeds by hand.
About 100 volunteers, including retired teachers and doctors, office workers and young families, have spent tens of thousands of hours venturing into often remote woods in the western Highlands and islands to search out seed-bearing trees.
