How Warming Oceans Affect Australia’s Flora, Fauna and Weather
Australia’s oceans are warming faster than many parts of the globe, with sea surface temperatures having risen by about 1.05 °C since 1900. In particular, the Tasman Sea on the east coast is heating at roughly twice the global average, while the Indian Ocean, the Coral Sea, and the southern waters are also registering substantial increases in heat content [1,2]. These warming seas do not exist in isolation: they drive changes in large-scale climate systems such as El Niño and La Niña, the Indian Ocean Dipole, and the Southern Annular Mode, which, in turn, shape Australia’s rainfall, temperature extremes, and broader weather patterns [3].
The consequences for Australia’s climate are profound. Warmer oceans mean more evaporation and greater atmospheric moisture. This results in heavier downpours in some regions and intensifies drought in others, depending on how the circulation systems shift [4]. Sea-level rise from thermal expansion compounds the impact of storms and surges on coastal communities [5]. Marine heatwaves, now longer and more frequent, have also been linked to stronger cyclones, altered rainfall and disruptive weather patterns [6]. These processes feed into conditions on land, prolonging fire seasons and leaving vegetation more flammable than in the past [7].
The health of Australia’s marine ecosystems is already showing signs of strain. Coral reefs are especially vulnerable: the Great Barrier Reef has endured multiple mass bleaching events in the past decade, with scientists estimating that 70 to 90 per cent of corals could be lost at 1.5 °C of global warming and up to 99 per cent at 2 °C [1]. In Western Australia, the Ningaloo Reef has been struck by the most severe bleaching in its recorded history, with coral death across 1,500 kilometres of reef [8]. As coral declines, so too does the rich diversity of fish and invertebrates that depend on it for habitat, and the reef’s capacity to protect coastlines or store carbon.
Fish and other marine fauna are also responding to rising sea temperatures by shifting their ranges. Many tropical species are moving southward into cooler temperate waters, but such migrations can destabilise established ecosystems and lead to unexpected predator–prey interactions [9]. Marine heatwaves have caused catastrophic fish kills, such as the 30,000 fish found dead off the Western Australian coast in early 2025 [10]. Meanwhile, kelp forests and seagrass meadows in southern Australia, which provide critical habitat for abalone, crayfish and numerous smaller species, are being eroded by repeated warming events [2]. Together, these changes destabilise commercial fisheries, undermine food security and threaten livelihoods tied to the sea [11].
The effects of warming oceans reach inland, shaping the condition of vegetation and wildlife across the continent. By altering rainfall and increasing drought frequency, ocean-driven climate changes stress forests and woodlands, reducing their capacity to regenerate and making them more vulnerable to pests and invasive species [7]. In some areas, cooler, wetter-adapted plants are retreating, while heat- and drought-tolerant species are expanding, reshaping ecosystems. This has direct consequences for wildlife: birds, marsupials and insects lose access to food and breeding sites when vegetation communities shift.
Coastal vegetation is especially vulnerable. Rising seas are pushing back mangroves, saltmarshes and estuarine woodlands, warmer waters and more frequent storm surges. Their loss weakens natural buffers against coastal erosion, reduces nursery grounds for fish, and strips ecosystems of one of their most effective carbon storage systems [12]. These changes ripple outward: when mangroves decline, fisheries weaken; when woodlands dry, wildlife disappears; when seagrasses die, carbon once stored safely in the seabed is released.
Australia’s flora and fauna are among the most unique in the world, and many species are tightly adapted to specific climates and narrow temperature ranges. The rapid pace of ocean and land warming, therefore, creates risks of irreversible decline. Beyond biodiversity, the services ecosystems provide — from fisheries and tourism to coastal protection and cultural connections to Country — are also at risk [5]. For Indigenous communities, who have tended both Sea Country and land Country for millennia, the erosion of these systems strikes at the heart of culture and identity.
The story of ocean warming is therefore not simply about marine systems. It is a story that connects reefs with forests, kelp beds with eucalypt woodlands, and corals with koalas. The warming seas shape the air we breathe, the food we eat, the weather we endure, and the landscapes we live among. If these systems unravel, the impacts cascade far beyond the shoreline. The good news is that we know what needs to be done. Cutting greenhouse gas emissions is the essential first step, reducing the driver of ocean warming. Alongside this, protecting and restoring coral reefs, kelp forests, seagrasses, mangroves, and forests can build resilience and buffer against the worst impacts. Adaptive management of fisheries, integrated coastal–terrestrial planning, and deeper engagement with community and Indigenous knowledge can all strengthen the web of resilience.
Yet, once again, we find that the responses being offered by institutions often ignore the urgency of the changes we are now clearly witnessing across the planet. Policy frameworks remain slow, fragmented, and primarily rooted in linear thinking — projecting cause and effect in straight lines, as though complex systems will respond predictably. The reality of climate and ecological breakdown is far more entangled. Complexity science shows that feedback loops, tipping points, and emergent properties define how ecosystems behave. However, most institutional responses still fail to integrate these insights. Instead of embracing non-linear strategies that account for thresholds, cascading risks, and resilience-building across scales, the majority of climate and biodiversity policies remain piecemeal, reactive, and incremental. What is missing is a deeper shift — from linear fixes to complexity-informed governance that matches the systemic, dynamic nature of the crisis itself.
References
Great Barrier Reef Marine Park Authority. Climate change and the reef [Internet]. GBRMPA; 2025 [cited 2025 Oct 28]. Available from: https://www2.gbrmpa.gov.au/learn/threats/climate-change
CSIRO. State of the Climate 2024: Oceans [Internet]. 2024 [cited 2025 Oct 28]. Available from: https://www.csiro.au/en/research/environmental-impacts/climate-change/State-of-the-Climate/Oceans
Department of Climate Change, Energy, Environment & Water. Climate and climate change — Marine State of the Environment [Internet]. 2021 [cited 2025 Oct 28]. Available from: https://soe.dcceew.gov.au/marine/pressures/climate-and-climate-change
Monash University. How warming oceans are already changing life across Australia far beyond the coastline [Internet]. Lens; 2025 Jun 8 [cited 2025 Oct 28]. Available from: https://lens.monash.edu/%40science/2025/06/08/1387646/how-warming-oceans-are-already-changing-life-across-australia-far-beyond-the-coastline
Millennium Alliance for Humanity and Biosphere. How global warming affects Australia [Internet]. 2024 [cited 2025 Oct 28]. Available from: https://maweb.org/how-global-warming-effects-australia
Reuters. Australia must brace for longer fire seasons, marine heatwaves ahead, report says [Internet]. 2024 Oct 30 [cited 2025 Oct 28]. Available from: https://www.reuters.com/world/asia-pacific/australia-must-brace-longer-fire-seasons-marine-heatwaves-ahead-report-says-2024-10-30
Wikipedia. Climate change in Australia [Internet]. 2025 [cited 2025 Oct 28]. Available from: https://en.wikipedia.org/wiki/Climate_change_in_Australia
The Guardian. WA’s longest and most intense marine heatwave killed coral across 1500km stretch [Internet]. 2025 Aug 12 [cited 2025 Oct 28]. Available from: https://www.theguardian.com/australia-news/2025/aug/12/was-longest-and-most-intense-marine-heatwave-killed-coral-across-1500km-stretch
Down To Earth. Australia’s reef fish must adapt, migrate or face extinction [Internet]. 2025 Jul [cited 2025 Oct 28]. Available from: https://www.downtoearth.org.in/climate-change/australias-reef-fish-must-adapt-migrate-or-they-might-go-extinct
The Guardian. Ocean heatwave likely killed 30,000 fish off Western Australia coast [Internet]. 2025 Jan 29 [cited 2025 Oct 28]. Available from: https://www.theguardian.com/australia-news/2025/jan/29/ocean-heatwave-likely-killed-30000-fish-off-western-australia-coast-government-says
Australian Marine Conservation Society. Climate change and the ocean [Internet]. 2025 [cited 2025 Oct 28]. Available from: https://www.marineconservation.org.au/climate-change/
Department of Climate Change, Energy, Environment & Water. Ocean–climate connection [Internet]. 2025 [cited 2025 Oct 28]. Available from: https://www.dcceew.gov.au/environment/marine/ocean-climate-connection
