Long stints of extreme ocean heat were experienced by nearly 40 million square kilometres of the region last year, including the waters surrounding Australia, the World Meteorological Organization (WMO) has revealed.
WMO secretary-general Celeste Saulo said ocean heat and acidification were together inflicting long-lasting damage on marine ecosystems and economies
"It is increasingly evident that we are fast running out of time to turn the tide," she said.
High ocean temperatures have been wreaking havoc on heat-sensitive coral reefs worldwide, with Australian authorities reporting the sixth mass bleaching event at the Great Barrier Reef in less than a decade.
Warming on land was also higher than it had ever been in 2024, with Thursday's report from the United Nations weather and climate agency identifying temperatures around 0.48C above the 1991–2020 average across the region.
Heatwaves were particularly acute in Western Australia, with the coastal town of Carnarvon reaching 49.9C in February and breaking existing temperature records by more than two degrees.
The southwest Pacific assessment aligns with global temperature records being consistently broken as concentrations of greenhouse gases in the atmosphere reach fresh highs.
Last year was the hottest on record and the first to surpass 1.5C warmer than pre-industrial times, the benchmark temperature under the Paris climate agreement.
The global pact has not yet been breached as it refers to long-term trends but more warming is expected, with a separate WMO report predicting a 70 per cent chance the average temperature over the next five years will exceed 1.5C.
The WMO regional report pre-dated Cyclone Alfred and the devastating flooding events Australia experienced in the first half of 2025 but captured above-average rainfall for the northern states in 2024.
A sea level rise in the Pacific region that exceeds global averages was also recorded, threatening island communities living near the coast.
Elsewhere in the region, Indonesia's glacier ice degraded 30 to 50 per cent compared to 2022.
If melting continues at the same rate, the ice is on track to disappear entirely by 2026 or soon after.
The Philippines was struck by twice as many cyclones as normal, with 12 storms hitting the country between September and November.
Climate patterns also influenced the year's weather events, including El Nino conditions at the start of 2024 in the tropical Pacific ocean that weakened to neutral conditions by the middle of the year.
Head of the federal Climate Change Authority Matt Kean said there was still "time to arrest this direction of travel to a hothouse destination" at an event in Sydney on Wednesday.
"First, we should ignore the doubters whose main mission seems to be to prolong the life of fossil fuel industries," he said while delivering the Talbot Oration at the Australian Museum.
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