Note: Single-source report; awaiting corroboration.
The Southwest Pacific region experienced its second warmest year on record in 2025, with average surface air temperatures approximately 0.37°C above the 1991–2020 average—second only to 2024—according to the State of the Climate in the South-West Pacific report.
The report highlights that the last remaining tropical glacier in Indonesia may disappear by the end of 2026, with the remaining ice cover now only about two percent of its 1988 extent. This loss is part of broader climate impacts affecting the region.
New ocean temperature data show long-term warming has led to more frequent, longer-lasting, and intensified marine heatwaves. In 2025, record-high ocean heat content was observed south of Australia, the southern Tasman Sea, parts of the tropical North Pacific between the Philippines and Hawaii, and locally south of Sumatra.
Continued warming has contributed to rising sea levels in the Southwest Pacific, averaging an increase of 3.7 millimeters per year from 1999 to 2025, threatening low-lying island nations and coastal settlements.
Marine heatwaves and ocean acidification have caused coral bleaching, fish mortality, disruptions to aquaculture, kelp forest loss, shifts in species distribution, and harmful algal blooms—impacting fisheries, tourism, and local economies. Despite less marine heatwave coverage than in the previous year, 2025 saw the most extensive marine heatwave recorded in a non-El Niño year, with a strong El Niño event possibly developing in 2026.