The South-West Pacific experienced its second-warmest year in 2025, with rising sea levels and intensified ocean acidification, as per a World Meteorological Organization (WMO) report. The region’s average annual surface air temperature in 2025 was about 0.37 degrees Celsius above the 1991-2020 average, marking it as the second-warmest year on record. Long-term ocean warming has led to more frequent and intense marine heatwaves, impacting marine ecosystems and dependent communities and industries.
Marine heatwaves, characterized by prolonged extreme heat, have resulted in coral bleaching, fish deaths, disruptions to aquaculture, and other detrimental effects. Notably, record-high ocean heat content was observed in various regions in 2025, including areas south of Australia, the southern Tasman Sea, and parts of the tropical North Pacific. Sea levels in the South-West Pacific rose at an average rate of 3.7 millimetres per year between 1999 and 2025.
Furthermore, ocean acidification continued as carbon dioxide absorption increased, leading to the lowest surface ocean pH values on record across much of the South-West Pacific in 2025. The region also faced extreme weather events, with tropical cyclones causing fatalities and economic losses. Cyclone Senyar, for instance, impacted over 10 million people in Indonesia and Malaysia, claiming more than 1,200 lives.
Armida Salsiah Alisjahbana, the executive secretary of the United Nations Economic and Social Commission for Asia and the Pacific, highlighted the intensifying risks in Asia and the Pacific due to rising heat. She emphasized the importance of early warning systems and prompt actions to mitigate the impacts on health, livelihoods, and infrastructure.
