(BSS/AFP) - The southwest Pacific region is facing "increasing risk" from ocean warming, marine heatwaves and rising sea levels, the United Nations` weather and climate agency warned Tuesday.

The vast waters of the southwest Pacific are becoming hotter and more acidic, harming local economies and marine ecosystems, the World Meteorological Organization said.

Meanwhile rising sea levels are threatening vulnerable coastal communities and low-lying island nations, the WMO said in its State of the Climate in the Southwest Pacific 2025 report.

The region experienced its second-warmest year on record in 2025 -- behind 2024 -- "with extreme weather causing widespread disruption, economic damage, and loss of life", the agency said.

The annual mean surface air temperature over both land and ocean areas in 2025 was about 0.37C above the 1991 to 2020 average.

"For many countries and territories in the southwest Pacific, the ocean is central to livelihoods, economies and resilience," said WMO chief Celeste Saulo.

"In 2025, the region experienced warming oceans, rising sea levels, marine heatwaves and ocean acidification, alongside tropical cyclones and the continued loss of tropical glacier ice."

In 2025, the remaining mountain ice cover in Papua, Indonesia, was estimated to be only about two percent of the ice area observed in 1988.

"The last remaining tropical glacier of the region is expected to disappear by the end of 2026 or early 2027," the WMO said.

- Ocean heat -

"Marine heatwave coverage in 2025 -- whilst lower than the previous year -- was the most extensive ever recorded in a year without an El Nino event," the WMO added.

"This is a worrisome sign for 2026, with a potentially strong El Nino event now developing."

From 1999 to 2025 the sea level rose at an average rate of 3.7 millimetres per year in the region.

Meanwhile, ocean waters are becoming more acidic as a result of absorbing increasing amounts of carbon dioxide.

"Ocean acidification, together with ocean warming and deoxygenation, is affecting marine ecosystems, habitats and biodiversity," the WMO said.

The Geneva-based agency`s regional reports aim to provide scientific support for decision-making and disaster risk reduction.