WMO 2025 Report: Indonesia's Last Tropical Glacier Will Disappear by Early 2027

The World Meteorological Organization (WMO) released its State of the Climate in the South-West Pacific 2025 report on 7 July 2026, documenting a region under accelerating climate stress . The report covers the second warmest year on record, unprecedented marine heatwaves, the terminal phase of the region's last tropical glacier, and the deadly impacts of Cyclone Senyar .

2025 Was the Second Warmest Year on Record for the Region

2025 was the second warmest year on record for the South-West Pacific, behind only 2024 . This follows a global pattern: the WMO's State of the Global Climate 2025 report confirmed that 2015-2025 are the hottest 11 years on record .

The warming was driven by long-term climate change rather than El Niño. As one WMO official noted, although the 2025 marine heatwave occurred in a non-El Niño year, the temperatures were still extreme .

Marine Heatwaves: Largest Non-El Niño Coverage Ever Observed

2025 experienced the largest marine heatwave coverage ever observed in the region during a non-El Niño year . These heatwaves disrupted ecosystems, bleached coral reefs, and harmed fisheries that local economies depend on .

For context, the 2024 report already documented record-breaking sea-surface temperatures and nearly 40 million km² affected by marine heatwaves—the largest area since 1993 . The 2025 report shows the trend continued even without El Niño amplification.

Puncak Jaya Glacier: 98% Ice Loss and Imminent Disappearance

The most dramatic finding concerns the last remaining tropical glacier in the South-West Pacific, located near Puncak Jaya in Papua, Indonesia.

• By 2025, the remaining ice cover was estimated to be only about 2% of the ice area observed in 1988—a 98% loss .
• Satellite data from September 2025 measured the glacier area at just 0.09 km², a 44% reduction from 2024 alone .
• The glacier is expected to disappear by the end of 2026 or early 2027 .

A separate analysis from the Columbia Climate School found that the peak lost 97% of its ice over the past 44 years, with four of its original five glaciers already gone . The thinning rate accelerated roughly 5.4-fold during the strong 2015-2016 El Niño, and the remaining glaciers are now in their terminal phase .

Sea-Level Rise: 3.7 mm per Year Between 1999 and 2025

Between 1999 and 2025, sea levels in the South-West Pacific rose at an average rate of 3.7 mm per year . This threatens low-lying island nations and coastal communities across the region. Globally, the mean sea level reached a record high in 2024, rising at 4.7 mm per year . The regional rate is close to the global average but particularly dangerous for the Pacific's small island developing states .

Ocean Acidification: Hotter and More Acidic Waters

The report states that the region's ocean waters are "becoming hotter and more acidic," harming local economies and marine ecosystems . A specific pH value for 2025 was not provided in the available press releases or summaries. However, the WMO's global report confirms that ocean acidification has continued over the past 41 years, with the ocean absorbing around 29% of anthropogenic CO₂ emissions in the past decade .

Impacts on Livelihoods: Cyclone Senyar and Fisheries

Cyclone Senyar was the deadliest single event of 2025 in the region. It was the first known tropical cyclone in the Strait of Malacca, affecting more than 10 million people and killing over 1,200 in Indonesia and Malaysia .

More broadly, hotter and more acidic waters disrupted fisheries and local economies across the South-West Pacific . WMO Secretary-General Celeste Saulo noted that "the ocean is central to livelihoods, economies and resilience," and that 2025 brought "warming oceans, rising sea levels, marine heatwaves and ocean acidification, alongside tropical cyclones and the continued loss of tropical glacier ice" .

El Niño in Mid-2026: Could It Accelerate the Final Melt?

As of early July 2026, El Niño conditions were present across the equatorial Pacific and were expected to strengthen into the Northern Hemisphere winter . This follows a brief La Niña in late 2025 and early 2026 .

The WMO report itself does not explicitly state that the 2026 El Niño will further accelerate glacier melt. However, independent research shows that the strong 2015-2016 El Niño amplified glacier thinning by roughly 5.4 times the previous rate . The remaining Puncak Jaya glacier has already lost 98% of its 1988 area and is expected to disappear by late 2026 or early 2027 regardless of El Niño . If El Niño conditions intensify regional warming, it could add stress during the glacier's terminal phase.

Key Indicators at a Glance

Indicator	Finding
2025 temperature rank	2nd warmest on record for the region
Marine heatwave extent	Largest non-El Niño coverage on record
Puncak Jaya glacier loss	98% of 1988 ice area gone; 0.09 km² left by Sept 2025
Glacier disappearance timeline	End of 2026 or early 2027
Sea-level rise rate (1999–2025)	3.7 mm/year
Ocean acidification	Waters hotter and more acidic, harming ecosystems
Deadliest event	Cyclone Senyar, >1,200 deaths
El Niño mid-2026	El Niño conditions present and strengthening as of July 2026