Oceans at a Turning Point in 2025

The world’s oceans reached record heat levels in 2025 as an international effort removed an unprecedented volume of plastic waste, highlighting both the accelerating impacts of climate change and the growing scale of ocean cleanup operations. According to the study, Ocean Heat Content Sets Another Record in 2025, the oceans absorbed an estimated 23 zetta joules of heat in 2025. Long-term datasets from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, Copernicus Marine, NOAA/NCEI and the CIGAR-RT meta-analysis all confirm a sustained increase in heat across the upper 2,000 m of the ocean since the late 1950s.

The study was led by Yuying Pan of the State Key Laboratory of Earth System Numerical Modeling and Application at the Institute of Atmospheric Physics of the Chinese Academy of Sciences. The analysis involved more than 50 scientists from 31 institutions worldwide.

“Global ocean warming continued unabated in 2025 in response to increased greenhouse gas concentrations and recent reductions in sulfate aerosols,” the authors wrote, noting that conditions evolved toward La Niña during the year.

Regionally, warming was widespread but uneven. About 33% of the global ocean ranked among its three warmest years on record, while roughly 57% fell within the Top 5. The strongest warming was observed in the Southern Ocean, the North Atlantic, the Mediterranean and parts of the Indo-Pacific, while relative cooling occurred in areas influenced by the transition to La Niña.

Global average sea surface temperature in 2025 was the third warmest in the instrumental record, remaining about 0.5°C above the 1981–2010 baseline. Scientists emphasized that ocean heat content is a key indicator of long-term climate change, as oceans absorb more than 90% of the excess heat trapped by greenhouse gases.

Rising ocean temperatures contribute to sea level rise, intensify heat waves, and fuel more extreme weather events. In 2025, warmer waters were linked to floods in Mexico and the US Pacific Northwest, droughts in the Middle East and increased disruption across Southeast Asia, as well as more intense tropical cyclones driven by higher evaporation and rainfall.

Record Plastic Removal From Oceans, Rivers

Against this backdrop of warming seas, The Ocean Cleanup reported a record year for marine debris removal. In 2025, the organization removed more than 25 million kg of trash from aquatic environments, bringing its total cumulative catch to over 45 million kg. The cleanup included plastic accumulated over decades in critical hotspots such as the Great Pacific Garbage Patch, located between Hawaii and California, one of the world’s largest concentrations of floating plastic.

Founded in 2013 by Dutch engineer Boyan Slat, The Ocean Cleanup combines offshore collection systems with river-based interceptors designed to stop plastic pollution before it reaches the ocean. The organization has focused on a dual strategy that targets both legacy plastic already circulating in ocean gyres and waste flowing from rivers, which account for a disproportionate share of marine plastic pollution.

Reaching this scale, the organization said, is the result of years of research, data-driven decision-making and technological adjustments across multiple countries. Plastic collected during operations is returned to land for treatment and recycling, with part of the material already reused in consumer products.

At the United Nations Ocean Conference in Nice, The Ocean Cleanup announced the launch of its 30 Cities Program, aimed at tackling up to one-third of plastic pollution entering the ocean from some of the world’s most polluting urban areas. The initiative combines river interception, coastal cleanup and policy engagement informed by marine pollution research.