By Abbas Nazil
The world’s oceans absorbed unprecedented amounts of heat in 2025, setting a new record and worsening extreme weather events across the globe.
Scientists say the surge in ocean heat is intensifying climate disasters, making storms stronger, rainfall heavier and marine ecosystems more fragile.
More than 90 percent of the excess heat generated by human carbon pollution is absorbed by the oceans, making them one of the clearest indicators of the accelerating climate crisis.
Researchers warn that this trend will continue until global greenhouse gas emissions are reduced to zero.
Nearly every year since 2000 has recorded a new high in ocean heat content, underscoring the persistent and long-term nature of global warming.
The extra heat stored in the oceans fuels more intense hurricanes and typhoons that strike coastal communities with greater destructive power.
It also contributes to heavier rainfall and increased flooding in many regions of the world.
Longer and more frequent marine heatwaves are another consequence, causing widespread damage to ocean life and coral reef systems.
Rising ocean temperatures are also driving sea level rise through the thermal expansion of seawater, placing billions of people in low-lying coastal areas at risk.
Although reliable measurements of ocean temperature date back to the mid-20th century, scientists believe the oceans are now hotter than at any point in at least the past 1,000 years.
They also say the current rate of ocean warming is faster than at any time in the past 2,000 years.
Unlike the oceans, the atmosphere holds much less heat and is more affected by natural climate cycles such as El Niño and La Niña.
Global average surface air temperatures in 2025 are expected to roughly match 2023 as the second-hottest year on record, behind 2024.
Last year, the planet shifted into the cooler La Niña phase of the Pacific climate cycle, slightly moderating atmospheric temperatures.
Professor John Abraham of the University of St Thomas in Minnesota said the constant breaking of temperature records has become alarmingly routine.
He said global warming is fundamentally driven by ocean warming and that the oceans reveal both how much the planet has warmed and how fast future warming will occur.
The findings were published in the journal Advances in Atmospheric Sciences.
The study analysed temperature data collected from a wide range of instruments across the world’s oceans.
Three independent research teams combined the data to calculate heat content in the upper 2,000 metres of the ocean, where most excess heat is stored.
Scientists estimated that the amount of heat absorbed by the oceans is equivalent to more than 200 times the total annual electricity consumption of humanity.
They concluded that ocean warming is exerting profound impacts on the entire Earth system.
Ocean heating is uneven, with some regions warming faster than others.
In 2025, especially high temperatures were recorded in the tropical and South Atlantic, the North Pacific and the Southern Ocean.
Researchers are particularly concerned about the Southern Ocean surrounding Antarctica, where winter sea ice has collapsed in recent years.
The North Atlantic and the Mediterranean Sea are also becoming warmer, saltier, more acidic and less oxygenated.
Scientists warn that these changes are weakening ocean ecosystems and threatening the life they support.
Professor Abraham said ocean heat records will continue to fall as long as the planet keeps accumulating heat.
He said the biggest uncertainty lies in human choices, stressing that reducing emissions could still help safeguard a livable future climate.
