Heat stored in warming oceans is increasingly driving deadly heatwaves on land intensifying storms raising sea levels and amplifying climate risks worldwide, according to a report published by Grist and featured on PreventionWeb.
The report says the world oceans absorb more than 90 per cent of the excess heat trapped by greenhouse gases making them a major driver of rising global temperatures and extreme weather. June 2026 was the hottest June ever recorded for the world’s oceans, while nearly 40 per cent of global ocean areas experienced marine heatwaves with parts of the Mediterranean Sea and Pacific Ocean recording temperatures more than 10°F above normal.
Scientists say the warming oceans are no longer just a marine issue but are increasingly influencing weather on land. A recent study cited in the report found that at least one fifth of heatwaves on land originate from unusually warm ocean conditions. Surface waters exchange heat and moisture with the atmosphere helping create hotter temperatures, prolonged heatwaves and more intense weather systems.
The report comes as many parts of the Northern Hemisphere continue to experience record-breaking heat. Several cities in the United States recorded temperatures above 100°F during the Fourth of July period, while Europe experienced its hottest June on record. Authorities in Europe have linked thousands of deaths to heat related causes.
Researchers believe recent heatwaves across Europe were fuelled by exceptionally warm Mediterranean waters, while marine heatwaves in the Gulf of Mexico contributed to dangerous heat and humidity across parts of the southern United States. Warm Pacific Ocean temperatures have also been linked to persistent heat domes over North America.
Scientists warn that warmer air can hold more moisture, increasing the likelihood of prolonged dry spells followed by intense rainfall. Ocean warming also contributes to sea level rise through thermal expansion, allowing tropical cyclones and storm surges to cause greater coastal damage.
The report notes that an emerging super El Niño in the Pacific is expected to further elevate global temperatures. According to the US National Oceanic and Atmospheric Administration, the developing event has an 81 per cent chance of becoming one of the strongest El Niño episodes on record.
Experts say while there is no conclusive evidence that climate change is making El Niño events stronger, rising global temperatures are amplifying their impacts, leading to more severe heatwaves, heavier rainfall, stronger cyclones in some regions and prolonged droughts in others.
Scientists emphasise that extreme heat has become an immediate public health threat rather than a future risk, underscoring the need for climate adaptation measures and efforts to reduce greenhouse gas emissions.