The world's oceans have absorbed more heat than previously thought over the last quarter of a century, scientists said Thursday, leaving Earth more sensitive still to the effects of climate change.

Oceans cover more than two thirds of the planet's surface and play a vital role in sustaining life on Earth.

According to their most recent assessment this month, scientists from the Intergovernmental Panel on Climate Change (IPCC) say the world's oceans have absorbed 90 percent of the temperature rise caused by man-made carbon emissions.

But new research published in the journal Nature used a novel method of measuring ocean temperature.

It found that for each of the last 25 years, oceans may have absorbed heat energy equivalent to as much as 150 times the amount of electricity mankind produces annually.

That is between 10-70 percent higher than previous studies showed.

Whereas those studies relied on tallying the excess heat produced by known man-made greenhouse gas emissions, a team of US-based scientists focused on two gases found naturally in the atmosphere: oxygen and carbon dioxide.

Both gases are soluble in water, but the rate at which water absorbs them decreases as it warms.

By measuring atmospheric oxygen and CO2 for each year, scientists were able to estimate how much heat oceans had absorbed on a global scale.

The authors initially calculated that oceans had warmed 60 percent more than previously thought.

However, after some controversy, they acknowledged mistakes in the margin-of-error calculations, and subsequently settled on a range of 10-70 percent.

"Our error margins are too big now to really weigh in on the precise amount of warming that's going on in the ocean," said author Ralph Keeling, of the UC San Diego's Scripps Institution of Oceanography, after being made aware of the error.

"We really muffed the error margins," he told the San Diego Tribune.

The IPCC warns that drastic measures need taking in order to limit global warming to 1.5 Celsius by the end of the century but the world produced a record amount of carbon emissions in 2017.