Everyone (most people, at least), agree that the world is getting warmer. Much of that warmth is absorbed by the world’s oceans, as water is a good conductor of heat. Unfortunately, researchers from Lawrence Livermore National Laboratory (LLNL) in California have more bad news: Not only are the oceans warming, they’re doing so much faster than anyone previously thought.

“This underestimation is a result of poor sampling prior to the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data-€sparse regions,” said LLNL oceanographer Paul Durack, lead author of a paper appearing in the October 5 issue of the journal Nature Climate Change.

The new study finds that the underestimates apply to the waters of the Southern Hemisphere, particularly the upper 700 meters. Satellite observations along with a suite of climate change models helped the researchers arrive at their findings. Earth’s oceans account for 90% of the excess heat stored, and the Southern Hemisphere contains 60% of Earth’s ocean water.

Climate change estimations work by simulating the relative increase in surface height linked to global warming. While these simulations tend to be consistent with accurate altimeter readings, things go askew when upper-ocean warming estimates are compared to observed heat content changes – the two should be consistent, but they’re not. It took improvements to the observational systems early this century to improve accuracy, meaning prior estimates were likely too conservative. The new tools, floats named “Argo” have been in place since 2004; 3,600 of them around the world record temperatures as deep at 2,000 meters.

“Prior to 2004, research has been very limited by the poor measurement coverage,” Durack said. “By using satellite data, along with a large suite of climate model simulations, our results suggest that global ocean warming has been underestimated by 24 to 58 percent. The conclusion that warming has been underestimated agrees with previous studies, however it’s the first time that scientists have tried to estimate how much heat we’ve missed.”

With more accurate estimates, climate scientists around the world may have to re-think Earth’s “energy budget” over the coming years.