2017 was only the second-warmest year on record, according to NASA. But when it comes to the ocean, temperatures have never been warmer.

New data from the Chinese Academy of Sciences’ Institute of Atmospheric Physics analyzing ocean data from the last half century shows a clear trend: The oceans are steadily getting warmer, with this year registering the hottest yet. And while the atmospheric temperature is more susceptible to year-to-year shifts, the data from the Earth’s waters shows the consistency with which our world is heating up.

“The ocean heat records are so impressive because they’re absolutely on a steady warming trend,” Robert Anderson, a geochemist at Columbia University, told VICE News. “People who point to pauses in global warming haven’t looked at the warming of the oceans.”

The new study, published Friday, analyzed data from the top 2,000 meters of ocean waters around the globe, concluding that ocean waters topped record temps in 2017.

Researchers around the world are able to measure the steadily rising temperatures in the ocean thanks to a group of floating robots, which are called Argo. The array of just around 4,000 free-drifting data-collecting floats have been drifting on ocean currents since 2000. Every ten days, they drop to a depth of 2,000 meters and, as they rise up, collect data on the temperature of salinity of the ocean waters.

The results are remarkable: The oceans have absorbed over 90 percent of the excess heat produced by anthropogenic global warming in the last 50 years, according to the U.N.’s Intergovernmental Panel on Climate Change. That’s a lot of heat, it turns out — the total energy absorbed by the oceans in 2017 alone, the study’s authors found, was equivalent to almost 700 times the total electricity that China generated in 2016.

“It really is a massive amount of heat,” Gregory Johnson, an oceanographer at the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Lab in Seattle, told VICE News. “It’s about 350 terawatts, which is more than five times the energy released by the type of atomic bomb dropped on Hiroshima, per second — continuously.”