For decades, the earth’s oceans have soaked up more than nine-tenths of the atmosphere’s excess heat trapped by greenhouse gas emissions. By stowing that extra energy in their depths, oceans have spared the planet from feeling the full effects of humanity’s carbon overindulgence. But as those gases build in the air, an energy overload is rising below the waves. A raft of recent research finds that the ocean has been heating faster and deeper than scientists had previously thought. And there are new signs that the oceans might be starting to release some of that pent-up thermal to significant global temperature increases in the coming years.