Oceans have been absorbing the world’s extra heat. But there’s a huge payback

As the ocean heats up, it expands, pushing up sea levels around the globe. Photograph: Kerem Yücel/AFP/Getty Images

By the end of March, the surface temperature of the world’s oceans was above anything seen in the 40 years that satellites have been measuring it.

Records were “headed off the charts” and, as the heat refused to fade for more than a month, the Earth marched into “uncharted territory”, scientists said.