This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration. 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. The temperature at the ocean’s surface—like on land—is being pushed higher by global heating but can jump around from one year to the next as weather systems come and go.