Billionaire’s gift pushes ocean sensors deeper in search of global warming’s hidden heat

Every day, thousands of robotic floats bob up and down, tracking temperatures in the world's oceans, which sop up an estimated 90% of the heat from global warming. In the course of a decade, the international Argo array has provided one of the steadiest signatures of the effect of greenhouse gas emissions. But Argo has its limits. The floats go no deeper than 2000 meters, warded off by the crushing pressures at greater depths.