The world’s oceans behave like a thermometer: As the water warms, it expands and sea levels rise. Geodesy researchers at the University of Bonn are able to measure this and determine how much the oceans are warming. For individual ocean basins, their method has revealed significant deviations from model calculations—in some cases in the double-digit percentage range.

The research is published in the journal Earth System Science Data, and they explain their findings below.