Ocean heat content is the dominant fast heat reservoir in the climate system and thus fundamental to studying changes in Earth’s energy budget. Past ocean temperature has been reconstructed locally using sediment cores, but the integration of these local changes to the entire ocean remains challenging due to sparse spatial coverage as well as circulation changes.

In the past decade a novel proxy for oceanic heat content has been established using noble gases derived from ancient air trapped in ice cores. Changes in the atmospheric concentrations of xenon and krypton mirror the anomalies in total ocean heat content, as they are driven by their temperature-dependent physical solubilities in seawater.

In this talk I will present the noble gas thermometer including its limitations, discuss insights gained from it about ocean heat content and the Earth’s energy budget, and preview what we can expect from it in the near future.