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The ocean's immense ability to store and release heat on centennial to millennial time scales modulates the impacts of climate perturbations. To gain a better understanding of past variations in mean ocean temperature (MOT), a noble gas‐based proxy measured from ancient air in ice cores has been developed. Here we assess non‐temperature effects that may influence the atmospheric noble gas ratios reconstructed from polar ice and how they impact the temperature signal with an intermediate complexity Earth system model. We find that changes in wind speed, sea‐ice extent, and ocean circulation have partially compensating effects on mean‐ocean noble gas saturation, leading to a slight reduction of noble gas undersaturation at the Last Glacial Maximum (LGM). Taking these effects and ice core measurements into account, our model suggests a revised MOT difference between the LGM and pre‐industrial of −2.1 ± 0.7°C that is also in improved agreement with other independent temperature reconstructions. Plain Language Summary: Most of the heat added to the climate system by anthropogenic climate change is taken up by the oceans. To better understand how the ocean responds to climate change over hundreds to thousands of years, an indirect measure for the mean ocean temperature (MOT) based on the temperature‐dependent solubility of noble gases has been developed. Noble gas concentrations of the past atmosphere are archived in air bubbles in polar ice cores, which have been used to reconstruct the MOT of the past 20,000 years when Earth's climate was propelled out of the last ice age. However, uncertainties remain regarding critical parameters that are required to derive the correct MOT of the past. Here we make use of an Earth system model that explicitly simulates the noble gases and allows us to assess these parameters in detail under modern and past climate conditions. We find that changes in wind, sea‐ice, and ocean circulation all play important roles in the partitioning of noble gases between the atmosphere and ocean. By taking these effects into account our model suggests a revised best‐estimate MOT cooling of the last ice age to −2.1 ± 0.7°C, which is about 0.5°C warmer than previous estimates. Key Points: Revised implementation of noble gases in Bern3D model tuned to observations of saturation anomaliesComplex interplay between air‐sea gas exchange, overturning circulation, and noble gas saturationIncluding saturation effects noble gas‐based mean ocean temperature of the last glacial maximum is 2°C colder than the Holocene [ABSTRACT FROM AUTHOR]

Ice core records from Antarctica show mostly synchronous temperature variations during the last deglacial transition, an indication that the climate of the entire continent reacted as one unit to the global changes. However, a record from the Taylor Dome ice core in the Ross Sea sector of East Antarctica has been suggested to show a rapid warming, similar in style and synchronous with the Oldest Dryas—Bølling warming in Greenland. Since publication of the Taylor Dome record, a number of lines of evidence have suggested that this interpretation is incorrect and reflects errors in the underlying time scale. The issues raised regarding the dating of Taylor Dome currently linger unresolved, and the original time scale remains the de facto chronology. We present new water isotope and chemistry data from nearby Taylor Glacier to resolve the confusion surrounding the Taylor Dome time scale. We find that the Taylor Glacier record is incompatible with the original interpretation of the Taylor Dome ice core, showing that the warming in the area was gradual and started at ∼18 ka BP (before 1950) as seen in other East Antarctic ice cores. We build a consistent, up‐to‐date Taylor Dome chronology from 0 to 60 ka BP by combining new and old age markers based on synchronization to other ice core records. The most notable feature of the new TD2015 time scale is a gas age—ice age difference of up to 12,000 years during the Last Glacial Maximum, by far the largest ever observed. Key Points: We present a new stable isotope and dust record from Taylor Glacier, Ross Sea area, AntarcticaThe Taylor Glacier record is incompatible with North‐South synchronous deglacial warmingTD2015: A revised Taylor Dome time scale for both ice and gas phases is introduced [ABSTRACT FROM AUTHOR]