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20^th century cooling of the deep ocean contributed to delayed acceleration of Earth's energy imbalance.

ABSTRACT: The historical evolution of Earth's energy imbalance can be quantified by changes in the global ocean heat content. However, historical reconstructions of ocean heat content often neglect a large volume of the deep ocean, due to sparse observations of ocean temperatures below 2000 m. Here, we provide a global reconstruction of historical changes in full-depth ocean heat content based on interpolated subsurface temperature data using an autoregressive artificial neural network, providing estimates of total ocean warming for the period 1946-2019. We find that cooling of the deep ocean and a small heat gain in the upper ocean led to no robust trend in global ocean heat content from 1960-1990, implying a roughly balanced Earth energy budget within -0.16 to 0.06 W m^-2 over most of the latter half of the 20th century. However, the past three decades have seen a rapid acceleration in ocean warming, with the entire ocean warming from top to bottom at a rate of 0.63 ± 0.13 W m^-2. These results suggest a delayed onset of a positive Earth energy imbalance relative to previous estimates, although large uncertainties remain.

SUBMITTER: Bagnell A

PROVIDER: S-EPMC8322321 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Increasing ocean wave energy observed in Earth's seismic wavefield since the late 20th century.

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