Abstract
Comment
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Oral
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IAMAS
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M12 - Earth's Energy Budget
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Global and Regional Drivers for Exceptional Climate Extremes in 2023-2024: Beyond the New Normal
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1. Shoshiro , Minobe*, Hokkaido University,Sapporo,Japan
2. Erik , Behrens, The National Institute of Water and Atmospheric Research,New Zealand
3. Kirsten , Findell, Geophysical Fluid Dynamics Laboratory,National Oceanic and Atmospheric Administration,Princeton,New Jersey,USA
4. Norman , Loeb, NASA Langley Research Center,Hampton,VA,USA
5. Benoit , Meyssignac, Universite de Toulouse,LEGOS (CNES/CNRS/IRD/UT3),31400 Toulouse,France
6. Rowan , Sutton, University of Reading and National Centre for Atmospheric Science,Reading,UK
*Presenting Author
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Climate records have been broken with alarming regularity in recent years, but the events of 2023?24 were exceptional even when accounting for recent climatic trends. To analyze these anomalies, we employ three novel approaches. First, we introduce the "Abnormal Record-Breaking (AB) test," an objective statistical framework designed to assess the significance of extreme conditions while accounting for recent trends and past variability. The AB-test indicates that Earths Energy Imbalance (EEI) was in an abnormally record-breaking state in early 2023, exceeding the range expected from recent trends and variability. To understand the contributions of EEI and El Ni?o to the anomalous 2023?24 climate, we conducted a heat budget analysis focusing on atmospheric energy and combined 0?100 m ocean heat content, which are closely related to both surface air temperature and sea surface temperature. During an El Ni?o, anomalous heat stored in the subsurface (100?300 m) layer is brought to the near surface and subsequently released into the atmosphere. Simultaneously, EEI contributes to heating of the near-surface ocean and the atmosphere. Our analysis shows that although the contributions of El Ni?o and EEI were of similar magnitude in the 2023 warming, the increase compared with previous El Ni?o events was markedly larger for EEI, with an increase of more than 75%. Therefore, the exceptional nature of 2023?24 resulted from a record-breaking EEI combined with a strong (but not record-breaking) El Ni?o. In addition to the global analysis, we investigate two key regions?the subtropical northeastern Atlantic and the Southern Ocean?where record-breaking conditions in 2023 were linked to distinct physical mechanisms. In the northeastern Atlantic, shortwave radiation played a dominant role in driving anomalously high sea surface temperatures, while in the Southern Ocean, changes in atmospheric circulation contributed to extreme conditions. These results indicate that if the recent trend in EEI persists, natural fluctuations such as ENSO variability will increasingly lead to amplified, record-breaking impacts, with 2023?2024 serving as a glimpse of future climate extremes.