A. Oldeman, M. Baatsen, A. S. von der Heydt, F. Selten, Henk A. Dijkstra
{"title":"Similar North Pacific variability despite suppressed El Niño variability in the warm mid-Pliocene climate","authors":"A. Oldeman, M. Baatsen, A. S. von der Heydt, F. Selten, Henk A. Dijkstra","doi":"10.5194/esd-15-1037-2024","DOIUrl":null,"url":null,"abstract":"Abstract. The mid-Pliocene is the most recent geological period with similar atmospheric CO2 concentration to the present day and similar surface temperatures to those projected at the end of this century for a moderate warming scenario. While not a perfect analogue, the mid-Pliocene can be used to study the functioning of the Earth system under similar forcings to a near future, especially regarding features in the climate system for which uncertainties exist in future projections. According to the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), the variability in the El Niño–Southern Oscillation (ENSO) was suppressed. In this study, we investigate how teleconnections of ENSO, specifically variability in the North Pacific atmosphere, respond to a suppressed ENSO according to PlioMIP2. The multi-model mean (MMM) shows a similar sea-level pressure (SLP) variability in the Aleutian Low (AL) in the mid-Pliocene and pre-industrial, but a per-model view reveals that the change in AL variability is related to the change in ENSO variability. Even though ENSO is suppressed, the teleconnection between ENSO sea-surface temperature (SST) anomalies, tropical precipitation, and North Pacific SLP anomalies is quite robust in the mid-Pliocene. We split AL variability in a part that is ENSO-related, and a residual variability which is related to internal stochastic variability, and find that the change in ENSO-related AL variability is strongly related to the change in ENSO variability itself, while the change in residual AL variability is unrelated to ENSO change. Since the internal atmospheric variability, which is the dominant forcing of the AL variability, is largely unchanged, we are able to understand that the AL variability is largely similar even though ENSO variability is suppressed. We find that the specific change in ENSO and AL variability depends on both the model equilibrium climate sensitivity and Earth system sensitivity. Finally, we present a perspective of (extra-)tropical Pacific variability in PlioMIP2, combining our results with literature findings on changes in the tropical mean climate and in the Pacific Decadal Oscillation (PDO).\n","PeriodicalId":7,"journal":{"name":"ACS Applied Polymer Materials","volume":"20 5","pages":""},"PeriodicalIF":4.4000,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Applied Polymer Materials","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/esd-15-1037-2024","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract. The mid-Pliocene is the most recent geological period with similar atmospheric CO2 concentration to the present day and similar surface temperatures to those projected at the end of this century for a moderate warming scenario. While not a perfect analogue, the mid-Pliocene can be used to study the functioning of the Earth system under similar forcings to a near future, especially regarding features in the climate system for which uncertainties exist in future projections. According to the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), the variability in the El Niño–Southern Oscillation (ENSO) was suppressed. In this study, we investigate how teleconnections of ENSO, specifically variability in the North Pacific atmosphere, respond to a suppressed ENSO according to PlioMIP2. The multi-model mean (MMM) shows a similar sea-level pressure (SLP) variability in the Aleutian Low (AL) in the mid-Pliocene and pre-industrial, but a per-model view reveals that the change in AL variability is related to the change in ENSO variability. Even though ENSO is suppressed, the teleconnection between ENSO sea-surface temperature (SST) anomalies, tropical precipitation, and North Pacific SLP anomalies is quite robust in the mid-Pliocene. We split AL variability in a part that is ENSO-related, and a residual variability which is related to internal stochastic variability, and find that the change in ENSO-related AL variability is strongly related to the change in ENSO variability itself, while the change in residual AL variability is unrelated to ENSO change. Since the internal atmospheric variability, which is the dominant forcing of the AL variability, is largely unchanged, we are able to understand that the AL variability is largely similar even though ENSO variability is suppressed. We find that the specific change in ENSO and AL variability depends on both the model equilibrium climate sensitivity and Earth system sensitivity. Finally, we present a perspective of (extra-)tropical Pacific variability in PlioMIP2, combining our results with literature findings on changes in the tropical mean climate and in the Pacific Decadal Oscillation (PDO).
期刊介绍:
ACS Applied Polymer Materials is an interdisciplinary journal publishing original research covering all aspects of engineering, chemistry, physics, and biology relevant to applications of polymers.
The journal is devoted to reports of new and original experimental and theoretical research of an applied nature that integrates fundamental knowledge in the areas of materials, engineering, physics, bioscience, polymer science and chemistry into important polymer applications. The journal is specifically interested in work that addresses relationships among structure, processing, morphology, chemistry, properties, and function as well as work that provide insights into mechanisms critical to the performance of the polymer for applications.