A multi-model assessment of the early last deglaciation (PMIP4 LDv1): a meltwater perspective

• Autores: Snoll, Brooke; Ivanovic, Ruza; Gregoire, Lauren; Sherriff Tadano, Sam; Menviel, Laurie; Obase, Takashi; Abe-Ouchi, Ayako; Bouttes, Nathaelle; He, Chengfei; He, Feng; Kapsch, Marie; Mikolajewicz, Uwe; Muglia, Juan; Valdes, Paul
• Año de publicación: 2024
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: DEGLACIATION; FRESHWATER FORCING; AMOC
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The last deglaciation (∼20–11 ka BP) is a period of a major, long-term climate transition from a glacial to interglacial state that features multiple centennial- to decadal-scale abrupt climate variations whose root cause is still not fully understood. To better understand this time period, the Paleoclimate Modelling Intercomparison Project (PMIP) has provided a framework for an internationally coordinated endeavour in simulating the last deglaciation whilst encompassing a broad range of models. Here, we present a multi-model intercomparison of 17 transient simulations of the early part of the last deglaciation (∼20–15 ka BP) from nine different climate models spanning a range of model complexities and uncertain boundary conditions and forcings. The numerous simulations available provide the opportunity to better understand the chain of events and mechanisms of climate changes between 20 and 15 ka BP and our collective ability to simulate them. We conclude that the amount of freshwater forcing and whether it follows the ice sheet reconstruction or induces an inferred Atlantic meridional overturning circulation (AMOC) history, heavily impacts the deglacial climate evolution for each simulation rather than differences in the model physics. The course of the deglaciation is consistent between simulations except when the freshwater forcing is above 0.1 Sv – at least 70 % of the simulations agree that there is warming by 15 ka BP in most places excluding the location of meltwater input. For simulations with freshwater forcings that exceed 0.1 Sv from 18 ka BP, warming is delayed in the North Atlantic and surface air temperature correlations with AMOC strength are much higher. However, we find that the state of the AMOC coming out of the Last Glacial Maximum (LGM) also plays a key role in the AMOC sensitivity to model forcings. In addition, we show that the response of each model to the chosen meltwater scenario depends largely on the sensitivity of the model to the freshwater forcing and other aspects of the experimental design (e.g. CO2 forcing or ice sheet reconstruction). The results provide insight into the ability of our models to simulate the first part of the deglaciation and how choices between uncertain boundary conditions and forcings, with a focus on freshwater fluxes, can impact model outputs. We can use these findings as helpful insight in the design of future simulations of this time period.
Fil: Snoll, Brooke. University Of Leeds.; Reino Unido
Fil: Ivanovic, Ruza. University Of Leeds.; Reino Unido
Fil: Gregoire, Lauren. University Of Leeds.; Reino Unido
Fil: Sherriff Tadano, Sam. University Of The Ryukyu; Japón
Fil: Menviel, Laurie. University of New South Wales; Australia
Fil: Obase, Takashi. The University Of Tokyo; Japón
Fil: Abe-Ouchi, Ayako. The University Of Tokyo; Japón
Fil: Bouttes, Nathaelle. Universite Paris-saclay (universite Paris-saclay);
Fil: He, Chengfei. University Of Miami. Rosenstiel School Of Marine Atmospheric Science; Estados Unidos
Fil: He, Feng. University of Wisconsin; Estados Unidos
Fil: Kapsch, Marie. Max Planck Institute For Meteorology; Alemania
Fil: Mikolajewicz, Uwe. Max Planck Institute For Meteorology; Alemania
Fil: Muglia, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina
Fil: Valdes, Paul. University Of Bristol;