A systematic study of the impact of freshwater pulses with respect to different geographical locations

• Published in: Climate Dynamics
• Main Authors: Roche, Didier, Wiersma, Ane, Renssen, Hans
• Other Authors: Department of Earth Sciences Amsterdam, VU University Amsterdam, Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Deltares The Netherlands
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Arctic; Iceberg*; Nordic Seas; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-03201059; https://hal.archives-ouvertes.fr/hal-03201059/document; https://hal.archives-ouvertes.fr/hal-03201059/file/Roche2010_Article_ASystematicStudyOfTheImpactOfF.pdf; https://doi.org/10.1007/s00382-009-0578-8

International audience The first comparative and systematic climatemodel study of the sensitivity of the climate response underLast Glacial Maximum (LGM) conditions to freshwaterperturbations at various locations that are known to havereceived significant amounts of freshwater during the LGM(21 kyr BP) climate conditions is presented. A series of tenregions representative of those receiving most of the meltwater from decaying ice-sheets during the deglaciation isdefined, comprising the border of LGM ice-sheets, outlets ofrivers draining part of the melting ice-sheets and iceberg meltzones. The effect of several given freshwater fluxes appliedseparately in each of these regions on regional and globalclimate is subsequently tested. The climate response is thenanalysed both for the atmosphere and oceans. Amongst theregions defined, it is found that the area close by anddynamically upstream to the main deep water formation zonein the North Atlantic are most sensitive to freshwater pulses,as is expected. However, some important differencesbetween Arctic freshwater forcing and Nordic Seas forcingare found, the former having a longer term response linked tosea-ice formation and advection whereas the latter exhibitsmore direct influence of direct freshening of the deep waterformation sites. Combining the common surface temperatureresponse for each respective zone, we fingerprint the particular surface temperature response obtained by addingfreshwater in a particular location. This is done to examine ifa surface climate response can be used to determine theorigin of a meltwater flux, which is relevant for the interpretation of proxy data. We show that it is indeed possible togenerally classify the fingerprints by their origin in terms ofsea-ice modification and modification of deep-water formation. Whilst the latter is not an unambiguous characterization of each zone, it nonetheless provides important clueson the physical mechanisms at work. In particular, it is shownthat in order to obtain a consistent see-saw ...