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  • 1
    Online Resource
    Online Resource
    Impact of Freshwater Release in the North Atlantic under Different Climate Conditions in an OAGCM
    American Meteorological Society ; 2009
    In:  Journal of Climate Vol. 22, No. 23 ( 2009-12-01), p. 6377-6403
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 22, No. 23 ( 2009-12-01), p. 6377-6403
    Abstract: The response of climate to freshwater input in the North Atlantic (NA) has raised a lot of concern about the issue of climate stability since the discovery of abrupt coolings during the last glacial period. Such coolings have usually been related to a weakening of the Atlantic meridional overturning circulation (AMOC), probably associated with massive iceberg surges or meltwater pulses. Additionally, the recent increase in greenhouse gases in the atmosphere has also raised the possibility of a melting of the Greenland ice sheet, which may impact the future AMOC, and thereby the climate. In this study, the extent to which the mean climate influences the freshwater release linked to ice sheet melting in the NA and the associated climatic response is explored. For this purpose the simulations of several climatic states [last interglacial, Last Glacial Maximum, mid-Holocene, preindustrial, and future (2 × CO2)] are considered, and the climatic response to a freshwater input computed interactively according to a surface heat flux budget over the ice sheets is analyzed. It is shown that the AMOC response is not linear with the freshwater input and depends on the mean climate state. The climatic responses to these different AMOC changes share qualitative similarities for the general picture, notably a cooling in the Northern Hemisphere and a southward shift of the intertropical convergence zone (ITCZ) in the Atlantic and across the Panama Isthmus. The cooling in the Northern Hemisphere is related to the sea ice cover response, which strongly depends on the responses of the atmospheric circulation, the local oceanic heat transport, and the density threshold of the oceanic convection sites. These feedbacks and the magnitude of temperature and precipitation changes outside the North Atlantic depend on the mean climate.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/2009JCLI3028.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2009
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 2
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    Impact of Greenhouse Gas Concentration Changes on Surface Energetics in IPSL-CM4: Regional Warming Patterns, Land–Sea Warming Ratios, and Glacial–Interglacial Differences
    American Meteorological Society ; 2009
    In:  Journal of Climate Vol. 22, No. 17 ( 2009-09-01), p. 4621-4635
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 22, No. 17 ( 2009-09-01), p. 4621-4635
    Abstract: The temperature response to a greenhouse gas (GHG) concentration change is studied in an ocean–atmosphere coupled model—L’Institut Pierre-Simon Laplace Coupled Model, version 4 (IPSL-CM4)—for both a glacial and an interglacial context. The response to a GHG concentration changing from Last Glacial Maximum (LGM) to preindustrial values is similar for both climatic contexts in terms of temperature pattern, but the magnitude is greater under modern ones. The model simulates the classical amplification of the temperature response in the northern high latitudes compared to lower latitudes and over the land surfaces compared to the ocean. The physical reasons for the differential warming according to the latitude and to the surface type are studied through an analysis of the energy flux changes, which are decomposed to consider and quantify many different physical processes. The results highlight the role of many different factors in the thermal response to a GHG forcing for different regions, and stress, for instance, the large effect of increased water vapor concentration in the atmosphere. Concerning the land–sea warming ratio, several fluxes contribute to the final value of the ratio, with latent flux having the greatest influence. The different contributions are quantified. The comparison of the flux changes between the interglacial and glacial contexts shows that the differences are more than a simple effect of different surface emissions of the base state. It suggests that the climatic context is particularly important for the cloud and oceanic advection responses to the forcing, along with albedo effects.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/2009JCLI2771.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2009
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 3
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    Mid-Holocene and last glacial maximum climate simulations with the IPSL model: part II: model-data comparisons
    Springer Science and Business Media LLC ; 2013
    In:  Climate Dynamics Vol. 40, No. 9-10 ( 2013-5), p. 2469-2495
    Details
    In: Climate Dynamics, Springer Science and Business Media LLC, Vol. 40, No. 9-10 ( 2013-5), p. 2469-2495
    Type of Medium: Online Resource
    ISSN: 0930-7575 , 1432-0894
    URL: Article
    DOI: 10.1007/s00382-012-1499-5
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2013
    detail.hit.zdb_id: 382992-3
    detail.hit.zdb_id: 1471747-5
    SSG: 16,13
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  • 4
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    Presentation and Evaluation of the IPSL‐CM6A‐LR Climate Model
    American Geophysical Union (AGU) ; 2020
    In:  Journal of Advances in Modeling Earth Systems Vol. 12, No. 7 ( 2020-07)
    Details
    In: Journal of Advances in Modeling Earth Systems, American Geophysical Union (AGU), Vol. 12, No. 7 ( 2020-07)
    Abstract: The IPSL‐CM6A‐LR model climatology is much improved over the previous version, although some systematic biases and shortcomings persist A long preindustrial control and a large number of historical and scenario simulations have been performed as part of CMIP6 The effective climate sensitivity of the IPSL model increases from 4.1 to 4.8 K between IPSL‐CM5A‐LR and IPSL‐CM6A‐LR
    Type of Medium: Online Resource
    ISSN: 1942-2466 , 1942-2466
    URL: Article
    DOI: 10.1029/2019MS002010
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2020
    detail.hit.zdb_id: 2462132-8
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  • 5
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    The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments
    Copernicus GmbH ; 2017
    In:  Geoscientific Model Development Vol. 10, No. 11 ( 2017-11-07), p. 4035-4055
    Details
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 10, No. 11 ( 2017-11-07), p. 4035-4055
    Abstract: Abstract. The Last Glacial Maximum (LGM, 21 000 years ago) is one of the suite of paleoclimate simulations included in the current phase of the Coupled Model Intercomparison Project (CMIP6). It is an interval when insolation was similar to the present, but global ice volume was at a maximum, eustatic sea level was at or close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. The LGM has been a focus for the Paleoclimate Modelling Intercomparison Project (PMIP) since its inception, and thus many of the problems that might be associated with simulating such a radically different climate are well documented. The LGM state provides an ideal case study for evaluating climate model performance because the changes in forcing and temperature between the LGM and pre-industrial are of the same order of magnitude as those projected for the end of the 21st century. Thus, the CMIP6 LGM experiment could provide additional information that can be used to constrain estimates of climate sensitivity. The design of the Tier 1 LGM experiment (lgm) includes an assessment of uncertainties in boundary conditions, in particular through the use of different reconstructions of the ice sheets and of the change in dust forcing. Additional (Tier 2) sensitivity experiments have been designed to quantify feedbacks associated with land-surface changes and aerosol loadings, and to isolate the role of individual forcings. Model analysis and evaluation will capitalize on the relative abundance of paleoenvironmental observations and quantitative climate reconstructions already available for the LGM.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    URL: Article
    URL: Article
    DOI: 10.5194/gmd-10-4035-2017
    DOI: 10.5194/gmd-10-4035-2017-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
    detail.hit.zdb_id: 2456725-5
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  • 6
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    Impact of dust in PMIP-CMIP6 mid-Holocene simulations with the IPSL model
    Copernicus GmbH ; 2021
    In:  Climate of the Past Vol. 17, No. 3 ( 2021-05-26), p. 1091-1117
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 17, No. 3 ( 2021-05-26), p. 1091-1117
    Abstract: Abstract. We investigate the climate impact of reduced dust during the mid-Holocene using simulations with the IPSL model. We consider simulations where dust is either prescribed from an IPSL PI simulation or from CESM simulations (Albani et al., 2015). In addition, we also consider an extreme mid-Holocene case where dust is suppressed. We focus on the estimation of the dust radiative effects and the relative responses of the African and Indian monsoon, showing how local dust forcing or orography affect atmospheric temperature profiles, humidity and precipitation. The simulated mid-Holocene climate is statistically different in many regions compared to previous mid-Holocene simulations with the IPSL models. However, it translates to only minor improvements compared to palaeoclimate reconstructions, and the effect of dust has little impact on mid-Holocene model skill over large regions. Our analyses confirm the peculiar role of dust radiative effect over bright surfaces such as African deserts compared to other regions, brought about by the change of sign of the dust radiative effect at the top of atmosphere for high surface albedo. We also highlight a strong dependence of results on the dust pattern. In particular, the relative dust forcing between West Africa and the Middle East impacts the relative climate response between India and Africa and between Africa, the western tropical Atlantic and the Atlantic meridional circulation. It also affects the feedback on the Atlantic Ocean thermohaline circulation. Dust patterns should thus be better constrained to fully understand the changes in the dust cycle and forcing during the mid-Holocene, which also informs on the potential changes in key dust feedbacks in the future.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    DOI: 10.5194/cp-17-1091-2021
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2217985-9
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  • 7
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    Online Resource
    Qu'apprend-on des grands changements climatiques passés ?
    Meteo et Climat, Societe Francaise de la Meteorologie et du Climat ; 2015
    In:  La Météorologie Vol. 8, No. 88 ( 2015), p. 25-
    Details
    In: La Météorologie, Meteo et Climat, Societe Francaise de la Meteorologie et du Climat, Vol. 8, No. 88 ( 2015), p. 25-
    Type of Medium: Online Resource
    ISSN: 0026-1181
    URL: Article
    DOI: 10.4267/2042/56359
    Language: French
    Publisher: Meteo et Climat, Societe Francaise de la Meteorologie et du Climat
    Publication Date: 2015
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  • 8
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    Progress in Paleoclimate Modeling*
    American Meteorological Society ; 2006
    In:  Journal of Climate Vol. 19, No. 20 ( 2006-10-15), p. 5031-5057
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 19, No. 20 ( 2006-10-15), p. 5031-5057
    Abstract: This paper briefly surveys areas of paleoclimate modeling notable for recent progress. New ideas, including hypotheses giving a pivotal role to sea ice, have revitalized the low-order models used to simulate the time evolution of glacial cycles through the Pleistocene, a prohibitive length of time for comprehensive general circulation models (GCMs). In a recent breakthrough, however, GCMs have succeeded in simulating the onset of glaciations. This occurs at times (most recently, 115 kyr b.p.) when high northern latitudes are cold enough to maintain a snow cover and tropical latitudes are warm, enhancing the moisture source. More generally, the improvement in models has allowed simulations of key periods such as the Last Glacial Maximum and the mid-Holocene that compare more favorably and in more detail with paleoproxy data. These models now simulate ENSO cycles, and some of them have been shown to reproduce the reduction of ENSO activity observed in the early to middle Holocene. Modeling studies have demonstrated that the reduction is a response to the altered orbital configuration at that time. An urgent challenge for paleoclimate modeling is to explain and to simulate the abrupt changes observed during glacial epochs (i.e., Dansgaard–Oescher cycles, Heinrich events, and the Younger Dryas). Efforts have begun to simulate the last millennium. Over this time the forcing due to orbital variations is less important than the radiance changes due to volcanic eruptions and variations in solar output. Simulations of these natural variations test the models relied on for future climate change projections. They provide better estimates of the internal and naturally forced variability at centennial time scales, elucidating how unusual the recent global temperature trends are.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/JCLI3899.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2006
    detail.hit.zdb_id: 246750-1
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  • 9
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    Mid-Holocene climate change over China: model–data discrepancy
    Copernicus GmbH ; 2019
    In:  Climate of the Past Vol. 15, No. 4 ( 2019-07-02), p. 1223-1249
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 15, No. 4 ( 2019-07-02), p. 1223-1249
    Abstract: Abstract. The mid-Holocene period (MH) has long been an ideal target for the validation of general circulation model (GCM) results against reconstructions gathered in global datasets. These studies aim to test GCM sensitivity, mainly to seasonal changes induced by the orbital parameters (longitude of the perihelion). Despite widespread agreement between model results and data on the MH climate, some important differences still exist. There is no consensus on the continental size (the area of the temperature anomaly) of the MH thermal climate response, which makes regional quantitative reconstruction critical to obtain a comprehensive understanding of the MH climate patterns. Here, we compare the annual and seasonal outputs from the most recent Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) models with an updated synthesis of climate reconstruction over China, including, for the first time, a seasonal cycle of temperature and precipitation. Our results indicate that the main discrepancies between model and data for the MH climate are the annual and winter mean temperature. A warmer-than-present climate condition is derived from pollen data for both annual mean temperature (∼0.7 K on average) and winter mean temperature (∼1 K on average), while most of the models provide both colder-than-present annual and winter mean temperature and a relatively warmer summer, showing a linear response driven by the seasonal forcing. By conducting simulations in BIOME4 and CESM, we show that surface processes are the key factors creating the uncertainties between models and data. These results pinpoint the crucial importance of including the non-linear responses of the surface water and energy balance to vegetation changes.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    URL: Article
    DOI: 10.5194/cp-15-1223-2019
    DOI: 10.5194/cp-15-1223-2019-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
    detail.hit.zdb_id: 2217985-9
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  • 10
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    An energy budget approach to understand the Arctic warming during the Last Interglacial
    Copernicus GmbH ; 2022
    In:  Climate of the Past Vol. 18, No. 3 ( 2022-03-31), p. 607-629
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 18, No. 3 ( 2022-03-31), p. 607-629
    Abstract: Abstract. The Last Interglacial period (129–116 ka) is characterised by a strong orbital forcing which leads to a different seasonal and latitudinal distribution of insolation compared to the pre-industrial period. In particular, these changes amplify the seasonality of the insolation in the high latitudes of the Northern Hemisphere. Here, we investigate the Arctic climate response to this forcing by comparing the CMIP6 lig127k and piControl simulations performed with the IPSL-CM6A-LR (the global climate model developed at Institut Pierre-Simon Laplace) model. Using an energy budget framework, we analyse the interactions between the atmosphere, ocean, sea ice and continents. In summer, the insolation anomaly reaches its maximum and causes a rise in near-surface air temperature of 3.1 ∘C over the Arctic region. This warming is primarily due to a strong positive anomaly of surface downwelling shortwave radiation over continental surfaces, followed by large heat transfer from the continents to the atmosphere. The surface layers of the Arctic Ocean also receive more energy but in smaller quantity than the continents due to a cloud negative feedback. Furthermore, while heat exchange from the continental surfaces towards the atmosphere is strengthened, the ocean absorbs and stores the heat excess due to a decline in sea ice cover. However, the maximum near-surface air temperature anomaly does not peak in summer like insolation but occurs in autumn with a temperature increase of 4.2 ∘C relative to the pre-industrial period. This strong warming is driven by a positive anomaly of longwave radiation over the Arctic Ocean enhanced by a positive cloud feedback. It is also favoured by the summer and autumn Arctic sea ice retreat (-1.9×106 and -3.4×106 km2, respectively), which exposes the warm oceanic surface and thus allows oceanic heat storage and release of water vapour in summer. This study highlights the crucial role of sea ice cover variations, Arctic Ocean, as well as changes in polar cloud optical properties on the Last Interglacial Arctic warming.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    DOI: 10.5194/cp-18-607-2022
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2217985-9
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