Emulation of long-term changes in global climate: application to the late Pliocene and future

Multi-millennial transient simulations of climate changes have a range of important applications, such as for investigating key geologic events and transitions for which high-resolution palaeoenvironmental proxy data are available, or for projecting the long-term impacts of future climate evolution...

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Published in:Climate of the Past
Main Authors: Lord, Natalie S., Crucifix, Michel, Lunt, Dan J., Thorne, Mike C., Bounceur, Nabila, Dowsett, Harry, O'Brien, Charlotte L., Ridgwell, Andy
Other Authors: UCL - SST/ELI/ELIC - Earth & Climate
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus GmbH 2017
Subjects:
Online Access:http://hdl.handle.net/2078.1/193527
https://doi.org/10.5194/cp-13-1539-2017
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spelling ftunistlouisbrus:oai:dial.uclouvain.be:boreal:193527 2023-05-15T16:41:39+02:00 Emulation of long-term changes in global climate: application to the late Pliocene and future Lord, Natalie S. Crucifix, Michel Lunt, Dan J. Thorne, Mike C. Bounceur, Nabila Dowsett, Harry O'Brien, Charlotte L. Ridgwell, Andy UCL - SST/ELI/ELIC - Earth & Climate 2017 http://hdl.handle.net/2078.1/193527 https://doi.org/10.5194/cp-13-1539-2017 eng eng Copernicus GmbH boreal:193527 http://hdl.handle.net/2078.1/193527 doi:10.5194/cp-13-1539-2017 urn:EISSN:1814-9332 info:eu-repo/semantics/openAccess Climate of the Past, Vol. 13, p. 1539-1571 (2017) Stratigraphy Palaeontology Global and Planetary Change info:eu-repo/semantics/article 2017 ftunistlouisbrus https://doi.org/10.5194/cp-13-1539-2017 2019-06-05T22:16:48Z Multi-millennial transient simulations of climate changes have a range of important applications, such as for investigating key geologic events and transitions for which high-resolution palaeoenvironmental proxy data are available, or for projecting the long-term impacts of future climate evolution on the performance of geological repositories for the disposal of radioactive wastes. However, due to the high computational requirements of current fully coupled general circulation models (GCMs), long-term simulations can generally only be performed with less complex models and/or at lower spatial resolution. In this study, we present novel long-term "continuous" projections of climate evolution based on the output from GCMs, via the use of a statistical emulator. The emulator is calibrated using ensembles of GCM simulations, which have varying orbital configurations and atmospheric CO2 concentrations and enables a variety of investigations of long-term climate change to be conducted, which would not be possible with other modelling techniques on the same temporal and spatial scales. To illustrate the potential applications, we apply the emulator to the late Pliocene (by modelling surface air temperature – SAT), comparing its results with palaeo-proxy data for a number of global sites, and to the next 200 kyr (thousand years) (by modelling SAT and precipitation). A range of CO2 scenarios are prescribed for each period. During the late Pliocene, we find that emulated SAT varies on an approximately precessional timescale, with evidence of increased obliquity response at times. A comparison of atmospheric CO2 concentration for this period, estimated using the proxy sea surface temperature (SST) data from different sites and emulator results, finds that relatively similar CO2 concentrations are estimated based on sites at lower latitudes, whereas higher-latitude sites show larger discrepancies. In our second illustrative application, spanning the next 200 kyr into the future, we find that SAT oscillations appear to be primarily influenced by obliquity for the first ∼ 120 kyr, whilst eccentricity is relatively low, after which precession plays a more dominant role. Conversely, variations in precipitation over the entire period demonstrate a strong precessional signal. Overall, we find that the emulator provides a useful and powerful tool for rapidly simulating the long-term evolution of climate, both past and future, due to its relatively high spatial resolution and relatively low computational cost. However, there are uncertainties associated with the approach used, including the inability of the emulator to capture deviations from a quasi-stationary response to the forcing, such as transient adjustments of the deep-ocean temperature and circulation, in addition to its limited range of fixed ice sheet configurations and its requirement for prescribed atmospheric CO2 concentrations. Article in Journal/Newspaper Ice Sheet DIAL@USL-B (Université Saint-Louis, Bruxelles) Climate of the Past 13 11 1539 1571
institution Open Polar
collection DIAL@USL-B (Université Saint-Louis, Bruxelles)
op_collection_id ftunistlouisbrus
language English
topic Stratigraphy
Palaeontology
Global and Planetary Change
spellingShingle Stratigraphy
Palaeontology
Global and Planetary Change
Lord, Natalie S.
Crucifix, Michel
Lunt, Dan J.
Thorne, Mike C.
Bounceur, Nabila
Dowsett, Harry
O'Brien, Charlotte L.
Ridgwell, Andy
Emulation of long-term changes in global climate: application to the late Pliocene and future
topic_facet Stratigraphy
Palaeontology
Global and Planetary Change
description Multi-millennial transient simulations of climate changes have a range of important applications, such as for investigating key geologic events and transitions for which high-resolution palaeoenvironmental proxy data are available, or for projecting the long-term impacts of future climate evolution on the performance of geological repositories for the disposal of radioactive wastes. However, due to the high computational requirements of current fully coupled general circulation models (GCMs), long-term simulations can generally only be performed with less complex models and/or at lower spatial resolution. In this study, we present novel long-term "continuous" projections of climate evolution based on the output from GCMs, via the use of a statistical emulator. The emulator is calibrated using ensembles of GCM simulations, which have varying orbital configurations and atmospheric CO2 concentrations and enables a variety of investigations of long-term climate change to be conducted, which would not be possible with other modelling techniques on the same temporal and spatial scales. To illustrate the potential applications, we apply the emulator to the late Pliocene (by modelling surface air temperature – SAT), comparing its results with palaeo-proxy data for a number of global sites, and to the next 200 kyr (thousand years) (by modelling SAT and precipitation). A range of CO2 scenarios are prescribed for each period. During the late Pliocene, we find that emulated SAT varies on an approximately precessional timescale, with evidence of increased obliquity response at times. A comparison of atmospheric CO2 concentration for this period, estimated using the proxy sea surface temperature (SST) data from different sites and emulator results, finds that relatively similar CO2 concentrations are estimated based on sites at lower latitudes, whereas higher-latitude sites show larger discrepancies. In our second illustrative application, spanning the next 200 kyr into the future, we find that SAT oscillations appear to be primarily influenced by obliquity for the first ∼ 120 kyr, whilst eccentricity is relatively low, after which precession plays a more dominant role. Conversely, variations in precipitation over the entire period demonstrate a strong precessional signal. Overall, we find that the emulator provides a useful and powerful tool for rapidly simulating the long-term evolution of climate, both past and future, due to its relatively high spatial resolution and relatively low computational cost. However, there are uncertainties associated with the approach used, including the inability of the emulator to capture deviations from a quasi-stationary response to the forcing, such as transient adjustments of the deep-ocean temperature and circulation, in addition to its limited range of fixed ice sheet configurations and its requirement for prescribed atmospheric CO2 concentrations.
author2 UCL - SST/ELI/ELIC - Earth & Climate
format Article in Journal/Newspaper
author Lord, Natalie S.
Crucifix, Michel
Lunt, Dan J.
Thorne, Mike C.
Bounceur, Nabila
Dowsett, Harry
O'Brien, Charlotte L.
Ridgwell, Andy
author_facet Lord, Natalie S.
Crucifix, Michel
Lunt, Dan J.
Thorne, Mike C.
Bounceur, Nabila
Dowsett, Harry
O'Brien, Charlotte L.
Ridgwell, Andy
author_sort Lord, Natalie S.
title Emulation of long-term changes in global climate: application to the late Pliocene and future
title_short Emulation of long-term changes in global climate: application to the late Pliocene and future
title_full Emulation of long-term changes in global climate: application to the late Pliocene and future
title_fullStr Emulation of long-term changes in global climate: application to the late Pliocene and future
title_full_unstemmed Emulation of long-term changes in global climate: application to the late Pliocene and future
title_sort emulation of long-term changes in global climate: application to the late pliocene and future
publisher Copernicus GmbH
publishDate 2017
url http://hdl.handle.net/2078.1/193527
https://doi.org/10.5194/cp-13-1539-2017
genre Ice Sheet
genre_facet Ice Sheet
op_source Climate of the Past, Vol. 13, p. 1539-1571 (2017)
op_relation boreal:193527
http://hdl.handle.net/2078.1/193527
doi:10.5194/cp-13-1539-2017
urn:EISSN:1814-9332
op_rights info:eu-repo/semantics/openAccess
op_doi https://doi.org/10.5194/cp-13-1539-2017
container_title Climate of the Past
container_volume 13
container_issue 11
container_start_page 1539
op_container_end_page 1571
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