Transient Climate Simulations of Orbital Effects on Mesozoic Climates

2021 ◽  
Author(s):  
Jan Landwehrs ◽  
Georg Feulner ◽  
Matteo Willeit ◽  
Benjamin Sames ◽  
Michael Wagreich
Keyword(s):  
Sea Level ◽  
Ice Sheets ◽  
System Model ◽  
Proxy Records ◽  
Orbital Cycles ◽  
Climate Simulations ◽  
First Results ◽  
Climate Background ◽  
Land Water ◽  
Background State

<p>The Mesozoic era (~252—66 Ma) is traditionally considered as a prolonged greenhouse period, witnessing the breakup of the Pangaean supercontinent. Orbital cycles have, for example, been invoked as drivers of e.g. Pangaean „Megamonsoon“ variability and eustatic sea level cycles in the Mesozoic.</p><p>We aim to contribute to a more comprehensive understanding of orbital effects on Mesozoic climates by employing the newly developed CLIMBER-X Earth System Model. Here, we primarily use its coupled atmosphere, ocean, sea ice and vegetation modules, but also include preliminary tests with dynamic carbon cycle and ice-sheets. We present first results from a set of transient climate simulations of four Mesozoic timeslices representative for Triassic, Jurassic, Early Cretaceous and Late Cretaceous boundary conditions (e.g. paleogeography and solar luminosity). The simulations each cover ~100,000 years and are driven by changing precession, obliquity, and eccentricity.</p><p>We would like to use the opportunity to discuss this approach and associated questions with the community. For example: Would changing paleogeography and climate background state have modified the response to orbital forcings? Could eustatic sea level cycles have been caused by orbitally-driven redistribution of water between the ocean and land water storages or should orbitally-forced ice sheets also have played a role in the alleged Mesozoic greenhouse? Which connections can be established to proxy records?</p>

scholarly journals Ice sheet dynamics within an earth system model: downscaling, coupling and first results

2014 ◽  
Vol 7 (5) ◽  
pp. 2003-2013 ◽  
Author(s):  
D. Barbi ◽  
G. Lohmann ◽  
K. Grosfeld ◽  
M. Thoma
Keyword(s):  
Empirical Relationship ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Coupled Model ◽  
Sensitivity Study ◽  
Snow Accumulation ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
First Results

Abstract. We present first results from a coupled model setup, consisting of the state-of-the-art ice sheet model RIMBAY (Revised Ice Model Based on frAnk pattYn), and the community earth system model COSMOS. We show that special care has to be provided in order to ensure physical distributions of the forcings as well as numeric stability of the involved models. We demonstrate that a suitable statistical downscaling is crucial for ice sheet stability, especially for southern Greenland where surface temperatures are close to the melting point. The downscaling of net snow accumulation is based on an empirical relationship between surface slope and rainfall. The simulated ice sheet does not show dramatic loss of ice volume for pre-industrial conditions and is comparable with present-day ice orography. A sensitivity study with high CO2 level is used to demonstrate the effects of dynamic ice sheets onto climate compared to the standard setup with prescribed ice sheets.

scholarly journals ISSM-SLPS: geodetically compliant Sea-Level Projection System for the Ice-sheet and Sea-level System Model v4.17

2020 ◽  
Vol 13 (10) ◽  
pp. 4925-4941
Author(s):  
Eric Larour ◽  
Lambert Caron ◽  
Mathieu Morlighem ◽  
Surendra Adhikari ◽  
Thomas Frederikse ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ocean Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Level System ◽  
Projection System ◽  
Forward Models ◽  
And Sea Level

Abstract. Understanding future impacts of sea-level rise at the local level is important for mitigating its effects. In particular, quantifying the range of sea-level rise outcomes in a probabilistic way enables coastal planners to better adapt strategies, depending on cost, timing and risk tolerance. For a time horizon of 100 years, frameworks have been developed that provide such projections by relying on sea-level fingerprints where contributions from different processes are sampled at each individual time step and summed up to create probability distributions of sea-level rise for each desired location. While advantageous, this method does not readily allow for including new physics developed in forward models of each component. For example, couplings and feedbacks between ice sheets, ocean circulation and solid-Earth uplift cannot easily be represented in such frameworks. Indeed, the main impediment to inclusion of more forward model physics in probabilistic sea-level frameworks is the availability of dynamically computed sea-level fingerprints that can be directly linked to local mass changes. Here, we demonstrate such an approach within the Ice-sheet and Sea-level System Model (ISSM), where we develop a probabilistic framework that can readily be coupled to forward process models such as those for ice sheets, glacial isostatic adjustment, hydrology and ocean circulation, among others. Through large-scale uncertainty quantification, we demonstrate how this approach enables inclusion of incremental improvements in all forward models and provides fidelity to time-correlated processes. The projection system may readily process input and output quantities that are geodetically consistent with space and terrestrial measurement systems. The approach can also account for numerous improvements in our understanding of sea-level processes.

scholarly journals Modelling ice sheet evolution and atmospheric CO<sub>2</sub> during the Late Pliocene

2019 ◽  
Author(s):  
Constantijn J. Berends ◽  
Bas de Boer ◽  
Aisling M. Dolan ◽  
Daniel J. Hill ◽  
Roderik S. W. van de Wal
Keyword(s):  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Mean Sea Level ◽  
Late Pliocene ◽  
Proxy Records ◽  
Global Mean Sea Level ◽  
Global Mean

Abstract. In order to investigate the relation between ice sheets and climate in a warmer-than-present world, recent research has focussed on the Late Pliocene, 3.6 to 2.58 million years ago. It is the most recent period in Earth history when such a climate state existed for a significant duration of time. Marine Isotope Stage (MIS) M2 (~ 3.3 Myr ago) is a strong positive excursion in benthic oxygen records in the middle of the otherwise warm and relatively stable Late Pliocene. However, the relative contributions to the benthic δ18O signal from deep-ocean cooling and growing ice sheets are still uncertain. Here, we present results from simulations of the late Pliocene with a hybrid ice-sheet–climate model, showing a reconstruction of ice sheet geometry, sea-level and atmospheric CO2. Initial experiments simulating the last four glacial cycles indicate that this model yields results which are in good agreement with proxy records in terms of global mean sea level, benthic oxygen isotope abundance, ice core-derived surface temperature and atmospheric CO2 concentration. For the Late Pliocene, our results show an atmospheric CO2 concentration during MIS M2 of 233–249 ppmv, and a drop in global mean sea level of 10 to 25 m. Uncertainties are larger during the warmer periods leading up to and following MIS M2. CO2 concentrations during the warm intervals in the Pliocene, with sea-level high stands of 8–14 m above present-day, varied between 320 and 400 ppmv, lower than indicated by some proxy records but in line with earlier model reconstructions.

scholarly journals Layered seawater intrusion and melt under grounded ice

2021 ◽  
Author(s):  
Alexander A. Robel ◽  
Earle Wilson ◽  
Helene Seroussi
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Seawater Intrusion ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Glacier Terminus ◽  
Grounding Line ◽  
Flow Through ◽  
And Sea Level

Abstract. Increasing melt of ice sheets at their floating or vertical interface with the ocean is a major driver of marine ice sheet retreat and sea level rise. However, the extent to which warm, salty seawater may drive melting under the grounded portions of ice sheets is still not well understood. Previous work has explored the possibility that dense seawater intrudes beneath relatively light subglacial freshwater discharge, similar to the salt wedge observed in many estuarine systems. In this study, we develop a generalized theory of layered seawater intrusion under grounded ice, including where subglacial hydrology occurs as a macroporous water sheet over impermeable beds or as microporous Darcy flow through permeable till. Using predictions from this theory, we show that seawater intrusion over hard beds may feasibly occur up to tens of kilometers upstream of a glacier terminus or grounding line. On the other hand, seawater is unlikely to intrude more than tens of meters through subglacial till. High-resolution simulations using the Ice-Sheet and Sea-Level System Model (ISSM) show that even just a few hundred meters of basal melt caused by seawater intrusion upstream of marine ice sheet grounding lines can cause projections of marine ice sheet volume loss to be 10–50 % higher or 100 % higher for kilometers of intrusion-induced basal melt. These results suggest that further observational, experimental and numerical investigations are needed to determine whether the conditions under which extensive seawater intrusion occurs and whether it will indeed drive rapid marine ice sheet retreat and sea level rise in the future.

scholarly journals Modelling ice sheet evolution and atmospheric CO<sub>2</sub> during the Late Pliocene

2019 ◽  
Vol 15 (4) ◽  
pp. 1603-1619 ◽  
Author(s):  
Constantijn J. Berends ◽  
Bas de Boer ◽  
Aisling M. Dolan ◽  
Daniel J. Hill ◽  
Roderik S. W. van de Wal
Keyword(s):  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Mean Sea Level ◽  
Late Pliocene ◽  
Proxy Records ◽  
Global Mean Sea Level ◽  
Global Mean

Abstract. In order to investigate the relation between ice sheets and climate in a warmer-than-present world, recent research has focussed on the Late Pliocene, 3.6 to 2.58 million years ago. It is the most recent period in Earth's history when such a warm climate state existed for a significant duration of time. Marine Isotope Stage (MIS) M2 (∼3.3 Myr ago) is a strong positive excursion in benthic oxygen records in the middle of the otherwise warm and relatively stable Late Pliocene. However, the relative contributions to the benthic δ18O signal from deep ocean cooling and growing ice sheets are still uncertain. Here, we present results from simulations of the Late Pliocene with a hybrid ice-sheet–climate model, showing a reconstruction of ice sheet geometry, sea level and atmospheric CO2. Initial experiments simulating the last four glacial cycles indicate that this model yields results which are in good agreement with proxy records in terms of global mean sea level, benthic oxygen isotope abundance, ice-core-derived surface temperature and atmospheric CO2 concentration. For the Late Pliocene, our results show an atmospheric CO2 concentration during MIS M2 of 233–249 ppmv and a drop in global mean sea level of 10 to 25 m. Uncertainties are larger during the warmer periods leading up to and following MIS M2. CO2 concentrations during the warm intervals in the Pliocene, with sea-level high stands of 8–14 m above the present day, varied between 320 and 400 ppmv, lower than indicated by some proxy records but in line with earlier model reconstructions.

Improving the representation of ice-sheet mass changes in the global inversion for sea-level contributions

2020 ◽  
Author(s):  
Matthias O. Willen ◽  
Bernd Uebbing ◽  
Martin Horwath ◽  
Jürgen Kusche ◽  
Roelof Rietbroek ◽  
...  
Keyword(s):  
Sea Level ◽  
A Priori ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Mass Change ◽  
Altimetry Data ◽  
Isostatic Adjustment ◽  
Ocean Mass ◽  
First Results ◽  
Ocean Altimetry

&lt;p&gt;&lt;span&gt;G&lt;/span&gt;&lt;span&gt;lobal-mean sea level rises (GMSLR) by 3.1-3.5 mm a&lt;sup&gt;-1 &lt;/sup&gt;&lt;/span&gt;&lt;span&gt;(1993-2017)&lt;/span&gt;&lt;span&gt; and &lt;/span&gt;&lt;span&gt;of which&lt;/span&gt;&lt;span&gt; about 50 % can be attributed to changes in global-mean ocean mass due to hydrological variations, m&lt;/span&gt;&lt;span&gt;ass changes&lt;/span&gt;&lt;span&gt; of land glaciers, &lt;/span&gt;&lt;span&gt;and&lt;/span&gt; &lt;span&gt;mass &lt;/span&gt;&lt;span&gt;c&lt;/span&gt;&lt;span&gt;hanges&lt;/span&gt;&lt;span&gt; of the major ice sheets in Greenland and Antarctica. The i&lt;/span&gt;&lt;span&gt;ce-sheet contributions&lt;/span&gt;&lt;span&gt; account for more than &lt;/span&gt;&lt;span&gt;the&lt;/span&gt;&lt;span&gt; half of the contemporary ocean mass change &lt;/span&gt;&lt;span&gt;and can be&lt;/span&gt;&lt;span&gt; observed w&lt;/span&gt;&lt;span&gt;ith&lt;/span&gt;&lt;span&gt; time-variable gravi&lt;/span&gt;&lt;span&gt;metry&lt;/span&gt;&lt;span&gt; by the Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission (GRACE-FO). In addition, geometric surface changes due to &lt;/span&gt;&lt;span&gt;the volume change of&lt;/span&gt;&lt;span&gt; ice sheets is also observed b&lt;/span&gt;&lt;span&gt;y polar &lt;/span&gt;&lt;span&gt;altimetry &lt;/span&gt;&lt;span&gt;missions&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;span&gt;Of particular importance here is the signal of glacial isostatic adjustment (GIA) which is superimposed with i&lt;/span&gt;&lt;span&gt;ce mass change&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Conventionally, the g&lt;/span&gt;&lt;span&gt;ravimetry&lt;/span&gt;&lt;span&gt; and ice-altimetry observations are processed independently. For ocean applications, a global fingerprint inversion (Rietbroek et al., 2016) allows to estimate individual mass and steric contributors to the sea-level budget by combi&lt;/span&gt;&lt;span&gt;ni&lt;/span&gt;&lt;span&gt;ng GRACE and ocean-altimetry data in a joint approach. To improve the estimates of the ice-sheet contributions to GMSLR, we present first results from additionally incorporating independent ice-altimetry data over Greenland and Antarctica into the fingerprint inversion. We examine the sensitivity of the sea-level contributions to the additional ice-altimetry data &lt;/span&gt;&lt;span&gt;(from &lt;/span&gt;&lt;span&gt;ERS-2, Envisat, ICESat, CryoSat-2 &lt;/span&gt;&lt;span&gt;missions)&lt;/span&gt;&lt;span&gt; and provide validation against independent estimates. &lt;/span&gt;&lt;span&gt;I&lt;/span&gt;&lt;span&gt;n our standard runs&lt;/span&gt;&lt;span&gt;, &lt;/span&gt;&lt;span&gt;GIA is &lt;/span&gt;&lt;span&gt;accounted for &lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt;s an a-priori correction during the inversion.&lt;/span&gt;&lt;span&gt; H&lt;/span&gt;&lt;span&gt;owever,&lt;/span&gt;&lt;span&gt; we demonstrate the potential and limitations of a regional inverse approach i&lt;/span&gt;&lt;span&gt;n which&lt;/span&gt;&lt;span&gt; GIA is separated from ice mass change &lt;/span&gt;&lt;span&gt;over Antarctica&lt;/span&gt;&lt;span&gt; using GRACE and ice altimetry. In our future work, we a&lt;/span&gt;&lt;span&gt;im to &lt;/span&gt;&lt;span&gt;parametrise&lt;/span&gt;&lt;span&gt; and&lt;/span&gt;&lt;span&gt; co-&lt;/span&gt;&lt;span&gt;estimate GIA &lt;/span&gt;&lt;span&gt;with&lt;/span&gt;&lt;span&gt;in the global inversion framework.&lt;/span&gt;&lt;/p&gt;

scholarly journals Ice sheet dynamics within an Earth system model: coupling and first results on ice stability and ocean circulation

2013 ◽  
Vol 6 (1) ◽  
pp. 1-35 ◽  
Author(s):  
D. Barbi ◽  
G. Lohmann ◽  
K. Grosfeld ◽  
M. Thoma
Keyword(s):  
Ocean Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Coupled Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
First Results ◽  
Ice Sheet Dynamics ◽  
Model Setup

Abstract. We present first results from a coupled model setup, consisting of a state-of-the-art ice sheet model (RIMBAY), and the community earth system model COSMOS. We show that special care has to be provided in order to ensure physical distributions of the forcings, as well as numeric stability of the involved models. We demonstrate that a statistical downscaling is crucial for ice sheet stability, especially for southern Greenland where surface temperature are close to the melting point. The simulated ice sheets are stable when forced with pre-industrial greenhouse gas parameters, with limits comparable with present day ice orography. A setup with high CO2 level is used to demonstrate the effects of dynamic ice sheets compared to the standard parameterisation; the resulting changes on ocean circulation will also be discussed.

scholarly journals ISSM-SLPS: geodetically compliant Sea-Level Projection System for the Ice-sheet and Sea-level System Model v4.17

2020 ◽  
Author(s):  
Eric Larour ◽  
Surendra Adhikari ◽  
Thomas Frederikse ◽  
Lambert Caron ◽  
Benjamin Hamlington ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ocean Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Level System ◽  
Projection System ◽  
Forward Models ◽  
And Sea Level

Abstract. Understanding future impacts of sea-level rise at the local level is paramount to mitigating its effects. In particular, quantifying the range of sea-level rise outcomes in a probabilistic way enables coastal planners to better adapt strategies, depending on cost and timing. For long-term projections, from present-day to the end of the 21st century, frameworks have been developed that provide such probabilistic projections. They rely on sea-level fingerprints where contributions from different processes are sampled at each individual time step and summed up to create probability distributions of sea-level rise for each desired location. While advantageous, this method does not readily allow for including new physics developed in forward models of each component. For example, couplings and feedbacks between ice sheets, ocean circulation, and solid-Earth uplift cannot easily be represented in such frameworks. Indeed, the main impediment to inclusion of more forward model physics in probabilistic sea-level frameworks is the availability of dynamically computed sea-level fingerprints that can be directly linked to local mass changes. Here, we demonstrate such an approach within the Ice-Sheet and Sea-level System Model (ISSM), where we develop a probabilistic framework that can readily be coupled to forward process models such as those for ice sheets, glacial-isostatic adjustment, hydrology and ocean circulation, among others. Through large scale uncertainty quantification, we demonstrate how this approach enables inclusion of incremental improvements in all forward models and provides fidelity to time-correlated processes. The projection system may readily process input and output quantities that are geodetically consistent with space and terrestrial measurement systems. The approach can also account for numerous improvements in our understanding of sea-level processes.

WALIS - Towards a global database of Last Interglacial sea-level proxies.

2021 ◽  
Author(s):  
Alessio Rovere ◽  
Deirdre Ryan ◽  
Matteo Vacchi ◽  
Alexander Simms ◽  
Andrea Dutton ◽  
...  
Keyword(s):  
Sea Level ◽  
Research Council ◽  
Geological Data ◽  
Sea Level Changes ◽  
Last Interglacial ◽  
Global Database ◽  
The World ◽  
First Results ◽  
Data Points ◽  
The Subject

&lt;p&gt;The standardization of geological data, and their compilation into geodatabases, is essential to allow more coherent regional and global analyses. In sea-level studies, the compilation of databases containing details on geological paleo sea-level proxies has been the subject of decades of work. This was largely spearheaded by the community working on Holocene timescales. While several attempts were also made to compile data from older interglacials, a truly comprehensive approach was missing. Here, we present the ongoing efforts directed to create the World Atlas of Last Interglacial Shorelines (WALIS), a project spearheaded by the PALSEA (PAGES/INQUA) community and funded by the European Research Council (ERC StG 802414). The project aims at building a sea-level database centered on the Last Interglacial (Marine Isotope Stage 5e, 125 ka), a period of time considered as an &quot;imperfect analog&quot; for a future warmer climate. The database is composed of 17 tables embedded into a mySQL framework with a total of more than 500 single fields to describe several properties related to paleo sea-level proxies, dated samples and metadata. In this presentation, we will show the first results of the global compilation, which includes nearly 2000 data points and will discuss its relevance in answering some of the most pressing questions related to sea-level changes in past warmer worlds.&amp;#160;&lt;/p&gt;

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