A dynamic ocean driven by changes in CO2 and Antarctic ice-sheet in the middle Miocene

Frigola, Amanda; Prange, Matthias; Schulz, Michael

doi:10.1016/j.palaeo.2021.110591

Cited by 8 publications

(9 citation statements)

References 58 publications

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“…Model‐data discrepancy near regions with variable paleotopography identified key regions that should be focused on for the next MioMIP, which will likely require greater model resolution to fully resolve (Acosta & Huber, 2020; Botsyun et al., 2022; Kiehl et al., 2021; Shields et al., 2021). Changes to the land ice‐sheets (Bradshaw et al., 2021; Frigola et al., 2021; Gasson et al., 2016; Goldner et al., 2013; Paxman et al., 2019), the use of newer cloud microphysics schemes (Carmichael et al., 2016; Erfani & Burls, 2019; Heavens et al., 2012; Sagoo & Storelvmo, 2017), implementation of different vegetation and soil properties (Acosta et al., 2022; Bradshaw et al., 2015, 2012; Tabor et al., 2020; Zhou et al., 2018), and accurately capturing ocean circulation (e.g., regional SST distribution) all have the ability to modify the global energy balance, radiative feedbacks, and plays a role in governing the hydrological cycle. Nevertheless, ascertaining accurate MioMIP model boundary conditions (e.g., topography, land‐ice, vegetation distribution) is still an active research area, especially since such processes are dynamic, can span over several millions of years, and thus have their own sets of uncertainties.…”

Section: Discussionmentioning

confidence: 99%

“…However, we also found using a MIP of opportunity to be a source of uncertainty in MioMIP1 model‐data comparison and presented substantial inter‐model differences. For example, changes in the plate tectonics reconstruction (Lunt et al., 2016), such as gateways (Tethys Sea, Central American Seaway, and Greenland‐Scotland Ridge) and large continental wetland systems, have an immense impact on local heat and moisture distribution (Bradshaw et al., 2021; Frigola et al., 2018, 2021; Fu et al., 2021; Goldner et al., 2014; Jeffery et al., 2012; Knorr & Lohmann, 2014; Stärz et al., 2017). Model‐data discrepancy near regions with variable paleotopography identified key regions that should be focused on for the next MioMIP, which will likely require greater model resolution to fully resolve (Acosta & Huber, 2020; Botsyun et al., 2022; Kiehl et al., 2021; Shields et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

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A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

Acosta,

Burls,

Pound

et al. 2023

Paleoceanog and Paleoclimatol

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The Miocene (23.03–5.33 Ma) is recognized as a period with close to modern‐day paleogeography, yet a much warmer climate. With large uncertainties in future hydroclimate projections, Miocene conditions illustrate a potential future analog for the Earth system. A recent opportunistic Miocene Model Intercomparison Project 1 (MioMIP1) focused on synthesizing published Miocene climate simulations and comparing them with available temperature reconstructions. Here, we build on this effort by analyzing the hydrological cycle response to Miocene forcings across early‐to‐middle (E2MMIO; 20.03–11.6 Ma) and middle‐to‐late Miocene (M2LMIO; 11.5–5.33 Ma) simulations with CO2 concentrations ranging from 200 to 850 ppm and providing a model‐data comparison against available precipitation reconstructions. We find global precipitation increases by ∼2.1 and 2.3% per degree of warming for E2MMIO and M2LMIO simulations, respectively. Models generally agree on a wetter than modern‐day tropics; mid and high‐latitude, however, do not agree on the sign of subtropical precipitation changes with warming. Global monsoon analysis suggests most monsoon regions, except the North American Monsoon, experience higher precipitation rates under warmer conditions. Model‐data comparison shows that mean annual precipitation is underestimated by the models regardless of CO2 concentration, particularly in the mid‐ to high‐latitudes. This suggests that the models may not be (a) resolving key processes driving the hydrological cycle response to Miocene boundary conditions and/or (b) other boundary conditions or processes not considered here are critical to reproducing Miocene hydroclimate. This study highlights the challenges in modeling and reconstructing the Miocene hydrological cycle and serves as a baseline for future coordinated MioMIP efforts.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

Acosta,

Burls,

Pound

et al. 2023

Paleoceanog and Paleoclimatol

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“…Acosta et al. (2024) shows that models with a strong AMOC for the early‐to‐middle Miocene, such as COSMOS (Hossain et al., 2021) and CCSM3 (Frigola et al., 2021), exhibit an annual mean ITCZ north of the equator (Figure S9 in Acosta et al. (2024)).…”

Section: Discussionmentioning

confidence: 99%

“…Insights from Miocene hydrological cycles simulated by other MioMIP1 models can provide additional information. Acosta et al (2024) shows that models with a strong AMOC for the early-to-middle Miocene, such as COSMOS (Hossain et al, 2021) and CCSM3 (Frigola et al, 2021), exhibit an annual mean ITCZ north of the equator (Figure S9 in Acosta et al ( 2024)). However, these models do not include a counterpart experiment with a weak AMOC or without…”

Section: Limitationsmentioning

confidence: 99%

Atlantic Meridional Overturning Circulation Influence on the Annual Mean Intertropical Convergence Zone Location in the Miocene

Liu,

Herold,

Huber

2024

Geophysical Research Letters

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The Intertropical Convergence Zone (ITCZ) has an annual mean location north of the equator today. The factors determining this location and the evolution to its modern state are actively debated. Here we investigate how the Atlantic Meridional Overturning Circulation (AMOC) influences the ITCZ during the early‐to‐middle Miocene. By conducting a sensitivity study with an open Canadian Arctic Archipelago gateway, we show that North Atlantic Deep‐Water formation strengthens the AMOC, in alignment with Miocene North Atlantic ventilation proxies. A vigorous AMOC increases northward Atlantic Ocean heat transport and cross‐equatorial atmospheric energy transport shifts southwards to compensate, pushing the ITCZ northwards. Our study supports AMOC development as a strong contributor to the ITCZ's northern location today. Existing proxy‐based interpretations of ITCZ history are too sparse to strongly confirm these results. We predict a strong in‐phase relationship between AMOC strength and ITCZ's northward location, which should be testable in high resolution paleoclimate records.

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“…Ultimately, AIS volume and deep ocean temperatures changes are determined by insolation, regulated by the prevailing climatic background, e.g., geography (Stärz et al, 2017;Colleoni et al, 2018;Paxman et al, 2020;Halberstadt et al, 2021), vegetation (Knorr et al, 2011), and greenhouse gas concentrations (Frigola et al, 2021;Burls et al, 2021;Gasson et al, 2016;Halberstadt et al, 2021). AIS volume and ocean temperatures are in fact also directly related, because the AIS size affects sea water temperatures, doing so in different ways at different ocean depths.…”

Section: Introductionmentioning

confidence: 99%

Miocene Antarctic ice sheet area responds significantly faster than volume to CO₂-induced climate change

Stap

Berends

Wal

2023

Preprint

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Abstract. The strongly varying benthic δ18O levels of the early and mid-Miocene (23 to 14 Myr ago) are primarily caused by a combination of changes in Antarctic ice sheet (AIS) volume and deep ocean temperatures. These factors are coupled since AIS changes affect deep ocean temperatures. It has recently been argued that this is due to changes in ice sheet area rather than volume, because area changes affect the surface albedo. This would be important when the transient AIS grows relatively faster in extent than in thickness, which we test here. We analyse simulations of Miocene AIS variability carried out using the three-dimensional ice-sheet model IMAU-ICE forced by warm (high CO2, no ice) and cold (low CO2, large East-AIS) climate snapshots. These simulations comprise equilibrium and idealised quasi-orbital transient runs with strongly varying CO2 levels (280 to 840 ppm). Our simulations show limited direct effect of East-AIS changes on Miocene orbital timescale benthic δ18O variability, because of the slow build-up of volume. However, we find that AIS area responds significantly faster and more strongly than volume to the applied forcing variability. Consequently, during certain intervals the ice sheet is receding at the margins, while ice is still building up in the interior. That means the AIS does not adapt to a changing equilibrium size at the same rate or with the same sign everywhere. Our results indicate that the Miocene Antarctic ice sheet affects deep ocean temperatures more than its volume suggests.

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A dynamic ocean driven by changes in CO2 and Antarctic ice-sheet in the middle Miocene

Cited by 8 publications

References 58 publications

A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

Atlantic Meridional Overturning Circulation Influence on the Annual Mean Intertropical Convergence Zone Location in the Miocene

Miocene Antarctic ice sheet area responds significantly faster than volume to CO₂-induced climate change

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A dynamic ocean driven by changes in CO2 and Antarctic ice-sheet in the middle Miocene

Cited by 8 publications

References 58 publications

A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

A Model‐Data Comparison of the Hydrological Response to Miocene Warmth: Leveraging the MioMIP1 Opportunistic Multi‐Model Ensemble

Atlantic Meridional Overturning Circulation Influence on the Annual Mean Intertropical Convergence Zone Location in the Miocene

Miocene Antarctic ice sheet area responds significantly faster than volume to CO2-induced climate change

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Miocene Antarctic ice sheet area responds significantly faster than volume to CO₂-induced climate change