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| dc.contributor.author | Quinn, C | |
| dc.contributor.author | Sieber, J | |
| dc.contributor.author | Heydt, ASVD | |
| dc.contributor.author | Lenton, TM | |
| dc.date.accessioned | 2018-09-12T13:05:55Z | |
| dc.date.issued | 2018-09-01 | |
| dc.description.abstract | The Mid-Pleistocene Transition, the shift from 41 kyr to 100 kyr glacial-interglacial cycles that occurred roughly 1 Myr ago, is often considered as a change in internal climate dynamics. Here we revisit the model of Quaternary climate dynamics that was proposed by Saltzman and Maasch (1988). We show that it is quantitatively similar to a scalar equation for the ice dynamics only when combining the remaining components into a single delayed feedback term. The delay is the sum of the internal times scales of ocean transport and ice sheet dynamics, which is on the order of 10 kyr. We find that, in the absence of astronomical forcing, the delayed feedback leads to bistable behaviour, where stable large-amplitude oscillations of ice volume and an equilibrium coexist over a large range of values for the delay. We then apply astronomical forcing. We perform a systematic study to show how the system response depends on the forcing amplitude. We find that over a wide range of forcing amplitudes the forcing leads to a switch from small-scale oscillations of 41 kyr to large-amplitude oscillations of roughly 100 kyr without any change of other parameters. The transition in the forced model consistently occurs near the time of the Mid-Pleistocene Transition as observed in data records. This provides evidence that the MPT could have been primarily a forcing-induced switch between attractors of the internal dynamics. Small additional random disturbances make the forcing-induced transition near 800 kyr BP even more robust. We also find that the forced system forgets its initial history during the small-scale oscillations, in particular, nearby initial conditions converge prior to transitioning. In contrast to this, in the regime of large-amplitude oscillations, the oscillation phase is very sensitive to random perturbations, which has a strong effect on the timing of the deglaciation events. | en_GB |
| dc.description.sponsorship | Q., J.S and T.L. have received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 643073. J.S. gratefully acknowledges the financial support of the EPSRC via grants EP/N023544/1 and EP/N014391/1. | en_GB |
| dc.identifier.citation | Published online 1 September 2018 | en_GB |
| dc.identifier.doi | 10.1093/climsys/dzy005 | |
| dc.identifier.uri | http://hdl.handle.net/10871/33979 | |
| dc.language.iso | en | en_GB |
| dc.publisher | Oxford University Press (OUP) | en_GB |
| dc.rights | © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. | |
| dc.type | Article | en_GB |
| dc.description | This is the author accepted manuscript. The final version is available from OUP via the DOI in this record | en_GB |
| dc.identifier.journal | Dynamics and Statistics of the Climate System | en_GB |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ |
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This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.