Session: Warm Climates (Mid-Holocene, Last interglacial, Deep-time, Pliocene)
Author: Deepak Chandan / firstname.lastname@example.org / University of Toronto
Co-author: Richard Peltier, University of Toronto;
The Pliocene Model Intercomparison Project, Phase 2 (PlioMIP2) is an international collaboration to simulate the climate of the mid-Pliocene interglacial, marine isotope stage KM5c (3.205 Mya), using a wide selection of climate models with the objective of understanding the nature of the warming that is known to have occurred during the broader mid-Pliocene warm period. PlioMIP2 builds upon the successes of PlioMIP by shifting focus onto a specific interglacial and by using a revised set of geographic and orbital boundary conditions (BCs). Recently, we have shown [Chandan and Peltier, 2017] that with the revised BCs the CCSM4 model simulates a mid-Pliocene which is more than twice as warm as that with the BCs used for PlioMIP Phase 1. The warming is more enhanced near the high-latitudes which is where most of the changes to the PlioMIP2 BCs have been made. The elevated warming in the high-latitudes leads to a better match of the simulated climatology to proxy based reconstructions than what was possible with the previous version of BCs.
We have recently completed additional PlioMIP2 sensitivity experiments using the CCSM4 model. Altogether, the nine experiments we have completed for PlioMIP2 constitute simulated model years at resolution. This is very likely the most extensive effort at any single institution, to date, to understand a specific time period of the past. Here, we present results obtained from applying a factorization methodology, that has been successfully used to understand the climate of past warm periods [Heinemann et al., 2009, Lunt et al., 2012], to investigate the impact of changes to the individual BCs (compared to present-day) in PlioMIP2 on the simulated mid-Pliocene climate. In addition to the PlioMIP2 simulations, we are currently performing simulations with an alternative set of BCs for the mid-Pliocene that we have reconstructed ourselves. These simulations allow us to assess the sensitivity of the mid-Pliocene climate to changes in global bathymetry and topography, which would not have been possible with only the PlioMIP2 experiments.
Chandan, D. and Peltier, W. R., Clim. Past, in revision, 2017
Heinemann et al., Clim. Past, 2009
Lunt et al., EPSL, 2012