Modelling 100 kyr of transient climate change during the Pliocene (MIS M2 to MIS KM5c)

Abstract:

The mid-Pliocene warm period (3.264–3.025 Ma) is a key target for palaeoclimate modellers in the investigation of warm intervals in Earth history. This research is driven by the need to evaluate climate models against geological data in order to assess model performance in warmer than present climates. The mid-Pliocene has generally been modelled using fixed-boundary condition climate model experiments, such as those performed for the Pliocene Model Intercomparison Project (PlioMIP). This means that orbital-timescale variability in climate is often overlooked. In the past data-model comparisons have primarily focussed on comparing snap-shot experiments (fixed boundary conditions) with time-averaged data (for example PRISM3 data which is representative of an average of ~250,000 years). In order to improve the validity of proxy-data and model comparisons it is critical that we move towards climate simulations that better capture changing bounding conditions occurring over orbital timescales and compare these with timeseries data.

Here, we present two sets of transient simulations; the first is centred on the warm interglacial peak, MIS KM5c (+/-20 kyr) whilst the second runs from the glacial peak MIS M2 through to MIS KM5c (~100 kyr). We use the full-complexity intermediate-resolution FAMOUS climate model driven by PRISM3 boundary conditions (which were also used in PlioMIP phase 1). Our initial experiments apply a changing orbit, with and without dynamic vegetation. We present an overview of climate variability during these time windows, but also discuss the difficulties that have been faced in such modelling and detail some ideal future directions to explore