Expanding PlioVAR to PlioMioVAR

For decades the mid-Pliocene warm period has been a data-model comparison target (PlioMIP, PlioVAR, PRISM). During the mid-Pliocene warm period (~3.2 Ma), global temperatures are estimated to be ~2.3°C warmer than today and atmospheric CO₂ is estimated at ~350-400. However, as modern atmospheric concentrations rise above 410 ppm, it is increasingly necessary to expand our efforts to other periods of sustained warmth. There is community interest in expanding into the Miocene (~23.03 to 5.33 Ma) when atmospheric CO₂ was ~600 ppm. Additionally, the ice sheet expansion and cooling of the mid-Miocene Climate Transition presents another opportunity to study threshold climate changes and forcing mechanisms, much like the Northern Hemisphere Glaciation during the Pliocene, a PlioVAR scientific objective.  Launching the MioPlioVAR Working Group will provide a framework for sharing best practices in community-wide engagement, database building and data-model comparison.

The MioPlioVAR Working Group has three main goals. The first is to maintain the existing PlioVAR database and expand to the Miocene by synthesizing climate records and including age model quality metadata. This will help identify the Miocene target for data-model comparison (likely the Miocene Climate Optimum) and identify gaps in our current Miocene paleoclimate records (temporal resolution, spatial coverage, proxy confidence). The second is to explore new data-model comparison studies to characterize climate variability including transient model simulations and coupled models with biogeochemistry. The third is to compare the long-term evolution of Pliocene and Miocene climate and consider forcing mechanisms like tectonic gateways or CO₂.