PlioVAR - Pliocene climate variability over glacial-interglacial timescales

 
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PAGES' PlioVAR working group was active between 2015 and 2018.

January 2019 Update

The group has been working behind the scenes and is now in a position to circulate the planned schedule for releasing the PlioVAR marine synthesis paper in 2019.

This work is being driven by Erin McClymont, Heather Ford and Sze Ling Ho, with contributions from the regional synthesis leaders (see below). We will be continuing to update the online database, but if you have new data or publications which have emerged in recent months or which will come out during 2019, please contact us so that we can include it into our synthesis work.

Please also note that although PlioVAR will shortly officially end as a PAGES working group, we are hoping to keep this informal network active so that we can circulate items of interest. We have provisionally been allocated some time for a short meeting at ICP in Sydney in September, for those who plan to attend.

PlioVAR Marine Synthesis paper (2019) – focus on MPWP

- January-March 2019: final review of data sets, age models, calibrations
- April 2019: first draft circulated to regional synthesis leaders
- May-June 2019: revisions to first draft, circulation of revisions to regional synthesis leaders
- July: aim to submit paper for review
- After: apply our methods to a MPWP vs ONHG comparison paper.

Regional synthesis leaders

Overall convenor: Erin McClymont (This email address is being protected from spambots. You need JavaScript enabled to view it.)
North Atlantic/Nordic Seas: Stijn de Schepper and Bjorg Risebrobakken (This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it.)
South Atlantic: Benjamin Petrick (This email address is being protected from spambots. You need JavaScript enabled to view it.)
Southern Ocean: Erin McClymont and Molly Patterson (This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it.)
Pacific Ocean: Heather Ford and Christina Ravelo (This email address is being protected from spambots. You need JavaScript enabled to view it. This email address is being protected from spambots. You need JavaScript enabled to view it.)
Indian Ocean: Kate Littler and Kaustubh Thirumalai (This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it.)
Statistical analysis: Sze Ling Ho (This email address is being protected from spambots. You need JavaScript enabled to view it.)

Overview

PlioMIP surface air temperature

Figure 1: Annual mean surface air temperature change in Celsius (Pliocene minus pre-industrial) from the PlioMIP ensemble (redrawn from Haywood et al. 2013).

The Pliocene epoch (~2.6-5.3 million years ago) is one of the best resolved examples of a climate state in long-term equilibrium with current or predicted near-future atmospheric CO2 concentrations, characterised by a globally warmer climate, reduced continental ice volume, and reduced ocean/atmosphere circulation intensity. The available data for this period can be constrained in time by multiple stratigraphic frameworks. The orbital forcing of solar radiation is known precisely, and many of the species existing today were also present. As a result, detailed understanding of climate forcings and feedbacks is possible through both data analysis and data-model integration.

Paleoclimate studies of the Pleistocene period (~11.7k-2.6 million years ago) have demonstrated the value of understanding climate variability on orbital timescales, whereby the unique spatial and temporal signatures of individual interglacials or glacial-interglacial cycles highlight sensitive regions or climate systems.

Recent modeling work confirms that such variability (and regional non-synchroneity) should also be expected in the Pliocene. However, Pliocene data density is lower than for the Pleistocene, and stratigraphical correlation may be more challenging (e.g. benthic d18O oscillations are more muted).

PlioVAR aimed to co-ordinate a synthesis of terrestrial and marine data to characterise spatial and temporal variability of Pliocene climate. In order to create such a globally distributed, orbitally-resolved synthesis a community effort is required, ensuring high quality data sets can be integrated using a robust stratigraphy, which is essential to underpin future data/model comparisons.

Key aims

Building on key priorities identified by the community at the PAGES-sponsored workshop, Multi-proxy approach to the reconstruction of the Pliocene climate, held in Barcelona in September 2014, PlioVAR identified three over-arching goals:

1. Synthesize late Pliocene climate data with orbital and sub-orbital scale resolution. Specifically, we will tackle two key climate transitions which have known forcings and known chronostratigraphic uncertainty, and which are best constrained with respect to data density: marine isotope stages M2-KM3 (glacial to interglacial transition) and the onset of northern hemisphere glaciation.

2. Examine the tools and experimental design of new climate modeling studies to characterise Pliocene climate variability, including transient model simulations.

3. Identify early Pliocene intervals to which the approaches of (1) and (2) can be applied in PlioVAR Phase 2, to compare and contrast the long-term evolution of Pliocene climate and consider the role of ocean gateways and CO2 forcing in the evolution of the Earth system.

The specific Phase 1 objectives, workplan, and envisaged products are outlined in further detail on the Scientific goals page.

The PlioVAR mailing list is still active here.

Questions can be sent to a member of the Steering Group.

 

 

References
Haywood AM, Hill DJ, Dolan AM, Otto-Bliesner BL, Bragg F, Chan WL, Chandler MA, Contoux C, Contoux C, Dowsett HJ, Jost A, Kamae Y, Lohmann G, Lunt DJ, Abe-Ouchi A, Pickering SJ, Ramstein G, Rosenbloom NA, Salzmann U, Sohl L, Stepanek C, Ueda H, Yan Q & Zhang Z (2013) Large-scale features of Pliocene climate: Results from the Pliocene Model Intercomparison Project, Climate of the Past 9:191-209, doi: 10.5194/cp-9-191-2013