Global impacts of a subaerial Barents Sea on the mid-Pliocene climate

A long-standing challenge for mid-Pliocene climate simulations is large underestimation of simulated surface warming in the Nordic Seas in comparison to sea surface temperature (SST) proxy records (Dowsett et al., 2013; McClymont et al., 2020). Previous modelling studies have proposed that geographic changes in the Barents-Kara Sea are of great importance for surface temperature change in the Nordic Seas (Hill, 2015). That is, changing the Barents Sea from a marine to a subaerial setting can give rise to evident warming in the Nordic Seas (Hill, 2015). Nevertheless, this geographic change has so far not been well considered in the Pliocene Modelling Intercomparison Project (Dowsett et al., 2016; Haywood et al., 2016 a, b), potentially due to the lack of quantitative reconstruction of this paleogeographic change. Recently, Lien et al. (2022) provided such reconstruction, which enables a test of the impact of a subaerial Barents Sea on mid-Pliocene climate. Based on iCESM1.2, we accordingly conducted sensitivity experiments where we changed bathymetry in the eastern Nordic Sea and topography in the Barents-Kara Sea region in a setup of otherwise unaltered PRISM4 mid-Pliocene boundary conditions. We demonstrate that the sea surface temperatures were warmer than pre-industrial values and Nordic Seas had warmed significantly. Our results hint that a subaerial Barents-Kara Sea might contribute to the data-model SST mismatch during the mid-Pliocene. References: Dowsett, H., Dolan, A., Rowley, D., Moucha, R., Forte, A. M., Mitrovica, J. X., . . . Haywood, A. (2016). The PRISM4 (mid-Piacenzian) paleoenvironmental reconstruction. Climate of the Past, 12(7), 1519-1538. doi:10.5194/cp-12-1519-2016 Dowsett, H. J., Foley, K. M., Stoll, D. K., Chandler, M. A., Sohl, L. E., Bentsen, M., . . . Zhang, Z. S. (2013). Sea Surface Temperature of the mid-Piacenzian Ocean: A Data-Model Comparison. Scientific Reports, 3. doi:ARTN 2013 10.1038/srep02013 Haywood, A. M., Dowsett, H. J., & Dolan, A. M. (2016). Integrating geological archives and climate models for the mid-Pliocene warm period. Nature Communications, 7. doi:ARTN 1064610.1038/ncomms10646 Haywood, A. M., Dowsett, H. J., Dolan, A. M., Rowley, D., Abe-Ouchi, A., Otto-Bliesner, B., . . . Salzmann, U. (2016). The Pliocene Model Intercomparison Project (PlioMIP) Phase 2: scientific objectives and experimental design. Climate of the Past, 12(3), 663-675. doi:10.5194/cp-12-663-2016 Hill, D. J. (2015). The non-analogue nature of Pliocene temperature gradients. Earth and Planetary Science Letters, 425, 232-241. doi:10.1016/j.epsl.2015.05.044 Lien, O. F., Hjelstuen, B. O., Zhang, X., & Sejrup, H. P. (2022). Late Plio-Pleistocene evolution of the Eurasian Ice Sheets inferred from sediment input along the northeastern Atlantic continental margin. Quaternary Science Reviews, 282. doi:ARTN 10743310.1016/j.quascirev.2022.107433 McClymont, E. L., Ford, H. L., Ho, S. L., Tindall, J. C., Haywood, A. M., Alonso-Garcia, M., . . . Zhang, Z. S. (2020). Lessons from a high-CO2 world: an ocean view from ∼ 3 million years ago. Climate of the Past, 16(4), 1599-1615. doi:10.5194/cp-16-1599-202