By Eleonora Santucci
Understanding how Antarctica will respond to ongoing climate change is one of the most pressing challenges in Earth Sciences. Surprisingly, one of the best ways to explore the future is to look into the past—in this particular case into the middle Pliocene Warm Period, (mPWP around 3.264 to 3.025 million years ago; de Boer et al., 2015) when atmospheric CO₂ levels were similar to today (Escutia et al., 2011).
My research focuses on marine sediment cores recovered in the Wilkes Land region (Escutia et al., 2011) some of those collected in front of the Totten Glacier (Donda et al., 2020), one of the largest glaciers in East Antarctica (Fig. 1). This area is one of the most sensitive sectors of the Antarctic Ice Sheet and plays a key role in controlling the global sea-level rise. During the mPWP, global temperatures were higher, and polar regions experienced significant environmental changes. This makes the Pliocene sedimentary record of the Wilkes Land region an ideal natural laboratory for studying how the Antarctic ice sheet and ocean system might respond to current global warming. However, reconstructing these past conditions is not straightforward: different geochemical proxies can sometimes produce conflicting results. This is where microfossils, such as diatoms, become essential.
Figure 1. Bathymetry of the study area of the Wilkes Land margin, East Antarctica. Site U1359 is marked with a red symbol; other Exp.318 sites are indicated in yellow. Modified from Escutia et al. (2011).
Diatoms are microscopic algae with siliceous cell walls that can be exceptionally well preserved in marine sediments. Because different species (Fig. 2) thrive under specific environmental conditions—such as temperature, sea-ice cover, and nutrient availability—their fossil assemblages provide valuable insights into past ocean conditions. In other words, they act as natural recorders of environmental change.
Figure 2. Selected diatoms from marine sediment cores collected from the Wilkes Land region in East Antarctica . Light microscope (LM) images of diatoms from IODP Expedition 318 made by Santucci. Scale bar = 40 µm.
Despite its importance for future sea-level rise, Wilkes Land remains relatively understudied compared to other parts of Antarctica. Yet, it holds key information about how ocean temperatures influence ice-sheet stability.
The research combines diatom-based micropaleontology with organic geochemical proxies (TEX₈₆), applied to marine sediment cores from the Wilkes Land margin, including material from international Antarctic drilling programmes such as IODP. The aim is to reconstruct ocean conditions during the warm Pliocene. Organic geochemical analyses (TEX₈₆) provide quantitative estimates of past ocean temperatures, whereas diatom assemblages offer independent constraints on surface-water conditions, including sea-ice extent and ocean productivity.
By integrating these methods, it becomes possible to identify agreements and discrepancies between different types of climate proxies, improving the reliability of paleoenvironmental reconstructions. In particular, this approach helps constrain temperature thresholds that may have triggered changes in the Antarctic cryosphere.
A key aspect of the research involves comparing modern diatom assemblages (Tolotti et al., 2024) with present-day ocean conditions and applying this relationship to the fossil record using statistical tools known as “transfer functions” (Crosta and Koç, 2007). This allows us to translate microfossil data into quantitative environmental parameters, bridging the gap between biology and climate reconstruction.
Although the work is still ongoing, this integrated approach has strong potential to improve our understanding of how ocean warming affects Antarctic ice dynamics. By refining reconstructions of past warm periods, we can better constrain future scenarios of sea-level rise and climate change.
About the author
Eleonora Santucci is a PhD student in Polar Sciences at Ca’ Foscari University of Venice and the University of Pisa. She holds a Master’s degree in Geological and Technological Sciences from the University of Pisa. Her research focuses on Antarctic micropaleontology, with particular emphasis on diatom assemblages and their application to paleoenvironmental and paleoclimatic reconstructions, using integrated micropaleontological and geochemical approaches.
References
Crosta, X., & Koç, N. (2007). Chapter eight diatoms: From micropaleontology to isotope geochemistry. Developments in marine geology, 1, 327-369. https://doi.org/10.1016/S1572-5480(07)01013-5
de Boer, B., Dolan, A. M., Bernales, J., Gasson, E., Goelzer, H., Golledge, N. R., … & Van De Wal, R. S. (2015). Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project. The Cryosphere Discussions, 8(6), 5539-5588. https://doi.org/10.5194/tc-9-881-2015
Donda, F., Leitchenkov, G., Brancolini, G., Romeo, R., De Santis, L., Escutia, C., … & Cotterle, D. (2020). The influence of Totten Glacier on the Late Cenozoic sedimentary record. Antarctic Science, 32(4), 288-300. https://doi.org/10.1017/S0954102020000188
Escutia, C., Brinkhuis, H., & Klaus, A. and the IODP Expedition 318 Scientists (2011). IODP Expedition 318: From greenhouse to icehouse at the Wilkes Land Antarctic margin. Scientific Drilling, 12, 15-23. https://doi.org/10.2204/iodp.sd.12.02.2011
Tolotti, R., Leventer, A., Donda, F., Armand, L., Noble, T., O’Brien, P., … & Corradi, N. (2024). Late Pliocene to recent depositional processes on the Sabrina Coast (East Antarctica): the diatom contribution. Journal of Micropalaeontology, 43(2), 349-382. https://doi.org/10.5194/jm-43-349-2024