Closing the Last Deglacial Global Sea Level Budget by Different Antarctic Deglaciation Models

Abstract

Closing the Last Deglacial Global Sea Level Budget by Different Antarctic Deglaciation Models Abstract: The last deglacial history of the Antarctic Ice Sheet (AIS), the world’s largest freshwater reservoir, is important for monitoring the current AIS change and projecting the future sea-level rise trend. However, due to the lack of direct observational constraints on AIS last deglacial history, currently, most of the knowledge of AIS deglaciation is from glacial isostatic adjustment (GIA) modelling studies. Currently, the most widely used AIS GIA models are ICE-6G_C (Argus et al., 2014, Peltier et al., 2015), W12 (Whitehouse et al., 2012a) and IJ05_R2 (Ivins et al., 2013). Although after combining with their preferred Earth models, they all show good capability to predict reasonable predictions compared to the geodetic observations (e.g, Global Positioning System), the great differences between their adopted deglaciation models would cause large uncertainties in their estimations. Here we show a global sea-level budget consistent GIA modelling approach to compare them with two high-quality far-field sea-level datasets (H18; Hibbert et al., 2018, L14; Lambeck et al., 2014) constructed using different underlying philosophies to test their compatibilities with the far-field sea-level observations. Similar to a previous study of Lambeck et al. (2014), the global sea-level budget in this study is defined by the global ice volume history reconstructed from each observational datasets. From our calculation, a large ice mass loss between 20-15 ka BP predicted by W12 is most likely to be incorrect, since it shows large inconsistencies with both observational datasets, suggesting that during this late glacial period, AIS should have a stable or an advanced phase. And during ~15-11 ka BP, far-field sea-level records shows a preference with ICE-6G_C, which is the only model with a distinct contribution to meltwater pulse 1a and 1b, showing good consistency with the much more dynamic cryospheric environment revealed by the new global ice volume history reconstruced from the H18 dataset, as well as previous GIA studies (e.g., Clark et al., 2002). Show more