How much ice does Antarctica lose during warm times in Earth’s history?

Ice loss from the East Antarctic Ice Sheet during late Pleistocene interglacials
David J. Wilson, Rachel A. Bertram, Emma F. Needham, Tina van de Flierdt, Kevin J. Welsh, Robert M. McKay, Anannya Mazumder, Christina R. Riesselman, Francisco J. Jiminez-Espejo, Carlota Escutia
Summarized by Time Scavengers collaborator Adriane Lam

Figure 1. An elevation map of Antarctica with a) the major regions labeled and b) a zoomed-in view of East Antarctica. The location of the sediment core (named U1361A) is denoted by the pale yellow dot. Image from Wilson et al. (2019).

Brief Summary: Today, sea level rise due to increasing global average temperatures is a huge threat to low-lying, coastal, and island communities. Sea level is rising, in part, from ice that is melting on Antarctica and Greenland. To understand how much sea level may rise in the near future, scientists look to the geologic past, when global temperatures were much warmer than today or close to the temperatures predicted for the coming decades. In this study, scientists looked at how much ice was lost from the Wilkes Subglacial Basin of East Antarctica during a time when global average temperatures were about 2 degrees Celsius warmer than pre-industrial values. They find that during these warmer periods, called interglacials, there was significant ice that melted from East Antarctica, and contributed to sea level rises. Thus, in the future, the ice melting from East Antarctica will contribute more to sea level rise than we previously thought.

Data used and Methods: Sediment from a deep-sea core drilled from the continental margin of East Antarctica was used in this study (Figure 1). From this sediment core, the authors analyzed the different types of sediment contained within the core through time. From the changes in sediments, the scientists could tell how much erosion was occurring. They also looked at the neodymium (Nd) isotopes from the sediments. Nd isotopes are a good way to also trace where the sediments in the core were coming from, so the scientists could determine not only how much erosion was taking place within East Antarctica, but where the eroded sediment was coming from. Increased erosion and a shift in the Nd isotope records indicate increased glacial melt and ice retreat on East Antarctica, thus the authors could tell through geologic time when and approximately how much the ice melted.

Results: Over the past 800,000 years, Earth’s climate has oscillated between cooler (glacial) and warmer (interglacial) periods (read more about this on our CO2 page). During some interglacial periods (times when the climate was warmer), the scientists found that the East Antarctic Ice Sheet began to erode the rock on which it sits and melted significantly. This led to increased sea levels within a world that was less warm than today.

Why is this study important? This study places new approximations on how much melting from East Antarctica could occur in a warming world, and how much that could raise sea level. Climate scientists think that if all the ice on East Antarctica were to melt, it would lead to approximately 53 meters of sea level rise globally! With the data from this study, it will provide new constraints on melting ice in a warming world, which will be incorporated into climate models of the future climate. This data will be given to policymakers to help us best prepare and mitigate the consequences of climate change.

Citation: Wilson, D. J., Bertram, R. A., Needham, E. F., van de Flierdt, T., Welsh, K. J., McKay, R. M., Mazumder, A., Riesselman, C. R., Jimenez-Espejo, F. J., and Escutia, C., 2019. Ice loss from the East Antarctic Ice Sheet during late Pleistocene interglacials. Nature 561, 383-386.

 

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