UK SWAIS 2C

As our planet is warming, global mean sea level is rising. Since the year 1900 this rise in sea level has been ~ 20 cm, initially due to the expansion of water under warmer temperatures and melting of mountain glaciers. However, over recent years the melting of the large ice sheets on Greenland and Antarctica has increased significantly, and loss of land ice (glaciers and ice sheets) is now the largest contributor to global mean sea level.

The polar ice sheets hold many tens of metres of sea level equivalent, but are slow to respond to enhanced greenhouse gas emissions (i.e. slower than global temperatures). With every degree of warming, society is hence facing a long-term commitment in sea level rise for centuries and millennia into the future. This is true, even if global emissions would be halted tomorrow, and future warming would be kept below 2 degrees C, the target set by the Paris agreement in 2015.

The West Antarctic Ice Sheet (WAIS) holds 4.3 m of sea level equivalent and is the part of Antarctica where most mass loss is observed today. This motivated the formation of an international consortium to recover sediments from two drill sites in the Ross Sea (Antarctica) to answer the following question: 'What is the sensitivity of the WAIS to 2C warming'.

This proposal presents the case how the UK community could best contribute and lead in answering this critical question by combining our unique expertise in generating combined data and modelling approaches to address three objectives:

(1) What was the configuration of the WAIS during past warm periods?
(2) How did the WAIS retreat and readvance in the geological past?
(3) How do changes in the Antarctic landscape through time affect ice dynamics?

We will use advanced laboratory methodologies to determine the chemical fingerprint of sediments and how this relates to where on the continent the sediment came from, when it was last exposed, how close to the ice sheet margin it was deposited and under what environmental conditions. By using this information in numerical models, we will overcome a longstanding limitation that the models used to predict the future are often providing contrasting results on past ice sheet configurations.

We will use a hierarchy of models, from simple ice sheet models to advanced coupled ice sheet and climate models to develop a more accurate picture of past WAIS dynamics and mechanisms in relation to ocean warming, atmospheric warming, and changing topography on land, consistent with observations from ice cores and marine sediment cores.