Constraining the Gas Hydrates Stability Zone beneath the Antarctic Ice Sheet from 40 Ma to the year 3000

Abstract

The Antarctic Ice Sheet (AIS) is one of the climate tipping elements on Earth and the largest potential contributor to sea level rise. While the consequences of ice sheet collapse on oceanic and atmospheric changes are well documented, its impact on the global carbon cycle remains critically ignored in the current global carbon budget. This is particularly important because the Antarctic Sedimentary Basins (ASBs) are thought to contain a reservoir of methane, a potent greenhouse gas, in the form of hydrates. The reservoir is estimated to be 400 Pg C today and has fluctuated over the past 40 Ma. However, the exact location of this reservoir remains unknown. Gas hydrates can form in a specific zone beneath the ice sheet where they are stable: the gas hydrate stability zone (GHSZ). This zone is created by a combination of high pressure from ice and sediment thickness in the terrestrial area, water column height, ice and sediment thickness in the marine shelf area, and low temperature in both areas. Determining the exact location of the GHSZ beneath the ice sheet and its fate under climate change is crucial to knowing where hydrates have formed and whether they will destabilise with ice retreat. We present the first spatial distribution of the GHSZ beneath the AIS, its volume and its evolution over the last 40 Ma and until the year 3000 under 2 Shared Socio-economic Pathways (SSPs)