Responses of Basal Melting of Antarctic Ice Shelves to the Climatic Forcing of the Last Glacial Maximum and CO2 Doubling

Abstract

Basal melting of the Antarctic ice shelves is an important factor in determining the stability of the Antarctic ice sheet. This study used the climatic outputs of an atmosphere-ocean general circulation model to force a circumpolar ocean model that resolves ice shelf cavity circulation to investigate the response of Antarctic ice shelf melting to different climatic conditions (i.e., to a doubling of CO 2 and to the Last Glacial Maximum conditions). Sensitivity experiments were also conducted to investigate the roles of both surface atmospheric change and changes of oceanic lateral boundary conditions. It was found that the rate of change of basal melt due to climate warming is much greater (by an order of magnitude) than that due to cooling. This is mainly because the intrusion of warm water onto the continental shelves, linked to sea ice production and climate change, is crucial in determining the basal melt rate of many ice shelves. Sensitivity experiments showed that changes of atmospheric heat flux and ocean temperature are both important for warm and cold climates. The offshore wind change, together with atmospheric heat flux change, strongly affected the production of both sea ice and high-density water, preventing warmer water approaching the ice shelves under a colder climate. These results reflect the importance of both water mass formation in the Antarctic shelf seas and subsurface ocean temperature in understanding the long-term response to climate change of the melting of Antarctic ice shelves.

Glacial CO<sub>2</sub> decrease and deep-water deoxygenation by iron fertilization from glaciogenic dust

“…Finally, we discuss underestimation of deoxygenation in the deep SO in LGM_all. Since simulated changes in the biological pump and sea-ice distributions are consistent with reconstructions (Obase et al, 2017), we turn our attention to changes in circulation. The simulated water mass age of the deep SO is younger in the LGM than in the PI by ~200 years (Fig.…”

Interannual-to-Multidecadal Responses of Antarctic Ice Shelf–Ocean Interaction and Coastal Water Masses during the Twentieth Century and the Early Twenty-First Century to Dynamic and Thermodynamic Forcing

“…With an increase in the available computing resources, several modeling studies have tried to include almost all of the ice shelves in a single model, such as circumpolar Southern Ocean or global ocean models (Timmermann et al 2012;Kusahara and Hasumi 2013;Schodlok et al 2016;Mathiot et al 2017;Naughten et al 2018). Using future projections by climate models as input, several ice shelf-ocean models produced predictions of how Antarctic ice shelves will respond to future climate changes (Hellmer et al 2012;Timmermann and Hellmer 2013;Obase et al 2017;Naughten et al 2018).…”

CO2‐Induced Ocean Warming of the Antarctic Continental Shelf in an Eddying Global Climate Model

“…Most of the land‐based ice mass loss is a result of the melting or calving of ice shelves buttressing the ice sheet (Depoorter et al, ). Ice shelf basal melt mainly results from intrusion of relatively warm and saline Circumpolar Deep Water (CDW) onto the continental shelf (e.g., Cook et al, ; Jenkins et al, ; Obase et al, ; Rignot & Jacobs, ). Typically, CDW is characterized by temperatures about 3°C–4°C above the seawater freezing point (Whitworth et al, ).…”