The Effect of Basal Melting of the Shirase Glacier Tongue on the CO₂ System in Lützow‐Holm Bay, East Antarctica

Abstract

The ocean absorbs more than 25% of anthropogenic carbon dioxide (CO 2 ) emitted by human activities (Friedlingstein et al., 2019;Le Quéré et al., 2016). The Southern Ocean accounts for 40% of the anthropogenic CO 2 absorbed by the ocean, and it plays an important role in the global carbon cycle as a sink of anthropogenic CO 2 (Gruber et al., 2019;Sabine et al., 2004;Takahashi et al., 2009). However, the estimation of air-sea CO 2 exchange is limited to the open water area of the Southern Ocean. The air-sea CO 2 flux on the Antarctic continental shelves, which are covered with sea ice seasonally or throughout the year, are uncertain because direct observations have been limited (Lenton et al., 2013). In the ocean, CO 2 exists in three different inorganic forms: as aqueous CO 2 (CO 2 (aq)), as HCO 3 − , and as CO 3 2−. The sum of the three different inorganic forms is called the dissolved inorganic carbon (DIC) (Zeebe & Wolf-Gladrow, 2001). The processes that affect the DIC in the polar oceans include: (1) photosynthesis and respiration by biological activity, (2) mixing of water masses (dilution effect by melting of shelf ice and sea ice), (3) precipitation and dissolution of calcium carbonate (CaCO 3 • 6H 2 O), and (4) air-sea CO 2 exchange. In the Antarctic coastal zone, (1) and ( 2) are considered to be especially important processes (e.g.,

Seasonal Variations and Drivers of Surface Ocean pCO2 in the Seasonal Ice Zone of the Eastern Indian Sector, Southern Ocean

“…(2006) have shown that the decrease of pCO 2 due to biological uptake exceeded the increase of pCO 2 due to increases of temperature from 54°S to 60°S along 52°W in 2001. Close to the continental margin, the decrease of dissolved inorganic carbon (DIC) of seawater by meltwater from sea ice and glacial ice leads to a reduction of pCO 2 and enhancement of atmospheric CO 2 uptake (Bates et al., 2014; Kiuchi et al., 2021). The results of Bates et al.…”

“…(2014) and Kiuchi et al. (2021) likely contain a spatiotemporal measurement bias associated with the icescape because the icescape is expected to precondition the surface environment (Deppeler & Davidson, 2017). Understanding the carbon cycle in the Antarctic seasonal ice zone requires eliminating the regional specificity of the data and obtaining highly accurate and diverse data for carbonate chemistry.…”

“…In the Southern Ocean, as sea surface temperature increases from winter to summer, primary production increases, and salinity decrease because of the inflow of freshwater from melting sea ice and glacial ice. Several previous studies have pointed out these seasonal effects (Arroyo et al, 2019;Kiuchi et al, 2021;Legge, 2017;Nakaoka et al, 2009;Nomura, 2014;Shadwick et al, 2017). For example, Nakaoka et al (2009) indicated that water column stratification and biology influence oceanic pCO 2 .…”

“…Close to the continental margin, the decrease of dissolved inorganic carbon (DIC) of seawater by meltwater from sea ice and glacial ice leads to a reduction of pCO 2 and enhancement of atmospheric CO 2 uptake (Bates et al, 2014;Kiuchi et al, 2021). The results of Bates et al (2014) and Kiuchi et al (2021) likely contain a spatiotemporal measurement bias associated with the icescape because the icescape is expected to precondition the surface environment (Deppeler & Davidson, 2017). Understanding the carbon cycle in the Antarctic seasonal ice zone requires eliminating the regional specificity of the data and obtaining highly accurate and diverse data for carbonate chemistry.…”

“…However, Shim et al (2006) have shown that the decrease of pCO 2 due to biological uptake exceeded the increase of pCO 2 due to increases of temperature from 54°S to 60°S along 52°W in 2001. Close to the continental margin, the decrease of dissolved inorganic carbon (DIC) of seawater by meltwater from sea ice and glacial ice leads to a reduction of pCO 2 and enhancement of atmospheric CO 2 uptake (Bates et al, 2014;Kiuchi et al, 2021). The results of Bates et al (2014) and Kiuchi et al (2021) likely contain a spatiotemporal measurement bias associated with the icescape because the icescape is expected to precondition the surface environment (Deppeler & Davidson, 2017).…”