Breakup of land-fast sea ice in Lutzow-Holm Bay, East Antarctica, and its teleconnection to tropical Pacific sea surface temperatures

A large land-fast sea ice breakup occurred in 2016 in Lutzow-Holm Bay, East Antarctica. The breakup caused calving from the Shirase Glacier Tongue. Although similar breakups and calving have been observed in the past, the timing and magnitudes are not well-constrained. The ice's breakup latitude during 1997-2016 was analyzed to investigate the variables controlling breakup and examine correlation with local calving for a longer period. The breakup latitude in April had a persistently high correlation with sea surface temperature (SST) in the tropical Pacific, which exceeds correlations with local atmospheric variables. The years of five out of six observed calving events from the mid-20th century can correspond to those of warm SST episodes and calving-front retreat in the 1980s to warmer SST shift. Our proposed teleconnection between tropical SST and Antarctic sea ice could lead to better predictions of breakup and might impact the glacier flux for a wider region. Plain Language Summary Land-fast sea ice forms along the Antarctic coast, and it occasionally breaks up significantly. The breakup event influences the flow of glaciers, which is otherwise held back by the fast ice. The breakup of land-fast sea ice and the discharge of glaciers have significant multidecadal variability as well as interannual variability. This study explores what controls the breakup phenomena of land-fast sea ice in Antarctica and finds the linkage with tropical sea surface temperatures. We find the environmental factors which are relevant to the ice breakup, and those variables are originally driven by the teleconnection from the tropical Pacific. We believe that our study makes a significant contribution in climate science by offering a causal mechanism that explains the previously observed multidecadal variability in ice extent in this region. Our model can explain five out of the last six calving events in a major glacier connected to this bay, offering hope for future predictions of ice behavior. This will also merit the logistics to Antarctic research stations.