Decadal Scale Variability of Larsen Ice Shelf Melt Captured by Antarctic Peninsula Ice Core

In this study, we used the stable water isotope record (delta O-18) from an ice core drilled in Palmer Land, southern Antarctic Peninsula (AP). Utilizing delta O-18 we identified two climate regimes during the satellite era. During the 1979-1998 positive interdecadal Pacific oscillation (IPO) phase, a low-pressure system north of the Weddell Sea drove southeasterly winds that are associated with an increase in warm air mass intrusion onto the Larsen shelves, which melted and a decreased sea ice concentration in the Weddell Sea/increase in the Bellingshausen Sea. This climate setting is associated with anomaly low delta O-18 values (compared with the latter IPO period). There is significantly more melt along the northern AP ice shelf margins and on the Larsen D and southern Larsen C during the 1979-1998 IPO positive phase. The IPO positive climatic setting was coincidental with the Larsen A ice shelf collapse. In contrast, during the IPO negative phase (1999-2011), northerly winds caused a reduction in sea ice in the Bellingshausen Sea/Drake Passage region. Moreover, a Southern Ocean north of the Weddell Sea high-pressure system caused low-latitude warm humid air over the tip and east of the AP, a setting that is associated with increased northern AP snowfall, a high delta O-18 anomaly, and less prone to Larsen ice shelf melt.

Automated summary

This study identifies two climate regimes in the southern Antarctic Peninsula based on the stable water isotope record. The positive phase of the interdecadal Pacific oscillation (IPO) from 1979 to 1998 led to increased melt and decreased sea ice concentration, while the negative IPO phase from 1999 to 2011 resulted in reduced melt and ice concentration in the Larsen shelves.