Variable Basal Melt Rates of Antarctic Peninsula Ice Shelves, 1994–2016. Issue 9 (5th May 2018)

• Record Type: Journal Article
• Authors: Adusumilli, Susheel; Fricker, Helen Amanda; Siegfried, Matthew R.; Padman, Laurie; Paolo, Fernando S.; Ligtenberg, Stefan R. M.
• Is Part Of: Geophysical research letters. Volume 45:Issue 9(2018)
• Page Start: 4086
• Page End: 4095
• Publication Date: 2018-05-05
• Subjects: Ice Shelves -- Satellite Altimetry -- Mass Balance -- Climate variability -- Antarctic Peninsula; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL076652
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We have constructed 23‐year (1994–2016) time series of Antarctic Peninsula (AP) ice‐shelf height change using data from four satellite radar altimeters (ERS‐1, ERS‐2, Envisat, and CryoSat‐2). Combining these time series with output from atmospheric and firn models, we partitioned the total height‐change signal into contributions from varying surface mass balance, firn state, ice dynamics, and basal mass balance. On the Bellingshausen coast of the AP, ice shelves lost 84 ± 34 Gt a −1 to basal melting, compared to contributions of 50 ± 7 Gt a −1 from surface mass balance and ice dynamics. Net basal melting on the Weddell coast was 51 ± 71 Gt a −1 . Recent changes in ice‐shelf height include increases over major AP ice shelves driven by changes in firn state. Basal melt rates near Bawden Ice Rise, a major pinning point of Larsen C Ice Shelf, showed large increases, potentially leading to substantial loss of buttressing if sustained. Plain Language Summary: Antarctica's ice shelves regulate the flow of grounded ice into the ocean, and enhancing our processes that control how ice shelves respond to atmospheric and oceanic drivers will ultimately improve estimates of sea level change. We have generated a 23‐year record of ice‐shelf height changes for the Antarctic Peninsula region using four satellite altimeters. We focussed our analysis on the height variability rather than just the long‐term trends so that we can better separate the contributions of the ocean and the atmosphere. Most ice shelves on the Peninsula showed height increases since 2009, at least temporarily reversing previously reported trends of declining height. At Larsen C Ice Shelf on the eastern coast of the Peninsula, this reversal was caused by reduced summertime surface melting. The resulting increase in surface‐snow air content may reduce the susceptibility of this ice shelf to the surface‐melt‐driven collapse previously seen on nearby ice shelves. We also found large variations in how fast the ocean is eroding the base of this ice shelf near a pinning point crucial to its stability. On the western coast, while their surface heights have also recently increased, the ice shelves have continued to lose mass from excess ocean melting. Key Points: New, 23‐year (1994–2016) records of Antarctic Peninsula ice shelf heights reveal recent increases, reversing previously reported declines Spatial and temporal variations of ice shelf height across the Antarctic Peninsula are linked to specific oceanic and atmospheric forcings Temporal variability of basal melt rates under Larsen C Ice Shelf provides insight into processes that will lead to changes in buttressing