2020-06-11 All-Hands Presentation Meeting Notes

Owned by Luke Van Roekel (Unlicensed)
Last updated: Sept 09, 2021 by Renata McCoy
2 min read

Presenter: Matt Hoffman

Title: Potential for tipping points in melting beneath Antarctic ice shelves triggered by melt from neighboring ice shelves

Abstract: 

The Filchner-Ronne Ice Shelf (FRIS) presently experiences modest basal melt rates, but model studies have highlighted the potential for an order of magnitude increase in melt rates should relatively warm modified Circumpolar Deep Water (mCDW) reach beneath the ice shelves. We investigate this potential FRIS melt instability using the Energy Exascale Earth System Model (E3SM) run in a global low-resolution configuration that includes ocean circulation beneath Antarctic ice shelves with fixed geometry and prognostic calculation of freshwater and heat fluxes from ice-shelf melting. We demonstrate the potential for FRIS melt instability by freshening and increasing stratification on the continental shelf due to high meltwater fluxes from nearby ice shelves in East Antarctica. We see this behavior in partially coupled simulations with only active ocean and sea-ice, as well as in fully-coupled simulations with active atmosphere and land components. Freshening from ice-shelf meltwater reduces ocean density on the continental shelf, deepening isopycnals near the shelf break and allowing sustained flow of mCDW from offshore onto the continental shelf and into the cavity beneath Filchner Ice Shelf. However, when ice-shelf melting is disabled from neighboring ice shelves in East Antarctica, the melt instability at FRIS is avoided, identifying meltwater as a potential contributing trigger for this instability. While E3SM indicates the possibility of such a domino effect in ice-shelf melting, we identify biases in the simulations that precondition the ocean for FRIS melt instability. Reducing these biases through increased regional resolution and improved ocean model tuning is the focus of ongoing work.  We also discuss the sensitivity of this tipping point behavior to atmospheric forcing and the potential for it to occur beneath the Ross Ice Shelf.

Date

 

Time

  • PT: 8:30 am
  • ET: 11:30 am

Call Info

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Attendees


Presentation

Time
Title
Presenter
Presentation
Recording
Notes

30 min


Tipping points in melting beneath Antarctic ice shelvesMatt Hoffman

Hoffman_FRIS_runaway_E3SMallhands3.pdf

MP4 Movie (on the E3SM YouTube Channel)