Two important studies out in @nature yesterday projecting future sea level rise from Antarctica and other sources which are likely to drive discussion among ice sheet modelers, so a https://abs.twimg.com/emoji/v2/... draggable="false" alt="đŸ§”" title="Thread" aria-label="Emoji: Thread"> with some thoughts and aggregated resources (1/n)
There are a number of great threads from co-authors and news stories on the headline findings, which I& #39;ll link at the bottom of this thread. Here, I’ll point out some of the bits I found the most interesting and how they point towards future research priorities (4/n)
There is a lack of consensus on cliff heights because the shear strength of damaged glacier ice is difficult to measure, but there are promising new approaches (e.g. from @LizzUltee ) using observations to infer these important parameters (6/n) https://doi.org/10.1017/jog.2020.65">https://doi.org/10.1017/j...
The best constraint on the calving rate at tall ice cliffs comes from Sermeq Kujalleq (aka Jakobshavn Isbrae) which retreated very rapidly from 2000 to 2015, though recently it has re-formed a small ice shelf with local ocean cooling (7/n) https://doi.org/10.1038/s41561-019-0329-3">https://doi.org/10.1038/s...
The only way to produce tall ice cliffs (i.e. which don& #39;t think viscous deformation) is the rapid collapse of ice shelves, which in this model occurs with enough surface melt driving hydrofracture (9/n)
...when intense melt events occur, likely due to an atmospheric river, which seem to be increasingly important drivers of Antarctic surface melt as shown by @JonathanWille (though not well captured by climate models) (12/n) https://doi.org/10.1038/s41561-019-0460-1">https://doi.org/10.1038/s...
Rapid calving at tall ice cliffs is necessary to fit paleo-constraints, the opposite conclusion of the 2019 study by @flimsin and colleagues, largely due to the addition of new higher Pliocene sea level constraints from recent studies (14/n) https://doi.org/10.1038/s41586-019-1619-z">https://doi.org/10.1038/s...
None of the constraints in this study (modern or paleo) rule out any simulations on the upper bound of the ensemble, indicating that much higher potential sea level rise from Antarctica is possible, though not simulated here (16/n)
...which raises the question of how we should design the prior (finite support?) in ensemble studies in the absence of high-end constraints, though @glacierandy et al. have done excellent work in this direction for Greenland projections (17/n) https://doi.org/10.1126/sciadv.aav9396">https://doi.org/10.1126/s...
The new study from @flimsin et al provides an interesting contrast largely because it provides probabilistic projections without constraints from sea level (though of course the models within it are validated on modern glaciological observations) (18/n)
2100 is exactly when many Antarctic models in ISMIP6 are beginning rapid ice loss, while others have changed little, leading to drastically divergent projections, which we’ve shown is an expected property of unstable systems (20/n) https://doi.org/10.1073/pnas.1904822116">https://doi.org/10.1073/p...
“Risk-averse” projections seem to be particularly useful for stakeholders who do not necessarily want to parse the differences between models and emissions scenarios, where risk-averse sea level decisions are very sensitive to high-end uncertainty (21/n) https://doi.org/10.1007/s10584-016-1664-7">https://doi.org/10.1007/s...
What I find so exciting about both studies is that they touch on so many of the interesting outstanding questions within our field and provide concrete connections from these fascinating glaciological puzzles to real consequences for coastal communities (22/n)
A thread from @danielgilford https://twitter.com/danielgilford/status/1389972985461846017">https://twitter.com/danielgil...
From @ScienceShaina https://twitter.com/ScienceShaina/status/1390001441578889220">https://twitter.com/ScienceSh...
Explainers/threads from @CarbonBrief https://twitter.com/CarbonBrief/status/1389960136496750593">https://twitter.com/CarbonBri...
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