Documentation for PISM, the Parallel Ice Sheet Model


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applications:201709 [2017/09/17 20:40] (current)
Ed Bueler created by copy of future_applications:201709
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 +====== September 2017 ======
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 +| **[[https://​​10.5194/​cp-13-959-2017|Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma]]** ||
 +| **investigators**:​ | [[http://​​antarctic/​about/​staff/​nick-golledge|N. Golledge]] and others|
 +| **journal**:​ | [[https://​​index.html|Climate of the Past]] |
 +Whether a "​tipping point" will be reached in the next few centuries, in the dynamics of various parts of the Antarctic ice sheet (AIS) as it responds to a warming world, is the most difficult prediction question. ​ It is an extreme challenge to models. ​ How complete a model must be, so as to resolve the relevant behavior of the (real) dynamical system, is unknown. ​ A negative result from modeling (i.e. no tipping points seen in model runs) has minimal value because a more-complete,​ or merely different, model may show a tipping point. ​ Insisting that a model include all possibly-relevant mechanisms is unfeasible to the point of silliness.
 +Tipping-point questions can be asked about the past states of the AIS, though using existing observations to resolve these questions is extraordinarily difficult. ​ This paper uses GCM/RCM and ice-sheet modeling to recreate conditions of the early to mid-Pliocene when atmospheric CO2 concentrations were similar to present day.  The focus of PISM application is on modeling grounding-line motion, ice shelf basal melt near the grounding line, and basal sliding. ​ A novel method here, relative to other AIS modeling literature, is an autocorrelation analysis of time series for (modeled) ice mass to find early-warning signs of impending tipping points. ​ A precursor to tipping-point-type destabilization,​ proximately by classic marine-based ice-sheet retreat, appears to be prolonged surface lowering in response to warm air temperatures.
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applications/201709.txt ยท Last modified: 2017/09/17 20:40 by Ed Bueler
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