Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration

Goldberg, David M.; Heimbach, Patrick; Joughin, Ian; Smith, Ben

doi:10.5194/tc-9-2429-2015

Cited by 60 publications

(106 citation statements)

References 52 publications

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“…The nonuniform onset and spreading of drawdown during the altimetry era visible in our results can be used to calibrate and test numerical simulations of the ASE glaciers [Goldberg et al, 2015]. Under persistent future oceanic forcing, models indicate that thinning will expand to larger areas in the PIG and THG basins, which would contribute to accelerated ice-mass loss and associated sea-level rise [e.g., Joughin et al, 2010Joughin et al, , 2014Cornford et al, 2015].…”

Section: Discussionmentioning

confidence: 99%

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Uneven onset and pace of ice‐dynamical imbalance in the Amundsen Sea Embayment, West Antarctica

Konrad

Gilbert

Cornford

et al. 2017

Geophysical Research Letters

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We combine measurements acquired by five satellite altimeter missions to obtain an uninterrupted record of ice sheet elevation change over the Amundsen Sea Embayment, West Antarctica, since 1992. Using these data, we examine the onset of surface lowering arising through ice‐dynamical imbalance, and the pace at which it has propagated inland, by tracking elevation changes along glacier flow lines. Surface lowering has spread slowest (<6 km/yr) along the Pope, Smith, and Kohler (PSK) Glaciers, due to their small extent. Pine Island Glacier (PIG) is characterized by a continuous inland spreading of surface lowering, notably fast at rates of 13 to 15 km/yr along tributaries draining the southeastern lobe, possibly due to basal conditions or tributary geometry. Surface lowering on Thwaites Glacier (THG) has been episodic and has spread inland fastest (10 to 12 km/yr) along its central flow lines. The current episodes of surface lowering started approximately 10 years before the first measurements on PSK, around 1990 on PIG, and around 2000 on THG. Ice‐dynamical imbalance across the sector has therefore been uneven during the satellite record.

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Section: Discussionmentioning

confidence: 99%

“…Modeling studies have indicated that rates of ice discharge from this sector are expected to further grow in future, in part due to ongoing ice dynamics and in part due to projected ocean warming [Joughin et al, 2010[Joughin et al, , 2014Favier et al, 2014;Seroussi et al, 2014;Cornford et al, 2015;Goldberg et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Uneven onset and pace of ice‐dynamical imbalance in the Amundsen Sea Embayment, West Antarctica

Konrad

Gilbert

Cornford

et al. 2017

Geophysical Research Letters

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“…Previous ice-flow modeling, which excluded the floating ice, suggested that these glaciers will continue to retreat even in the absence of a change in forcing (Goldberg et al, 2015). Since changes in the ASE are thought to be ocean-forced, however, understanding of processes over the floating ice and at the grounding line is key to explaining recent behavior and to any prediction of future behavior.…”

Section: Study Areamentioning

confidence: 99%

Changes in flow of Crosson and Dotson ice shelves, West Antarctica, in response to elevated melt

et al. 2018

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Abstract. Crosson and Dotson ice shelves are two of the most rapidly changing outlets in West Antarctica, displaying both significant thinning and grounding-line retreat in recent decades. We used remotely sensed measurements of velocity and ice geometry to investigate the processes controlling their changes in speed and grounding-line position over the past 20 years. We combined these observations with inverse modeling of the viscosity of the ice shelves to understand how weakening of the shelves affected this speedup. These ice shelves have lost mass continuously since the 1990s, and we find that this loss results from increasing melt beneath both shelves and the increasing speed of Crosson. High melt rates persisted over the period covered by our observations (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014), with the highest rates beneath areas that ungrounded during this time. Grounding-line flux exceeded basin-wide accumulation by about a factor of 2 throughout the study period, consistent with earlier studies, resulting in significant loss of grounded as well as floating ice. The near doubling of Crosson's speed in some areas during this time is likely the result of weakening of its margins and retreat of its grounding line. This speedup contrasts with Dotson, which has maintained its speed despite increasingly high melt rates near its grounding line, likely a result of the sustained competency of the shelf. Our results indicate that changes to melt rates began before 1996 and suggest that observed increases in melt in the 2000s compounded an ongoing retreat of this system. Advection of a channel along Dotson, as well as the grounding-line position of Kohler Glacier, suggests that Dotson experienced a change in flow around the 1970s, which may be the initial cause of its continuing retreat.

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“…Similarly, Golledge et al (2008) obtained a thin, more extensive Younger Dryas ice sheet in Scotland with increased sliding. As also explained above from a theoretical perspective (mass continuity), a shallow geometry is associated with high sliding.…”

Section: Sensitivity To Sliding and Deformation Parametersmentioning

confidence: 99%

“…This time dependency has implications for other model studies of long-term dynamics of glaciers and ice caps. With growing availability of data, such studies may consider a "dynamic" or "transient" calibration (e.g., Oerlemans, 1997a;Davies et al, 2014;Goldberg et al, 2015), as opposed to a "snapshot" calibration. The "transient" method uses several sets of observations to infer model parameters, ideally at dynamically and climatically different states.…”

Section: Sensitivity To Sliding and Deformation Parametersmentioning

confidence: 99%

Simulating the evolution of Hardangerjøkulen ice cap in southern Norway since the mid-Holocene and its sensitivity to climate change

et al. 2017

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Abstract. Understanding of long-term dynamics of glaciers and ice caps is vital to assess their recent and future changes, yet few long-term reconstructions using ice flow models exist. Here we present simulations of the maritime Hardangerjøkulen ice cap in Norway from the mid-Holocene through the Little Ice Age (LIA) to the present day, using a numerical ice flow model combined with glacier and climate reconstructions.In our simulation, under a linear climate forcing, we find that Hardangerjøkulen grows from ice-free conditions in the mid-Holocene to its maximum extent during the LIA in a nonlinear, spatially asynchronous fashion. During its fastest stage of growth (2300-1300 BP), the ice cap triples its volume in less than 1000 years. The modeled ice cap extent and outlet glacier length changes from the LIA until today agree well with available observations. Volume and area for Hardangerjøkulen and several of its outlet glaciers vary out-of-phase for several centuries during the Holocene. This volume-area disequilibrium varies in time and from one outlet glacier to the next, illustrating that linear relations between ice extent, volume and glacier proxy records, as generally used in paleoclimatic reconstructions, have only limited validity.We also show that the present-day ice cap is highly sensitive to surface mass balance changes and that the effect of the ice cap hypsometry on the mass balancealtitude feedback is essential to this sensitivity. A mass balance shift by +0.5 m w.e. relative to the mass balance from the last decades almost doubles ice volume, while a decrease of 0.2 m w.e. or more induces a strong mass balance-altitude feedback and makes Hardangerjøkulen disappear entirely. Furthermore, once disappeared, an additional +0.1 m w.e. relative to the present mass balance is needed to regrow the ice cap to its present-day extent. We expect that other ice caps with comparable geometry in, for example, Norway, Iceland, Patagonia and peripheral Greenland may behave similarly, making them particularly vulnerable to climate change.

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Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration

Cited by 60 publications

References 52 publications

Uneven onset and pace of ice‐dynamical imbalance in the Amundsen Sea Embayment, West Antarctica

Uneven onset and pace of ice‐dynamical imbalance in the Amundsen Sea Embayment, West Antarctica

Changes in flow of Crosson and Dotson ice shelves, West Antarctica, in response to elevated melt

Simulating the evolution of Hardangerjøkulen ice cap in southern Norway since the mid-Holocene and its sensitivity to climate change

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