Modeling the evolution of the Juneau Icefield between 1971 and 2100 using the Parallel Ice Sheet Model (PISM)

Ziemen, Florian; Hock, Regine; Aschwanden, Andy; Khroulev, C.; Kienholz, Christian; Melkonian, A. K.; Zhang, Jing

doi:10.1017/jog.2016.13

Cited by 48 publications

(95 citation statements)

References 52 publications

(95 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Starting from ice-free conditions, Hardangerjøkulen grows to only 20 % of its present-day volume under a modern climate. This is in stark contrast to the Juneau Icefield in Alaska, an ice field in a similar climatic setting, which in model simulations regrows close to modern ice volume under present-day mass balance conditions (Ziemen et al, 2016). The authors attribute this insensitivity to initial conditions to the complex topography of the Juneau Icefield, with numerous outlet glaciers able to retreat up to high altitudes where positive mass balance areas persist even under future warming scenarios.…”

Section: Mass Balance Sensitivity and Hysteresismentioning

confidence: 81%

“…However, long-term reconstructions using ice flow models are rare. Most existing quantitative modeling studies of GICs are restricted to timescales of decades (e.g., Leysinger-Vieli and Gudmundsson, 2004;Raper and Braithwaite, 2009) or centuries (Jouvet et al, 2009;Giesen and Oerlemans, 2010;Aðalgeirsdóttir et al, 2011;Zekollari et al, 2014;Zekollari and Huybrechts, 2015;Ziemen et al, 2016). Only a very limited number of studies exist for the longer timescales (e.g., Flowers et al, 2008;Laumann and Nesje, 2014).…”

mentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2017

View full text Add to dashboard Cite

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.

show abstract

Section: Mass Balance Sensitivity and Hysteresismentioning

confidence: 81%

mentioning

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

View full text Add to dashboard Cite

show abstract

“…However, no clear trend in climate such as cooling or increased precipitation was found during this period to explain such a slowdown Ziemen et al, 2016). Field observations of the equilibrium line altitudes and surface mass balances on Lemon Creek and Taku glaciers (JIF) also do not support a slowdown (WGMS, 2017).…”

Section: Introductionmentioning

confidence: 92%

“…A modeling study also found a negative mass balance for the entire JIF (−0.33 m w.e. a −1 ) for 1971-2010 (Ziemen et al, 2016). Their 40-year mass balance is a result of glacier mass stability until 1996 and rapid mass loss afterwards.…”

Section: Introductionmentioning

confidence: 99%

Brief communication: Unabated wastage of the Juneau and Stikine icefields (southeast Alaska) in the early 21st century

et al. 2018

View full text Add to dashboard Cite

Abstract. The large Juneau and Stikine icefields (Alaska) lost mass rapidly in the second part of the 20th century. Laser altimetry, gravimetry and field measurements suggest continuing mass loss in the early 21st century. However, two recent studies based on time series of Shuttle Radar Topographic Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation models (DEMs) indicate a slowdown in mass loss after 2000. Here, the ASTER-based geodetic mass balances are recalculated carefully avoiding the use of the SRTM DEM because of the unknown penetration depth of the C-band radar signal. We find strongly negative mass balances from 2000 to 2016 (−0.68 ± 0.15 m w.e. a −1 for the Juneau Icefield and −0.83 ± 0.12 m w.e. a −1 for the Stikine Icefield), in agreement with laser altimetry, confirming that mass losses are continuing at unabated rates for both icefields. The SRTM DEM should be avoided or used very cautiously to estimate glacier volume change, especially in the North Hemisphere and over timescales of less than ∼ 20 years.

show abstract

“…Moreover, reanalysis climate products available for the region, including NCEP-NCAR, typically have coarse resolution that neither represents the complex topography of Alaska mountain ranges nor includes high-elevation weather station data (Lader and others, 2016). Together, these issues help explain our difficulty in reproducing point mass-balance observations and their associated balance gradients with our mass-balance modeling, as was also the case for recent modeling studies on Yakutat Glacier and the Juneau Icefield, both in Alaska (Trüssel and others, 2015;Ziemen and others, 2016). These challenges help us frame our discussion for monitoring recommendations for the future.…”

Section: Discussionmentioning

confidence: 74%

The challenge of monitoring glaciers with extreme altitudinal range: mass-balance reconstruction for Kahiltna Glacier, Alaska

et al. 2018

Self Cite

View full text Add to dashboard Cite

ABSTRACT. Glaciers spanning large altitudinal ranges often experience different climatic regimes with elevation, creating challenges in acquiring mass-balance and climate observations that represent the entire glacier. We use mixed methods to reconstruct the 1991-2014 mass balance of the Kahiltna Glacier in Alaska, a large (503 km 2 ) glacier with one of the greatest elevation ranges globally (264-6108 m a.s.l.). We calibrate an enhanced temperature index model to glacier-wide mass balances from repeat laser altimetry and point observations, finding a mean net mass-balance rate of −0.74 mw.e. a −1 ( ± σ = 0.04, std dev. of the best-performing model simulations). Results are validated against mass changes from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites, a novel approach at the individual glacier scale. Correlation is strong between the detrended modeland GRACE-derived mass change time series (R 2 = 0.58 and p ≪ 0.001), and between summer (R 2 = 0.69 and p = 0.003) and annual (R 2 = 0.63 and p = 0.006) balances, lending greater confidence to our modeling results. We find poor correlation, however, between modeled glacier-wide balances and recent single-stake monitoring. Finally, we make recommendations for monitoring glaciers with extreme altitudinal ranges, including characterizing precipitation via snow radar profiling.

show abstract

Modeling the evolution of the Juneau Icefield between 1971 and 2100 using the Parallel Ice Sheet Model (PISM)

Abstract: ABSTRACT. We study the evolution of the Juneau Icefield, one of the largest icefields in North America (>3700 km 2 ), using the Parallel Ice Sheet Model (PISM

Cited by 48 publications

References 52 publications

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

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

Brief communication: Unabated wastage of the Juneau and Stikine icefields (southeast Alaska) in the early 21st century

The challenge of monitoring glaciers with extreme altitudinal range: mass-balance reconstruction for Kahiltna Glacier, Alaska

Contact Info

Product

Resources

About