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  • English  (6)
  • 2010-2014  (6)
  • 1
    Online Resource
    Online Resource
    A minimal model for reconstructing interannual mass balance variability of glaciers in the European Alps
    Copernicus GmbH ; 2012
    In:  The Cryosphere Vol. 6, No. 1 ( 2012-01-17), p. 71-84
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 6, No. 1 ( 2012-01-17), p. 71-84
    Abstract: Abstract. We present a minimal model of the glacier surface mass balance. The model relies solely on monthly precipitation and air temperatures as forcing. We first train the model individually for 15 glaciers with existing mass balance measurements. Based on a cross validation, we present a thorough assessment of the model's performance outside of the training period. The cross validation indicates that our model is robust, and our model's performance compares favorably to that from a less parsimonious model based on seasonal sensitivity characteristics. Then, the model is extended for application on glaciers without existing mass balance measurements. We cross validated the model again by withholding the mass balance information from each of the 15 glaciers above during the model training, in order to measure its performance on glaciers not included in the model training. This cross validation indicates that the model retains considerable skill even when applied on glaciers without mass balance measurements. As an exemplary application, the model is then used to reconstruct time series of interannual mass balance variability, covering the past two hundred years, for all glaciers in the European Alps contained in the extended format of the world glacier inventory. Based on this reconstruction, we present a spatially detailed attribution of the glaciers' mass balance variability to temperature and precipitation variability.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    URL: Article
    DOI: 10.5194/tc-6-71-2012
    DOI: 10.5194/tc-6-71-2012-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2393169-3
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  • 2
    Online Resource
    Online Resource
    Spatial patterns of North Atlantic Oscillation influence on mass balance variability of European glaciers
    Copernicus GmbH ; 2012
    In:  The Cryosphere Vol. 6, No. 3 ( 2012-06-14), p. 661-673
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 6, No. 3 ( 2012-06-14), p. 661-673
    Abstract: Abstract. We present and validate a set of minimal models of glacier mass balance variability. The most skillful model is then applied to reconstruct 7735 individual time series of mass balance variability for all glaciers in the European Alps and Scandinavia. Subsequently, we investigate the influence of atmospheric variability associated with the North Atlantic Oscillation (NAO) on the glaciers' mass balances. We find a spatial coherence in the glaciers' sensitivity to NAO forcing which is caused by regionally similar mechanisms relating the NAO forcing to the mass balance: in southwestern Scandinavia, winter precipitation causes a correlation of mass balances with the NAO. In northern Scandinavia, temperature anomalies outside the core winter season cause an anti-correlation between NAO and mass balances. In the western Alps, both temperature and winter precipitation anomalies lead to a weak anti-correlation of mass balances with the NAO, while in the eastern Alps, the influences of winter precipitation and temperature anomalies tend to cancel each other, and only on the southern side a slight anti-correlation of mass balances with the NAO prevails.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    URL: Article
    DOI: 10.5194/tc-6-661-2012
    DOI: 10.5194/tc-6-661-2012-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2393169-3
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  • 3
    Online Resource
    Online Resource
    Twentieth-Century Global-Mean Sea Level Rise: Is the Whole Greater than the Sum of the Parts?
    American Meteorological Society ; 2013
    In:  Journal of Climate Vol. 26, No. 13 ( 2013-07-01), p. 4476-4499
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 26, No. 13 ( 2013-07-01), p. 4476-4499
    Abstract: Confidence in projections of global-mean sea level rise (GMSLR) depends on an ability to account for GMSLR during the twentieth century. There are contributions from ocean thermal expansion, mass loss from glaciers and ice sheets, groundwater extraction, and reservoir impoundment. Progress has been made toward solving the “enigma” of twentieth-century GMSLR, which is that the observed GMSLR has previously been found to exceed the sum of estimated contributions, especially for the earlier decades. The authors propose the following: thermal expansion simulated by climate models may previously have been underestimated because of their not including volcanic forcing in their control state; the rate of glacier mass loss was larger than previously estimated and was not smaller in the first half than in the second half of the century; the Greenland ice sheet could have made a positive contribution throughout the century; and groundwater depletion and reservoir impoundment, which are of opposite sign, may have been approximately equal in magnitude. It is possible to reconstruct the time series of GMSLR from the quantified contributions, apart from a constant residual term, which is small enough to be explained as a long-term contribution from the Antarctic ice sheet. The reconstructions account for the observation that the rate of GMSLR was not much larger during the last 50 years than during the twentieth century as a whole, despite the increasing anthropogenic forcing. Semiempirical methods for projecting GMSLR depend on the existence of a relationship between global climate change and the rate of GMSLR, but the implication of the authors' closure of the budget is that such a relationship is weak or absent during the twentieth century.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-12-00319.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2013
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 4
    Online Resource
    Online Resource
    Past and future sea-level change from the surface mass balance of glaciers
    Copernicus GmbH ; 2012
    In:  The Cryosphere Vol. 6, No. 6 ( 2012-11-12), p. 1295-1322
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 6, No. 6 ( 2012-11-12), p. 1295-1322
    Abstract: Abstract. We present estimates of sea-level change caused by the global surface mass balance of glaciers, based on the reconstruction and projection of the surface mass balance of all the individual glaciers of the world, excluding the ice sheets in Greenland and Antarctica. The model is validated using a leave-one-glacier-out cross-validation scheme against 3997 observed surface mass balances of 255 glaciers, and against 756 geodetically observed, temporally integrated volume and surface area changes of 341 glaciers. When forced with observed monthly precipitation and temperature data, the glaciers of the world are reconstructed to have lost mass corresponding to 114 ± 5 mm sea-level equivalent (SLE) between 1902 and 2009. Using projected temperature and precipitation anomalies from 15 coupled general circulation models from the Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble, they are projected to lose an additional 148 ± 35 mm SLE (scenario RCP26), 166 ± 42 mm SLE (scenario RCP45), 175 ± 40 mm SLE (scenario RCP60), or 217 ± 47 mm SLE (scenario RCP85) during the 21st century. Based on the extended RCP scenarios, glaciers are projected to approach a new equilibrium towards the end of the 23rd century, after having lost either 248 ± 66 mm SLE (scenario RCP26), 313 ± 50 mm SLE (scenario RCP45), or 424 ± 46 mm SLE (scenario RCP85). Up until approximately 2100, ensemble uncertainty within each scenario is the biggest source of uncertainty for the future glacier mass loss; after that, the difference between the scenarios takes over as the biggest source of uncertainty. Ice mass loss rates are projected to peak 2040 ∼ 2050 (RCP26), 2050 ∼ 2060 (RCP45), 2070 ∼ 2090 (RCP60), or 2070 ∼ 2100 (RCP85).
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    URL: Article
    DOI: 10.5194/tc-6-1295-2012
    DOI: 10.5194/tc-6-1295-2012-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2393169-3
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  • 5
    Online Resource
    Online Resource
    Feedbacks and mechanisms affecting the global sensitivity of glaciers to climate change
    Copernicus GmbH ; 2014
    In:  The Cryosphere Vol. 8, No. 1 ( 2014-01-07), p. 59-71
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 8, No. 1 ( 2014-01-07), p. 59-71
    Abstract: Abstract. Mass loss by glaciers has been an important contributor to sea level rise in the past, and is projected to contribute a substantial fraction of total sea level rise during the 21st century. Here, we use a model of the world's glaciers to quantify equilibrium sensitivities of global glacier mass to climate change, and to investigate the role of changes in glacier hypsometry for long-term mass changes. We find that 21st century glacier-mass loss is largely governed by the glacier's response to 20th century climate change. This limits the influence of 21st century climate change on glacier-mass loss, and explains why there are relatively small differences in glacier-mass loss under greatly different scenarios of climate change. The projected future changes in both temperature and precipitation experienced by glaciers are amplified relative to the global average. The projected increase in precipitation partly compensates for the mass loss caused by warming, but this compensation is negligible at higher temperature anomalies since an increasing fraction of precipitation at the glacier sites is liquid. Loss of low-lying glacier area, and more importantly, eventual complete disappearance of glaciers, strongly limit the projected sea level contribution from glaciers in coming centuries. The adjustment of glacier hypsometry to changes in the forcing strongly reduces the rates of global glacier-mass loss caused by changes in global mean temperature compared to rates of mass loss when hypsometric changes are neglected. This result is a second reason for the relatively weak dependence of glacier-mass loss on future climate scenario, and helps explain why glacier-mass loss in the first half of the 20th century was of the same order of magnitude as in the second half of the 20th century, even though the rate of warming was considerably smaller.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    DOI: 10.5194/tc-8-59-2014
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2393169-3
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  • 6
    Online Resource
    Online Resource
    Modeling energy and mass balance of Shallap Glacier, Peru
    Copernicus GmbH ; 2013
    In:  The Cryosphere Vol. 7, No. 6 ( 2013-11-22), p. 1787-1802
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 7, No. 6 ( 2013-11-22), p. 1787-1802
    Abstract: Abstract. We calculated the distributed surface mass and energy balance of Shallap Glacier, Cordillera Blanca, Peru (9° S, 77° W, 4700–5700 m a.s.l., ~ 7 km2), on hourly time steps for two years (September 2006–August 2008) using a process-based model and meteorological measurements as input. Model parameter combinations were optimized against 21 temporal readings of 20 stakes in the ablation zone of the glacier. Uncertainty caused by model input parameters and parameterization schemes was estimated using a leave-one out cross-validation scheme, which yields values of root mean square deviation (RMSD) of surface height change 〈 1 m (〈 10% of the measured amplitude) for all stakes. With the best parameter combination (smallest RMSD) applied, the modeled annual surface mass balance of the glacier was −0.32 ± 0.4 m w.e. (water equivalent) for September 2006–August 2007 and 0.51 ± 0.56 m w.e. for September 2007–August 2008. While the mass balance above 5000 m was similar in both years (Δ 0.33 ± 0.68 m w.e.) due to similar annual sums of solid precipitation, a difference of 1.97 ± 0.68 m w.e. was calculated for the lower parts of the glacier. This difference is associated with more frequent occurrence of higher snow line altitudes during the first year, which was mainly caused by a higher fraction of liquid precipitation due to higher mean air temperatures. As the net shortwave budget was found to be the main source for ablation throughout the year at Shallap Glacier, lower surface albedo especially caused by lower solid precipitation amounts explains most of the difference in modeled ablation and mass balance between the two years.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    URL: Article
    DOI: 10.5194/tc-7-1787-2013
    DOI: 10.5194/tc-7-1787-2013-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2013
    detail.hit.zdb_id: 2393169-3
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