403 research outputs found
Northern hemispheric land ice distribution outside of Greenland during the Quaternary
No full textFrom the combination of orbital theory with benthic δ18O it has been suggested which obliquity cycles led to interglacials during the Quaternary. Here, we use a model-based deconvolution of this benthic δ18O record to calculate northern hemispheric land ice outside of Greenland, from which an alternative distribution of glacial and interglacial periods is defined.
Model output is compared with independent reconstructions of δ18O_seawater, sea level and atmospheric CO2 concentrations.
All data plotted in the figures of the article:
Köhler, P. & van de Wal, R. S. W. Interglacials of the Quaternary defined by northern hemispheric land ice distribution outside of Greenland, Nature Communications, 2020, 11, 5124, doi:10.1038/s41467-020-18897-5.
are compiled here
Berends_vandeWal_2016_GMD_supplement
No full text<p>Data files required to run the Matlab scripts provided as a supplement to the paper by Berends and van de Wal in GMD, 2016.</p>
Greenland’s contribution to global sea-level rise by the end of the 21st century
No full textThe Greenland ice sheet holds enough water to raise the global sea level with ~7 m. Over the last few decades, observations manifest a substantial increase of the mass loss of this ice sheet. Both enhanced melting and increase of the dynamical discharge, associated with calving at the outlet-glacier fronts, are contributing to the mass imbalance. Using a dynamical and thermodynamical ice-sheet model, and taking into account speed up of outlet glaciers, we estimate Greenland’s contribution to the 21st century global sea-level rise and the uncertainty of this estimate. Boundary fields of temperature and precipitation extracted from coupled climate-model projections used for the IPCC Fourth Assessment Report, are applied to the icesheet model. We implement a simple parameterization for increased flow of outlet glaciers, which decreases the bias of the modeled present-day surface height. It also allows for taking into account the observed recent increase in dynamical discharge, and it can be used for future projections associated with outlet-glacier speed up. Greenland contributes 0–17 cm to global sea-level rise by the end of the 21st century. This range includes the uncertainties in climate-model projections, the uncertainty associated with scenarios of greenhouse-gas emissions, as well as the uncertainties in future outlet-glacier discharge. In addition, the range takes into account the uncertainty of the ice-sheet model and its boundary fields
A commentary on “how to interpret expert judgment assessments of twenty-first century sea-level rise” by Hylke de Vries and Roderik SW van de Wal
No full textWe clarify key aspects of the evaluation, by de Vries and van de Wal (2015), of our expert elicitation paper on the contributions of ice sheet melting to sea level rise due to future global temperature rise scenarios (Bamber and Aspinall 2013), and extend the conversation with further analysis of their proposed approach for combining expert uncertainty judgments. We thank de Vries and van de Wal (2015: [VW15]) for their detailed consideration of Bamber and Aspinall (2013: [BA13]), and welcome this opportunity to clarify the work presented in BA13 and extend the analysis of VW15. The problem of finding a science-based quantification of uncertainty for poorly constrained physical models with large societal impacts deserves high priority in the climate community. This entails crossing discipline boundaries and will take that community outside its usual scientific comfort zone. We therefore salute the authors of VW13 for venturing into this alien terrain and welcome the opportunity to address some of the issues they raise. The present commentary discusses certain important and unique attributes of BA13’s expert weighting scheme that are misinterpreted in VW15, then addresses the Bconsensus distribution^ of VW15, their Blevel of consensus^, and the issue of lognormal fitting elicited data
Berends_etal_2020_CP_Supplement
No full textSupplement to Berends, C. J., de Boer, B., and van de Wal, R. S. W.: Reconstructing the Evolution of Ice Sheets, Sea Level and Atmospheric CO2 During the Past 3.6 Million Years, Clim. Past Discuss., https://doi.org/10.5194/cp-2020-52, in review, 2020.
Results from three separate simulations of the last 3.6 Myr with the hybrid ice-sheet - climate model
MIS 5e relative sea-level changes in the Mediterranean Sea: Contribution of isostatic disequilibrium
No full textSea-level indicators dated to the Last Interglacial, or Marine Isotope Stage (MIS) 5e, have a twofold value. First, they can be used to constrain the melting of Greenland and Antarctic Ice Sheets in response to global warming scenarios. Second, they can be used to calculate the vertical crustal rates at active margins. For both applications, the contribution of glacio- and hydro-isostatic adjustment (GIA) to vertical displacement of sea-level indicators must be calculated. In this paper, we re-assess MIS 5e sea-level indicators at 11 Mediterranean sites that have been generally considered tectonically stable or affected by mild tectonics. These are found within a range of elevations of 2–10 m above modern mean sea level. Four sites are characterized by two separate sea-level stands, which suggest a two-step sea-level highstand during MIS 5e. Comparing field data with numerical modeling we show that (i) GIA is an important contributor to the spatial and temporal variability of the sea-level highstand during MIS 5e, (ii) the isostatic imbalance from the melting of the MIS 6 ice sheet can produce a >2.0 m sea-level highstand, and (iii) a two-step melting phase for the Greenland and Antarctic Ice Sheets reduces the differences between observations and predictions. Our results show that assumptions of tectonic stability on the basis of the MIS 5e records carry intrinsically large uncertainties, stemming either from uncertainties in field data and GIA models. The latter are propagated to either Holocene or Pleistocene sea-level reconstructions if tectonic rates are considered linear through time
SEAWISE data, Impact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections
No full textImpact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections, Renske C. de Winter, Thomas J. Reerink, Aimée B. A. Slangen, Hylke de Vries, Tamsin Edwards, and Roderik S. W. van de Wal. https://doi.org/10.5194/nhess-2017-86, Nat. Hazards Earth Syst. Sci., 17, 1–17, 2017
Data support Figures 4 - 8 and A2-A4
Dataset for "Brief communication: On calculating the sea-level contribution in marine ice-sheet models"
No full textThis archive provides the data in Figures 3 and S1 of the publication 'Brief communication: On calculating the sea-level contribution in marine ice-sheet models' by Heiko Goelzer, Violaine Coulon, Frank Pattyn, Bas de Boer, and Roderik van de Wal. The Cryosphere, 2020</p
SEAWISE data, Impact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections
No full textImpact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections, Renske C. de Winter, Thomas J. Reerink, Aimée B. A. Slangen, Hylke de Vries, Tamsin Edwards, and Roderik S. W. van de Wal. https://doi.org/10.5194/nhess-2017-86, Nat. Hazards Earth Syst. Sci., 17, 1–17, 2017
Data support Figures 4 - 8 and A2-A4
Response to commentary by J. L. Bamber, W. P. Aspinall and R. M. Cooke (2016)
No full textIn a commentary paper, Bamber et al. (Nat Clim Change 3:424–427, 2016) respond to our recent assessment (De Vries and Van de Wal Clim Change 1–14, 2015) of their expert judgment based study on projections of future sea level rise due to the melting of the large ice sheets (Bamber and Aspinall Nat Clim Chang 3:424–427, 2013). In this response we comment on their remarks
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