Titel Deelnemers "Korte inhoud" "Validation of North Sea models: sub report 2. The impact of sea level rise on hydrodynamics: North Sea and Scheldt estuary" "K. Chu, Joris Vanlede, Sven Smolders, Boudewijn Decrop, Frank Mostaert" "The influence of Sea Level Rise (SLR) on the tidal characteristics in the North Sea and in the Scheldt estuary is evaluated in a scenario analysis for three scenarios of SLR: 1 m, 2 m and 3 m respectively. DCSMv6-ZUNOv4 and SCALDIS are selected as the modelling instruments. The models are run for 2 spring-neap cycles in 2015 without wind and pressure forcing (purely harmonic run).In the North Sea, the M2 tidal amplitude increases in the Southern Bight under SLR. Along the Belgian coast, the M2 amplitude increases with 2 cm, 4 cm and 6 cm with SLR of 1 m, 2 m and 3 m. The M2 tidal phase decreases, consistent with the faster propagation of the tidal wave in deeper water. The southern amphidromic point (closest to the Belgian Coastal Zone - BCZ) is expected to move north-eastwards with SLR of 1 and 2m. In the scenario of SLR of 3m, the amphidromic point shifts to the north-west.In the Scheldt Estuary, the changes on high water level are generally in proportion to the SLR of 1m, 2m and 3m. However the high water level drops in the Upper Sea Scheldt, mainly because the overflowing dikes of the Flood Control Areas (FCA’s) are represented in the model mesh, and the depoldered areas become drowned with SLR. Note that this corresponds to an initial response without autonomous development. In reality, SLR will not occur overnight, and the estuarine morphology will change on a longer timescale. The redistribution of sediments (erosion/deposition) will modify the hydrodynamics in the estuary, which in turn will change the morphology in a feed-back loop that is difficult to model accurately.The tidal asymmetry along the thalweg is evaluated based on tidal duration (falling/rising, ebb/flood) and velocities (maximum and mean) under different SLR scenarios. With SLR the initial effect in the estuary is that it becomes less ebb-dominant in terms of duration asymmetry upstream of km 100 (more equal timing of periods of ebb and flood). But the estuary becomes more ebb-dominant in terms of velocity asymmetry. The different results for different definitions of tidal asymmetry does not allow a straightforward interpretation in terms of expected morphological response, and warrants future research, e.g. with a sediment transport model." "Potential and use of archaeological and historical data for a reconstruction of the sea level curve of the last 3000 years in the coastal zone of the southern North Sea. Results of a case study" "Sjoerd Kluiving, Michel Lascaris, Adriaan De Kraker, Hans Renes, Guus Borger, Steven Soetens" "This paper demonstrates that methodologies from various disciplines can be utilised to explain the coastal development of the southern North Sea during the last 3000 years. The potential and uses of archaeological data are tested against the applicability of delivering data for reconstructing sea level or local water level curves. Geology, archaeology, and historical geography are disciplines that assess changes in absolute and regional sea levels, deposition, subsidence, or rises in surface level. In this paper a selection of the national archaeological database (ARCHIS2) from the western Netherlands is presented as archaeological proxy data that might help reconstruct the relationship between occupational history and landscape development. The case study around Katwijk in the western Netherlands presents the known history and geology of the area, as well as the archaeological data present. Results show that data within ARCHIS2 is of too poor quality and that even with the help of excavation reports the required resolution for reconstructing local water level curves is currently not present in the recorded data. Archaeological data that has been recorded generally lacks precision in data location (x, y, and z) and generally does not have an absolute time control. The ideal database or model is the creation of a GIS (Geographic Information System) that can integrate data from the different disciplines. All data should be transparent and have a spatial and temporal resolution, so that data from different disciplines can corroborate each other. Its accuracy can then be compared so the better dataset to provide the optimal insight into landscape change associated with the sizes of coastal inlets and the local variations of tidal amplitudes." "Branched glycerol dialkyl glycerol tetraethers and crenarchaeol record post-glacial sea level rise and shift in source of terrigenous brGDGTs in the Kara Sea (Arctic Ocean)" "Cindy De Jonge, Alina Stadnitskaia, Georgy Cherkashov, Jaap S. Sinninghe Damste" "This study evaluates the glycerol dialkyl glycerol tetraether (GDGT) distribution and provenance in sediments (spanning a minimum of 13.3 ka) from the St. Anna Trough (Northern Kara Sea). The site has experienced extensive fluctuation in the delivery of river-derived organic matter (OM), caused by a eustatic change in sea level. This is in line with the record of the concentration of the isoprenoid GDGT, crenar-chaeol, produced by marine Thaumarchaota, which was low at the bottom of the core, increasing gradually in the most shallow unit. The concentration of branched (br) GDGTs showed an opposite trend and a marked shift in distribution. The deepest sediments (> 10 ka), with a distribution currently encountered in surface sediments in front of the Yenisei River, are characterized by terrigenous brGDGTs, whereas the distribution in the shallowest unit (< 10 ka) is strongly influenced by marine, in-situ brGDGTs. During the shift from terrigenous to marine-sourced brGDGTs, there was one horizon where a pronounced shift in the brGDGT distribution was observed and the brGDGT concentration significantly decreased. As the brGDGTs delivered to the current Kara Sea system are derived from several sources, we postulate that a temporary change in the relative importance of the brGDGT sources happened during this interval. Both in-situ production and changing brGDGT provenance have implications for paleoclimate reconstruction using brGDGTs. In-situ production of marine brGDGTs results in a higher reconstructed pH. However, these in-situ produced brGDGTs did not influence the reconstructed mean annual air temperature (MAT), when the MAT(mrs) calibration was used. Changes in the relative contribution of brGDGT sub-pools were shown, however, to influence both soil pH reconstruction and MAT reconstruction. (C) 2015 Elsevier Ltd. All rights reserved." "Millennial total sea level commitments projected with the Earth system model of intermediate complexity LOVECLIM" "Heiko Goelzer, Philippe Huybrechts, Sarah Raper, Marie-France Loutre, H. Goosse, Thierry Fichefet" "Sea-level is expected to rise for a long time to come, even after stabilization of human-induced climatic warming. Here we use simulations with the Earth system model of intermediate complexity LOVECLIM to project sea-level changes over the third millennium forced with atmospheric greenhouse gas concentrations that stabilize by either 2000 or 2100 AD. The model includes 3D thermomechanical models of the Greenland and Antarctic ice sheets coupled to an atmosphere and an ocean model, a global glacier melt algorithm to account for the response of mountain glaciers and ice caps, and a procedure for assessing oceanic thermal expansion from oceanic heat uptake. Four climate change scenarios are considered to determine sea-level commitments. These assume a 21st century increase in greenhouse gases according to SRES scenarios B1, A1B and A2 with a stabilization of the atmospheric composition after the year 2100. One additional scenario assumes 1000 years of constant atmospheric composition from the year 2000 onwards. For our preferred model version, we find an already committed total sea-level rise of 1.1 m by 3000 AD. In experiments with greenhouse gas concentration stabilization at 2100 AD, the total sea-level rise ranges between 2.1 m (B1), 4.1 m (A1B) and 6.8 m (A2). In all scenarios, more than half of this amount arises from the Greenland ice sheet, thermal expansion is the second largest contributor, and the contribution of glaciers and ice caps is small as it is limited by the available ice volume of maximally 25 cm of sea-level equivalent. Additionally, we analysed the sensitivity of the sea-level contributions from an ensemble of nine different model versions that cover a large range of climate sensitivity realized by model parameter variations of the atmosphere-ocean model. Selected temperature indices are found to be good predictors for sea-level contributions from the different components of land ice and oceanic thermal expansion after 1000 years." "Effect of uncertainty in surface mass balance–elevation feedback on projections of the future sea level contribution of the Greenland ice sheet" "Tamsin L. Edwards, Xavier Fettweis, Olivier Gagliardini, Fabien Gillet-Chaulet, J.m. Gregory, Heiko Goelzer, M. Hoffman, Philippe Huybrechts, Tony Payne, Mauro Perego, Stephen Price, Aurelien Quiquet" "We apply a new parameterisation of the Greenland ice sheet (GrIS) feedback between surface mass balance (SMB: the sum of surface accumulation and surface ablation) and surface elevation in the MAR regional climate model (Edwards et al., 2014) to projections of future climate change using five ice sheet models (ISMs). The MAR (Modèle Atmosphérique Régional: Fettweis, 2007) climate projections are for 2000-2199, forced by the ECHAM5 and HadCM3 global climate models (GCMs) under the SRES A1B emissions scenario. The additional sea level contribution due to the SMB-elevation feedback averaged over five ISM projections for ECHAM5 and three for HadCM3 is 4.3% (best estimate; 95% credibility interval 1.8-6.9%) at 2100, and 9.6% (best estimate; 95% credibility interval 3.6-16.0%) at 2200. In all results the elevation feedback is significantly positive, amplifying the GrIS sea level contribution relative to the MAR projections in which the ice sheet topography is fixed: the lower bounds of our 95% credibility intervals (CIs) for sea level contributions are larger than the ""no feedback"" case for all ISMs and GCMs. Our method is novel in sea level projections because we propagate three types of modelling uncertainty - GCM and ISM structural uncertainties, and elevation feedback parameterisation uncertainty - along the causal chain, from SRES scenario to sea level, within a coherent experimental design and statistical framework. The relative contributions to uncertainty depend on the timescale of interest. At 2100, the GCM uncertainty is largest, but by 2200 both the ISM and parameterisation uncertainties are larger. We also perform a perturbed parameter ensemble with one ISM to estimate the shape of the projected sea level probability distribution; our results indicate that the probability density is slightly skewed towards higher sea level contributions." "The Earth’s Cryosphere and Sea Level Change" "This book gives a comprehensive overview of our present understanding of the Earth's cryosphere, its changes and their consequences for mean sea level changes. Since the middle of the 19th century there has been an increase of sea level height by 20-25 cm. Some 10 cm of this is due to net losses from glaciers, the remainder being due to mass losses from land ice and thermal expansion of the oceans. The mean sea level rise is slowly accelerating; at present it is some 3 mm/year. Recent space observations made by the GRACE satellite combined with ocean temperature and volume measurements have enabled the separate contributions to sea level rise from melting ice and from thermal expansion to be better estimated. The estimation of mean sea level change is complicated by changes in land level due to tectonic effects and to ongoing changes following the most recent major glaciation. The book gives an up-to-date survey of our present knowledge of this crucial subject." "Future Sea Level Change Under Coupled Model Intercomparison Project Phase 5 and Phase 6 Scenarios From the Greenland and Antarctic Ice Sheets" "Antony J. Payne, Sophie Nowicki, Ayako Abe-Ouchi, Cecile Agosta, Patrick Alexander, Torsten Albrecht, Xylar Asay-Davis, Andy Aschwanden, Alice Barthel, Thomas J. Bracegirdle, Reinhard Calov, Christopher Chambers, Youngmin Choi, Richard Cullather, Joshua Cuzzone, Christophe Dumas, Tamsin L. Edwards, Denis Felikson, Xavier Fettweis, Benjamin K. Galton-Fenzr, Heiko Goelzer, Rupert Gladstone, Nicholas R. Golledge, Jonathan M. Gregory, Ralf Greve, Tore Hattermann, Matthew J. Hoffman, Angelika Humbert, Philippe Huybrechts, Nicolas C. Jourdain, Thomas Kleiner, Peter Kuipers Munneke, Eric Larour, Sébastien Le Clec'H, Victoria Lee, Gunter Leguy, William H. Lipscomb, Christopher M. Little, Daniel P. Lowry, Mathieu Morlighem, Isabel Nias, Frank Pattyn, Tyler Pelle, Stephen F. Price, Aurelien Quiquet, Ronja Reese, Martin Rueckamp, Nicole-Jeanne Schlege, Helene Seroussi, Andrew Shepherd, Erika Simon, Donald A. Slater, Robin S. Smith, Fiammetta Straneo, Sainan Sun, Lev Tarasov, Luke D Trusel, Jonas Van Breedam, Roderik van de Wal, Michiel Van Den Broeke, Ricarda Winkelmann, Chen Zhao, Tong Zhang, Thomas Zwinger" "Projections of the sea level contribution from the Greenland and Antarctic ice sheets (GrIS and AIS) rely on atmospheric and oceanic drivers obtained from climate models. The Earth System Models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) generally project greater future warming compared with the previous Coupled Model Intercomparison Project phase 5 (CMIP5) effort. Here we use four CMIP6 models and a selection of CMIP5 models to force multiple ice sheet models as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We find that the projected sea level contribution at 2100 from the ice sheet model ensemble under the CMIP6 scenarios falls within the CMIP5 range for the Antarctic ice sheet but is significantly increased for Greenland. Warmer atmosphere in CMIP6 models results in higher Greenland mass loss due to surface melt. For Antarctica, CMIP6 forcing is similar to CMIP5 and mass gain from increased snowfall counteracts increased loss due to ocean warming." "Enhanced basal lubrication and the contribution of the Greenland ice sheet to future sea level rise" "Sarah R. Shannon, Tony Payne, Ian D. Bartholomew, Michiel Van Den Broeke, Tamsin L. Edwards, Xavier Fettweis, Olivier Gagliardini, Fabien Gillet-Chaulet, Heiko Goelzer, Matthew J. Hoffman, Philippe Huybrechts, D. Mair, Pete Nienow, Mauro Perego, Stephen Price, Paul Smeets, Andrew J. Sole, Roderik S. W. Van De Wal, Thomas Zwinger" "We assess the effect of enhanced basal sliding on the flow and mass budget of the Greenland ice sheet, using a newly developed parameterization of the relation between meltwater runoff and ice flow. A wide range of observations suggest that water generated by melt at the surface of the ice sheet reaches its bed by both fracture and drainage through moulins. Once at the bed, this water is likely to affect lubrication, although current observations are insufficient to determine whether changes in subglacial hydraulics will limit the potential for the speedup of flow. An uncertainty analysis based on our best-fit parameterization admits both possibilities: continuously increasing or bounded lubrication. We apply the parameterization to four higher-order ice-sheet models in a series of experiments forced by changes in both lubrication and surface mass budget and determine the additional mass loss brought about by lubrication in comparison with experiments forced only by changes in surface mass balance. We use forcing from a regional climate model, itself forced by output from the European Centre Hamburg Model (ECHAM5) global climate model run under scenario A1B. Although changes in lubrication generate widespread effects on the flow and form of the ice sheet, they do not affect substantial net mass loss; increase in the ice sheet's contribution to sea-level rise from basal lubrication is projected by all models to be nomore than 5% of the contribution from surface mass budget forcing alone." "Spatial and taxonomic variation of mercury concentration in low trophic level fauna from the Mediterranean Sea" "Kate Buckman, Oksana Lane, Jože Kotnik, Arne Bratkic, Francesca Sprovieri, Milena Horvat, Nicola Pirrone, David Evers, Celia Chen" "Studies of mercury (Hg) in the Mediterranean Sea have focused on pollution sources, air-sea mercury exchange, abiotic mercury cycling, and seafood. Much less is known about methylmercury (MeHg) concentrations in the lower food web. Zooplankton and small fish were sampled from the neuston layer at both coastal and open sea stations in the Mediterranean Sea during three cruise campaigns undertaken in the fall of 2011 and the summers of 2012 and 2013. Zooplankton and small fish were sorted by morphospecies, and the most abundant taxa (e.g. euphausiids, isopods, hyperiid amphipods) analyzed for methylmercury (MeHg) concentration. Unfiltered water samples were taken during the 2011 and 2012 cruises and analyzed for MeHg concentration. Multiple taxa suggested elevated MeHg concentrations in the Tyrrhenian and Balearic Seas in comparison with more eastern and western stations in the Mediterranean Sea. Spatial variation in zooplankton MeHg concentration is positively correlated with single time point whole water MeHg concentration for euphausiids and mysids and negatively correlated with maximum chlorophyll a concentration for euphausiids, mysids, and “smelt” fish. Taxonomic variation in MeHg concentration appears driven by taxonomic grouping and feeding mode. Euphausiids, due to their abundance, relative larger size, importance as a food source for other fauna, and observed relationship with surface water MeHg are a good candidate biotic group to evaluate for use in monitoring the bioavailability of MeHg for trophic transfer in the Mediterranean and potentially globally." "Projecting Antarctica's contribution to future sea level rise from basal ice shelf melt using linear response functions of 16 ice sheet models (LARMIP-2)" "Anders Levermann, Ricarda Winkelmann, Torsten Albrecht, Heiko Goelzer, Nicholas R. Golledge, Ralf Greve, Philippe Huybrechts, Jim Jordan, Gunter Leguy, Mathieu Morlighem, Frank Pattyn, David Pollard, Aurelien Quiquet, Christian Rodehacke, Helene Seroussi, Johannes Sutter, Tong Zhang, Jonas Van Breedam, Reinhard Calov, Robert DeConto, Christophe Dumas, Julius Garbe, G Hilmar Gudmundsson, Matthew J. Hoffman, Angelika Humbert, Thomas Kleiner, William H. Lipscomp, Malte Meinshausen, Esmond G Ng, Sophie Nowicki, Mauro Perego, Stephen Price, Fuyuki Saito, Nicole-Jeanne Schlegel, Sainan Sun, Roderik S. W. Van De Wal" "The sea level contribution of the Antarctic ice sheet constitutes a large uncertainty in future sea level projections. Here we apply a linear response theory approach to 16 state-of-the-art ice sheet models to estimate the Antarctic ice sheet contribution from basal ice shelf melting within the 21st century. The purpose of this computation is to estimate the uncertainty of Antarctica’s future contribution to global sea level rise that arises from large uncertainty in the oceanic forcing and the associated ice shelf melting. Ice shelf melting is considered to be a major if not the largest perturbation of the ice sheet’s flow into the ocean. However, by computing only the sea level contribution in response to ice shelf melting, our study is neglecting a number of processes such as surface-mass-balance-related contributions. In assuming linear response theory, we are able to capture complex temporal responses of the ice sheets, but we neglect any self-dampening or self-amplifying processes. This is particularly relevant in situations in which an instability is dominating the ice loss. The results obtained here are thus relevant, in particular wherever the ice loss is dominated by the forcing as opposed to an internal instability, for example in strong ocean warming scenarios. In order to allow for comparison the methodology was chosen to be exactly the same as in an earlier study (Levermann et al., 2014) but with 16 instead of 5 ice sheet models. We include uncertainty in the atmospheric warming response to carbon emissions (full range of CMIP5 climate model sensitivities), uncertainty in the oceanic transport to the Southern Ocean (obtained from the time-delayed and scaled oceanic subsurface warming in CMIP5 models in relation to the global mean surface warming), and the observed range of responses of basal ice shelf melting to oceanic warming outside the ice shelf cavity. This uncertainty in basal ice shelf melting is then convoluted with the linear response functions of each of the 16 ice sheet models to obtain the ice flow response to the individual global warming path. The model median for the observational period from 1992 to 2017 of the ice loss due to basal ice shelf melting is 10.2 mm, with a likely range between 5.2 and 21.3 mm. For the same period the Antarctic ice sheet lost mass equivalent to 7.4 mm of global sea level rise, with a standard deviation of 3.7 mm (Shepherd et al., 2018) including all processes, especially surface-mass-balance changes. For the unabated warming path, Representative Concentration Pathway 8.5 (RCP8.5), we obtain a median contribution of the Antarctic ice sheet to global mean sea level rise from basal ice shelf melting within the 21st century of 17 cm, with a likely range (66th percentile around the mean) between 9 and 36 cm and a very likely range (90th percentile around the mean) between 6 and 58 cm. For the RCP2.6 warming path, which will keep the global mean temperature below 2 ◦C of global warming and is thus consistent with the Paris Climate Agreement, the procedure yields a median of 13 cm of global mean sea level contribution. The likely range for the RCP2.6 scenario is between 7 and 24 cm, and the very likely range is between 4 and 37 cm. The structural uncertainties in the method do not allow for an interpretation of any higher uncertainty percentiles. We provide projections for the five Antarctic regions and for each model and each scenario separately. The rate of sea level contribution is highest under the RCP8.5 scenario. The maximum within the 21st century of the median value is 4 cm per decade, with a likely range between 2 and 9 cm per decade and a very likely range between 1 and 14 cm per decade."