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For this reason, practitioners can decide whether to treat the uncertainties as fully independent, fully dependent, or in between depending on their level of risk-averseness. For the independent case (all co-variances zero), we take the median values of AR6 for the different components and define the high-end to be cha...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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Other processes which may play a role are related to debris cover and ice-ocean interaction. Only one of the glacier models taking part in GlacierMIP2 includes a parameterization of frontal ablation/calving (Huss & Hock, 2015), such that there is potential for underestimation of mass loss in the GlacierMIP2 ensemble as...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) ensemble mean results indicated a contribution of 0.096 ± 0.052 m for RCP8.5/SSP5-8.5 in 2100 for a representative range of CMIP5 GCMs (Goelzer et al., 2020), where an unaccounted contribution for committed sea level of 6 ± 2 mm is additionally added (Goelz...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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Figure 2: Causal relation between processes leading to a high-end contribution of Greenland to sea level rise (SLR). Critical processes are albedo, ocean forcing and atmospheric circulation changes. These three processes impact the surface mass balance (SMB). Outlet glaciers change by changes in SMB and ocean forcing a...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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Observations of basal melt are hampered by the inaccessibility of the sub-ice-shelf cavities, and modeling of basal melt is challenging both because of the lack of observational validation and the limited resolution of the cavities that is possible in models covering continental scales. To date, most ocean model compon...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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The Antarctic Buttressing Model Intercomparison project (ABUMIP; Sun et al., 2020) shows that instantaneous and sustained loss of all Antarctic ice shelves leads to multi-meter SLR over several centuries (1–12 m in 500 yr from present). The participating models did not include MICI, and the variation in magnitude of ic...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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For Greenland and Antarctica, the lines of evidence include an assessment of the physical processes. While we cannot define a precise percentile for the total high-end SLR, our interpretation of the multiple lines of evidence as outlined in the Greenland and Antarctic Sections above, is that it lies in the tail and com...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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References^a Approach/processes This paper AR6 (Table 9.8 and Table 9.11) Remarks 2100 +2°C Thermal expansion Fox-Kemper et al. (2021) AR6 assessment 0.18b 0.18 Glaciers Marzeion et al. (2020) Temperature change, ensemble 10 climate models, 10 glacier models 0.15 0.11 Gree...
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Considering 2050, there is little difference between low and high-temperature scenarios, as the tails of the distribution are more constrained on decadal time scales. This reflects that the major source of uncertainty—the break-up of major ice shelves in Antarctica—is not foreseen over these time scales. Addressing 215...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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First, among these uncertainties is the rate of ice loss caused by MICI in Antarctica. The only continental-scale model attempting to quantify the contribution of MICI to future SLR, uses constraints based on observations of calving at the termini of large marine-terminating glaciers in Greenland. However, the geometry...
https://sealeveldocs.readthedocs.io/en/latest/vandewal22.html
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Slangen et al. (2022) Title: The evolution of 21st century sea-level projections from IPCC AR5 to AR6 and beyond Keywords: Sea-level changes, Numerical modelling, Climate change, Coastal change Corresponding author: Aimée B.A. Slangen Citation: Slangen, A. B. A., Palmer, M. D., Camargo, C. M. L., Church, J. A., Edward...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Impact statement Sea-level rise is an important aspect of climate change, with potentially large consequences for coastal communities around the world. Sea-level change is therefore an active area of research that has seen many developments in the past decades. Based on the available research, the Intergovernmental Pa...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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One thing that all sea-level projections have in common, despite the different approaches and methodologies, is an uncertainty that grows substantially through time. The uncertainties in regional sea-level projections over the coming years to decades result primarily from internal climate variability (see e.g., Palmer ...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Here, we will first discuss ‘how we got here’: recent methodological developments in process-based sea-level projections for the 21st century, with a brief recap of the IPCC sea-level projection methods up to IPCC AR5, followed by a discussion of the key differences between AR5, SROCC and AR6 projections (section ‘Key ...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Table 1: High-level summary of the methods used in the AR5, SROCC and AR6 reports to project global mean and regional SLC (1° × 1° resolution) to 2100. Note: This is an adapted version of Table 9.7 in Fox-Kemper et al. (Reference Fox-Kemper, Hewitt, Xiao, Aðalgeirsdóttir, Drijfhout, Edwards, Golledge, Hemer, Kopp, Krin...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Figure 1: Comparison of 21st century projections of global mean SLC in AR5, SROCC and AR6. Total GMSL and individual contributions, between 1995 and 2014 and 2100 (m), median values and likely ranges of medium confidence projections, for (a) RCP2.6/SSP1–2.6 and (b) RCP8.5/SSP5–8.5. See also Table 9.8 in Fox-Kemper et a...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Differences in the projected contributions to SLC In AR5, the assessments of glacier and ice sheet contributions were based on a range of individual models and publications. The only difference in the SROCC projections with respect to AR5 was the reassessment of the Antarctic dynamics contribution, by replacing the AR...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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A comparison of the GMSL projections to 2100 in the different reports reveals a number of differences (Figure 1a,b). In the land ice contributions, we see a narrowing of the likely ranges for glaciers (under both scenarios) and the Greenland ice sheet (under SSP5–8.5), and a widening of the Antarctic ice sheet likely r...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Sea-level projections outside the likely range One of the key uncertainties in sea-level projections is the dynamic contribution of the ice sheets (i.e., processes related to the flow of the ice). AR5 assessed the likely dynamical contribution of the Antarctic Ice Sheet by 2100 at −2 to 18.5 cm, but also noted that ‘B...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Wang et al. (Reference Wang, Church, Zhang and Chen2021a) also evaluated GMSL and regional projections from AR5 and SROCC against different tide gauge and altimetry time series for the period 2007–2018. They found that the GMSL trends for 2007–2018 from AR5 projections are almost identical to observed trends and well w...
https://sealeveldocs.readthedocs.io/en/latest/slangen22.html
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Figure 4: Ocean dynamic SLC northwest of Europe, as simulated by (a) the CMIP5 GCM HadGEM2-ES and (b) dynamically downscaled using regional ocean model NEMO-AMM7, and by (c) the CMIP5 GCM MPI-ESM-LR and (d) dynamically downscaled, for the scenario RCP8.5 (2074–2099 minus 1980–2005). Figure adapted from Hermans et al. (...
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Li et al. (2022) Title: The Impact of Horizontal Resolution on Projected Sea-Level Rise Along US East Continental Shelf With the Community Earth System Model Key Points: The high resolution (HR) Community Earth System Model reduces biases in dynamic sea level (DSL) and circulation on US east continental shelf Compared...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Most climate simulations submitted for CMIPs are based on standard resolution (a nominal horizontal resolution of 1˚) climate models (e.g., Flato et al., 2013). Recent advancements of computing power and storage capacity have enabled high resolution (HR) climate simulations. Based on comparisons of a pair of century lo...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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For global simulations, the deep ocean typically takes thousands of years to reach an equilibrium (Danabasoglu, 2004; Griffies et al., 2014). Due to the relatively short spin-up time (250 years), model drift exists in the CESM simulations (see Chang et al., 2020). The impacts of such drift, however, can be minimized by...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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The global mean steric sea level (urn:x-wiley:19422466:media:jame21583:jame21583-math-0037) is computed as the global average of local steric sea level (urn:x-wiley:19422466:media:jame21583:jame21583-math-0038): urn:x-wiley:19422466:media:jame21583:jame21583-math-0039 (2) urn:x-wiley:19422466:media:jame21583:jame21583-...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Figure 1: Left column: mean dynamic sea level (DSL) from Altimeter observation (a), high resolution (HR) (b) and low resolution (LR) (c). Right column: Variance of daily DSL from Altimeter observation (d), HR (e) and LR (f). For the variance of observed sea level, we first compute anomalies from the global mean and the...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Figure 4: Trends of dynamic sea level (DSL) (a), (d), local steric height component (b), (e), and mass transport component (c), (f) from the low resolution (LR) (left column) and high resolution (HR) (right column). Trends are computed from the TNST simulations from 2,001 to 2,100 and corrected by the CTRL simulations ...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Two factors contribute to the local steric height differences between LR and HR: bathymetry and in-situ density. Along the US southeast continental shelf, bathymetry in LR is deeper than that in HR and ETOPO5 (Figures 7a–7c). In addition, the land-sea mask in LR does not accurately represent the coastline due to the co...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Figure 9: Atlantic Meridional Overturning Circulation (AMOC) overturning streamfunction climatological mean for low resolution (LR) (a) and high resolution (HR) (b). AMOC overturning streamfunctions are averaged during the last 100 years (year 401–500) of the CTRL simulations to minimize model drift. (c) Comparison of ...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Here we examine the difference in DSL patterns between LR and HR with geostrophic balance. The geostrophic balance is typically valid in the open ocean and the mid shelf (Fewings & Lentz, 2010). At the inner shelf and coastal zone, geostrophic balance does not hold because of the significance of friction, wave and wind...
https://sealeveldocs.readthedocs.io/en/latest/li22james.html
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Bamber et al. (2019) Title: Ice sheet contributions to future sea-level rise from structured expert judgment Key Points: Potential contributions of ice sheets to future sea-level rise (SLR) remain the largest source of uncertainty in SLR projections For a +2 °C temperature scenario, consistent with the Paris Agreement...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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Since then, regional- and continental-scale, process-based modeling of ice sheets has advanced substantially (8, 9, 14–16), with the inclusion of new positive feedbacks that could potentially accelerate mass loss, and negative feedbacks that could potentially slow it. These include solid Earth and gravitational process...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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Fig. 1: PDFs for the L (blue) and H (red) temperature scenarios for the combined ice sheet SLR contributions at (A) 2100 and (B) 2300. All four time intervals are shown in SI Appendix, Fig. S2. The horizontal bars show the fifth, 17th, 50th (median), 83rd, and 95th percentile values. The baseline rate of 0.76 mm⋅a−1 is...
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Statistically, the declining GrIS share and declining GrIS/AIS ratio reflect a higher mean estimate but slightly less skewed distribution for GrIS than for WAIS, and a long tail for EAIS (Fig. 3), as well as the assessed dependence structure between different terms. Physically, this is likely a result of the role of hi...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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The present SEJ demonstrates a shift in expert opinion since BA13 (i.e., in 2012), when it was found that the GrIS had the narrowest 90% credible range but the largest median SLR rate (13). Here, the GrIS still has the largest median value (for both L and H), but the upper tail of the distribution is now comparable to ...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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Conclusions This study suggests that experts’ judgments of uncertainties in projections of the ice sheet contribution to SLR have grown during the last 6 y and since publication of the AR5. This is likely a consequence of a focused effort by the glaciological community to refine process understanding and improve proce...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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EU elicitation: Gaël Durand, Johannes Fuerst, Hilmar Gudmundsson, Anders Levermann, Frank Pattyn, Catherine Ritz, Ingo Sasgen, Aimee Slangen, Bert Wouters The assessments were combined using equal weighting and performance-based weighting. In the EU expert panel, one expert provided judgments based on a conceptual inte...
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Other DMs in Table 2, besides EW, are PW01, the performance weighted combination of the eight weighted experts, and PWOpt, the performance weighted combination with the cutoff chosen to optimize the combined score of the DM. Indeed, the combined score of PWOpt (0.4914) is (only) slightly greater than that of PW01 (0.47...
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Three random variables (Runoff, Discharge and Accumulation) for each of the three ice sheets yield 36 pairs of variables. Potential dependences between ice sheets were also identified. Based on judgments of size and relevance, the analysis team pared this down to 10 pairs corresponding to the colored nodes in Figure S8...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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A talk on this subject was given at the Banff research center in 2013 by Roger Cooke and can be streamed from http://www.birs.ca/events/2013/5-day-workshops/13w5146/videos/watch/201305221037-Cooke.html A talk on performance weighting was given at the Centers for Disease Control and Prevention in Atlanta GA on May 23, 2...
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In other words, a very high value of one variable tends not to entrain a high value of the other with two Gaussian variables, but this will not be true for variables characterized by other distributions. Results The calculations were performed by Aspinall and Cooke defining a regular vine, using the experts’ responses...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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Surface mass balance Between atmospheric circulation/moisture transport changes (AM) and albedo changes (AC), which do you consider more important for determining surface mass balance of grounded ice during the 21st, 22nd, and 23rd century. 2°C scenario Sheet GrIS WAIS EAIS 21st 22nd 23rd 21st 22nd 23rd 21st 22nd 23rd...
https://sealeveldocs.readthedocs.io/en/latest/bamber19.html
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Yuan and Kopp (2021) Title: Emulating Ocean Dynamic Sea Level by Two-Layer Pattern Scaling Key Points: An emulator for DSL changes is developed based on a two-layer energy balance model and a two-layer pattern scaling technique The two-layer emulator can better capture the evolution of DSL in corresponding coupled GCM...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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Building upon Bilbao et al. (2015)’s speculation about the relative importance of shallow and deep warming under different scenarios, we developed a bivariate pattern scaling, which uses a multiple linear regression with two predictors: GSAT and global-mean deep ocean temperature change. The two temperature changes can...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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To calibrate FaIR-2LM, we adjust parameter settings (listed in Table 1) based on previous studies (Forster et al., 2013; Geoffroy, Saint-Martin, et al., 2013a; Zelinka et al., 2014). The radiative forcing in FaIR-2LM is driven by the default emission trajectory for each scenario in FaIR 1.3, but scaled by two parameter...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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There is little agreement on either surface- or deep-layer slopes across the five GCMs over most parts of the Atlantic basin (Figure 1). This may reflect limited skill in simulating strong western boundary currents (e.g., the Atlantic Meridional Overturning Circulation (AMOC)) in the GCMs, which have a relatively coars...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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We apply Latin hypercube sampling (LHS, Stein, 1987) to the parameter sets of lambda, gamma, gamma_{epsilon} by sampling 1,000 sets from the 99,734 parameter sets. For each parameter, LHS divides the probability density function of the 99,734 samples into 1,000 portions that have equal area. A sample is taken from each...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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Figure 3: widehat{{zos}} predicted by univariate pattern scaling and two-layer pattern scaling at the grid cell (a) over Western Pacific (14.5˚N, 127˚E) and (b) over the North Atlantic (40˚N, 73˚W) for the five models in the three scenarios. The zos simulated by corresponding GCMs is shown by scatters in which colors i...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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Comparing the DSL projections between the period of 2081-2100 and the period of 2271-2290 (Figure 5), the median estimate is lower and the 66% range of uncertainty is narrower at the end of 21st century than that at the end of 23rd century in moderate-to high-emission scenarios (RCP4.5, SSP3-7.0 and RCP8.5). But in RCP...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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Table 2: The Averaged RMSE Between the DSL Simulated by GCMs and the DSL Predicted by Univariate/Two-Layer Pattern Scaling Across Five Models. Note: The averaged RMSEs and the reduction of RMSE from univariate pattern scaling approach to two-layer pattern scaling are calculated for the three RCP scenarios, respectively...
https://sealeveldocs.readthedocs.io/en/latest/yuankopp21.html
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References Bilbao, R. A. F., Gregory, J. M., & Bouttes, N. (2015). Analysis of the regional pattern of sea level change due to ocean dynamics and density change for 1993–2099 in observations and CMIP5 AOGCMs. Climate Dynamics, 45, 2647-2666. https://doi.org/10.1007/s00382-015-2499-z Bronselaer, B., Winton, M., Griffie...
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Kopp, R. E., Hay, C. C., Little, C. M., & Mitrovica, J. X. (2015). Geographic Variability of Sea-Level Change. Current Climate Change Reports, 1(3), 192–204. https://doi.org/10.1007/s40641-015-0015-5 Kuhlbrodt, T., & Gregory, J. M. (2012). Ocean heat uptake and its consequences for the magnitude of sea level rise and c...
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Stein, M. (1987). Large sample properties of simulations using latin hypercube sampling. Technometrics, 29, 143–151. https://doi.org/10.1080/00401706.1987.10488205 Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M. M. B., Allen, S. K., Boschung, J., et al. (2013). Climate change 2013: The physical science basis. Cont...
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Church et al. (2013) Title: Evaluating the ability of process based models to project sea-level change Key Points: Evaluation of CMIP5 and other process-based models using observations Process-based models, when properly calibrated, can reproduce a significant portion of the observed sea-level rise. Ocean thermal expa...
https://sealeveldocs.readthedocs.io/en/latest/church13.html
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Figure 1: Comparisons of modelled and observed (a) ocean thermal expansion (observations in blue), (b) glacier contributions, (c) changes in terrestrial storage (the sum of aquifer depletion and reservoir storage) and (d) and the rate of change (10 year centred average) for the terms in (a) to (c). Individual model sim...
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There are also direct human related interventions in the hydrological cycle that impact the amount of water stored on land. This occurs principally through the building of reservoirs (Chao et al 2008, Lettenmaier and Milly 2009) and the depletion of groundwater (Konikow 2011, Wada et al 2012). For reservoir storage, we...
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Secondly, there may be contributions related to internally generated variability on decadal timescales (Delworth and Knutson 2000). Marzeion et al (2012) have also computed glacier mass changes using observed rather than simulated temperature change (figure 1(b), blue line). An additional contribution of about 20 mm is...
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Church and White (2011) Title: Sea-Level Rise from the Late 19th to the Early 21st Century Keywords: Sea level, Climate change, Satellite altimeter, Tide gauge Corresponding author: Church Citation: Church, J. A. & White, N. J. (2011). Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys in Geophysics,...
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The second approach uses spatial functions which represent the large-scale patterns of variability to interpolate between the widely distributed coastal and island sea-level observations and thus to estimate global sea level (as distinct from coastal sea level). This technique was first developed by Chambers et al. (20...
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Satellite Altimeter Data Processing Techniques The TOPEX/Poseidon, Jason-1 and OSTM/Jason-2 satellite altimeter missions measure sea surface height (SSH) relative to the centre of mass of the Earth along the satellite ground track. A number of instrumental and geophysical corrections must be applied. Every 10 days (on...
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Christiansen et al. (2010) tested the robustness of various reconstruction techniques, including an approach similar to that developed by Church et al. (2004) using thermosteric sea level calculated from climate model results. They used an ensemble of model results (derived by randomising the phase of the principal com...
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As a further test of the effectiveness of the EOFs to represent the interannual variability in GMSL, we computed EOFs using shorter periods of 9 and 12 years, similar to our earlier analyses (Church et al. 2004; Church and White 2006). The resulting estimates are well within the uncertainties. The atmospheric pressure ...
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Figure 5: Global average sea level from 1860 to 2009 as estimated from the coastal and island sea-level data (blue). The one standard deviation uncertainty estimates plotted about the low passed sea level are indicated by the shading. The Church and White (2006) estimates for 1870-2001 are shown by the red solid line a...
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Figure 6: Global average sea level from 1860 to 2009 as estimated from the coastal and island sea-level data (blue) compared with estimates of Jevrejeva et al. (2006, brown), Holgate and Woodworth (2004, red) and from a simple average of the gauges (yellow). All series are set to have the same average value over 1960-1...
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References Ablain MA, Cazenave A, Valladeau G, Guinehut S (2009) A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993-2008. Ocean Sci 5:193-2001 Allan R, Ansell T (2006) A new globally complete monthly historical gridded mean sea level pressure dataset (HadSLP2)...
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Holgate SJ (2007) On the decadal rates of sea level change during the twentieth century. Geophys Res Lett 34:L01602. doi:10.1029/2006GL028492 Holgate SJ, Woodworth PL (2004) Evidence for enhanced coastal sea level rise during the 1990s. Geophys Res Lett 31:L07305. doi:10.1029/2004GL019626 Hunter J (2010) Estimating sea...
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Couldrey et al. (2021) Title: What causes the spread of model projections of ocean dynamic sea-level change in response to greenhouse gas forcing? Key Points: Ocean model diversity in AOGCMs is a key source of uncertainty in sea-level projections under greenhouse gas forcing. Increased air-sea heat flux sets the broad...
https://sealeveldocs.readthedocs.io/en/latest/couldrey21.html
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Developing a more complete understanding of the climate response to idealized 1pctCO2 forcing provides insight into how we expect the climate to respond to moderate greenhouse gas and aerosol emissions by the end of this century. However, even when AOGCMs are forced with this simple, idealized setup, they produce a ran...
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Time-dependent CO2 and other forcing causes a varying magnitude of sea-level change, while the spatial pattern is relatively time-invariant (Hawkes 2013; Perrette et al. 2013; Slangen et al. 2014; Bilbao et al. 2015). This phenomenon of ‘pattern scaling’ means that time-dependent forcing is not necessary for our invest...
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Experiment 5 All three perturbations are applied together in the FAF-all experiment. This experiment serves two purposes: to assess how well the perturbations mimic the effect of CO2 forcing as in 1pctCO2, and to determine the extent to which the perturbations counteract or amplify each other’s effects on sea level whe...
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In plots of Δ𝜁𝑁, we subtract the area mean to reveal the spatial pattern of non-steric sea-level change, since spatial anomalies are the quantity of interest for this work. According to recent terminology conventions (Gregory et al. 2019), Δ𝜁 is related to other components of sea-level change through Δ𝜁=Δ𝐵+Δ𝑅𝑚+Δ...
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The OHC change due all three convergences of temperature in (8), Δh, is Δℎ=Δ𝑇𝑐𝑝0𝜌0Δ𝑧, (9) where ∆T, is the difference of the model’s temperature field (T) between the final decades of FAF-heat and FAF-passiveheat (9). In FAF-heat, the heat flux changes the transport processes (Φ′ ≠ 0) and the temperature (𝑇′ ≠ 0)...
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The three prominent features of regional sea-level change identified in previous work (Church et al. 2013; Slangen et al. 2014; Gregory et al. 2016) are apparent here: (1) the Southern Ocean meridional gradient with positive Δζ north of 55° S and negative Δζ at higher latitudes, (2) the meridional dipole of positive Δζ...
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The CMIP5 ensemble uses ten different ocean components (ignoring version differences) among its 19 members (Table 2). In the 16 different CMIP6 AOGCMs shown, there are eight different ocean model components. In the CMIP6 ensemble, six models use a version of NEMO (Nucleus for European Modelling of the Ocean), three use...
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The maps of ∆ζT, ∆ζS and ∆ζN show that the wind forced sea-level change in the Southern Ocean is almost entirely thermosteric (Fig. 7c), as suggested by Gregory et al. (2016). The perturbation causes heat to accumulate between 55° and 30° S while higher latitudes cool (Fig. 6a, g). This is consistent with a wind driven...
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The steric sea-level rise in the Atlantic subpolar gyre, north of 45° N, is due predominantly to positive ∆ζS (i.e. freshening), opposed by weaker negative ∆ζT (Fig. 8c). North of 45° N, there is positive ∆ζS and weaker negative ∆ζT,, in agreement with previous work (Bouttes et al. 2014; Saenko et al. 2015). This is co...
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Fig. 9: Comparison of the multi model ensemble mean zonally- and depth-integrated OHC change in response to heat flux forcing (a) and zonal mean dynamic sea-level change (b) for 11 AOGCMs, showing Δζ (black solid line), the thermosteric component ΔζT (red dotted line) and the sum of thermo- and halosteric components (c...
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For most of the global ocean, Δζsum − Δζall is small and therefore Δζsum approximates the patterns of Δζall. However, small values of multi-model mean Δζsum − Δζall are not necessarily indicative of agreement between models that the responses to perturbations sum linearly. In the western North Pacific and Southern Ocea...
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OHU in the North Atlantic is characterized by positive passive heat uptake that is partially opposed by the perturbed transport (Fig. 12c, e, g). Strong negative Δℎ[Φ′(𝑇−)] and Δℎ[Φ′(𝑇′)] mean that the effect of transport change here is large, cooling the basin. Furthermore, this transport change manifests differentl...
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Previous work has highlighted that individual models when forced with different surface fluxes can produce diverse ocean responses in terms of sea level (Bouttes and Gregory 2014) and ocean heat uptake (Huber and Zanna 2017). Indeed, the uncertainty in surface fluxes is key challenge for climate modelling. By forcing d...
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Caveats, unmodeled processes and further outlook FAFMIP experiments were designed to provide insight into the causes of model spread in greenhouse gas-forced climate change experiments, particularly the 1pctCO2 experiment. The design aimed to mimic the magnitude of 100 years of 1pctCO2 forcing, but the North Atlantic ...
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Conclusions This work documents how FAFMIP experiments are useful tools to derive a new understanding of the drivers of dynamic sea-level change in idealized greenhouse gas forcing experiments. Notably, these latest FAFMIP results show that: Most of the spread of predictions of dynamic sea-level change in response to ...
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Kopp et al. (2014) Title: Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites Key Points: Rates of local sea-level rise differs from rate of global sea-level rise Differences arise from land motion, ocean dynamics, and Antarctic mass balance Local sea-level rise can dramat...
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We first present our framework and projections for selected locations (projections for all tide-gauge locations are included in the Supporting Information), then assess the effects of sea-level rise on coastal flooding risk at these locations. Throughout, we seek to employ transparent assumptions and an easily replicab...
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Figure S2: Static equilibrium sea-level fingerprints employed for (a) GIS, (b) EAIS, (c) WAIS, and (d) median glaciers and ice cap mass loss. Units are meters of local sea level change per meter global sea level change. Glacier and Ice Caps For each RCP, we generate mass balance projections for 17 different source re...
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Glacial Isostatic Adjustment, Tectonics, and Other Non-Climatic Local Effects GIA, tectonics, and other non-climatic local effects that can be approximated as linear trends over the twentieth century are assumed to continue unchanged in the 21st and 22nd centuries. This is a good assumption for GIA, but imperfect for ...
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4 -8 to 15 -11 to 33 -14 to 91 <155 5 -5 to 16 -9 to 33 -11 to 88 <150 6 -4 to 17 -8 to 35 -10 to 93 <155 TE 37 28-46 22-52 12-62 <65 26 18-34 13-40 4-48 <55 19 13-26 8-31 1-38 <40 LWS 5 3-7 2-8 -0 to 11 <11 5 3-7 2-8 -0 to 11 <11 5 3-7 2-8 -0 to 11 <11 Total 79 62-100 52-121 39-176 <245 59 45-77 36-93 24-147 <215 50 3...
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Figure S8: Sources of variance in raw (left) and fractional terms (right), for a range of sites under RCP 2.6. Comparison With Other Global Projections By construction, our likely projections of GSL in 2100 are close to those of AR5 (Table 1), though differ slightly (e.g., in RCP 8.5 in 2100, 0.6 – 1.0 m vs. AR5’s 0....
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Added on top of the climatically driven factors reflected in R are the global effects of land water storage (not shown in Figure 6) and the effects of local land motion (Figure 6c). Moderately high rates of land subsidence can be associated with GIA, as in the northeastern United States (e.g., 1.3 ± 0.2 mm/yr at New Yo...
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Sea-level rise at Key West, Florida, is closer to the global mean, with a likely range in RCP 8.5 by 2100 of 0.6 – 1.1 m (median R = 1.00, likely range of 0.83 – 1.15, background rise of 0.5 ± 0.4 mm/yr). By contrast, the deltaic western Gulf of Mexico coastline experiences some of the fastest rates of sea-level rise i...
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Figure S9: Sources of variance in raw (left) and fractional terms (right), for a range of sites under RCP 8.5. To test the robustness of our results, we examine three alternate assumptions regarding ice sheet mass loss and two alternative assumptions regarding the robustness of GCM projections (Supporting Information ...
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Table 4: Expected number of years with flood events of a given height under different RCPs. Heights for U.S. sites are with respect to the local mean higher high water datum for the 1983–2001 epoch. Heights for non-U.S. sites are with respect to the local mean sea level datum for the 1983–2001 epoch. Figure 7: Expected...
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Third, our background rate estimates are the result of an algorithm applied to a global database of tide-gauge data, with different sites having been subjected to different degrees of quality control. Some tide-gauge sites may have experienced datum shifts or other local sources of errors not identified by the analysis...
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Gaussian process model for tide gauge data The Gaussian process prior for sea level has a mean given by the GIA projections of the ICE-5G VM2-90 model [Peltier , 2004] and a covariance given by the covariance function $k(r_1,t_1,r_2,t_2)$. The covariance is the sum of three terms: one representing GSL change ($k_{glob...
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Bassis, J. N., and C. C. Walker (2012), Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice, Proc. R. Soc. A Math. Phys. Eng. Sci., 468(2140), 913 – 931, doi:10.1098/rspa.2011.0422. Bender, M. A., T. R. Knutson, R. E. Tuleya, J. J. Sirutis, G. A. Vecchi, S. T. Garner, and...
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Horton, B. P., S. Rahmstorf, S. E. Engelhart, and A. C. Kemp (2014), Expert assessment of sea-level rise by AD 2100 and AD 2300, Quat. Sci. Rev., 84, 1 – 6, doi:10.1016/j.quascirev.2013.11.002. Horton, R. M., V. Gornitz, D. A. Bader, A. C. Ruane, R. Goldberg, and C. Rosenzweig (2011), Climate hazard assessment for stak...
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Marzeion, B., A. H. Jarosch, and M. Hofer (2012), Past and future sea-level change from the surface mass balance of glaciers, Cryosphere, 6, 1295 – 1322, doi:10.5194/tc-6-1295-2012. Meinshausen, M., et al. (2011), The RCP greenhouse gas concentrations and their extensions from 1765 to 2300, Clim. Change, 109(1-2), 213 ...
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Rignot, E., J. Mouginot, M. Morlighem, H. Seroussi, and B. Scheuchl (2014), Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophys. Res. Lett., doi:10.1002/2014GL060140. Schaeffer, M., W. Hare, S. Rahmstorf, and M. Vermeer (2012), Long-t...
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