Sensitivity of Twenty-First-Century Global-Mean Steric Sea Level Rise to Ocean Model Formulation

2013 ◽  
Vol 26 (9) ◽  
pp. 2947-2956 ◽  
Author(s):  
Robert Hallberg ◽  
Alistair Adcroft ◽  
John P. Dunne ◽  
John P. Krasting ◽  
Ronald J. Stouffer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Radiative Forcing ◽  
Ocean Model ◽  
First Century ◽  
Model Formulation ◽  
Steric Sea Level ◽  
Near Surface ◽  
Twenty First Century ◽  
Global Mean

Abstract Two comprehensive Earth system models (ESMs), identical apart from their oceanic components, are used to estimate the uncertainty in projections of twenty-first-century sea level rise due to representational choices in ocean physical formulation. Most prominent among the formulation differences is that one (ESM2M) uses a traditional z-coordinate ocean model, while the other (ESM2G) uses an isopycnal-coordinate ocean. As evidence of model fidelity, differences in twentieth-century global-mean steric sea level rise are not statistically significant between either model and observed trends. However, differences between the two models’ twenty-first-century projections are systematic and both statistically and climatically significant. By 2100, ESM2M exhibits 18% higher global steric sea level rise than ESM2G for all four radiative forcing scenarios (28–49 mm higher), despite having similar changes between the models in the near-surface ocean for several scenarios. These differences arise primarily from the vertical extent over which heat is taken up and the total heat uptake by the models (9% more in ESM2M than ESM2G). The fact that the spun-up control state of ESM2M is warmer than ESM2G also contributes by giving thermal expansion coefficients that are about 7% larger in ESM2M than ESM2G. The differences between these models provide a direct estimate of the sensitivity of twenty-first-century sea level rise to ocean model formulation, and, given the span of these models across the observed volume of the ventilated thermocline, may also approximate the sensitivities expected from uncertainties in the characterization of interior ocean physical processes.

scholarly journals Explaining the Spread in Global Mean Thermosteric Sea Level Rise in CMIP5 Climate Models*

2015 ◽  
Vol 28 (24) ◽  
pp. 9918-9940 ◽  
Author(s):  
Angélique Melet ◽  
Benoit Meyssignac
Keyword(s):  
Twentieth Century ◽  
Sea Level ◽  
Radiative Forcing ◽  
Climate Models ◽  
First Century ◽  
Model Ensemble ◽  
Ocean Heat Uptake ◽  
Feedback Parameter ◽  
Twenty First Century ◽  
Global Mean

Abstract The ocean stores more than 90% of the energy excess associated with anthropogenic climate change. The resulting ocean warming and thermal expansion are leading contributors to global mean sea level (GMSL) rise. Confidence in projections of GMSL rise therefore depends on the ability of climate models to reproduce global mean thermosteric sea level (GMTSL) rise over the twentieth century. This study first compares the GMTSL of the climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to observations over 1961–2005. Although the model ensemble mean is within the uncertainty of observations, the model ensemble exhibits a large spread. The authors then aim to explain the spread in CMIP5 climate model GMTSL over the twentieth and twenty-first centuries. It is shown that the climate models’ GMTSL rise depends linearly on the time-integrated radiative forcing F (under continuously increasing radiative forcing). The constant of proportionality μ expresses the transient thermosteric sea level response of the climate system, and it depends on the fraction of excess heat stored in the ocean, the expansion efficiency of heat, the climate feedback parameter, and the ocean heat uptake efficiency. The across-model spread in μ explains most (>70%) of the across-model spread in GMTSL rise over the twentieth and twenty-first centuries, while the across-model spread in time-integrated F explains the rest. The time-integrated F explains less variance in the across-model GMTSL rise in twenty-first-century than in twentieth-century simulations, as the spread in F is reduced over the twenty-first century because the anthropogenic aerosol forcing, which is a large source of uncertainty in F, becomes relatively smaller.

scholarly journals Contribution of Land Water Storage Change to Regional Sea-Level Rise Over the Twenty-First Century

2021 ◽  
Vol 9 ◽  
Author(s):  
Sitar Karabil ◽  
Edwin H. Sutanudjaja ◽  
Erwin Lambert ◽  
Marc F. P. Bierkens ◽  
Roderik S. W. Van de Wal
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Climate Models ◽  
Sea Level Change ◽  
First Century ◽  
Level Change ◽  
Regional Sea Level ◽  
Twenty First Century ◽  
Land Water ◽  
Global Mean

Change in Land Water Storage (LWS) is one of the main components driving sea-level rise over the twenty-first century. LWS alteration results from both human activities and climate change. Up to now, all components to sea-level change are usually quantified upon a certain climate change scenario except land water changes. Here, we propose to improve this by analyzing the contribution of LWS to regional sea-level change by considering five Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models forced by three different Representative Concentration Pathway (RCP) greenhouse gas emission scenarios. For this analysis, we used LWS output of the global hydrological and water resources model, PCR-GLOBWB 2, in order to project regional sea-level patterns. Projections of ensemble means indicate a range of LWS-driven sea-level rise with larger differences in projections among climate models than between scenarios. Our results suggest that LWS change will contribute around 10% to the projected global mean sea-level rise by the end of twenty-first century. Contribution of LWS to regional sea-level rise is projected to be considerably larger than the global mean over several regions, up to 60% higher than global average of LWS-driven sea-level rise, including the Pacific islands, the south coast of Africa and the west coast of Australia.

scholarly journals “We Would Ride Safely in the Harbor of the Future”: Historical Parallels between the Existential Threats of Yellow Fever and Sea Level Rise in New Orleans and Norfolk

2020 ◽  
Vol 12 (2) ◽  
pp. 331-335
Author(s):  
Morris W. Foster ◽  
Emily E. Steinhilber
Keyword(s):  
Nineteenth Century ◽  
Sea Level Rise ◽  
New Orleans ◽  
Sea Level ◽  
Yellow Fever ◽  
First Century ◽  
Climate Resilience ◽  
Sanitary Reform ◽  
Twenty First Century ◽  
And Sea Level

AbstractThe nineteenth-century experiences of yellow fever epidemics in New Orleans and Norfolk present historical parallels for how those cities, and others, are experiencing existential threats from climate change and sea level rise in the twenty-first century. In particular, the nineteenth-century “sanitary reform” movement can be interpreted as a model for challenges facing twenty-first-century “climate resilience” initiatives, including denialism and political obfuscation of scientific debates as well as tensions between short-term profit and the cost of long-term infrastructure investments and between individualism and communitarianism. The history of sanitary reform suggests that, at least in the United States, climate resilience initiatives will advance largely on a regional basis through extended local debates around these and other challenges until resilient infrastructure and practices are taken for granted, much as sanitary waterworks and sewers are today.

scholarly journals The ability of societies to adapt to twenty-first-century sea-level rise

2018 ◽  
Vol 8 (7) ◽  
pp. 570-578 ◽  
Author(s):  
Jochen Hinkel ◽  
Jeroen C. J. H. Aerts ◽  
Sally Brown ◽  
Jose A. Jiménez ◽  
Daniel Lincke ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
First Century ◽  
Twenty First Century

scholarly journals Scenarios of Twenty-First Century Mean Sea Level Rise at Tide-Gauge Stations Across Canada

2020 ◽  
Vol 58 (4) ◽  
pp. 287-301
Author(s):  
Guoqi Han ◽  
Zhimin Ma ◽  
Aimée B.A. Slangen
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
First Century ◽  
Mean Sea Level ◽  
Twenty First Century

scholarly journals The Reversibility of Sea Level Rise

2013 ◽  
Vol 26 (8) ◽  
pp. 2502-2513 ◽  
Author(s):  
N. Bouttes ◽  
J. M. Gregory ◽  
J. A. Lowe
Keyword(s):  
Thermal Expansion ◽  
Sea Level Rise ◽  
Sea Level ◽  
Co2 Emissions ◽  
Radiative Forcing ◽  
Global Climate ◽  
Surface Air Temperature ◽  
Time Profile ◽  
Step Response ◽  
Global Mean

Abstract During the last century, global climate has been warming, and projections indicate that such a warming is likely to continue over coming decades. Most of the extra heat is stored in the ocean, resulting in thermal expansion of seawater and global mean sea level rise. Previous studies have shown that after CO2 emissions cease or CO2 concentration is stabilized, global mean surface air temperature stabilizes or decreases slowly, but sea level continues to rise. Using idealized CO2 scenario simulations with a hierarchy of models including an AOGCM and a step-response model, the authors show how the evolution of thermal expansion can be interpreted in terms of the climate energy balance and the vertical profile of ocean warming. Whereas surface temperature depends on cumulative CO2 emissions, sea level rise due to thermal expansion depends on the time profile of emissions. Sea level rise is smaller for later emissions, implying that targets to limit sea level rise would need to refer to the rate of emissions, not only to the time integral. Thermal expansion is in principle reversible, but to halt or reverse it quickly requires the radiative forcing to be reduced substantially, which is possible on centennial time scales only by geoengineering. If it could be done, the results indicate that heat would leave the ocean more readily than it entered, but even if thermal expansion were returned to zero, the geographical pattern of sea level would be altered. Therefore, despite any aggressive CO2 mitigation, regional sea level change is inevitable.

Sea-level rise and its possible impacts given a ‘beyond 4°C world’ in the twenty-first century

2011 ◽  
Vol 369 (1934) ◽  
pp. 161-181 ◽  
Author(s):  
Robert J. Nicholls ◽  
Natasha Marinova ◽  
Jason A. Lowe ◽  
Sally Brown ◽  
Pier Vellinga ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Temperature Rise ◽  
Full Range ◽  
Ice Sheets ◽  
Time Frame ◽  
First Century ◽  
Climate Mitigation ◽  
Twenty First Century ◽  
The Impact

The range of future climate-induced sea-level rise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-level rise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m—the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the impact potential is severe, with the real risk of the forced displacement of up to 187 million people over the century (up to 2.4% of global population). This is potentially avoidable by widespread upgrade of protection, albeit rather costly with up to 0.02 per cent of global domestic product needed, and much higher in certain nations. The likelihood of protection being successfully implemented varies between regions, and is lowest in small islands, Africa and parts of Asia, and hence these regions are the most likely to see coastal abandonment. To respond to these challenges, a multi-track approach is required, which would also be appropriate if a temperature rise of less than 4°C was expected. Firstly, we should monitor sea level to detect any significant accelerations in the rate of rise in a timely manner. Secondly, we need to improve our understanding of the climate-induced processes that could contribute to rapid sea-level rise, especially the role of the two major ice sheets, to produce better models that quantify the likely future rise more precisely. Finally, responses need to be carefully considered via a combination of climate mitigation to reduce the rise and adaptation for the residual rise in sea level. In particular, long-term strategic adaptation plans for the full range of possible sea-level rise (and other change) need to be widely developed.

Impacts and responses to sea-level rise: a global analysis of the SRES scenarios over the twenty-first century

2006 ◽  
Vol 364 (1841) ◽  
pp. 1073-1095 ◽  
Author(s):  
Robert J Nicholls ◽  
Richard S.J Tol
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Analysis ◽  
Cost Benefit ◽  
Atmospheric Temperature ◽  
Global Scale ◽  
First Century ◽  
Twenty First Century ◽  
Sres Scenarios ◽  
The Impact

Taking the Special Report on Emission Scenarios (SRES) climate and socio-economic scenarios (A1FI, A2, B1 and B2 ‘future worlds’), the potential impacts of sea-level rise through the twenty-first century are explored using complementary impact and economic analysis methods at the global scale. These methods have never been explored together previously. In all scenarios, the exposure and hence the impact potential due to increased flooding by sea-level rise increases significantly compared to the base year (1990). While mitigation reduces impacts, due to the lagged response of sea-level rise to atmospheric temperature rise, impacts cannot be avoided during the twenty-first century by this response alone. Cost–benefit analyses suggest that widespread protection will be an economically rational response to land loss due to sea-level rise in the four SRES futures that are considered. The most vulnerable future worlds to sea-level rise appear to be the A2 and B2 scenarios, which primarily reflects differences in the socio-economic situation (coastal population, Gross Domestic Product (GDP) and GDP/capita), rather than the magnitude of sea-level rise. Small islands and deltaic settings stand out as being more vulnerable as shown in many earlier analyses. Collectively, these results suggest that human societies will have more choice in how they respond to sea-level rise than is often assumed. However, this conclusion needs to be tempered by recognition that we still do not understand these choices and significant impacts remain possible. Future worlds which experience larger rises in sea-level than considered here (above 35 cm), more extreme events, a reactive rather than proactive approach to adaptation, and where GDP growth is slower or more unequal than in the SRES futures remain a concern. There is considerable scope for further research to better understand these diverse issues.

scholarly journals Correction for Nicholls and Tol, Impacts and responses to sea-level rise: a global analysis of the SRES scenarios over the twenty-first century

2006 ◽  
Vol 364 (1849) ◽  
pp. 3539-3540
Author(s):  
Robert J. Nicholls ◽  
Richard S. J. Toll
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Analysis ◽  
First Century ◽  
Print Version ◽  
Related Article ◽  
Correct Figure ◽  
Article Type ◽  
Twenty First Century ◽  
Sres Scenarios

Correction for ‘Impacts and responses to sea-level rise: a global analysis of the SRES scenarios over the twenty-first century’ by Robert J. Nicholls and Richard S. J. Toll (Phil. Trans. R. Soc. A 364 , 1073–1095. (doi: 10.1098/rsta.2006.1754 )). Figure 10 in the print version of this paper is incorrect; the correct figure is shown in the next page. The first full paragraph of p. 1089 in the print version of this paper is incorrect; the correct paragraph is as follows.

scholarly journals The transient sensitivity of sea level rise

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 181-186
Author(s):  
Aslak Grinsted ◽  
Jens Hesselbjerg Christensen
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Dioxide Emissions ◽  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Greenhouse Gas Emission ◽  
Rate Of Change ◽  
Intergovernmental Panel ◽  
Global Mean

Abstract. Recent assessments from the Intergovernmental Panel on Climate Change (IPCC) imply that global mean sea level is unlikely to rise more than about 1.1 m within this century but will increase further beyond 2100. Even within the most intensive future anthropogenic greenhouse gas emission scenarios, higher levels are assessed to be unlikely. However, some studies conclude that considerably greater sea level rise could be realized, and a number of experts assign a substantially higher likelihood of such a future. To understand this discrepancy, it would be useful to have scenario-independent metrics that can be compared between different approaches. The concept of a transient climate sensitivity has proven to be useful to compare the global mean temperature response of climate models to specific radiative forcing scenarios. Here, we introduce a similar metric for sea level response. By analyzing the mean rate of change in sea level (not sea level itself), we identify a nearly linear relationship with global mean surface temperature (and therefore accumulated carbon dioxide emissions) both in model projections and in observations on a century scale. This motivates us to define the “transient sea level sensitivity” as the increase in the sea level rate associated with a given warming in units of meters per century per kelvin. We find that future projections estimated on climate model responses fall below extrapolation based on recent observational records. This comparison suggests that the likely upper level of sea level projections in recent IPCC reports would be too low.

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