Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise

Overpeck, Jonathan T.; Otto‐Bliesner, Bette L.; Miller, Gifford H.; Muhs, Daniel R.; Alley, Richard B.; Kiehl, J. T.

doi:10.1126/science.1115159

Cited by 419 publications

(267 citation statements)

References 36 publications

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“…A more thorough analysis of sea level records, in other words, seems to permit even higher sea level than the IPCC's figure. The IPCC summary estimate, like other similar estimates (e.g., Overpeck et al, 2006), is based upon examining a few key coral reef terrace localities. The IPCC highlights Hawaii and Bermuda (Muhs et al, 2002); Overpeck et al (2006) also highlight the Bahamas, Western Australia, and the Seychelles Islands.…”

Section: Comparison To Past Estimates Of Last Interglacial Sea Levelmentioning

confidence: 99%

Probabilistic assessment of sea level during the last interglacial stage

Kopp¹,

Simons²,

Mitrovica³

et al. 2009

Nature

698

578

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The Last Interglacial (LIG) stage (ca. 130-115 ka), with polar temperatures likely 3-5 • C warmer than today, serves as a partial analogue for low-end future warming scenarios. Multiple indicators suggest that LIG global sea level (GSL) was higher than at present; based upon a small set of local sea level indicators, the Intergovernmental Panel on Climate Change (IPCC)'s Fourth Assessment Report inferred an elevation of approximately 4-6 m. While this estimate may be correct, it is based upon overly simplistic assumptions about the relationship between local sea level and global sea level. Sea level is often viewed as a simple function of changing global ice volume. This perspective neglects local variability, which arises from several factors, including the distortion of the geoid and the elastic and isostatic deformation of the solid Earth by shifting ice masses. Accurate reconstruction of past global and local sea levels, as well as ice sheet volumes, therefore requires integrating globally distributed data sets of local sea level indicators. To assess the robustness of the IPCC's global estimate and search for patterns in local sea level that are diagnostic of meltwater sources, we have compiled a comprehensive database that includes a variety of local sea level indicators from 47 localities, as well as a global sea level record derived from oxygen isotopes. We generate a global synthesis from these data using a novel statistical approach that couples Gaussian process regression to Markov Chain Monte Carlo simulation of geochronological errors. Our analysis strongly supports the hypothesis that global sea level during the Last Interglacial was higher than today, probably peaking between 6-9 m above the present level. This level is close to that expected from the complete melting of the Greenland Ice Sheet, or from major melting of both the Greenland and West Antarctic Ice Sheets. In the period when sea level was within 10 m of the modern value, the fastest rate of sea level rise sustained for a 1 ky period was likely about 80-110 cm per century. Combined with the evidence for mildly higher temperatures during the LIG, our results highlight the vulnerability of ice sheets to even relatively low levels of sustained global warming.

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Section: Comparison To Past Estimates Of Last Interglacial Sea Levelmentioning

confidence: 99%

Probabilistic assessment of sea level during the last interglacial stage

Kopp¹,

Simons²,

Mitrovica³

et al. 2009

Nature

698

578

View full text Add to dashboard Cite

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“…The WAIS comprises about 10% by volume of the entire Antarctic ice sheet, and in volume is equivalent to a 5-to 6-m rise in sea level (Vaughan and Spouge 2002;Oppenheimer and Alley 2004;Overpeck et al 2006). It is maintained by a balance of precipitation across the sheet, and seaward flow across the ice sheet, to the floating ice shelves.…”

Section: Previous Literaturementioning

confidence: 99%

Global estimates of the impact of a collapse of the West Antarctic ice sheet: an application of FUND

2008

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The threat of an abrupt and extreme rise in sea level is widely discussed in the media, but little understood in practise, especially the likely impacts of such a rise including a potential adaptation response. This paper explores for the first time the global impacts of extreme sea-level rise, triggered by a hypothetical collapse of the West Antarctic Ice Sheet (WAIS). As the potential contributions remain uncertain, a wide range of scenarios are explored: WAIS contributions to sea-level rise of between 0.5 and 5 m/century. Together with other business-as-usual sea-level contributions, in the worst case this gives an approximately 6-m rise of global-mean sea level from 2030 to 2130. Global exposure to extreme sea-level rise is significant: it is estimated that roughly 400 million people (or about 8% of global population) are threatened by a 5-m rise in sea level, just based on 1995 data. The coastal module within the Climate Framework for Uncertainty, Negotiation and Distribution (FUND) model is tuned with global data on coastal zone characteristics concerning population, land areas and land use, and then used for impact analysis under the extreme sea-level rise scenarios. The model considers the interaction of (dry)land loss, wetland loss, protection costs and human displacement, assuming perfect adaptation based on cost-benefit analysis. Unlike earlier analyses, response costs are represented in a non- linear manner, including a sensitivity analysis based on response costs. It is found that much of the world's coast would be abandoned given these extreme scenarios, although according to the global model, significant lengths of the world's coast are worth defending even in the most extreme case. This suggests that actual population displacement would be a small fraction of the potential population displacement, and is consistent with the present distribution of coastal population, which is heavily concentrated in specific areas. Hence, a partial defence can protect most of the world's coastal population. However, protection costs rise substantially diverting large amounts of investment from other sectors, and large areas of (dry)land and coastal wetlands are still predicted to be lost. Detailed case studies of the WAIS collapse in the Netherlands, Thames Estuary and the Rhone delta suggest greater abandonment than shown by the global model, probably because the model assumes perfect implementation of coastal protection and does not account for negative feedbacks when implementation is imperfect. The significant impacts found in the global model together with the potential for greater impacts as found in the detailed case studies shows that the response to abrupt sea-level rise is worthy of further research.Climatic Change (2008) 91:171-191 DOI 10.1007/s10584-008-9424-

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“…We include comparisons to CCSM3 simulations for 130 and 120 ka to evaluate this assumption. We also evaluate a sensitivity simulation with the West Antarctic Ice Sheet (WAIS) removed to test the impact of its extent being much reduced during the LIG [18,24]. We conclude with a comparison to a HadCM3 125 ka simulation, which gives an indication of the robustness of the temperature responses across models, as well as a comparison to the warmth projected for the end of this century.…”

Section: Introductionmentioning

confidence: 99%

How warm was the last interglacial? New model–data comparisons

Otto‐Bliesner

Rosenbloom

Stone

et al. 2013

Phil. Trans. R. Soc. A.

Self Cite

171

208

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A Community Climate System Model, Version 3 (CCSM3) simulation for 125 ka during the Last Interglacial (LIG) is compared to two recent proxy reconstructions to evaluate surface temperature changes from modern times. The dominant forcing change from modern, the orbital forcing, modified the incoming solar insolation at the top of the atmosphere, resulting in large positive anomalies in boreal summer. Greenhouse gas concentrations are similar to those of the pre-industrial (PI) Holocene. CCSM3 simulates an enhanced seasonal cycle over the Northern Hemisphere continents with warming most developed during boreal summer. In addition, year-round warming over the North Atlantic is associated with a seasonal memory of sea ice retreat in CCSM3, which extends the effects of positive summer insolation anomalies on the high-latitude oceans to winter months. The simulated Arctic terrestrial annual warming, though, is much less than the observational evidence, suggesting either missing feedbacks in the simulation and/or interpretation of the proxies. Over Antarctica, CCSM3 cannot reproduce the large LIG warming recorded by the Antarctic ice cores, even with simulations designed to consider observed evidence of early LIG warmth in Southern Ocean and Antarctica records and the possible disintegration of the West Antarctic Ice Sheet. Comparisons with a HadCM3 simulation indicate that sea ice is important for understanding model polar responses. Overall, the models simulate little global annual surface temperature change, while the proxy reconstructions suggest a global annual warming at LIG (as compared to the PI Holocene) of approximately 1 ° C, though with possible spatial sampling biases. The CCSM3 SRES B1 (low scenario) future projections suggest high-latitude warmth similar to that reconstructed for the LIG may be exceeded before the end of this century.

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Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise

Cited by 419 publications

References 36 publications

Probabilistic assessment of sea level during the last interglacial stage

Probabilistic assessment of sea level during the last interglacial stage

Global estimates of the impact of a collapse of the West Antarctic ice sheet: an application of FUND

How warm was the last interglacial? New model–data comparisons

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