Sources and implications of deep uncertainties surrounding sea-level projections

Bakker, A.; Louchard, Domitille; Keller, Klaus

doi:10.1007/s10584-016-1864-1

Cited by 62 publications

(43 citation statements)

References 43 publications

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“…In general, all else being equal, humans exhibit a preference for the less ambiguous gamble. In sea‐level rise projections, deep uncertainty is reflected in the spread among different probabilistic projections—where there is substantial deep uncertainty, differing but comparably justifiable approaches can yield substantially different probabilistic projections (Bakker, Louchard, & Keller, ; Le Cozannet et al, ; Wong et al, ).…”

Section: Projections Of Relative Sea Level Changementioning

confidence: 99%

Usable Science for Managing the Risks of Sea‐Level Rise

et al. 2019

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Sea-level rise sits at the frontier of usable climate climate change research, because it involves natural and human systems with long lags, irreversible losses, and deep uncertainty. For example, many of the measures to adapt to sea-level rise involve infrastructure and land-use decisions, which can have multigenerational lifetimes and will further influence responses in both natural and human systems. Thus, sea-level science has increasingly grappled with the implications of (1) deep uncertainty in future climate system projections, particularly of human emissions and ice sheet dynamics; (2) the overlay of slow trends and high-frequency variability (e.g., tides and storms) that give rise to many of the most relevant impacts; (3) the effects of changing sea level on the physical exposure and vulnerability of ecological and socioeconomic systems; and (4) the challenges of engaging stakeholder communities with the scientific process in a way that genuinely increases the utility of the science for adaptation decision making. Much fundamental climate system research remains to be done, but many of the most critical issues sit at the intersection of natural sciences, social sciences, engineering, decision science, and political economy. Addressing these issues demands a better understanding of the coupled interactions of mean and extreme sea levels, coastal geomorphology, economics, and migration; decision-first approaches that identify and focus research upon those scientific uncertainties most relevant to concrete adaptation choices; and a political economy that allows usable science to become used science.Plain Language Summary The impacts of sea-level rise pose growing threats to coastal communities, economies, and ecosystems, and decisions made today-in areas like land-use policies, coastal development, and infrastructure investment-will affect exposure and vulnerability for generations to come. Thus, the usability of sea-level science is a pressing concern. Ensuring usability requires grappling with deep uncertainty in long-term sea-level projections, the relationship between long-term trends and the impacts of short-lived extreme events, and the ways in which the physical coast, as well as people and ecosystems along the coast, respond to increasingly frequent flooding. At the same time, it also requires more extensive and deliberate stakeholder engagement throughout the scientific process, as well as cognizance of the political economy of linking stakeholder-engaged science to action.

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Section: Projections Of Relative Sea Level Changementioning

confidence: 99%

Usable Science for Managing the Risks of Sea‐Level Rise

et al. 2019

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“…An additional time lag parameter could be incorporated into the parameterization and model calibration framework, although additional data should be included. Potential future data for assimilation may include paleoclimate data from the Pliocene [11] as well as expert assessment regarding future Antarctic ice sheet mass loss [3,36]. These approaches hold promise for refining the estimates of the trigger temperature ( Fig.…”

Section: /22mentioning

confidence: 99%

Impacts of Antarctic fast dynamics on sea-level projections and coastal flood defense

2017

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Strategies to manage the risks posed by future sea-level rise hinge on a sound characterization of the inherent uncertainties. One of the major uncertainties is the possible rapid disintegration of large fractions of the Antarctic ice sheet in response to rising global temperatures. This could potentially lead to several meters of sea-level rise during the next few centuries. Previous studies have typically been silent on two coupled questions: (i) What are probabilistic estimates of this "fast dynamics" contribution to sea-level rise? (ii) What are the implications for strategies to manage coastal flooding risks? Here, we present probabilistic hindcasts and projections of sea-level rise to 2100. The fast dynamics mechanism is approximated by a simple parameterization, designed to allow for a careful quantification of the uncertainty in its contribution to sea-level rise. We estimate that global temperature increases ranging from 1.9 to 3.1°C coincide with fast Antarctic disintegration, and these contributions account for sea-level rise of 21-74 centimeters this century (5-95% range, Representative Concentration Pathway 8.5). We use a simple cost-benefit analysis of coastal defense to demonstrate in a didactic exercise how neglecting this mechanism and associated uncertainty can (i) lead to strategies which fall sizably short of protection targets and (ii) increase the expected net costs.

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“…Mercer (1978) speculated about the fact that this instability could be triggered through a rise in oceanic temperatures. Collapse of the WAIS sector could cause a sea-level increase of 3-5 m (Bamber et al, 2009;Feldmann and Levermann, 2015;Sutter et al, 2016), with major implications for coastal zones (Nicholls and Cazenave, 2010). From a modeling perspective, projections differ considerably in future sea-level contributions depending on the model used and the process parameterizations therein (Bakker et al, 2017a, b;DeConto and Pollard, 2016;Golledge et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

The Antarctic Ice Sheet response to glacial millennial-scale variability

et al. 2019

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The Antarctic Ice Sheet (AIS) is the largest ice sheet on Earth and hence a major potential contributor to future global sea-level rise. A wealth of studies suggest that increasing oceanic temperatures could cause a collapse of its marine-based western sector, the West Antarctic Ice Sheet, through the mechanism of marine ice-sheet instability, leading to a sea-level increase of 3-5 m. Thus, it is crucial to constrain the sensitivity of the AIS to rapid climate changes. The last glacial period is an ideal benchmark period for this purpose as it was punctuated by abrupt Dansgaard-Oeschger events at millennial timescales. Because their center of action was in the North Atlantic, where their climate impacts were largest, modeling studies have mainly focused on the millennial-scale evolution of Northern Hemisphere (NH) paleo ice sheets. Sea-level reconstructions attribute the origin of millennial-scale sea-level variations mainly to NH paleo ice sheets, with a minor but not negligible role of the AIS. Here we investigate the AIS response to millennialscale climate variability for the first time. To this end we use a three-dimensional, thermomechanical hybrid, ice sheetshelf model. Different oceanic sensitivities are tested and the sea-level equivalent (SLE) contributions computed. We find that whereas atmospheric variability has no appreciable effect on the AIS, changes in submarine melting rates can have a strong impact on it. We show that in contrast to the widespread assumption that the AIS is a slow reactive and static ice sheet that responds at orbital timescales only, it can lead to ice discharges of around 6 m SLE, involving substantial grounding line migrations at millennial timescales.

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Sources and implications of deep uncertainties surrounding sea-level projections

Cited by 62 publications

References 43 publications

Usable Science for Managing the Risks of Sea‐Level Rise

Usable Science for Managing the Risks of Sea‐Level Rise

Impacts of Antarctic fast dynamics on sea-level projections and coastal flood defense

The Antarctic Ice Sheet response to glacial millennial-scale variability

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