Global environmental consequences of twenty-first-century ice-sheet melt

Golledge, Nicholas R.; Keller, Elizabeth D.; Gomez, Natalya; Naughten, Kaitlin A.; Bernales, Jorge; Trusel, Luke D.; Edwards, Tamsin

doi:10.1038/s41586-019-0889-9

Cited by 367 publications

(445 citation statements)

References 123 publications

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“…There is, for example, no addition of melt water from ice sheets in either of them even though there is considerable warming in both of them. Recent research has shown a strong influence of melt water forcing on the transient evolution of coupled climate models (Golledge et al 2019). We will come back to what distinguishes these two branches in terms of changes in the general circulation in the discussion and conclusions section.…”

Section: Resultsmentioning

confidence: 95%

An update on the thermosteric sea level rise commitment to global warming

Hieronymus

2019

Environ. Res. Lett.

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The equilibrium thermosteric sea level rise caused by global warming is evaluated in several coupled climate models. The thermosteric sea level rise is found to be well approximated as a linear function of the mean ocean temperature increase in the models. However, the mean ocean temperature increase as a function of the mean surface temperature increase differs between the models. Our models can be divided into two branches; models with an Atlantic meridional overturning circulation that increases with warming have large mean ocean temperature increases and vice versa. These two different branches give estimates of the equilibrium thermosteric sea level rise per degree of surface warming that are respectively 98% and 21% larger than the estimate given in the IPCC Fifth Assessment Report. Our estimates of the equilibrium thermosteric sea level rise are also used to infer an equilibrium sea level sensitivity, a parameter akin to the often used equilibrium climate sensitivity metric.

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Section: Resultsmentioning

confidence: 95%

An update on the thermosteric sea level rise commitment to global warming

Hieronymus

2019

Environ. Res. Lett.

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“…In the left panel, g* and g** refer to two interpretations of the Coupled Model Intercomparison Project Phase 5 ensemble uncertainty (see Le Bars et al, 2017). loss are much higher than those of other recent publications (Golledge et al, 2015;Levermann et al, 2014;Ritz et al, 2015), because their model produces widespread early surface melting of ice shelves, leading to hydrofracturing and complete collapse (as occurred for the Larsen B ice shelf in 2002), and subsequent marine ice cliff instability (MICI) in many places. While this is physically plausible, this chain of processes has so far not been observed, and the most recent publications Golledge et al, 2019) find a much smaller Antarctic contributions by 2100 as well as that it is not essential that the ice cliff mechanism is required to simulate paleo sea level observations. For those regions where Antarctica is currently retreating (Thwaites glacier in particular), the general understanding is that it is not due to the above mentioned chain of processes but rather due to enhanced basal melting below the ice shelves (Joughin et al, 2014;Rignot et al, 2014).…”

Section: /2018ef001071mentioning

confidence: 94%

“…Very low confidence: Third, we combine the probability distributions of studies based on DP16, notably Kopp et al (2017) and Le Bars et al (2017). We assign a very low confidence to these studies due to their results being conditional on a single and observationally poorly constrained line of evidence (i.e., a single ice sheet model), and the much lower projections from the most recent studies Golledge et al, 2019).…”

Section: /2018ef001071mentioning

confidence: 99%

Meeting User Needs for Sea Level Rise Information: A Decision Analysis Perspective

et al. 2019

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Despite widespread efforts to implement climate services, there is almost no literature that systematically analyzes users' needs. This paper addresses this gap by applying a decision analysis perspective to identify what kind of mean sea level rise (SLR) information is needed for local coastal adaptation decisions. We first characterize these decisions, then identify suitable decision analysis approaches and the sea level information required, and finally discuss if and how these information needs can be met given the state of the art of sea level science. We find that four types of information are needed: (i) probabilistic predictions for short‐term decisions when users are uncertainty tolerant; (ii) high‐end and low‐end SLR scenarios chosen for different levels of uncertainty tolerance; (iii) upper bounds of SLR for users with a low uncertainty tolerance; and (iv) learning scenarios derived from estimating what knowledge will plausibly emerge about SLR over time. Probabilistic predictions can only be attained for the near term (i.e., 2030–2050) before SLR significantly diverges between low and high emission scenarios, for locations for which modes of climate variability are well understood and the vertical land movement contribution to local sea levels is small. Meaningful SLR upper bounds cannot be defined unambiguously from a physical perspective. Low‐ to high‐end scenarios for different levels of uncertainty tolerance and learning scenarios can be produced, but this involves both expert and user judgments. The decision analysis procedure elaborated here can be applied to other types of climate information that are required for mitigation and adaptation purposes.

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“…Understanding past changes is critical in order to improve projections of Antarctic ice sheet evolution over the next decades and centuries in response to climate change. Previous modeling studies showed variable Antarctic contribution to sea level rise over the coming century, depending on the physical processes included (e.g., Edwards et al, 2019), forcing used (e.g., Golledge et al, 2015;Schlegel et al, 2018) or model parameterizations (e.g., Bulthuis et al, 2019), leading to results varying between a few mm to more than 1 meter of sea level contribution by the end of the century (Ritz et al, 2015;Pollard et al, 2015;Little et al, 2013;Levermann et al, 2014). Model intercomparison efforts such as Ice2Sea (Edwards et al, 2014) and SeaRISE 35 (Sea-level Response to Ice Sheet Evolution, Bindschadler et al, 2013;Nowicki et al, 2013a) highlighted the large discrepancies in numerical ice flow model results, even when similar climate conditions are applied for model forcing.…”

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confidence: 99%

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Seroussi¹,

Goelzer²,

Morlighem³

2020

Preprint

122

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Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and inform on the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimated the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes and the forcings employed. This study presents results from 18 simulations from 15 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100, forced with different scenarios from the Cou-5 pled Model Intercomparison Project Phase 5 (CMIP5) representative of the spread in climate model results. The contribution of the Antarctic ice sheet in response to increased warming during this period varies between -7.8 and 30.0 cm of Sea Level Equivalent (SLE). The evolution of the West Antarctic Ice Sheet varies widely among models, with an overall mass loss up to 21.0 cm SLE in response to changes in oceanic conditions. East Antarctica mass change varies between -6.5 and 16.5 cm SLE, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario 10 forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional mass loss of 8 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 AOGCMs show an overall mass loss of 10 mm SLE compared to simulations done under present-day 15 conditions, with limited mass gain in East Antarctica.

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Global environmental consequences of twenty-first-century ice-sheet melt

Cited by 367 publications

References 123 publications

An update on the thermosteric sea level rise commitment to global warming

An update on the thermosteric sea level rise commitment to global warming

Meeting User Needs for Sea Level Rise Information: A Decision Analysis Perspective

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

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