Climate-change–driven accelerated sea-level rise detected in the altimeter era

Nerem, R. S.; Beckley, B. D.; Fasullo, John T.; Hamlington, B. D.; Masters, Dallas; Mitchum, Gary T.

doi:10.1073/pnas.1717312115

Cited by 846 publications

(591 citation statements)

References 32 publications

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“…Our modelled spatial pattern of mass loss (Figure 2) is consistent with observations (e.g., Gardner et al, 2018;Nerem et al, 2018;Rignot et al, 2019;Shepherd, 2018). While temporally coincident estimates of changes in grounding-line fluxes over the period 1994-2012 are not available for all ice streams, available coincident observations (Rignot et al, 2019) have the same general spatial pattern (as in Figure 2).…”

Section: Discussionsupporting

confidence: 84%

Instantaneous Antarctic ice sheet mass loss driven by thinning ice shelves

Gudmundsson

Paolo

Adusumilli

et al. 2019

Geophysical Research Letters

169

144

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Recent observations show that the rate at which the Antarctic ice sheet (AIS) is contributing to sea level rise is increasing. Increases in ice-ocean heat exchange have the potential to induce substantial mass loss through the melting of its ice shelves. Lack of data and limitations in modeling, however, has made it challenging to quantify the importance of ocean-induced changes in ice shelf thickness as a driver for ongoing mass loss. Here, we use a numerical ice sheet model in combination with satellite observations of ice shelf thinning from 1994 to 2017 to quantify instantaneous changes in ice flow across all AIS grounding lines, resulting from changes in ice shelf buttressing alone. Our process-based predictions are in good agreement with observed spatial patterns of ice loss, providing support for the notion that a significant portion of the current ice loss of the AIS is ocean driven and caused by a reduction in ice shelf buttressing.Plain Language Summary The Antarctic ice sheet is currently losing mass, but the causes for the mass loss remain unclear. It has been suggested that the reduction in the thickness of the floating ice shelves that surround the ice sheet, for example, due to ocean warming or changes in ocean circulation, may be responsible for some of the observed ice loss. However, this hypothesis has remained untested. Here, we use a state-of-the art numerical ice flow model to calculate the direct mass loss due to observed changes in ice shelves between 1994 and 2017. We find that the magnitude and spatial variability of modelled changes of inland ice are in good agreement with observations, suggesting that a substantial portion of the recent ice loss from the grounded Antarctic ice sheet has been driven by changes in its thinning ice shelves. The process we consider (ice shelf buttressing) relates to changes in forces within the ice alone and is therefore effectively instantaneous (i.e., only limited by the speed of stress transition within the ice). Besides providing a possible explanation for a large part of the ongoing mass loss, this finding also shows that we are not protected against the impact of the Antarctic ice sheet on global sea levels by a long response time.

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Section: Discussionsupporting

confidence: 84%

Instantaneous Antarctic ice sheet mass loss driven by thinning ice shelves

Gudmundsson

Paolo

Adusumilli

et al. 2019

Geophysical Research Letters

169

144

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“…Cumulative mass loss from WNA glaciers over the period 2000-2018 could potentially account for 0.32 ± 11-mm global sea level rise equivalent, about 0.6% of observed SLR over the period 1993-2017 (Nerem et al, 2018). Our estimate is an upper limit as it assumes that meltwater from glacier mass loss was directly conveyed to the ocean and not stored in intermediate locations (e.g., proglacial lakes formed over the last 18 years).…”

Section: /2018gl080942mentioning

confidence: 89%

Heterogeneous Changes in Western North American Glaciers Linked to Decadal Variability in Zonal Wind Strength

Menounos

Hugonnet

Shean

et al. 2019

Geophysical Research Letters

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Western North American (WNA) glaciers outside of Alaska cover 14,384 km2 of mountainous terrain. No comprehensive analysis of recent mass change exists for this region. We generated over 15,000 multisensor digital elevation models from spaceborne optical imagery to provide an assessment of mass change for WNA over the period 2000–2018. These glaciers lost 117 ± 42 gigatons (Gt) of mass, which accounts for up to 0.32 ± 0.11 mm of sea level rise over the full period of study. We observe a fourfold increase in mass loss rates between 2000–2009 [−2.9 ± 3.1 Gt yr−1] and 2009–2018 [−12.3 ± 4.6 Gt yr−1], and we attribute this change to a shift in regional meteorological conditions driven by the location and strength of upper level zonal wind. Our results document decadal‐scale climate variability over WNA that will likely modulate glacier mass change in the future.

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“…In this context, global sea level rise has been accelerating in recent decades (Nerem et al, 2018). The projected sea-level rise, of between 65 and 98 cm by the end of the 21st century (Church et al, 2013;Nerem et al, 2018), is expected to cause mangrove migration to higher coastal plains (Cohen et al, 2009Cohen and Lara, 2003). The rate of sea level rise has risen from about 2.5 millimeters per year in the 1990s to about 3.4 millimeters per year today.…”

Section: Projections For the End Of The 21st Centurymentioning

confidence: 99%

Impacts of Holocene and modern sea‐level changes on estuarine mangroves from northeastern Brazil

Cohen

Figueiredo

Oliveira

et al. 2019

Earth Surf Processes Landf

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Projections of the impacts of modern Relative Sea Level (RSL) rise on estuarine mangroves should be supported by coastal topographic data and records of mangrove dynamics under past RSL change. This work identified inland and seaward mangrove migrations along the Jucuruçu River (Bahia, Northeastern Brazil), during the Holocene based on sedimentary features, palynological and geochemical (δ 13 C, δ 15 N, C/N) data integrated with digital elevation models. During the Middle Holocene, in response to RSL rise, the estuary saw mangrove forest establish up to~37 km inland. RSL stood between -1.4 (+0.36/-2.2 m) and +1 (2.19/0.2 m) around 7400 cal yr BP, and rose to a highest position of +3.25 (4.22/2.45 m) reached around 5350 cal yr BP. That marine incursion caused the inland replacement of freshwater vegetation by mangroves on tidal flats. Since then, the estuary experienced RSL fall, reducing inland tidal water salinity towards the Late Holocene, making that the mangroves were replaced by freshwater floodplain vegetation. Today, in the seaward part of the estuary near its mouth, mangroves occupy an area of~10 km 2 along tidal channels. Considering a RSL rise of 98 cm up to the end of the 21 st century, at a rate significantly higher than that of Middle Holocene RSL rise (1.5 mm/yr) and fall (0.6 mm/yr), the current mangrove substrates are expected to drown and/or eroded near the coast, while new mangroves may establish inland, at topographically higher tidal flats in nowadays freshwater-tidal zones. Mangrove area could expand over 13 km 2 of coastal and flood plain. Following the same interaction between RSL/climate changes and Holocene mangrove dynamics, such upstream mangrove migration may be attenuated or intensified by changes in fluvial discharge.

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Climate-change–driven accelerated sea-level rise detected in the altimeter era

Cited by 846 publications

References 32 publications

Instantaneous Antarctic ice sheet mass loss driven by thinning ice shelves

Instantaneous Antarctic ice sheet mass loss driven by thinning ice shelves

Heterogeneous Changes in Western North American Glaciers Linked to Decadal Variability in Zonal Wind Strength

Impacts of Holocene and modern sea‐level changes on estuarine mangroves from northeastern Brazil

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