Widespread ice sheet retreat in southern Greenland associated with northward expansion and warming of North Atlantic subtropical water masses

2021 ◽  
Author(s):  
Antoon Kuijpers ◽  
Camilla S. Andresen ◽  
Antje H. L. Voelker
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Water Masses ◽  
Subsurface Water ◽  
Mode Water ◽  
Subtropical Water ◽  
Northward Expansion ◽  
Eastern North Atlantic

<p>In the past decades a northward expansion of North Atlantic subtropical water masses<sup>1-3</sup> and warming of subtropical mode water<sup>4,5</sup> (350 – 400 m depth) has been observed. Paleoceanographic records from interglacials prior to 400 ka (‘early Brunhes ‘) reveal a marked inter-hemispheric climate asymmetry with  the average position of the ocean subtropical front in the eastern North Atlantic having shifted at least 4<sup>o</sup> latitude to the north<sup>6,7</sup>. Northward displacement of climate and vegetation belts and previously inferred reduction in sea ice cover at northern high latitudes<sup>7</sup> has later been confirmed by modelling studies<sup>8</sup>. North Atlantic ocean circulation was characterized by an enhanced eastern boundary current poleward transport of warm, (sub)tropical  water masses both at surface and subsurface depth<sup>9,10</sup>.  In recent years (paleo)oceanographic studies of Greenland fjords<sup>  </sup>have demonstrated  that ‘warm’ and saline subsurface water masses of subtropical origin are responsible for sub-glacial melting processes  of Greenland  tide- water glaciers<sup>11-13</sup>. In periods of the early Brunhes interglacials (MIS 11, 13, 15) during which the eastern North Atlantic was characterized by enhanced northward transport of warm, (sub)tropical water masses<sup>9,10</sup>, large parts of the southern Greenland Ice Sheet had melted away and a boreal forest could develop here<sup>14,15</sup> . We conclude that at that time the presence of much warmer, subtropical water masses at subsurface depth in Greenland fjords combined with advection of warm, subtropical air masses with increased precipitation potential from the expanded ocean subtropical gyre region had been responsible for widespread melting of the southern Greenland Ice Sheet. Presently, ongoing  northward expansion and warming of North Atlantic subtropical water masses must therefore be considered to be a process leading to further acceleration of widespread melting of the  (southern) Greenland Ice Sheet.    </p><ul><li>1)   Polovina, J.J. et al. 2008. Geophys. Res. Lett. 35 (3), doi:10.1029/2007GL031745</li> <li>2)   Frundt, B. et al. 2013. Progr. Oceanogr. 116, 246-260, doi:10.1016/j.pocean.2013.07.004</li> <li>3)   Yang, H. et al. 2020. Geophys. Res. Lett. 47 (5), doi:10.1029/2019GL085868</li> <li>4)   Sugimoto, S. et al. 2017. Nature Clim. Change 7, 656-658, doi:10.1038/nclimate3371</li> <li>5)   Wu, L. et al. 2012. Nature Change 2, 161-166, doi:10.1038/nclimate1353</li> <li>6)   Jansen, J.H.F. 1986. Science 232, 619-622</li> <li>7)   Kuijpers, A. Palaeogeogr., Palaeoclimat., Palaeoecol. 76, 67-83</li> <li>8)   Kleinen, T. et al. 2014. Quat. Intern. 348, 247-265, doi:10.1016/j.quaint.2013.12.028</li> <li>9)   Volker, A.H.L. et al. 2010. Clim. Past, 6, 531–552,doi:10.5194/cp-6-531-2010</li> <li>10) Maiorano, P. et al. 2015. Glob. Change 133, 35-48. doi:10.1016/j.glopacha.2015.07.009</li> <li>11) Straneo, F., Heimbach, P. 2013. Nature 504, 36-43</li> <li>12) Adresen, C.S. et al. 2011. The Holocene 21(2), 211-224, doi:10.1177/0959683610378877</li> <li>13) Andresen, C.S. et al. 2013. Shelf. Res. 71, 45-51, doi:10.1016/j.cst.2013.10.003</li> <li>14) Willerslev, E. et al., 2007. Science 317 (5834), 111-114</li> <li>15) De Vernal, A. and Hillaire-Marcel, C., 2008. Science 320, 1622-1625</li> </ul>

scholarly journals Glacial–interglacial Nd isotope variability of North Atlantic Deep Water modulated by North American ice sheet

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ning Zhao ◽  
Delia W. Oppo ◽  
Kuo-Fang Huang ◽  
Jacob N. W. Howe ◽  
Jerzy Blusztajn ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Deep Water ◽  
North American ◽  
Isotope Composition ◽  
Ice Sheet ◽  
North Atlantic Deep Water ◽  
Water Masses ◽  
Nd Isotope ◽  
Nd Isotope Composition

AbstractThe Nd isotope composition of seawater has been used to reconstruct past changes in the contribution of different water masses to the deep ocean. In the absence of contrary information, the Nd isotope compositions of endmember water masses are usually assumed constant during the Quaternary. Here we show that the Nd isotope composition of North Atlantic Deep Water (NADW), a major component of the global overturning ocean circulation, was significantly more radiogenic than modern during the Last Glacial Maximum (LGM), and shifted towards modern values during the deglaciation. We propose that weathering contributions of unradiogenic Nd modulated by the North American Ice Sheet dominated the evolution of the NADW Nd isotope endmember. If water mass mixing dominated the distribution of deep glacial Atlantic Nd isotopes, our results would imply a larger fraction of NADW in the deep Atlantic during the LGM and deglaciation than reconstructed with a constant northern endmember.

The Global Last Glacial Maximum: the Eastern North Atlantic (marine sediments) and the Greenland Ice Sheet climatic signal

2022 ◽  
pp. 189-194
Author(s):  
Samuel Toucanne ◽  
Amaelle Landais ◽  
Filipa Naughton ◽  
Teresa Rodrigues ◽  
Natalia Vázquez Riveiros ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Marine Sediments ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Climatic Signal ◽  
Eastern North Atlantic

Greenland melting signatures in model simulations and oceanic observations

2021 ◽  
Author(s):  
Sophie Stolzenberger ◽  
Roelof Rietbroek ◽  
Claudia Wekerle ◽  
Bernd Uebbing ◽  
Jürgen Kusche
Keyword(s):  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ocean Model ◽  
Freshwater Flux ◽  
Model Simulations ◽  
The North ◽  
Sea Level Anomalies ◽  
The North Atlantic ◽  
The Impact

<p>The impact of Greenland freshwater on oceanic variables in the North Atlantic has been controversially discussed in the past. Within the framework of the German research project GROCE (Greenland Ice Sheet Ocean Interaction), we present a comprehensive study using ocean modelling results including and excluding the Greenland freshwater flux. The aim of this study is whether signatures of Greenland ice sheet melting found in ocean model simulations are visible in the observations. Therefore, we estimate changes in temperature, salinity, steric heights and sea level anomalies since the 1990s. The observational database includes altimetric and gravimetric satellite data as well as Argo floats. We will discuss similarities/differences between model simulations and observations for smaller regions around Greenland in the North Atlantic. As these experiments are available for two different horizontal resolutions, we will furthermore be able to assess the effects of an increased model resolution.</p>

On the role of atmospheric feedbacks in sustaining the anomalous warmth of the MIS-11 interglacial

2021 ◽  
Author(s):  
Brian Crow ◽  
Matthias Prange ◽  
Michael Schulz
Keyword(s):  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Interglacial Period ◽  
Climate Modelling ◽  
Ice Dynamics ◽  
The North ◽  
Atmospheric Feedbacks ◽  
The North Atlantic

<p>Historical estimates of the melt rate and extent of the Greenland ice sheet (GrIS) are poorly constrained, due both to incomplete understanding of relevant ice dynamics and the magnitude of forcing acting upon the ice sheet (e.g., Alley et al. 2010). Previous assessments of the Marine Isotope Stage 11 (MIS-11) interglacial period have determined it was likely one of the warmest and longest interglacial periods of the past 800 kyr, leading to melt of at least half the present-day volume of the Greenland ice sheet (Robinson et al. 2017). An enhanced Atlantic meridional overturning circulation (AMOC) is commonly cited as sustaining the anomalous warmth across the North Atlantic and Greenland (e.g., Rachmayani et al. 2017), but little is known about potential atmospheric contributions. Paleorecords from this period are sparse, and detailed climate modelling studies of this period have been heretofore very limited. The climatic conditions over Greenland and the North Atlantic region, and how they may have contributed to the melt of the GrIS during MIS-11, are therefore not well understood. By utilizing climate simulations with the Community Earth System Model (CESM), our study indicates that changes in atmospheric eddy behavior, including eddy fluxes of heat and precipitation, made significant contributions to the negative mass balance conditions over the GrIS during the MIS-11 interglacial. Thus, accounting for the effects of atmospheric feedbacks in a warmer-than-present climate is a necessary component for future analyses attempting to better constrain the extent and rate of melt of the GrIS.</p>

Accelerated mass loss from Greenland ice sheet: Links to atmospheric circulation in the North Atlantic

2015 ◽  
Vol 128 ◽  
pp. 61-71 ◽  
Author(s):  
Ki-Weon Seo ◽  
Duane E. Waliser ◽  
Choon-Ki Lee ◽  
Baijun Tian ◽  
Ted Scambos ◽  
...  
Keyword(s):  
Mass Loss ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The North ◽  
The North Atlantic

scholarly journals The Occurrence and Properties of Long-Lived Liquid-Bearing Clouds over the Greenland Ice Sheet and Their Relationship to the North Atlantic Oscillation

2018 ◽  
Vol 57 (4) ◽  
pp. 921-935 ◽  
Author(s):  
Jonathan Edwards-Opperman ◽  
Steven Cavallo ◽  
David Turner
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Positive Phase ◽  
Cloud Base ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractStratiform liquid-bearing clouds (LBCs), defined herein as either pure liquid or mixed-phase clouds, have a large impact on the surface radiation budget across the Arctic. LBCs lasting at least 6 h are observed at Summit, Greenland, year-round with a maximum in occurrence during summer. Mean cloud-base height is below 1 km for 85% of LBC cases identified, 59% have mean liquid water path (LWP) values between 10 and 40 g m−2, and most produce sporadic light ice-phase precipitation. During their occurrence, the atmosphere above the ice sheet is anomalously warm and moist, with southerly winds observed over much of the ice sheet, including at Summit. LBCs that occur when the North Atlantic Oscillation (NAO) is in the negative phase correspond to strong ridging centered over the Greenland Ice Sheet (GIS), allowing for southwesterly flow over the GIS toward Summit. During the positive phase of the NAO, the occurrence of LBCs corresponds to a cyclone located off the southeastern coast of the ice sheet, which leads to easterly-to-southeasterly flow toward Summit. Furthermore, air parcels at Summit frequently originate from below the elevation of Summit, indicating that orographic lift along the ice sheet is a factor in the occurrence of LBCs at Summit. LBCs are more frequently observed during the negative NAO, and both the LWP and precipitation rate are larger in LBCs occurring during this phase. Mean LWP in LBCs occurring during the negative NAO is 15 g m−2 larger than in LBCs occurring during the positive phase.

Late-Holocene North Atlantic climate ‘seesaws’, storminess changes and Greenland ice sheet (GISP2) palaeoclimates

The Holocene ◽  
2003 ◽  
Vol 13 (3) ◽  
pp. 381-392 ◽  
Author(s):  
Alastair G. Dawson ◽  
Lorne Elliott ◽  
Paul Mayewski ◽  
Peter Lockett ◽  
Sean Noone ◽  
...  
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
North Atlantic Climate

scholarly journals Increased variability in Greenland Ice Sheet runoff from satellite observations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Thomas Slater ◽  
Andrew Shepherd ◽  
Malcolm McMillan ◽  
Amber Leeson ◽  
Lin Gilbert ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Model Simulations ◽  
Climate Model Simulations

AbstractRunoff from the Greenland Ice Sheet has increased over recent decades affecting global sea level, regional ocean circulation, and coastal marine ecosystems, and it now accounts for most of the contemporary mass imbalance. Estimates of runoff are typically derived from regional climate models because satellite records have been limited to assessments of melting extent. Here, we use CryoSat-2 satellite altimetry to produce direct measurements of Greenland’s runoff variability, based on seasonal changes in the ice sheet’s surface elevation. Between 2011 and 2020, Greenland’s ablation zone thinned on average by 1.4 ± 0.4 m each summer and thickened by 0.9 ± 0.4 m each winter. By adjusting for the steady-state divergence of ice, we estimate that runoff was 357 ± 58 Gt/yr on average – in close agreement with regional climate model simulations (root mean square difference of 47 to 60 Gt/yr). As well as being 21 % higher between 2011 and 2020 than over the preceding three decades, runoff is now also 60 % more variable from year-to-year as a consequence of large-scale fluctuations in atmospheric circulation. Because this variability is not captured in global climate model simulations, our satellite record of runoff should help to refine them and improve confidence in their projections.

scholarly journals Modelling snow accumulation on Greenland in Eemian, glacial inception and modern climates in a GCM

2012 ◽  
Vol 8 (2) ◽  
pp. 1523-1565 ◽  
Author(s):  
H. J. Punge ◽  
H. Gallée ◽  
M. Kageyama ◽  
G. Krinner
Keyword(s):  
Mass Balance ◽  
Ocean Circulation ◽  
Accumulation Rate ◽  
High Surface ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Snow Accumulation ◽  
Local Climate ◽  
North East ◽  
Surface Climate

Abstract. Changing climate conditions on Greenland influence the snow accumulation rate and surface mass balance (SMB) on the ice sheet and, ultimately, its shape. This can in turn affect local climate via orography and albedo variations and, potentially, remote areas via changes in ocean circulation triggered by melt water or calving from the ice sheet. Examining these issues in the IPSL global model requires improving the representation of snow at the ice sheet surface. In this paper, we present the new snow scheme implemented in LMDZ, the atmospheric component of the IPSL coupled model. We analyze surface climate and SMB on the Greenland ice sheet under insolation and oceanic boundary conditions for modern, but also for two different past climates, the last glacial inception (115 kyr BP) and the Eemian (126 kyr BP). While being limited by the low resolution of the GCM, present-day SMB is on the same order of magnitude as recent regional model findings. It is affected by a moist bias of the GCM in Western Greenland and a dry bias in the north-east. Under Eemian conditions, the SMB diminishes largely, and melting affects areas with today high surface altitude including recent ice core drilling sites as NEEM. In contrast, glacial inception conditions lead to a higher mass balance overall due to the reduced melting in the colder summer climate. Compared to the widely applied positive degree day (PDD) parameterization of SMB, our direct modelling results suggest a weaker sensitivity of SMB to changing climatic forcing. In addition, significant differences in surface climate and SMB are found between simulations using monthly climatological mean and actual interannually varying monthly mean forcings for the ocean surface temperature and sea ice cover, in particular for the Eemian.

scholarly journals Small impact of surrounding oceanic conditions on 2007–2012 Greenland Ice Sheet surface mass balance

2014 ◽  
Vol 8 (2) ◽  
pp. 1453-1477 ◽  
Author(s):  
B. Noël ◽  
X. Fettweis ◽  
W. J. van de Berg ◽  
M. R. van den Broeke ◽  
M. Erpicum
Keyword(s):  
Mass Balance ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Katabatic Winds ◽  
Surface Mass ◽  
The North ◽  
The North Atlantic ◽  
Surface Melt

Abstract. During recent summers (2007–2012), several surface melt records were broken over the Greenland Ice Sheet (GrIS). The extreme summer melt resulted in part from a persistent negative phase of the North-Atlantic Oscillation (NAO), favouring warmer than normal conditions over the GrIS. In addition, it has been suggested that significant anomalies in sea ice cover (SIC) and sea surface temperature (SST) may partially explain recent anomalous GrIS surface melt. To assess the impact of 2007–2012 SIC and SST anomalies on GrIS surface mass balance (SMB), a set of sensitivity experiments was carried out with the regional climate model MAR. These simulations suggest that changes in SST and SIC in the seas surrounding Greenland do not significantly impact GrIS SMB, due to the katabatic winds blocking effect. These winds are strong enough to prevent oceanic near-surface air, influenced by SIC and SST variability, from penetrating far inland. Therefore, the ice sheet SMB response is restricted to coastal regions, where katabatic winds are weaker. However, anomalies in SIC and SST could have indirectly affected the surface melt by changing the general circulation in the North Atlantic region, favouring more frequent warm air advection to the GrIS.

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