@article {edgerton_evaluating_2024,
	title = {Evaluating middle to late Holocene climate variability from δ18O of aquatic invertebrate remains in southwestern Greenland},
	journal = {Quaternary Science Reviews},
	volume = {333},
	year = {2024},
	month = {06/2024},
	pages = {108664},
	abstract = {Holocene paleotemperature records from ice-free margins of Greenland suggest spatiotemporal heterogeneity in the timing of key climate transitions following retreat of the Greenland Ice Sheet. However, the paucity of high-resolution climate records from this region limits our understanding of the timing, spatial variation, and drivers of Holocene climate variability. Here, we present a middle to late Holocene climate reconstruction based on δ18O of aquatic invertebrate (chironomid and cladoceran) remains and sediment geochemistry from lake sediments to elucidate millennial to submillennial-scale drivers of climate in southwestern Greenland. We establish that our site, Arrowhead Lake, is a through-flowing basin with an integrated signal of annual meteoric water with no evidence of significant evaporative enrichment. Core sediment geochemistry captures the transition from minerogenic-dominated to organic-rich sediments \~{}8~cal ka BP. Chitin-based δ18O measurements of both chironomid head capsules and ephippia exhibit similar temporal variability through the record, broadly decreasing from 8.2~cal ka BP to present, concurrent with decreasing summer insolation and regional Neoglacial cooling. A simplified assumption that temperature is the sole driver of changes in isotopes of precipitation yields an estimated average temperature change from the middle to late Holocene at Arrowhead Lake of 2.1{\textendash}3.0~{\textdegree}C, comparable to existing estimates of middle to late Holocene temperature decline in western Greenland. Depleted δ18O values after 3.3~cal ka BP correspond to the onset of Neoglacial cooling and independent evidence for a slowdown of the West Greenland Current, and suggests that both temperature and sea-ice variability were important controls on isotopic variability at this site. Highly depleted isotopic values at 8.2~cal ka BP followed by high isotopic variability in the early part of the middle Holocene suggests that our record may capture regional 8.2 ka cooling. This new isotope record provides insight into climate influences during the middle and late Holocene along the western Greenland margin that are important for understanding how ongoing melt of the Greenland Ice Sheet and amplified warming in the Arctic may impact the climate system.},
	keywords = {Chitin, Greenland, Holocene, paleoclimatology, Stable isotopes, δO},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2024.108664},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379124001653},
	author = {Edgerton, Briana A. and Axford, Yarrow and Chipman, Melissa L.}
}
@article {puleo_younger_2022,
	title = {Younger Dryas and early Holocene climate in south Greenland inferred from oxygen isotopes of chironomids, aquatic Moss, and Moss cellulose},
	journal = {Quaternary Science Reviews},
	volume = {296},
	year = {2022},
	month = {11/2022},
	pages = {107810},
	abstract = {Ice core records have long indicated that the Younger Dryas began and ended with large, abrupt climate shifts over Greenland. Key climatic features remain unknown, including the magnitude of warming during the Younger Dryas-Holocene transition along with the seasonality and spatial variability of Younger Dryas climate changes across Greenland. Here, we use geochemical and paleoecological proxies from lake sediments at Lake N14 in south Greenland to address these outstanding questions. Radiocarbon dating and diatom assemblages confirm early deglaciation and isolation of Lake N14 before \~{}13,600~cal~yr BP, consistent with previous work. Oxygen isotope ratios (δ18O) of chironomid head capsules, bulk aquatic moss, and aquatic moss-derived cellulose are used to reconstruct oxygen isotopes of past lake water and annual precipitation. Oxygen isotope proxies indicate annual precipitation δ18O values increased by 5.9{\textendash}7.7{\textperthousand} at the end of the Younger Dryas. Following the Younger Dryas, moss and cellulose δ18O values show a clear decline in precipitation δ18O values of 2{\textendash}3{\textperthousand} from \~{}11,540{\textendash}11,340~cal~yr BP that may correspond with the Preboreal Oscillation. Reconstructed precipitation δ18O values then gradually increased from 11,300{\textendash}10,100~cal~yr BP. All three aquatic organic materials register similar shifts in precipitation δ18O values over time, and they closely parallel the δ18O shifts observed in ice cores. This evidence strongly supports the utility of these methods for reconstructing lake water δ18O, and furthermore precipitation δ18O values where lake water reflects precipitation. The relatively large shift in isotopic composition of precipitation at Lake N14 suggests that shifts in temperature, precipitation seasonality, and/or moisture sources at the end of the Younger Dryas were even larger in south Greenland than they were in central Greenland, most likely because of the proximity to major changes in North Atlantic Ocean circulation. The annual air temperature change estimated at Lake N14 at the end of the Younger Dryas is also very large (\~{}18~{\textpm}~7~{\textdegree}C) compared to the summer warming previously inferred from chironomid species assemblages there (\~{}6~{\textdegree}C). This indicates that the strongest warming at the end of the Younger Dryas occurred in the winter season, consistent with past observations of intensified Younger Dryas seasonality at Lake N14 and elsewhere in Greenland.},
	keywords = {Chironomids, Deglaciation, diatoms, Greenland, Holocene, Micropaleontology, paleoclimatology, paleolimnology, Stable isotopes, Younger Dryas},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2022.107810},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379122004413},
	author = {Puleo, Peter J. K. and Masterson, Andrew L. and Medeiros, Andrew S. and Schellinger, Grace and Steigleder, Regan and Woodroffe, Sarah and Osburn, Magdalena R. and Axford, Yarrow}
}
@article {2688,
	title = {Holocene temperature and landscape history of southwest Greenland inferred from isotope and geochemical lake sediment proxies},
	journal = {Quaternary Science Reviews},
	volume = {239},
	year = {2020},
	month = {Jan-07-2020},
	pages = {106358},
	abstract = {Terrestrial temperature reconstructions from the ice-free margins of Greenland are critical for constraining the sensitivity of the Greenland ice sheet to past climate change. Numerous investigations have clarified the glacial history of southwest Greenland in recent decades; however, very few local quantitative temperature reconstructions exist as context for changes in the cryosphere. We examine sedimentary records from two lakes south of Nuuk, Greenland (informally named lakes T1 and T2), and investigate millennial scale Holocene climate change using a multi-proxy approach. Changes in X-Ray fluorescence spectroscopy (XRF), δ15N, δ13C and biogenic silica concentrations of bulk lake sediments mark the transition from a marine environment to isolated lakes as relative sea level fell in the early Holocene. δ18O values of subfossil insects (chironomids) from lakes T1 and T2 decreased by 2{\textendash}3{\textperthousand} from c. 8.8 ka BP (minimum limiting age for the onset of lacustrine sediment deposition in lake T2; ka BP = thousands of years before 1950) to 1 ka BP. Existing isotope-independent temperature reconstructions from the west coast of Greenland suggest that these changes in δ18O values accompanied gradual cooling of 2{\textendash}4 {\textdegree}C, concomitant with decreasing summer insolation. There is widespread regional evidence that this cooling resulted in progressive regrowth of local glaciers and of the ice sheet. The regional consensus on the magnitude of this temperature change indicates that the local, modern modeled temperature - precipitation δ18O relationship cannot be used to quantify millennial-scale temperature changes at these sites through the Holocene. This reinforces that studies utilizing δ18O-based proxies to infer temperature change should carefully assess local isotope-temperature relationships over space and time.},
	keywords = {Chironomids, glaciers, Greenland, Isolation basins, lake sediments, oxygen isotopes, Paleotemperatures, Stable isotopes},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106358},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379120303206},
	author = {Lasher, G. Everett and Axford, Yarrow and Masterson, Andrew L. and Berman, Karalyn and Larocca, Laura J.}
}
@article {2689,
	title = {Local glaciers record delayed peak Holocene warmth in south Greenland},
	journal = {Quaternary Science Reviews},
	volume = {241},
	year = {2020},
	month = {Jan-08-2020},
	pages = {106421},
	abstract = {Local glaciers and ice caps (GICs) respond sensitively and quickly, on the scale of decades to centuries, to climate variations. Continuous records of past fluctuations in GIC size provide information on the timing and magnitude of Holocene climate shifts, and a longer-term perspective on 21st century glacier retreat. Although there is broad-scale agreement on millennial-scale trends in Holocene climate variability and fluctuations in local GICs in Greenland, regional variations are only loosely constrained. Here we present three Holocene proglacial lake sediment records from South Greenland, an area with abundant local glaciers but few Holocene-length paleoclimate records. In addition, we use geospatial analysis to model past equilibrium-line altitudes (ELAs) and thereby constrain the magnitude of ablation-season temperature change during the warmest and coolest periods of the Holocene. Physical and geochemical sedimentary characteristics show that two of the proglacial lakes continued to receive glacial meltwater input until \~{}7.3 and \~{}7.1 ka BP. The survival of local glaciers implies that South Greenland remained relatively cool, and that summer temperatures gradually warmed, but did not warm well beyond 1.2 {\textdegree}C above present in the early Holocene. In the mid-Holocene, from \~{}7.1 to 5.5 ka BP, organic sedimentation at these two sites indicates that local glaciers became very small, or more likely melted away completely. The glaciers within the third lake{\textquoteright}s catchment melted away prior to \~{}5.2 ka BP, as sediments deposited earlier in the Holocene could not be dated at this site. We estimate that summer temperatures increased by at least 1.2{\textendash}1.8 {\textdegree}C above present by \~{}7.3{\textendash}7.1 ka BP. Our results are consistent with other observations that suggest a north-to-south gradient in the timing of Holocene thermal maximum conditions, with southern Greenland experiencing a delayed warming relative to other regions in Greenland. As summer temperatures cooled in the Neoglacial, our records show that sustained glacier regrowth began \~{}3.1 ka BP with glaciers in the southernmost catchment, which at present, receive the most precipitation. In the other two catchments, which host smaller glaciers in a drier environment, regrowth began at \~{}1.3 and \~{}1.2 ka BP, the timing of which is in agreement with other glacial records from the Arctic Atlantic region. Local glaciers reached their maximum late Holocene extents during a cooler, second phase of the Little Ice Age (LIA) \~{}0.2-0.1 ka BP, that we estimate was at least 0.4{\textendash}0.9 {\textdegree}C cooler than present. Overall, these findings improve understanding of the spatio-temporal dynamics of Holocene glacier and climate change in Greenland, potentially yielding valuable information about their future response.},
	keywords = {Equilibrium-line altitudes, Greenland, Holocene thermal maximum, lake sediments, Little ice age, Mountain glaciers, Paleotemperatures},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106421},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379120303838},
	author = {Larocca, Laura J. and Axford, Yarrow and Bj{\o}rk, Anders A. and Lasher, G. Everett and Brooks, Jeremy P.}
}
@article {2708,
	title = {Multiple independent records of local glacier variability on Nuussuaq, West Greenland, during the Holocene},
	journal = {Quaternary Science Reviews},
	volume = {215},
	year = {2019},
	month = {Jan-07-2019},
	pages = {253 - 271},
	abstract = {The sensitivity of mountain glaciers to small-scale climate fluctuations makes records of their past extent among the best proxies for identifying spatio-temporal climate variability. Here we build on the few existing Holocene records of local glacier change in Greenland by using three independent geochronological methods{\textemdash}proglacial lake sediment analysis, cosmogenic 10Be surface-exposure dating, and in situ 14C burial modeling{\textemdash}to reconstruct continuous records of Holocene glacier variability on Nuussuaq, West Greenland. 10Be ages of perched boulders indicate eastern Nuussuaq was deglaciated between \~{}11.0 and 10.5 ka. Radiocarbon-dated sediments from two lakes on Nuussuaq contain mineral-rich layers between \~{}9.6 and 9.0 and \~{}8.7{\textendash}8.0 cal ka BP that may be correlative with nearby ice sheet moraines deposited in the early Holocene. Multiple proxies for glacier size indicate frequent, high-amplitude glacier fluctuations superimposed on net glacier growth during the late Holocene, with significant ice expansion phases at \~{}3.7 ka, 2.8 ka, and throughout the past \~{}2 ka. Mean 10Be ages from five nested moraine crests confirm that local glacier extents on Nuussuaq culminated during both the Little Ice Age [\~{}1470 C.E. (n = 3) and 1750 C.E. (n = 3)] and the preceding centuries (\~{}520{\textendash}1320 C.E.; n = 11). Results reveal that local glaciers on Nuussuaq episodically advanced and retreated at centennial timescales throughout the Holocene, most likely in response to regional climate changes in West Greenland superimposed on the progressive insolation-driven cooling trend in the Northern Hemisphere. Our new 10Be moraine chronologies coupled with other glacier-size proxies corroborate an emerging pattern of significant summer cooling and glacier expansion in the centuries prior to the Little Ice Age in the Arctic.},
	keywords = {Cosmogenic 10Be, Cosmogenic in situ 14C, Greenland, Holocene, lake sediment, Mountain glaciers, Neoglaciation},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2019.05.007},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379118308771},
	author = {Schweinsberg, Avriel D. and Briner, Jason P. and Licciardi, Joseph M. and Bennike, Ole and Lifton, Nathaniel A. and Graham, Brandon L. and Young, Nicol{\'a}s E. and Schaefer, Joerg M. and Zimmerman, Susan H.}
}
@article {2709,
	title = {Holocene mountain glacier history in the Sukkertoppen Iskappe area, southwest Greenland},
	journal = {Quaternary Science Reviews},
	volume = {197},
	year = {2018},
	month = {Jan-10-2018},
	pages = {142 - 161},
	abstract = {Mountain glaciers and ice caps (GIC) independent of the Greenland Ice Sheet respond rapidly to climate variations and records of their past extent provide information on the natural envelope of climate variability. Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ 10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland. Following local deglaciation \~{}10-9 ka, sediments from proglacial Crash Lake record a glacier advance at \~{}9 ka that is indistinguishable from nearby ice sheet moraines, implying a synchronous response of GIC and the Greenland Ice Sheet to a centennial-scale climate event. Following this local glacier advance, GIC experienced net recession until \~{}4.6 ka. Radiocarbon ages of in situ moss (n = 29) and Crash Lake sediments reveal intervals of glacier expansion at \~{}1.8, 1.2 and 0.7 ka that are superimposed on an overall trend of net glacier expansion throughout the late Holocene. In situ 14C concentrations from bedrock adjacent to radiocarbon-dated moss samples further constrain the duration of ice cover through the Holocene in this region. We find that our glacier-size proxy records during the past \~{}4 ka are broadly consistent with relatively lower temperatures recorded in GISP2 and occur during, or following, intervals of volcanic perturbations. Thus, we speculate that volcanic activity, although less frequent and intense than in the early Holocene and during the Little Ice Age, may have led to centennial-scale variability imprinted on net glacier expansion due to decreasing summer insolation through the late Holocene.},
	keywords = {Cosmogenic in situ 14C, Glacier fluctuations, Greenland, Holocene, lake sediment, Neoglaciation},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2018.06.014},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379118302531},
	author = {Schweinsberg, Avriel D. and Briner, Jason P. and Miller, Gifford H. and Lifton, Nathaniel A. and Bennike, Ole and Graham, Brandon L.}
}
@article {2529,
	title = {Holocene climate and environmental history of East Greenland inferred from lake sediments},
	journal = {Journal of Paleolimnology},
	volume = {57},
	year = {2017},
	month = {Jan-04-2017},
	pages = {321 - 341},
	abstract = {Prediction of future Arctic climate and environmental changes, as well as associated ice-sheet behavior, requires placing present-day warming and reduced ice extent into a long-term context. Here we present a record of Holocene climate and glacier fluctuations inferred from the paleolimnology of small lakes near Istorvet ice cap in East Greenland. Calibrated radiocarbon dates of organic remains indicate deglaciation of the region before ~10,500 years BP, after which time the ice cap receded rapidly to a position similar to or less extensive than present, and lake sediments shifted from glacio-lacustrine clay to relatively organic-rich gyttja. The lack of glacio-lacustrine sediments throughout most of the record suggests that the ice cap was similar to or smaller than present throughout most of the Holocene. This restricted ice extent suggests that climate was similar to or warmer than present, in keeping with other records from Greenland that indicate a warm early and middle Holocene. Middle Holocene magnetic susceptibility oscillations, with a ~200-year frequency in one of the lakes, may relate to solar influence on local catchment processes. Following thousands of years of restricted extent, Istorvet ice cap advanced to within 365 m of its late Holocene limit at ~AD 1150. Variability in the timing of glacial and climate fluctuations, as well as of sediment organic content changes among East Greenland lacustrine records, may be a consequence of local factors, such as elevation, continentality, water depth, turbidity, and seabirds, and highlights the need for a detailed spatial array of datasets to address questions about Holocene climate change.},
	keywords = {De Vries cycle, Glacially fed lakes, Greenland, Holocene, Paleoclimate},
	issn = {0921-2728},
	doi = {10.1007/s10933-017-9951-5},
	url = {http://link.springer.com/10.1007/s10933-017-9951-5},
	author = {Lusas, Amanda R. and Hall, Brenda L. and Lowell, Thomas V. and Kelly, Meredith A. and Bennike, Ole and Levy, Laura B. and Honsaker, William}
}
@article {2601,
	title = {Holocene temperatures and isotopes of precipitation in Northwest Greenland recorded in lacustrine organic materials},
	journal = {Quaternary Science Reviews},
	volume = {170},
	year = {2017},
	month = {Jan-08-2017},
	pages = {45 - 55},
	abstract = {Reconstructions of Holocene lake water isotopic composition based upon subfossil aquatic organic material offer new insights into Arctic
climate. We present quantitative estimates of warmth during the Holocene Thermal Maximum in northwest Greenland, inferred from oxygen isotopes of chironomid head capsules and aquatic moss preserved in lake sediments. delta O-18 values of chironomids from surface sediments of multiple Greenland lakes indicate that these subfossil remains record the delta O-18 values of the lake water in which they grow. Our lake water delta O-18 reconstruction is supported by downcore agreement with delta O-18 values in aquatic moss and chironomid remains. delta O-18 of both organic materials from Secret Lake decrease after 4 ka (ka = thousands of years ago) by 3 parts per thousand into the Neoglacial. We argue that lake water at Secret Lake primarily reflects precipitation delta O-18 values, which is strongly correlated with air temperature in NW Greenland, and that this signal is biased towards summer and early autumn conditions. Other factors may have influenced Secret Lake delta O-18 values through the Holocene, including evaporation of lake water and changing seasonality and source of precipitation. The maximum early Holocene summer and early autumn-biased temperature anomaly at Secret Lake is 2.5-4 degrees C warmer than present from 7.7 (the beginning of our record) to similar to 6 ka. The maximum late Holocene cold anomaly (which includes the Little Ice Age) is 1.5-3 degrees C colder than present. These ranges of possible temperature anomalies reflect uncertainty in the delta O-18 temperature relationship for precipitation at the study site through the Holocene. (C) 2017 Elsevier Ltd. All rights reserved.},
	keywords = {Chironomids, Greenland, Holocene, paleoclimatology, paleolimnology, Stable isotopes},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2017.06.016},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0277379116305650http://api.elsevier.com/content/article/PII:S0277379116305650?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0277379116305650?httpAccept=text/plain},
	author = {Lasher, G. Everett and Axford, Yarrow and McFarlin, Jamie M. and Kelly, Meredith A. and Osterberg, Erich C. and Berkelhammer, Max B.}
}
@article { ISI:000364884400008,
	title = {Early deglacial onset of southwestern Greenland ice-sheet retreat on the continental shelf},
	journal = {QUATERNARY SCIENCE REVIEWS},
	volume = {128},
	year = {2015},
	month = {NOV 15},
	pages = {117-126},
	type = {Article},
	abstract = {The Greenland ice sheet (GrIS) advanced onto the continental shelf during the last glacial period. While deglacial records for when the GrIS withdrew onto the modern coastline are relatively abundant, the timing of early GrIS retreat on the shelf is poorly constrained. Here we use planktic foraminiferal delta O-18, sediment grain size, sedimentation rates, and C-14 ages in southeastern Davis Strait core HU87033-008 to develop an early deglaciation chronology of the southwestern GrIS while on the continental shelf. Sedimentation rates, and especially silt and clay fractions, are high between similar to 20.5 and similar to 17.1 ka, suggesting that the southwestern GrIS margin was near or at the shelf break, where it released subglacially derived sediment-laden meltwater. A peak in sedimentation rates of similar to 110 cm ka(-1) between similar to 19.3 ka and similar to 18.6 ka, combined with an initial decrease in planktic delta O-18 of similar to 0.5 per mil, suggests an early deglacial pull back of the GrIS margin from the shelf break with a concurrent increase in surface ocean meltwater discharge. A subsequent planktic delta O-18 decrease of similar to 1.0 per mil combined with a drop in silt and clay sedimentation rates at 18-17 ka likely record further GrIS retreat inland from the shelf break. Terrestrial Be-10 surface exposure ages indicate that the GrIS margin remained on the continental shelf until similar to 11 ka, yet the cause of this subsequent ice-margin stability on the inner shelf is not known. Our new records provide the first evidence that the southwestern GrIS margin may have begun to deglaciate at the same time as other Northern Hemisphere ice sheets. As Labrador Sea water temperatures likely remained near glacial values until similar to 15 ka, we suggest that initial southwestern GrIS retreat was in response to rising global sea level from retreat of other ice sheets and/or the initial deglacial rise in boreal summer insolation. (C) 2015 Elsevier Ltd. All rights reserved.},
	keywords = {Davis Strait, Deglaciation, Greenland, Retreat forcings, sea level, Sedimentation rate},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2015.10.008},
	author = {Winsor, Kelsey and Carlson, Anders E. and Welke, Bethany M. and Reilly, Brendan}
}
