@article {2883,
	title = {Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes},
	journal = {Geophysical Research Letters},
	volume = {47},
	year = {2020},
	month = {Apr-03-2022},
	abstract = {The release of long-stored carbon from thawed permafrost could fuel increased methanogenesis in northern lakes, but it remains unclear whether old carbon substrates released from permafrost are metabolized as rapidly by methanogenic microbial communities as recently produced organic carbon. Here, we apply methane (CH4) clumped isotope (Δ18) and 14C measurements to test whether rates of methanogenesis are related to carbon substrate age. Results from culture experiments indicate that Δ18 values are negatively correlated with CH4 production rate. Measurements of ebullition samples from thermokarst lakes in Alaska and glacial lakes in Sweden indicate strong negative correlations between CH4 Δ18 and the fraction modern carbon. These correlations imply that CH4 derived from older carbon substrates is produced relatively slowly. Relative rates of methanogenesis, as inferred from Δ18 values, are not positively correlated with CH4 flux estimates, highlighting the likely importance of environmental variables other than CH4 production rates in controlling ebullition fluxes.},
	keywords = {clumped isotopes, ebullition flux, lakes, methane, permafrost, radiocarbon},
	issn = {0094-8276},
	doi = {10.1029/2019GL086756},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086756},
	author = {Douglas, Peter M. J. and Gonzalez Moguel, Regina and Walter Anthony, Katey M. and Wik, Martin and Crill, Patrick M. and Dawson, Katherine S. and Smith, Derek A. and Yanay, Ella and Lloyd, Max K. and Stolper, Daniel A. and Eiler, John M. and Sessions, Alex L.}
}
@article {2817,
	title = {Deglacial temperature controls on no-analog community establishment in the Great Lakes Region},
	journal = {Quaternary Science Reviews},
	volume = {234},
	year = {2020},
	month = {Jan-04-2020},
	pages = {106245},
	abstract = {Understanding the drivers of vegetation dynamics and no-analog communities in eastern North America is hampered by a scarcity of independent temperature indicators. We present a new branched glycerol dialkyl glycerol tetraether (brGDGT) temperature record from Bonnet Lake, Ohio (18{\textendash}8 ka) and report uncertainty estimates based on Bayesian linear regression and bootstrapping. We also reanalyze a previously published brGDGT record from Silver Lake, Ohio, using improved chromatographic methods. All pollen- and brGDGT-based temperature reconstructions showed qualitatively similar deglacial trends but varying magnitudes. Separating 5- and 6- methyl brGDGTs resulted in substantially lower estimates of deglacial temperature variations (6.4 {\textdegree}C) than inferred from earlier brGDGT methods and pollen (11.8 {\textdegree}C, 12.0 {\textdegree}C respectively). Similar trends among proxies suggest good fidelity of brGDGTs to temperature, despite calibration uncertainties. At both sites, the rise and decline of no-analog communities closely track brGDGT-inferred temperatures, with a lag of 0{\textendash}150 years. The timing of temperature and ecological events varies between Bonnet and Silver Lakes, likely due to age model uncertainties. Climate sensitivity analyses indicate a linear sensitivity of vegetation composition to temperature variations, albeit noisy and significant only with a 500-year bin. The formation of no-analog plant communities in the upper Midwest is closely linked to late-glacial warming, but other factors, such as temperature seasonality or end-Pleistocene megafaunal extinctions, remain viable.},
	keywords = {biomarkers, brGDGT, Climate sensitivity, Lagoons \& swamps, lakes, No-analog, North America, paleoclimatology, Pleistocene, pollen, sedimentology, Temperature, vegetation},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106245},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0277379119303713},
	author = {Fastovich, David and Russell, James M. and Jackson, Stephen T. and Williams, John W.}
}
@article {2838,
	title = {Slope failures within and upstream of Lake Quinault, Washington, as uneven responses to Holocene earthquakes along the Cascadia subduction zoneAbstract},
	journal = {Quaternary Research},
	volume = {89},
	year = {2018},
	month = {Jan-01-2018},
	pages = {178 - 200},
	abstract = {Investigation of Lake Quinault in western Washington, including a reflection seismic survey, analysis of piston cores, and preliminary mapping in the steep, landslide-prone Quinault River catchment upstream of the lake, reveals evidence for three episodes of earthquake disturbance in the past 3000 yr. These earthquakes triggered failures on the lake{\textquoteright}s underwater slopes and delta front, as well as subaerial landsliding, partial channel blockage, and forced fluvial sediment aggradation. The ages of the three Lake Quinault disturbance events overlap with those of coseismically subsided, coastal marsh soils nearby in southwest Washington that are interpreted to record ruptures of the Cascadia megathrust. Absent from Lake Quinault, however, are signals of obvious disturbance from five additional subduction earthquakes inferred to have occurred during the period of record. The lack of evidence for these events may reflect the limitations of the data set derived from the detrital, river-dominated lake stratigraphy but may also have bearing on debates about segmentation and the distribution of slip along the Cascadia subduction zone during prior earthquakes.},
	keywords = {Cascadia, Earthquake, lakes, Paleoseismic, Sediment},
	issn = {0033-5894},
	doi = {10.1017/qua.2017.96},
	url = {https://www.cambridge.org/core/product/identifier/S0033589417000965/type/journal_article},
	author = {Leithold, Elana L. and Wegmann, Karl W. and Bohnenstiehl, Delwayne R. and Smith, Stephen G. and Noren, Anders and O{\textquoteright}Grady, Ryan}
}
@article {2846,
	title = {Temperature variations in the southern Great Lakes during the last deglaciation: Comparison between pollen and GDGT proxies},
	journal = {Quaternary Science Reviews},
	volume = {182},
	year = {2018},
	month = {Jan-02-2018},
	pages = {78 - 92},
	abstract = {Our understanding of deglacial climate history in the southern Great Lakes region of the United States is primarily based upon fossil pollen data, with few independent and multi-proxy climate reconstructions. Here we introduce a new, well-dated fossil pollen record from Stotzel-Leis, OH, and a new deglacial temperature record based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) at Silver Lake, OH. We compare these new data to previously published records and to a regional stack of pollen-based temperature reconstructions from Stotzel-Leis, Silver Lake, and three other well-dated sites. The new and previously published pollen records at Stotzel-Leis are similar, but our new age model brings vegetation events into closer alignment with known climatic events such as the Younger Dryas (YD). brGDGT-inferred temperatures correlate strongly with pollen-based regional temperature reconstructions, with the strongest correlation obtained for a global soil-based brGDGT calibration (r2 = 0.88), lending confidence to the deglacial reconstructions and the use of brGDGT and regional pollen stacks as paleotemperature proxies in eastern North America. However, individual pollen records show large differences in timing, rates, and amplitudes of inferred temperature change, indicating caution with paleoclimatic inferences based on single-site pollen records. From 16.0 to 10.0ka, both proxies indicate that regional temperatures rose by \~{}10 {\textdegree}C, roughly double the \~{}5 {\textdegree}C estimates for the Northern Hemisphere reported in prior syntheses. Change-point analysis of the pollen stack shows accelerated warming at 14.0 {\textpm} 1.2ka, cooling at 12.6 {\textpm} 0.4ka, and warming from 11.6 {\textpm} 0.5ka into the Holocene. The timing of B{\o}lling-Aller{\o}d (B-A) warming and YD onset in our records lag by \~{}300{\textendash}500 years those reported in syntheses of temperature records from the northern mid-latitudes. This discrepancy is too large to be attributed to uncertainties in radiocarbon dating, and correlation between pollen and brGDGT temperature reconstructions rules out vegetation lags as a cause. However, the YD termination appears synchronous among the brGDGT record, regional pollen stack, and Northern Hemisphere stack. The cause of the larger and lagged temperature changes in the southern Great Lakes relative to Northern Hemisphere averages remains unclear, but may be due to the effects of continentality and ice sheet extent on regional climate evolution.},
	keywords = {Continental biomarkers, GDGT, Lagoons and Swamps, lakes, North America, paleoclimatology, Pleistocene, pollen, sedimentology},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2017.12.011},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0277379117306467},
	author = {Watson, Benjamin I. and Williams, John W. and Russell, James M. and Jackson, Stephen T. and Shane, Linda and Lowell, Thomas V.}
}
@article {2447,
	title = {Holocene variability in hydrology, vegetation, fire, and eolian activity in the Nebraska Sand Hills, USA},
	journal = {The Holocene},
	volume = {23},
	year = {2013},
	month = {Jan-04-2013},
	pages = {515 - 527},
	abstract = {This study combined multiple aquatic and terrestrial proxies, including diatoms, pollen, grain size, and bulk-sediment chemistry to reconstruct the history
of three lake sites located in the central Sand Hills of Nebraska, USA. Long-term changes in effective moisture are evident at all sites, with significant
changes occurring at ~6000, ~4000, and ~ 2000 cal. yr BP. Both aquatic and terrestrial indicators suggest that effective moisture was low between
10,000 and ~6000 cal. yr BP, and that this time interval was the driest period of the Holocene. The dominance of benthic and tychoplanktic diatom taxa
indicates relatively shallow lake-level, high sand influx indicates moderately high eolian activity, and the pollen assemblage suggests xeric grasslands with
abundant mud flats. About 6000 cal. yr BP, all three sites experienced an increase in effective moisture. Lake-level rise is indicated by increases in planktic
and tychoplanktic diatoms relative to benthic taxa, while greater abundance of grass pollen and charcoal, and decreased eolian flux indicate stabilized
dunes with dense vegetation sufficient to fuel local fires. A significant hydrologic shift recorded at all sites occurred at ~4000 cal. yr BP. This event was
characterized by substantial lake-level rise, yet decreased grass cover and fire frequency, and increased eolian activity. Water-table rise may have been
caused by a combination of factors including: (1) formation of dune-dams that blocked old drainage channels, (2) reduced grass cover and hence reduced
evapotranspiration, and (3) changes in the frequency and duration of drought. The most likely cause(s) of the differential response of the terrestrial and
aquatic systems at this time is not clear, none-the-less the late Holocene was not nearly as dry as the interval prior to 6000 cal. yr BP. The last ~2000
yr were characterized by several short-term fluctuations in lake level, including an interval of drought between 950 and 750 cal. yr BP, coincident with
increased eolian activity during the latter part of the Medieval Climatic Anomaly.},
	keywords = {diatoms, drought, Holocene climate change, lakes, Nebraska Sand Hills, pollen},
	issn = {0959-6836},
	doi = {10.1177/0959683612463100},
	url = {http://journals.sagepub.com/doi/10.1177/0959683612463100},
	author = {Schmieder, Jens and Fritz, Sherilyn C and Grimm, Eric C and Jacobs, Kimberly C and Brown, Kendrick J and Swinehart, James B and Porter, Stephen C}
}
@article {2448,
	title = {A regional-scale climate reconstruction of the last 4000 years from lakes in the Nebraska Sand Hills, USA},
	journal = {Quaternary Science Reviews},
	volume = {30},
	year = {2011},
	month = {Jan-06-2011},
	pages = {1797 - 1812},
	abstract = {High-resolution paleohydrological reconstructions were carried out in five shallow lakes in the Nebraska Sand Hills across an eastewest transect in order to 1) determine whether long-term droughts of the past 4000 years were spatially and temporally coherent across the region, 2) distinguish local variation in
climate or hydrology from regional patterns of change, and 3) compare the paleolimnological results with the existing dune-inferred drought records. Diatom-inferred lake-level was reconstructed for all sites and compared with other regional records. Alterations between high and low lake-levels were
frequent during the past 4000 years, which suggests that shifts between dry and wet periods were prevalent across the Sand Hills. Extended multi-decadal to centennial-scale droughts were more common prior to 2000 years BP, while the last two millennia were hydrologically more variable and climate conditions alternated on shorter timescales. Despite some discrepancies among the five records, the paleohydrological reconstructions refine the Holocene drought history of the Nebraska Sand Hills, particularly between w2200 and 4000 cal a BP. Many of the observed drought events are contemporaneous with severe droughts documented at sites in the northern Great Plains and Rocky Mountains, lending support for the severity and regional significance of these events in western North America.},
	keywords = {diatoms, Droughts, Great Plains, Holocene, lakes, Nebraska Sand Hills, paleolimnology},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2011.04.011},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0277379111001132http://api.elsevier.com/content/article/PII:S0277379111001132?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0277379111001132?httpAccept=text/plain},
	author = {Schmieder, J. and Fritz, S.C. and Swinehart, J.B. and Shinneman, A.L.C. and Wolfe, A.P. and Miller, G. and Daniels, N. and Jacobs, K.C. and Grimm, E.C.}
}
