Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America

Menking, Kirsten M.; Anderson, Roger Y.; Shafike, Nabil; Syed, Kamran H.; Allen, Bruce D.

doi:10.1016/j.yqres.2004.07.005

Cited by 63 publications

(51 citation statements)

References 25 publications

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“…9). This increased precipitation over southern North America is suggested by pollen-based reconstructions (Jackson et al 2000) and from consideration on lake shorelines (Menking et al 2004). A more detailed and quantitative analysis of model/data comparison would be of interest, especially using new pollen-based reconstructions taking the CO 2 effect into account (Wu et al 2007).…”

Section: Discussionmentioning

confidence: 96%

Northern hemisphere storm tracks during the last glacial maximum in the PMIP2 ocean-atmosphere coupled models: energetic study, seasonal cycle, precipitation

et al. 2008

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Mid-latitude eddies are an important component of the climatic system due to their role in transporting heat, moisture and momentum from the tropics to the poles, and also for the precipitation associated with their fronts, especially in winter. We study northern hemisphere stormtracks at the Last Glacial Maximum (LGM) and their influence on precipitation using ocean-atmosphere general circulation model (OAGCM) simulations from the second phase of the Paleoclimate Modelling Intercomparison Project (PMIP2). The difference with PMIP1 results in terms of sea-surface temperature forcing, fundamental for storm-track dynamics, is large, especially in the eastern North Atlantic where sea-ice extends less to the south in OAGCMs compared to atmospheric-only GCMs. Our analyses of the physics of the eddies are based on the equations of eddy energetics. All models simulate a consistent southeastward shift of the North Pacific storm-track in winter, related to a similar displacement of the jet stream, partly forced by the eddies themselves. Precipitation anomalies are consistent with storm-track changes, with a southeastward displacement of the North Pacific precipitation pattern. The common features of North Atlantic changes in the LGM simulations consist of a thinning of the storm-track in its western part and an amplification of synoptic activity to the southeast, in the region between the Azores Islands and the Iberian Peninsula, which reflects on precipitation. This southeastward extension is related to a similar displacement of the jet, partly forced by the eddies. In the western North Atlantic, the synoptic activity anomalies are at first order related to baroclinic generation term anomalies, but the mean-flow baroclinicity increase due to the presence of the Laurentide ice-sheet is partly balanced by a loss of eddy efficiency to convert energy from the mean flow. Moisture availability in this region is greatly reduced due to more advection of dry polar air by stationary waves, leading to less synopticscale latent heat release and hence less precipitation also. In terms of seasonality, the stormy season is shifted later in the year by a few days to a month depending on the season and the model considered. This shift does not directly reflect on the first-order seasonal cycle of precipitation, which also depends on other mechanisms, especially in summer.

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Section: Discussionmentioning

confidence: 96%

Northern hemisphere storm tracks during the last glacial maximum in the PMIP2 ocean-atmosphere coupled models: energetic study, seasonal cycle, precipitation

et al. 2008

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“…Smaller, closed basin lakes are more likely to respond rapidly to watershed scale changes in precipitation, runoff/infiltration and evaporation (Menking et al, 2004;Garcia and Stokes, 2006).…”

Section: Assessing Surprise Valley As a Terminal Basinmentioning

confidence: 99%

“…Modeling of the Estancia Basin lake system hydrology (highstands and stillstands listed in Table 6) concluded that rainfall might have doubled relative to modern values to produce large pluvial lakes (Menking et al, 2004).…”

Section: Recordsmentioning

confidence: 99%

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An Assessment of Late Pleistocene to Middle Holocene Lake Level Fluctuations in Surprise Valley, California

Ibarra¹

2018

Preprint

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Knowledge of Earth’s climate history and sensitivity, combined with modeling past and future climate, are central to informing policy decisions regarding future climate change. The hydrologic response to future warming scenarios due to increased anthropogenic CO2 emissions remains uncertain. Freshwater availability in the arid western United States is projected to decrease in availability as increased agricultural, urban and industrial uses continue to stress supplies. Motivated by the potential for dramatic future hydrologic changes, studies recording the abrupt transitions between different equilibrium states of natural past climate variability shed light on our understanding of the modern climate system.The presence of pluvial lakes in the Basin and Range Province, in the western United States, during the late Pleistocene (40 to 10 ka) indicates far greater moisture availability during the Pleistocene glacials. This study investigates the timing and magnitude of the most recent pluvial lake cycle that filled Surprise Valley, California using geophysical, geochemical and geochronologic tools. Spanning 31.2 to 4.6 ka, this new lake level record places the highest lake level, at 180 meters above present day playa, at 13.9 ± 1.2 ka. This age appears to be nearly synchronous with highstands of Lake Lahontan to the south and the Chewaucan Basin to the north. Additionally, most of the Basin and Range lake highstands, including Lake Surprise, follow peaks in precipitation minus evapotranspiration (P-ET) by 8-10 kyr. By compiling a diverse set of paleoclimate data available for western North America, I found that the timing and geographic distribution of lake highstands is inconsistent with increased precipitation in response to shifting westerly winds, the current model for the genesis of large lakes in western North America. Rather, lakes levels are more strongly correlated with changes in summer insolation, suggesting that lake highstands were likely facilitated by colder temperatures and increased humidity due to the presence of continental ice sheets and increased atmospheric convergence. I compared the constraints from lake and soil-based records to Atmosphere-Ocean General Circulation Model simulations from the Paleoclimate Model Intercomparison Project 2. Based on model-proxy intercomparison, the Atmosphere-Ocean General Circulation Models, the same models used to also assess future climatic changes, poorly predict hydrologic quantities for the Last Glacial Maximum.

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“…Complete erosion of the cover is a conservative bounding assumption for modeling purposes. Minimum value based on infiltration through 2 ft of engineered cover under current climate (Peace and Goering, 2005); maximum value based on two times the current maximum precipitation in a natural analog vegetative cover to account for future climates (Waugh, 1997;Menking et al, 2004 Based on field data reported in Gelhar et al (1992). This is used in the FRAMES/MEPAS models for liquid transport to the groundwater.…”

Section: Thickness Of Cover and Clean Overburden [M]mentioning

confidence: 99%

Probabilistic performance-assessment modeling of the mixed waste landfill at Sandia National Laboratories.

Peace¹,

Goering²,

Miller³

et al. 2005

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A probabilistic performance assessment has been conducted to evaluate the fate and transport of radionuclides (amercium-241, cesium-137, cobalt-60, plutonium-238, plutonium-239, radium-226, radon-222, strontium-90, thorium-232, tritium, uranium-238), heavy metals (lead and cadmium), and volatile organic compounds (VOCs) at the Mixed Waste Landfill (MWL). Probabilistic analyses were performed to quantify uncertainties inherent in the system and models for a 1,000-year period, and sensitivity analyses were performed to identify parameters and processes that were most important to the simulated performance metrics. Comparisons between simulated results and measured values at the MWL were made to gain confidence in the models and perform calibrations when data were available. In addition, long-term monitoring requirements and triggers were recommended based on the results of the quantified uncertainty and sensitivity analyses.At least one-hundred realizations were simulated for each scenario defined in the performance assessment. Conservative values and assumptions were used to define values and distributions of uncertain input parameters when site data were not available. Results showed that exposure to tritium via the air pathway exceeded the regulatory metric of 10 mrem/year in about 2% of the 3 simulated realizations when the receptor was located at the MWL (continuously exposed to the air directly above the MWL). Simulations showed that peak radon gas fluxes exceeded the design standard of 20 pCi/m 2 /s in about 3% of the realizations if up to 1% of the containers of sealed radium-226 sources were assumed to completely degrade in the future. If up to 100% of the containers of radium-226 sources were assumed to completely degrade, 30% of the realizations yielded radon surface fluxes that exceeded the design standard. For the groundwater pathway, simulations showed that none of the radionuclides or heavy metals (lead and cadmium) reached the groundwater during the 1,000-year evaluation period. Tetrachloroethylene (PCE) was used as a proxy for other VOCs because of its mobility and potential to exceed maximum contaminant levels in the groundwater relative to other VOCs. Simulations showed that PCE reached the groundwater, but only 1% of the realizations yielded aquifer concentrations that exceeded the regulatory metric of 5 µg/L.Based on these results, monitoring triggers have been proposed for the air, surface soil, vadose zone, and groundwater at the MWL. Specific triggers include numerical thresholds for radon concentrations in the air, tritium concentrations in surface soil, infiltration through the vadose zone, and uranium and select VOC concentrations in groundwater. The proposed triggers are based on U.S. Environmental Protection Agency and Department of Energy regulatory standards. If a trigger is exceeded, then a trigger evaluation process will be initiated which will allow sufficient data to be collected to assess trends and recommend corrective actions, if necessary.4 Acknowledgments

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Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America

Cited by 63 publications

References 25 publications

Northern hemisphere storm tracks during the last glacial maximum in the PMIP2 ocean-atmosphere coupled models: energetic study, seasonal cycle, precipitation

Northern hemisphere storm tracks during the last glacial maximum in the PMIP2 ocean-atmosphere coupled models: energetic study, seasonal cycle, precipitation

An Assessment of Late Pleistocene to Middle Holocene Lake Level Fluctuations in Surprise Valley, California

Probabilistic performance-assessment modeling of the mixed waste landfill at Sandia National Laboratories.

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