A comparison of western Great Basin paleoclimate records for the last 3000 yr: Evidence for multidecadal- to millennial-scale drought

ABSTRACT This paper summarizes the hydrological variability in eastern California (central Sierra Nevada) for the past 3000 yr based on three distinct paleoclimate proxies, δ18O, total inorganic carbon (TIC), and magnetic susceptibility (chi). These proxies, which are recorded in lake sediments of Pyramid Lake and Walker Lake, Nevada, and Mono Lake and Owens Lake, California, indicate lake-level changes that are mostly due to variations in Sierra Nevada snowpack and rainfall. We evaluated lake-level changes in the four Great Basin lake systems with regard to sediment-core locations and lake-basin morphologies, to the extent that these two factors influence the paleoclimate proxy records. We documented the strengths and weaknesses of each proxy and argue that a systematic study of all three proxies together significantly enhances our ability to characterize the regional pattern, chronology, and resolution of hydrological variability. We used paleomagnetic secular variation (PSV) to develop paleomagnetic chronostratigraphies for all four lakes. We previously published PSV records for three of the lakes (Mono, Owens, Pyramid) and developed a new PSV record herein for Walker Lake. We show that our PSV chronostratigraphies are almost identical to previously established radiocarbon-based chronologies, but that there are differences of 20–200 yr in individual age records. In addition, we used eight of the PSV inclination features to provide isochrons that permit exacting correlations between lake records. We also evaluated the temporal resolution of our proxies. Most can document decadal-scale variability over the past 1000 yr, multidecadal-scale variability for the past 2000 yr, and centennial-scale variability between 2000 and 3000 yr ago. Comparisons among our proxies show a strong coherence in the pattern of lake-level variability for all four lakes. Pyramid Lake and Walker Lake have the longest and highest-resolution records. The δ18O and TIC records yield the same pattern of lake-level variability; however, TIC may allow a somewhat higher-frequency resolution. It is not clear, however, which proxy best estimates the absolute amplitude of lake-level variability. Chi is the only available proxy that records lake-level variability in all four lakes prior to 2000 yr ago, and it shows consistent evidence of a large multicentennial period of drought. TIC, chi, and δ18O are integrative proxies in that they display the cumulative record of hydrologic variability in each lake basin. Tree-ring estimations of hydrological variability, by contrast, are incremental proxies that estimate annual variability. We compared our integrated proxies with tree-ring incremental proxies and found a strong correspondence among the two groups of proxies if the tree-ring proxies are smoothed to decadal or multidecadal averages. Together, these results indicate a common pattern of wet/dry variability in California (Sierra Nevada snowpack/rainfall) extending from a few years (notable only in the tree-ring data) to perhaps 1000 yr. Notable hydrologic variability has occurred at all time scales and should continue into the future.

Climatic Extremes and Human Resilience: An Examination of Two Hydrographic Basins in the Great Basin (northern Nevada, USA)

<p>The purpose of this paper is to look at the prehistoric human settlement patterns in the northern Great Basin of the United States<br>in light of a variety of climate proxies.  The intent is to look at the response of Great Basin hunter-gatherers in response to extreme climatic events.  <br>Focus will be on two US Geological Survey designated hydrographic basins: the Black Rock Basin and <br>the Truckee Basin.  The Black Rock Basin contains the Quinn River which originates in the Montanna Mountains and terminates into a seasonal lake<br>on the Black Rock playa.  The Truckee Basin contains the Truckee River which flows from Lake Tahoe in the Sierra Nevada range <br>to the terminal Pyramid Lake.  </p><p>Radiocarbon dates from excavated archaeological sites in the two basins are used as a demographic and settlement proxy.  Climate proxies<br>from the two basins include: oxygen isotope data from Pyramid Lake, pollen cores from Mud Meadows spring and Summit Lake, and tree ring <br>data from the Jackson Mountains. </p><p>Both basins see initial human settlement during the Younger Dryas period, with a growth in population/settlements through 8000 BP. After<br>approximately 7800 BP, there is a paucity of dated sites until approximately 4000 BP.  Whether this is due to the 8.2 kya BP climatic event and/or<br>the Mount Mazama volcanic eruption, is uncertain.  Oxygen isotope data from Pyramid Lake does indicate a period of hyper-aridity throughout the<br>northern Great Basin between ca. 8-4 kya BP.  The aridity declines after 4 kya based on the oxygen isotope data, and settlement in the <br>two basins increases.  With the onset of the Late Holocene Drought, ca. 2500 BP, population/settlement declines are seen except around <br>major lakes, north of 42N latitude, and elevations above 2000m. After 2000 BP, population/settlement increases throughout both basins.  Notable<br>increases of population/settlement occurs in the Late Antique Little Ice Age and continues throughout the Medieval Climatic Anomaly (MCA). Environmental proxy data indicates the MCA was a period of extreme aridity in the northern Great Basin. Despite ameorilating conditions in both basins after the MCA and in the Little Ice Age, population/settlement declines after circa 700 BP.    </p>

Gregg Deal's White Indian (2016): The Decolonial Possibilities of Museum Performance

Gregg Deal (Pyramid Lake Paiute) is a performance and visual artist whose work deals explicitly in decolonizing the contemporary experience of Indigenous peoples. An analysis of his performance ofWhite Indian in 2016 at the Denver Art Museum opens up the possibilities of performance as a method for museums to decolonize their spaces and curation.

Climatology of Lake-Effect Precipitation Events over Lake Tahoe and Pyramid Lake

The frequency, timing, and environmental conditions of lake-effect (LE) precipitation over Lake Tahoe and Pyramid Lake in northern California and western Nevada were examined for the 14 winters (September–March) from 1996/97 through 2009/10. Weather Surveillance Radar-1988 Doppler (WSR-88D) data from Reno, Nevada (KRGX), were used to identify 62 LE events. LE precipitation occurred as single bands extending downwind from overlake areas, and as isolated regions of overlake precipitation with little or no extension over land. Mesoscale vortices were also identified during both Lake Tahoe and Pyramid Lake LE events. An average of 4.4 LE events occurred each winter in the Lake Tahoe and Pyramid Lake region, with events occurring most frequently in October. LE events had an average duration of 6.3 h, approximately half the duration of LE events observed over Lake Champlain, the New York State Finger Lakes, or the Great Salt Lake. The observed conditions during LE events in the Lake Tahoe and Pyramid Lake region typically had 1) mean surface air temperatures below freezing, 2) mean surface wind speeds of <2.0 m s−1 (notably weaker than during lake effect in other areas), 3) a mean lake–air temperature difference of 11.5°C, and 4) a mean lake–700-hPa temperature difference of 20.9°C.