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southern basin of Lake Titicaca (Lago Wiñaymarka) con-Two century-scale time series in northern Bolivia constrain the tains an incomplete Holocene record because it was almost ages of abrupt changes in the physical, geochemical, and biological completely desiccated prior to about 3500 14 C yr B.P. (Wirr-characteristics of sediments obtained from lakes that(More)
We review the history of the South American summer monsoon (SASM) over the past ∼ 2000 yr based on high-resolution stable isotope proxies from speleothems, ice cores and lake sediments. Our review is complemented by an analysis of an isotope-enabled atmospheric general circulation model (GCM) for the past 130 yr. Proxy records from the monsoon belt in the(More)
The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines(More)
Lake-level history for Birch Lake, Alaska, was reconstructed using seismic profiles and multiproxy sedimentary analyses including sedimentology, geochemistry, magnetic susceptibility, and palynology. Twenty-two seismic profiles (18 km total) and eight sediment cores taken from the lake margin to its depo-center at 13.5 m provide evidence for low lake stands(More)
Analyses of sediment cores from two lakes in the central Brooks Range provide temperature and moisture balance information for the past ∼8500 cal yr at century-scale resolution. Two methods of oxygen isotope analysis are used to reconstruct past changes in the effective moisture (precipitation minus evaporation) and temperature. Effective moisture is(More)
tions developed irrigated agriculture that sustained dense Paleolimnological and archaeological records that span human populations in apparently arduous environments. The 3500 years from Lake Titicaca and the surrounding Bolivian – emergence, persistence, and subsequent collapse of the Ti-Peruvian altiplano demonstrate that the emergence of agricul-wanaku(More)
a r t i c l e i n f o Keywords: South American summer monsoon oxygen isotopes precessional forcing abrupt climate change lake sediments Oxygen isotope ratios of authigenic calcite (δ 18 O cal) measured at annual to decadal resolution from Laguna Pumacocha document Andean precipitation variability during the last 11,200 years. Modern limnological data show(More)
Multiple paleoclimate proxies are required for robust assessment of past hydroclimatic conditions. Currently, estimates of drought variability over the past several thousand years are based largely on tree-ring records. We produced a 1,500-y record of winter precipitation in the Pacific Northwest using a physical model-based analysis of lake sediment oxygen(More)
Lake-level variations at Marcella Lake, a small, hydrologically closed lake in the southwestern Yukon Territory, document changes in effective moisture since the early Holocene. Former water levels, driven by regional palaeohydrology, were reconstructed by multiproxy analyses of sediment cores from four sites spanning shallow to deep water. Marcella Lake(More)
Integrating protocol data manipulations is a strategy for increasing the throughput of network protocols. The idea is to combine a series of protocol layers into a pipeline so as to access message data more efficiently. This paper introduces a widely-applicable technique for integrating protocols. This technique not only improves performance, but also(More)