Learn 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)
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)
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)
Decadal and centennial mean state changes in South American summer monsoon (SASM) precipitation during the last 2,300 years are detailed using an annually resolved authigenic calcite record of precipitation δ(18)O from a varved lake in the Central Peruvian Andes. This unique sediment record shows that δ(18)O peaked during the Medieval Climate Anomaly (MCA)(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)
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)
Here we document at century to millennial scale the regional changes of precipitation^evaporation from the late Pleistocene to present with multiproxy methods on a north^south transect of lake sites across the eastern cordillera of the central Andes. The transect of study sites covers the area from V14 ‡S to 20 ‡S and includes core studies from seven lakes(More)
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)
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)
Analyses of sediment cores from Jellybean Lake, a small, evaporation-insensitive groundwater-fed lake, provide a record of changes in North Pacific atmospheric circulation for the last¨7500 yr at 5-to 30-yr resolution. Isotope hydrology data from the southern Yukon indicate that the oxygen isotope composition of water from Jellybean Lake reflects the(More)