Search results for "Paleoclima"

Paleoclimate and bubonic plague: a forewarning of future risk?

2010

Background Human cases of plague (Yersinia pestis) infection originate, ultimately, in the bacterium's wildlife host populations. The epidemiological dynamics of the wildlife reservoir therefore determine the abundance, distribution and evolution of the pathogen, which in turn shape the frequency, distribution and virulence of human cases. Earlier studies have shown clear evidence of climatic forcing on contemporary plague abundance in rodents and humans. Results We find that high-resolution palaeoclimatic indices correlate with plague prevalence and population density in a major plague host species, the great gerbil (Rhombomys opimus), over 1949-1995. Climate-driven models trained on these…

Old World Megadroughts and Pluvials During the Common Era

2015

An atlas of megadroughts in Europe and in the Mediterranean Basin during the Common Era provides insights into climate variability.

South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy

2013

AbstractThe IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore>100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use…

DETECTING VOLCANIC ERUPTIONS IN TEMPERATURE RECONSTRUCTIONS BY DESIGNED BREAK-INDICATOR SATURATION

2016

We present a methodology for detecting breaks at any point in time-series regression models using an indicator saturation approach, applied here to modelling climate change. Building on recent developments in econometric model selection for more variables than observations, we saturate a regression model with a full set of designed break functions. By selecting over these break functions using an extended general-to-specific algorithm, we obtain unbiased estimates of the break date and magnitude. Monte Carlo simulations confirm the approximate properties of the approach. We assess the methodology by detecting volcanic eruptions in a time series of Northern Hemisphere mean temperature spanni…

A late Eemian aridity pulse in central Europe during the last glacial inception

2005

How do ice ages begin? It's an obvious question to ask as we enjoy the relative luxury of an interglacial, but a hard one to answer. A look at past transitions may give some clues as to how this period will one day come to an end. A climate reconstruction based on sediments found beneath a lake in the Eifel mountains in Germany provides evidence of an extreme climate event lasting 468 years right at the end of the last interglacial. Dust storms, aridity, bushfires and the loss of trees associated with a warm climate coincided with a southward shift of the warm waters of the North Atlantic drift. In terms of insolation — the rate of delivery of the Sun's radiation to Earth — conditions then …

Coherent South American Monsoon variability during the last millennium revealed through high‐resolution proxy records

2019

The bivalve <i>Glycymeris planicostalis</i> as a high-resolution paleoclimate archive for the Rupelian (Early Oligocene) …

2015

Abstract. Current global warming is likely to result in a unipolar glaciated world with unpredictable repercussions on atmospheric and oceanic circulation patterns. These changes are expected to affect seasonal extremes and the year-to-year variability of seasonality. To better constrain the mode and tempo of the anticipated changes, climatologists require ultra-high-resolution proxy data of time intervals in the past, e.g., the Oligocene, during which boundary conditions were similar to those predicted for the near future. In the present paper, we assess whether such information can be obtained from shells of the long-lived bivalve mollusk Glycymeris planicostalis from the late Rupelian of…

Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar …

2016

Abstract The study presents the results of a heavy mineral analysis from a 38 m long record of lacustrine Eifel maar sediments from a core section of the Dehner dry maar. The record encompasses the period from 29,000 to about 12,500 b2k. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size Index (GSI and CSI). The results indicate that during the early stages of MIS2 (39 to 30 m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by low GSI and CSI ratios resulting from a reduce…

2020

Abstract. A compilation of the published literature on dust content in terrestrial and marine sediment cores was synchronized with pollen data and speleothem growth phases on the Greenland Ice Core Chronology 2005 (GICC05) time axis. Aridity patterns for eight key areas of the global climate system have been reconstructed for the last 60 000 years. These records have different time resolutions and different dating methods, i.e. different types of stratigraphy. Nevertheless, all regions analysed in this study show humid conditions during early Marine Isotope Stage 3 (MIS3) and the early Holocene or deglaciation, but not always at the same time. Such discrepancies have been interpreted as reg…

Organic lacustrine sediment varves as indicators of past precipitation changes: a 3,000-year climate record from Central Finland

2015

Annually laminated (varved) sediments from Lake Kallio-Kourujärvi, Central Finland, provide high-resolution sedimentological data for the last three millennia. These varves consist of two laminae that represent (1) deposition during the spring-to-autumn growing season, composed of degraded organic matter and a variety of microfossils, and (2) deposition during winter, composed of fine-grained homogenous organic matter. Because of the absence of a clastic lamina, these varves differ from the typical, well-described, clastic-organic varve sequences in Fennoscandian lakes. Such organic varves in Finnish lakes have not been studied in detail before. Three thousand varves were counted and their …