Search results for "HOLOCENE"

Pollen and Plant Macroremain Analyses for the Reconstruction of Environmental Changes in the Early Metal Period

2006

A sharp increase in human population density and the same time fundamental changes in the location of settlement, moving away from earlier inhabited places points to significant changes in the environment. This period with a sharp decrease in anthropogenic indicators and poor records of slash and burn cultivation and field crop-growing is named “transition” period (Vasks et.al.1998) and indicates the lack of stable and continuous inhabitant sites. This phenomena can be explained by the small size of settlements at the Early Iron Age, expressed by a weak cultural layer and these could be defined as separate farmsteads. Modern farming practices, especially modern tillage, adversely affected t…

How do the 1982/83 and 1997/98 El Niños rank in a geological record from Peru?

2007

Two very strong El Nino events during the years 1982/83 and 1997/98 caused dramatic economical and social damages worldwide. However, it is quite uncertain how these events rank in a long-term perspective and how frequent events of similar magnitude were in the past. Very-high-resolution proxy data for flood events in the El Nino key region of Peru are presented. Strong flood events in the hyper-arid northern and northern central Peru coastal desert occur during El Nino events. The flood data are derived from a laminated marine sediment core. The proxy data reveal that both modern events were recorded as the strongest sediment discharges in the 106KL flood record over the last millennium. S…

The far south: the Pleistocene–Holocene transition in Nerja Cave (Andalucı́a, Spain)

2002

Abstract The archaeological site of Cueva de Nerja (Malaga, Spain) provides significant data about the bioclimatic conditions of one of the most southern European temperate regions. The bioclimatic and palaeogeographic changes that have occurred during the 20,000 years of human occupation of the site can be analysed by relating the geodynamic processes, the palaeobotany and the palaeofauna recovered from its archaeological deposits.

Late Holocene Asian summer monsoon variability reflected byδ18O in tree-rings from Tibetan junipers

2011

[1] Recent warming in High Asia might have a strong impact on Asian summer monsoon variability with consequences for the hydrological cycle. Based on correlations between climate data, the tree-ring δ18O of high-elevation junipers is an indicator of August precipitation. Thus, our 800-year long annually resolved oxygen isotope series reflects long-term variations in summer monsoon activity on the southern Tibetan plateau. Summer precipitation was reduced during 13th–15th centuries and since the 19th century, whereas the Little Ice Age period (15th–19th century) was rather moist. The late 20th century was among the driest periods during the past 800 years, showing a tendency to slightly wett…

A major Holocene ENSO anomaly during the Medieval period

2004

[1] Here, we present a high resolution marine El Nino flood record from Peru. A period of extreme drought without strong flooding occurred from A.D. 800–1250. Anomalous precipitation patterns characterized the entire Indo-Pacific ENSO domain, with dry events in the northern Arabian Sea and the mid-latitudes of both Americas, coinciding with wet periods in the Atlantic Cariaco Basin. The occurrence of contemporaneous moisture anomalies in other archives in the ENSO region highlights the role of El Nino strength in global climate evolution during the late Medieval period when temperature reconstructions show a rather heterogeneous pattern.

How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i&gt…

2019

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 an…

A new marker for sea surface temperature trend during the last centuries in temperate areas: Vermetid reef

2004

The presence of Vermetid reefs in temperate waters, their diffusion in the Mediterranean Sea, and the possibility of performing 14 C ages allowed the use of Vermetids as an indicator of sea level changes. We present new data on sea climate trend fluctuations that could be interpreted as Sea Surface Temperature (SST) variations, recorded on Vermetid (Dendropoma petraeum) reefs, by means of isotopic analysis. The isotopic records show positive values of the d 18 O relative to present-day values in the period between 1600 and 1850 AD; this deviation occurs in association with the climatic cooling event known as Little Ice Age (LIA). Subsequently, we can observe the warming trend that character…

Is the Anthropocene really worthy of a formal geologic definition?

2014

Scientists are actively debating whether the Anthropocene, the geologic time span (GTS) we are now living in, should be considered a period, epoch, or age in the geologic timescale. The solution is not easy, because the beginning of this GTS is undefined and the end unknown. In fact, there is no agreement on when the Anthropocene began, the proposed dates ranging from the Second World War, when radioactive fallout branded soils and sediments all over the world, to little after the end of the last glacial period, i.e. 11.7 thousand years ago, therefore coinciding with the onset of the Holocene. We are in favour of a concurrence of the Anthropocene with the Holocene, although a major impact …

Arctica islandica (Bivalvia): A unique paleoenvironmental archive of the northern North Atlantic Ocean

2013

Abstract High-resolution environmental proxy data from the extratropical North Atlantic prior to the instrumental era are of critical importance to decipher processes and mechanisms of global change. In this regard, shells of the extremely long-lived bivalve mollusc, Arctica islandica ( Linnaeus, 1767 ), have gained particular attention during the last decade because they serve as reliable, subseasonally resolved multi-proxy archives of environmental variability in that very region. With a lifespan of more than 500 years, A. islandica is the longest-lived solitary animal. Its shell grows periodically throughout life and contains distinct annual and daily growth increments. These growth patt…

2019

Abstract. Here, we present the first quantitative speleothem record of lignin oxidation products (LOPs), which has been determined in a Holocene stalagmite from the Herbstlabyrinth Cave in central Germany. In addition, we present LOP results from 16 months of drip water monitoring. Lignin is only produced by vascular plants and therefore has the potential to be an unambiguous vegetation proxy and to complement other vegetation and climate proxies in speleothems. We compare our results with stable isotope and trace element data from the same sample. In the stalagmite, LOP concentrations show a similar behavior to P, Ba and U concentrations, which have previously been interpreted as vegetatio…