نتایج جستجو برای: holocene
تعداد نتایج: 8437 فیلتر نتایج به سال:
The future response of the Greenland Ice Sheet (GIS) and its potential contribution to sea level rise are uncertain. Rapid changes of Greenland’s outlet glaciers over the past decade have made it difficult to extrapolate ice sheet change into the future. This significant short-term variability highlights the need for longer-term, geologic (e.g., Holocene) records of ice margin fluctuations. How...
In this study, we use a sophisticated highresolution atmosphere-ocean coupled climate model, ECEarth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka), there was more summer insolation on the Northern Hemisphere than today, which intensified the meridional temperature and pressure gradients. Over North Africa, monso...
Introduction The study of lake sediments has been widely used in recent decades to identify past climate and environmental changes. Lake basins have significant spatial and temporal patterns and provide valuable evidences of physical and chemical changes. However, in general, the climate of the Holocene period has been more stable and uniform than previous glacial and interglacial periods. How...
Studying the peatlands accumulation and carbon (C) storage in monsoonal areas could provide useful insights into the response of C dynamics to climate variation in the geological past. Here, we integrated 40 well-dated peat/lake sediment cores to reveal the peatlands evolution history in the Sanjiang Plain and examine its links to East Asian monsoon variations during the Holocene. The results s...
Fire regimes have changed during the Holocene due to changes in climate, vegetation, and in human practices. Here, we hypothesise that changes in fire regime may have affected the global CO2 concentration in the atmosphere through the Holocene. Our data are based on quantitative reconstructions of biomass burning deduced from stratified charcoal records from Europe, and South-, Central- and Nor...
Midge remains (Insecta: Diptera: Chironomidae and Chaoboridae) from two upland lake basins on the Cumberland Peninsula of Baffin Island were analyzed and the results used in a transfer function to reconstruct paleotemperatures. This upland region remained ice-free throughout the last glacial cycle and the two lake basins retain sediments deposited during the previous interglacial period as well...
[1] The stable carbon (dC) and oxygen (dO) isotopic compositions of four Holocene specimens of Montastraea sp. and Siderastrea sp. coral skeletons from the Dominican Republic were analyzed to examine decadal-scale fluctuations in regional precipitation. The specimens range in length from 47 to 197 years individually and range in age from 7.2 to 5.2 kyr. Oscillations in the dC and dO of coral sk...
The seasonal balance of moisture has a significant effect on natural ecosystems and culture in southwestern North America (SWNA), and it thus is necessary to understand the cause of this moisture variability in order to better predict the scope of potential future changes. Studies of modern SWNA climate indicate that most of the annual moisture at this site comes from monsoonal summer precipita...
The precipitation climatology and the underlying climate mechanisms of the eastern Mediterranean, West Asia, and the Indian subcontinent are reviewed, with emphasis on upper and middle tropospheric flow in the subtropics and its steering of precipitation. Holocene climate change of the region is summarized from proxy records. The Indian monsoon weakened during the Holocene over its northernmost...
Glacial-interglacial changes in the distribution of C3/C4 vegetation on the Chinese Loess Plateau have been related to East Asian summer monsoon intensity and position, and could provide insights into future changes caused by global warming. Here, we present δ(13)C records of bulk organic matter since the Last Glacial Maximum (LGM) from 21 loess sections across the Loess Plateau. The δ(13)C val...
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