We have studied a 33.7 m deep ice core from a small polythermal Scandinavian ice cap to determine whether it is possible to recover pre-20th century climatic information from the glacier. Ice ...structural studies show a significant change from clear ice above 11 m depth (superimposed ice indicating refreezing) to bubbly ice below 11 m depth, indicating this is the transition between Little Ice Age (LIA) and 20th century ice. Calculations with a Nye-age model, along with a mass balance reconstruction, show that this structural boundary likely formed in the last part of the LIA, which in this region ended about 1910. The ice below this boundary was sampled and analysed for stable isotopic composition and ionic content, which both show significant variations with depth. The stable isotope record likely contains cycles of annual duration during the LIA. The chemistry in the ice core indicates that the information is useful, and can be used to interpret climatic and environmental variables during the LIA. A comparison of Riukojietna ion chemistry and oxygen isotope records with similar records from other glaciers in this region reveals a clear continental-maritime gradient. Changes in this gradient with time may be possible to resolve using such ice core records. Results from this study demonstrate that ice cores from glaciers in this climatic environment can be useful in revealing environmental conditions from climatically colder periods and yield pre-industrial benchmark values for chemical loading and oxygen isotopes, but that hiatuses complicate the depth-age relationship.
Whether the solar activity was very low, and especially whether the solar cycle existed, during the Maunder Minimum (1645–1715 AD), have been disputed for a long time. In this paper we use the Guliya ...NO3− data, which can reflect the solar activity, to analyze the characteristics of the solar activity during the Maunder Minimum. The results show that the solar activity was indeed low, and solar cycle displayed normal as present, i.e. about 11a, in that period. Moreover, it was found that the solar activity contains a 36-year periodic component probably, which might be related to the variations in the length of the sunspot cycle. This finding is of importance for the study of the relationship between the sun variability and the Earth climate change.
Extensive archives of volcanic history are available from ice cores recovered from the Antarctic and Greenland ice sheets that receive and preserve sulfuric acid fallout from explosive volcanic ...eruptions. The continuous, detailed (average 1.2 samples per year) sulfate measurements of a 200‐m ice core from a remote East Antarctica site (Plateau Remote) provide a record of Southern Hemisphere volcanism over the last 4100 years. This extends the volcanic record beyond the last 1000 years covered by previous Antarctic ice cores. An average of 1.3 eruptions per century is recorded in East Antarctic snow during the last 4100 years. The record shows that on average eruptions have been more frequent and more explosive during the most recent 2000 years than in the previous 2100 years. Intervals up to 500 years are observed in which few explosive volcanic signals are detected. These periods include 2000–1500 B.C. (no eruptions), 500–1 B.C. (two eruptions), and 700–1200 A.D. (two eruptions). This new Plateau Remote volcanic record is compared with those from previous Antarctic ice cores covering the last 1000 years. In terms of dates for volcanic events, the new record is in excellent agreement with the earlier records. However, significant discrepancies are found between these records in relative signal magnitude (volcanic flux) of several well‐known events. The discrepancies among the records may be explained by the differences in the glaciology at the ice core sites, analytical techniques used for sulfate and sulfuric acid measurement, and the selection of detection thresholds for volcanic signals. Comparison with Greenland ice core volcanic records indicates that during the last millennium, nine large, low‐latitude eruptions contributed significant amounts of volcanic aerosols to the atmosphere of both hemispheres, potentially affecting global climate. In contrast, only one or possibly two such eruptions are found in the first millennium A.D.
Based on the data of temperature changes revealed by means of various paldennometric proxy indices, it ie found that the magnitude of temperature decrease became large with altitude in the equatorial ...regions during the Last Glacial Maximum. The direct cauw of this phenomenon was the change in temperature lapee rate, which was about (0.1 ±0.05)°C/100 m larger in the equator during the Last Glacial Maximum than at present. Moreover, the analyses show that CLIMAP possibly underestimated the sea surface temperature decrease in the equatorial regions during the Last Glacial Maximum
A36Cl peak was found in the predicted section of Guliya ice core, from the Qinghai-Tibetan Plateau, at about 37 kaBP. This cannot be interpreted by means of changes in the accumulation rate, but by ...the enhanced cosmogenic isotope production rate in the atmosphere. Compared with the records of10Be and36Cl in the other regions, the peaks of the cosmogenic isotopes are global and can be considered as time marks. An intriguing fact is that the peaks coincided with cold periods.
Recent snow and firn core samples from South Pole contain increased sulfate (SO42−) concentrations during 1992–1994 as a result of the June 1991 Pinatubo eruption and the August 1991 Cerro Hudson ...eruption in Chile. Traces of Pinatubo tephra (volcanic ash) were identified in the 1993 and 1994 snow layers, supporting the conclusion that increased SO42− in 1993–1994 is from the Pinatubo eruption. Although the Pinatubo eruption preceded Hudson, its SO42− signal in south polar snow follows and is resolved from that of Hudson. The deposition of the Pinatubo SO42− aerosol was delayed due to the long transport to the high southern latitudes and its initial existence at high altitudes in the Antarctic atmosphere. Multi‐year, multi‐site sampling demonstrates that the volcanic signals are well preserved and spatially consistent. Measurements on 2 firn cores show that the South Pole SO SO42− flux from Pinatubo is 10.9±1.2 kg km−2 over 2.2 years, while the Hudson flux is 3.2±0.6 kg km−2 in 1.1 years. These results, when combined with satellite‐determined Pinatubo sulfur dioxide (SO2) emission, make it possible to link quantitatively the atmospheric aerosol mass loading from a low‐latitude volcanic eruption to its signal in polar ice cores.
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