scholarly journals Trends and features of climatic changes in the past 5000 years recorded by the Dunde ice core

1992 ◽  
Vol 16 ◽  
pp. 21-24 ◽  
Author(s):  
Yao Tandong ◽  
L. G. Thompson
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
The Tibetan Plateau ◽  
Temperature Relation ◽  
The Core ◽  
The Past ◽  
Ice Cap ◽  
The Qilian Mountains

Α δ18O record from Dunde Ice Cap, located in the Qilian mountains on the northeastern margin of the Tibetan Plateau, has been analyzed and interpreted. With an ice temperature of –7.3°C at a depth of 10 m and –4.7°C at the bottom of the ice cap, and an accumulation rate of 400 mm a−1, the Dunde core has provided interesting results. The upper part of this core, core D-l, can be easily dated by a combination of δ18O, microparticle concentration and conductivity. It can also be dated as far back as 4550 BP by counting dust layers in ice. Based on the time scale established by the above methods and on the δ18O–temperature relation, the δ18O fluctuations in the upper 120 m of the core can be interpreted as mainly due to climatic changes during the past ~ 5000 years. The warmest periods in the past ~ 5000 years in the core were found to be centered on the present, 3000, and 4100 BP, and the colder periods center around 500, 1200, 4000, and 4500 BP. It is clear from the ice-core record that the Little Ice Age was only one of many cold periods in the past, although it was the coldest period in the past 500 years.

scholarly journals Trends and features of climatic changes in the past 5000 years recorded by the Dunde ice core

1992 ◽  
Vol 16 ◽  
pp. 21-24 ◽  
Author(s):  
Yao Tandong ◽  
L. G. Thompson
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
The Tibetan Plateau ◽  
Temperature Relation ◽  
The Core ◽  
The Past ◽  
Ice Cap ◽  
The Qilian Mountains

Α δ18O record from Dunde Ice Cap, located in the Qilian mountains on the northeastern margin of the Tibetan Plateau, has been analyzed and interpreted. With an ice temperature of –7.3°C at a depth of 10 m and –4.7°C at the bottom of the ice cap, and an accumulation rate of 400 mm a−1, the Dunde core has provided interesting results. The upper part of this core, core D-l, can be easily dated by a combination of δ18O, microparticle concentration and conductivity. It can also be dated as far back as 4550 BP by counting dust layers in ice. Based on the time scale established by the above methods and on the δ18O–temperature relation, the δ18O fluctuations in the upper 120 m of the core can be interpreted as mainly due to climatic changes during the past ~ 5000 years. The warmest periods in the past ~ 5000 years in the core were found to be centered on the present, 3000, and 4100 BP, and the colder periods center around 500, 1200, 4000, and 4500 BP. It is clear from the ice-core record that the Little Ice Age was only one of many cold periods in the past, although it was the coldest period in the past 500 years.

Ice-Core Pollen Record of Climatic Changes in the Central Andes during the last 400 yr

2005 ◽  
Vol 64 (2) ◽  
pp. 272-278 ◽  
Author(s):  
Kam-biu Liu ◽  
Carl A. Reese ◽  
Lonnie G. Thompson
Keyword(s):  
Little Ice Age ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
Striking Similarity ◽  
Pollen Record ◽  
Dry Period ◽  
Proxy Records ◽  
Ice Cap ◽  
Ice Accumulation

AbstractThis paper presents a high-resolution ice-core pollen record from the Sajama Ice Cap, Bolivia, that spans the last 400 yr. The pollen record corroborates the oxygen isotopic and ice accumulation records from the Quelccaya Ice Cap and supports the scenario that the Little Ice Age (LIA) consisted of two distinct phases�"a wet period from AD 1500 to 1700, and a dry period from AD 1700 to 1880. During the dry period xerophytic shrubs expanded to replace puna grasses on the Altiplano, as suggested by a dramatic drop in the Poaceae/Asteraceae (P/A) pollen ratio. The environment around Sajama was probably similar to the desert-like shrublands of the Southern Bolivian Highlands and western Andean slopes today. The striking similarity between the Sajama and Quelccaya proxy records suggests that climatic changes during the Little Ice Age occurred synchronously across the Altiplano.

scholarly journals Climatic Records from the Dunde Ice Cap, China

1988 ◽  
Vol 10 ◽  
pp. 178-182 ◽  
Author(s):  
Lonnie G. Thompson ◽  
Wu Xiaoling ◽  
Ellen Mosley-Thompson ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Average Thickness ◽  
The Past ◽  
Bedrock Topography ◽  
Ice Cap ◽  
Pulse Radar ◽  
Oxygen Isotope Ratios ◽  
Ice Core Record ◽  
Climatic Record

Results from the first glaciological investigation of the Dunde ice cap demonstrate that a long, highly temporally resolvable climatic ice-core record is preserved in this ice cap. Measurements of stratigraphy, microparticle concentrations, liquid conductivity, and oxygen-isotope ratios from three snow pits in 1984 suggest that the annual accumulation is approximately 200 mm (water equivalent). Measurement of microparticle concentrations and conductivities of pit samples collected in 1986 confirm the existence of annual dust layers and an annual accumulation rate of ∼200 mm/year over the past 5 years. Bore-hole temperatures of –5.4°C at 30 m indicate that the ice cap is polar. Mono-pulse radar depth determinations yield an average thickness of 140 m, which (coupled with the smooth bedrock topography and the current accumulation rate) suggest that the Dunde ice cap should contain at least a 3000 year climatic record. A drilling program to recover that record from this subtropical location is planned for 1987.

scholarly journals Temperature variations over the past millennium on the Tibetan Plateau revealed by four ice cores

2007 ◽  
Vol 46 ◽  
pp. 362-366 ◽  
Author(s):  
Tandong Yao ◽  
Keqin Duan ◽  
L.G. Thompson ◽  
Ninglian Wang ◽  
Lide Tian ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
19Th Century ◽  
Northern Hemisphere ◽  
Ice Core ◽  
Ice Cores ◽  
Ice Age ◽  
The Tibetan Plateau ◽  
Late 19Th Century ◽  
The Past ◽  
Northern Tibetan Plateau

AbstractTemperature variation on the Tibetan Plateau over the last 1000 years has been inferred using a composite δ18O record from four ice cores. Data from a new ice core recovered from the Puruogangri ice field in the central Tibetan Plateau are combined with those from three other cores (Dunde, Guliya and Dasuopu) recovered previously. The ice-core δ18O composite record indicates that the temperature change on the whole Tibetan Plateau is similar to that in the Northern Hemisphere on multi-decadal timescales except that there is no decreasing trend from AD 1000 to the late 19th century. The δ18O composite record from the northern Tibetan Plateau, however, indicates a cooling trend from AD 1000 to the late 19th century, which is more consistent with the Northern Hemisphere temperature reconstruction. The δ18O composite record reveals the existence of the Medieval Warm Period and the Little Ice Age (LIA) on the Tibetan Plateau. However, on the Tibetan Plateau the LIA is not the coldest period during the last millennium as in other regions in the Northern Hemisphere. The present study indicates that the 20th-century warming on the Tibetan Plateau is abrupt, and is warmer than at any time during the past 1000 years.

scholarly journals Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

1990 ◽  
Vol 14 ◽  
pp. 363-363
Author(s):  
Wu Xiaoling ◽  
Li Zhongqin ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Surface Strain ◽  
Entire Length ◽  
Ice Age ◽  
Cooperative Research ◽  
Ice Cap ◽  
Annual Layer ◽  
Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

scholarly journals Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

1990 ◽  
Vol 14 ◽  
pp. 363
Author(s):  
Wu Xiaoling ◽  
Li Zhongqin ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Surface Strain ◽  
Entire Length ◽  
Ice Age ◽  
Cooperative Research ◽  
Ice Cap ◽  
Annual Layer ◽  
Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

scholarly journals Climatic Records from the Dunde Ice Cap, China

1988 ◽  
Vol 10 ◽  
pp. 178-182 ◽  
Author(s):  
Lonnie G. Thompson ◽  
Wu Xiaoling ◽  
Ellen Mosley-Thompson ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Average Thickness ◽  
The Past ◽  
Bedrock Topography ◽  
Ice Cap ◽  
Pulse Radar ◽  
Oxygen Isotope Ratios ◽  
Ice Core Record ◽  
Climatic Record

Results from the first glaciological investigation of the Dunde ice cap demonstrate that a long, highly temporally resolvable climatic ice-core record is preserved in this ice cap. Measurements of stratigraphy, microparticle concentrations, liquid conductivity, and oxygen-isotope ratios from three snow pits in 1984 suggest that the annual accumulation is approximately 200 mm (water equivalent). Measurement of microparticle concentrations and conductivities of pit samples collected in 1986 confirm the existence of annual dust layers and an annual accumulation rate of ∼200 mm/year over the past 5 years. Bore-hole temperatures of –5.4°C at 30 m indicate that the ice cap is polar. Mono-pulse radar depth determinations yield an average thickness of 140 m, which (coupled with the smooth bedrock topography and the current accumulation rate) suggest that the Dunde ice cap should contain at least a 3000 year climatic record. A drilling program to recover that record from this subtropical location is planned for 1987.

scholarly journals 10,000 years of melt history of the 2015 Renland ice core, EastGreenland

2019 ◽  
Author(s):  
Tetsuro Taranczewski ◽  
Johannes Freitag ◽  
Olaf Eisen ◽  
Bo Vinther ◽  
Sonja Wahl ◽  
...  
Keyword(s):  
Ice Core ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Strong Increase ◽  
Past Century ◽  
Additional Information ◽  
The Past ◽  
Ice Cap ◽  
History Of ◽  
Paleoclimate Records

Abstract. An ice core drilled in 2015 on the Renland ice cap at the eastern margin of Greenland has been inspected with regard to its melt content. The thickness of a melt layer reflects the temperature level at the time of melt generation. Hence the melt layers are an indicator of past regional summer temperatures in East Greenland, a region where paleoclimate records are sparse. Melt layers have been identified almost along the whole core, resulting in a melt record reaching back 10,000 years. By gathering additional information about melt rates as well as high-resolution densities in two shallow cores, we developed an approach to correct the annual melt content for the ice volume that gets lost by the thinning process. The result is a melt record with decadal- to centennial- scale resolution for the last two millennia, and the most accurate Holocene climate record for Eastern Greenland so far. The observed changes of annual melt rates show a warm early Holocene, with melt rates higher than in the recent past century, and minimum melting during the Little Ice Age. Current melt rates show a strong increase for the early 20th century as well as for the time since the end of the past century, with the recent 2012 extreme melting of the Greenland Ice Sheet being the strongest melt event in the past 500 years.

scholarly journals Glaciological Reconnaissance of an Ice Core Drilling Site, Penny Ice Cap, Baffin Island

1984 ◽  
Vol 30 (104) ◽  
pp. 3-15 ◽  
Author(s):  
G. Holdsworth
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Surface Air Temperature ◽  
Tritium Concentration ◽  
Mean Annual Temperature ◽  
Climatic Data ◽  
Baffin Island ◽  
The Core ◽  
Ice Cap ◽  
The Mean

AbstractA site situated close to the main divide of the Penny Ice Cap, Baffin Island was occupied in 1979 for the purpose of determining the suitability of this ice cap for providing proxy climatic data and other environmental time series for a span of 104a. A 20 m core was extracted and analysed for stable oxygen isotopes, tritium concentration, pH, electrolytic conductivity, major ion concentrations, and particulate concentration. An adjacent dedicated shallow core was analysed for pollen content to determine if a significant seasonal variation in the pollen rain existed. From these measurements, and from the observations made on the stratigraphic character of the core, the mean net accumulation rate over the approximately 30 year period covered by the core is found to be about 0.43 m water equivalent per year. This is in agreement with a single value determined 26 years earlier at a nearby site (Ward and Baird, 1954). The mean annual temperature in the bore hole was found to be close to −14.4° C, possibly some 2–5 deg warmer than the expected mean annual surface air temperature at the site. This difference is due to the expulsion of latent heat upon freezing of melt water at depth in the snow-pack which gives rise to the many ice layers observed in the core. The percentage thickness of ice layers per year may be correlated with summer temperatures.Total ice depths were measured using a 620 MHz radar echo-sounder. In the vicinity of the divide, over an area of 1 km2, the ice depths vary from about 460 to 515 m. These values compare favourably with values determined from an airborne radar depth-sounding flight carried out over the ice cap by a joint U.S.–Danish mission operating out of Søndre Strømfjord, Greenland. The data suggest that the ice-cap divide would be a worthwhile location to deep core drill with an expected useful coverage of at least the Holocene period.

scholarly journals An ice-core record over the last two centuries from Penny Ice Cap, Baffin Island, Canada

2002 ◽  
Vol 35 ◽  
pp. 29-35 ◽  
Author(s):  
Kumiko Goto-Azuma ◽  
Roy M. Koerner ◽  
David A. Fisher
Keyword(s):  
Environmental Changes ◽  
Ice Core ◽  
Sea Salt ◽  
Ice Age ◽  
Baffin Island ◽  
Ion Chemistry ◽  
Sea Ice Extent ◽  
The Core ◽  
Ice Cap ◽  
Ice Core Record

AbstractIn order to reconstruct climatic and environmental changes in the Canadian Arctic, an 85 m deep ice core drilled in 1995 on Penny Ice Cap, Baffin Island, was analyzed for ions and δ18O. In addition to the core, snow-pit samples collected in 1994 and 1995 were also analyzed. Elution of ions caused by summer melting was observed in the pits. Due to the heavy summer melting on this ice cap, seasonal variations of ion chemistry and δ18O were not always present in the core. Comparisons of this core with a previously reported core drilled 2.5 maway show that the noise contained in single annual time series is 40–50% for ions and 25% for δ18O. the ice-core data, however, provide us with a reasonable proxy record of climatic and environmental changes during the last two centuries on better than a decadal basis. Sulfate and nitrate concentrations started to increase around 1900 and 1960, respectively, due to anthropogenic influx transported from the industrialized regions in North America. Sea-salt concentrations began to increase around the mid-19th century and were elevated throughout the 20th century. This trend of sea-salt concentrations is similar to that of melt percentage, which is a measure of summer temperature. Warming after the Little Ice Age would have reduced the sea-ice extent and led to the elevated sea-salt concentrations on Penny Ice Cap.

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