scholarly journals Topographic effect creates non-climatic variations in ice-core based temperature records of the last millennium

2021 ◽  
Author(s):  
Remi Dallmayr ◽  
Johannes Freitag ◽  
Thomas Laepple ◽  
Frank Wilhelms ◽  
Daniela Jansen ◽  
...  
Keyword(s):  
Ice Core ◽  
Last Millennium ◽  
Topographic Effect ◽  
Climatic Variations ◽  
Temperature Records

Ice-core based assessment of nitrogen deposition in the central Tibetan Plateau over the last millennium

2021 ◽  
pp. 152692
Author(s):  
Xiang Zou ◽  
Shugui Hou ◽  
Shuangye Wu ◽  
Hongxi Pang ◽  
Ke Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Nitrogen Deposition ◽  
Ice Core ◽  
Last Millennium ◽  
Central Tibetan Plateau

scholarly journals A 3500-Year Ice Chemistry Record From The Dominion Range, Antarctica: Linkages Between Climatic Variations and Precipitation Chemistry

1990 ◽  
Vol 14 ◽  
pp. 358-358
Author(s):  
Mary Jo Spencer ◽  
Paul A. Mayewski ◽  
W. Berry Lyons ◽  
Mark S. Twickler ◽  
Pieter Grootes
Keyword(s):  
Oxygen Isotope ◽  
Global Climate ◽  
Ice Core ◽  
Precipitation Chemistry ◽  
Climate Forcing ◽  
Climatic Forcing ◽  
Climatic Variations ◽  
Oxygen Isotope Record ◽  
Isotope Record

In 1984 a 200-m ice core was collected from a local accumulation basin in the Dominion Range, Transantarctic Mountains, Antarctica. A complete oxygen isotope record has been obtained and a considerable portion of the core has been analyzed in detail for chloride, nitrate, sulfate, and sodium. About half of the chloride is due to sea salt with the remainder originating as gaseous HCl. Nitrate levels have increased markedly over the last 1000 years whereas the levels of the other constituents have remained fairly constant.The oxygen isotope results suggest that this region of Antarctica is responding to long-term global climate forcing as well as to shorter-term climatic variations. This data will be compared with the anion and sodium records in order to determine the effects of climatic forcing on these other records. In particular, nitrate appears to vary in concert with fluctuations in long-term climate. Additionally, variations in each constituent over the 3500 year period will be examined in detail to determine the influence of other processes which affect their concentrations.

scholarly journals Characterization and formation of melt layers in polar snow: observations and experiments from West Antarctica

2005 ◽  
Vol 51 (173) ◽  
pp. 307-312 ◽  
Author(s):  
Sarah B. Das ◽  
Richard B. Alley
Keyword(s):  
Field Experiments ◽  
Preferential Flow ◽  
Ice Core ◽  
Ice Cores ◽  
West Antarctica ◽  
Near Surface ◽  
Fine Grained ◽  
Ice Core Record ◽  
Temperature Records ◽  
Polar Snow

AbstractSurface melting rarely occurs across most of the Antarctic ice sheet, away from the warmer coastal regions. Nonetheless, isolated melt features are preserved in the firn and ice in response to infrequent and short-lived melting events. An understanding of the formation and occurrence of these melt layers will help us to interpret records of past melt occurrences from polar ice cores such as the Siple Dome ice-core record from West Antarctica. A search in the near-surface firn in West Antarctica found that melt features are extremely rare, and consist of horizontal, laterally continuous, one to a few millimeter thick, ice layers with few air bubbles. The melt layers found date from the 1992/93 and 1991/92 summers. Field experiments to investigate changes in stratigraphy taking place during melt events reproduced melt features as seen in the natural stratigraphy. Melting conditions of varying intensity were created by passively heating the near-surface air for varying lengths of time inside a clear plastic hotbox. Melt layers formed due entirely to preferential flow and subsequent refreezing of meltwater from the surface into near-surface, fine-grained, crust layers. Continuous melt layers were formed experimentally when positive-degree-day values exceeded 1ºC-day, a value corresponding well with air-temperature records from automatic weather station sites where melt layers formed in the recent past.

scholarly journals Recent ice-core climate records from the Cordillera Blanca, Peru

1995 ◽  
Vol 21 ◽  
pp. 225-230 ◽  
Author(s):  
M. E. Davis ◽  
L. G. Thompson ◽  
E. Mosley-Thompson ◽  
P. N. Lin ◽  
V. N. Mikhalenko ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Warming Trend ◽  
Isotopic Ratios ◽  
Weather Station ◽  
Climate Record ◽  
Climatic Variations ◽  
Recent Warming ◽  
Lower Elevation ◽  
Oxygen Isotopic

Ice cores recently drilled to bedrock on the col of Huascarán (9°06′ S, 77°36′ W, 6047 m a.s.l.) offer the potential for a long, annually resolved climate record from tropical South America. This paper presents the record from 1950 to 1993 preserved in microparticle and nitrate concentrations and oxygen-isotopic ratios. Average monthly temperatures from a satellite-linked automatic weather station installed on nearby Hualcán in 1991 are presented. Annual temperatures from local high-altitude meteorological stations, along with the annual Huascarán isotopic record, show a warming trend over the last two decades. The marked preservation of the climate record in oxygen-isotopic ratios on Huascarán is absent at lower-elevation sites, which have been affected by the recent warming. This paper demonstrates the establishment of a time-scale for the Huascarán core, the preservation of the climatic signal with depth and the linkage of the ice-core “proxy-climate” parameters with measured climatic variations.

scholarly journals Modelling binge–purge oscillations of the Laurentide ice sheet using a plastic ice sheet

2008 ◽  
Vol 48 ◽  
pp. 177-182 ◽  
Author(s):  
H.C. Steen-Larsen ◽  
D. Dahl-Jensen
Keyword(s):  
Melting Point ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Climate Feedbacks ◽  
Heinrich Events ◽  
Basal Sliding ◽  
Pressure Melting ◽  
Temperature Records

AbstractA simple combined heat and ice-sheet model has been used to calculate temperatures at the base of the Laurentide ice sheet. We let the ice sheet surge when the basal temperature reaches the pressure-melting temperature. Driving the system with the observed accumulation and temperature records from the GRIP ice core, Greenland, produces surges corresponding to the observed Heinrich events. This suggests that the mechanism of basal sliding, initiated when the basal temperature reaches the melting point, can explain the surges of the Laurentide ice sheet. This study highlights the importance of the surface temperature and accumulation rate as a means of forcing the timing and strength of the Heinrich events, thus implying important ice-sheet climate feedbacks.

scholarly journals Younger Dryas ice-margin retreat in Greenland, new evidence from Southwest Greenland

2020 ◽  
Author(s):  
Svend Funder ◽  
Anita H. L. Sørensen ◽  
Nicolaj K. Larsen ◽  
Anders Bjørk ◽  
Jason P. Briner ◽  
...  
Keyword(s):  
Ice Core ◽  
Temperature Drop ◽  
Younger Dryas ◽  
Greenland Ice Sheet ◽  
Subsurface Water ◽  
Glacier Mass Balance ◽  
Sea Ice Extent ◽  
The Rich ◽  
Temperature Records ◽  
Southwest Greenland

Abstract. Cosmogenic 10Be dates from bedrock knobs on six outlying tiny islands along a stretch of 300 km of the Southwest Greenland coast, indicate that the Greenland Ice Sheet (GrIS) margin here was retreating on the inner shelf close to the coast during the Younger Dryas (YD) cold period. A survey of recently published 10Be and 14C-dated records show that this unexpected behaviour of the ice-margin has been seen also in other parts of Greenland, but with very large variations in extent and speed of retreat even between neighbouring areas. In contrast to this, landforms appearing in high resolution bathymetry surveys on the shelf, have recently been suggested to indicate YD readvance or long-lasting ice-margin still stand on mid shelf, far from the coast. However, these features have been dated primarily by correlation with cold periods in the ice core temperature records, and therefore cannot inform about the ice-margin/climate relation. Ice-margin retreat during a YD cooling has been explained by advection of warm subsurface water melting the ice-margin, and by increased seasonality of the climate with the temperature drop mainly in winter, with high impact on sea ice extent and duration, but little effect on glacier mass balance. This study therefore adds to the complexity of the climate/ice-margin relation, where local factors may for some time overrule or mute overall temperature change. It also points to the urgent need for climate-independent dating of the rich treasure trove of information coming from the shelf in these years.

scholarly journals Persistent draining of the stratospheric 10Be reservoir after the Samalas volcanic eruption (1257 CE)

2020 ◽  
Author(s):  
Mélanie Baroni ◽  
Edouard Bard ◽  
Jean-Robert Petit ◽  
Sophie Viseur ◽  
Aster Team
Keyword(s):  
Ice Core ◽  
Volcanic Eruptions ◽  
Solar Modulation ◽  
Last Millennium ◽  
Climatic Impact ◽  
Air Masses ◽  
Sulphate Aerosols ◽  
Long Time ◽  
Modelling Studies ◽  
Volcanic Aerosols

<p>More than 2,000 analyses of beryllium‐10 (<sup>10</sup>Be) and sulphate concentrations were performed at a nominal subannual resolution on an ice core covering the last millennium as well as on shorter records from three sites in Antarctica (Dome C, South Pole, and Vostok) to better understand the increase in <sup>10</sup>Be deposition during stratospheric volcanic eruptions.</p><p>A significant increase in <sup>10</sup>Be concentration is observed in 14 of the 26 volcanic events studied. The slope and intercept of the linear regression between <sup>10</sup>Be and sulphate concentrations provide different and complementary information. Slope is an indicator of the efficiency of the draining of <sup>10</sup>Be atoms by volcanic aerosols depending on the amount of sulphur dioxide (SO<sub>2</sub>) released and on the altitude it reaches in the stratosphere. The intercept provides an appreciation of the <sup>10</sup>Be production in the stratospheric reservoir, ultimately depending on solar modulation (Baroni et al., 2019, JGR).</p><p>Among all the identified events, the Samalas event (1257 CE) stands out as the biggest eruption of the last millennium with the lowest positive slope. It released (158 ± 12) Tg of SO<sub>2</sub> up to an altitude of 43 km in the stratosphere (Lavigne et al., 2013, PNAS ; Vidal et al., 2016, Sci. Rep.). We hypothesize that the persistence of volcanic aerosols in the stratosphere after the Samalas eruption has drained the stratospheric <sup>10</sup>Be reservoir for a decade.</p><p>The persistence of Samalas sulphate aerosols might be due to the increase of SO<sub>2</sub> lifetime because of: (i) the exhaustion of the OH reservoir required for sulphate formation (e.g. (Bekki, 1995, GRL; Bekki et al., 1996, GRL; Savarino et al., 2003, JGR); and/or, (ii) the evaporation followed by photolysis of gaseous sulphuric acid back to SO<sub>2</sub> at altitudes higher than 30 km (Delaygue et al., 2015, Tellus; Rinsland et al., 1995, GRL). In addition, the lifetime of air masses increases to 5 years above 30 km altitude compared with 1 year for aerosols and air masses in the lower stratosphere (Delaygue et al., 2015, Tellus). When this high-altitude SO<sub>2</sub> finally returns below the 30 km limit, it could be oxidized back to sulphate and forms new sulphate aerosols. These processes could imply that the <sup>10</sup>Be reservoir is washed out over a long time period following the end of the eruption of Samalas.</p><p>This would run counter to modelling studies that predict the formation of large particle sizes and their rapid fall out due to the large amount of SO<sub>2</sub>, which would limit the climatic impact of Samalas-type eruptions (Pinto et al., 1989, JGR; Timmreck et al., 2010, 2009, GRL).</p>

Comparison of isotopic signatures in ice core and speleothem records to an isotope enabled climate model simulation for the last millennium

2021 ◽  
Author(s):  
Yannick Heiser ◽  
Janica Bühler ◽  
Mathieu Casado ◽  
Kira Rehfeld
Keyword(s):  
Climate Variability ◽  
Climate Model ◽  
Southern Oscillation ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Last Millennium ◽  
Polar Ice ◽  
Geophysical Research ◽  
Ice Core Records

<div> <div> <div> <p>Stable water isotope ratios (δ18O) measured in e.g. ice-cores or speleothems have long been established as temperature proxies and are used to reconstruct past climate variability but still require more quantification on spatial and temporal scales. The high resolution ice-core archives are mainly found in polar and alpine regions, whereas the speleothem records mostly grow in caves in low to mid-latitudes. To bridge between the archives, models are needed to compare the climate variability stored in both ice-cores and speleothems, which will help to evaluate future projections of climate variability.</p> <p>Here, we compare a transient isotope enabled simulation from the Hadley Center Climate Model version 3 (iHadCM3) [1, 2] to polar ice-core records from the iso2k database [3] for the last millennium (LM, 850-1850 CE). We analyze time-averaged isotope ratios and their variability on decadal to centennial timescales to systematically evaluate the offsets and correlation patterns between simulated and recorded isotopes to specific climatic drivers. For better comparability between speleothem and ice core-archives, we also include non-polar ice core records, as well as monitored precipitation δ18O from a global database.</p> <p>We find the time-averaged δ18O offsets between the simulation and ice-core records to be fairly small for most of the polar ice-core sites, indicating a low simulation climate offset.<br>As expected, we find the simulated δ18O variability to be higher in the polar regions of ice-core locations, compared to the simulated variability at speleothem cave locations. Recorded δ18O variability is also generally higher as stored in ice-cores, compared to that stored in speleothems. Both speleothems and ice-core records show damping effects on decadal time scales, which can in part be attributed to the temporal resolution of the individual records. This comparison of different proxy archives to isotope-enabled GCM output shows a promising way to evaluate the model’s capability to resolve δ18O variability.</p> <div> <div> <div> <p>[1]  Bühler, J. C. et al. Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium. Climate of the Past: Discussions 1–30 (2020).</p> <p>[2]  Tindall, J. C., Valdes, P. J. & Sime, L. C. Stable water isotopes in HadCM3: Isotopic signature of El Niño-Southern Oscillation and the tropical amount effect. Journal of Geophysical Research Atmospheres 114, 1–12 (2009).</p> <p>[3] Konecky, B. L. et al. The Iso2k database: A global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate. Earth System Science Data 12, 2261–2288 (2020).</p> </div> </div> </div> </div> </div> </div>

scholarly journals Wavelet analysis reveals periodic oscillations in a 1700 year ice-core record from Guliya, China

2006 ◽  
Vol 43 ◽  
pp. 132-136 ◽  
Author(s):  
Meixue Yang ◽  
Tandong Yao ◽  
Xiaohua Gou ◽  
Huijun Wang ◽  
Thomas Neumann
Keyword(s):  
Wavelet Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Past Climate ◽  
Ice Caps ◽  
The Past ◽  
Ice Cap ◽  
Temperature And Precipitation ◽  
Temperature Records ◽  
Precipitation Records

AbstractIce cores contribute important records of past climate changes. As one of the thickest ice caps in central Asia, the Guliya ice cap (35°17′ N, 81°29′ E) provides valuable information for this critical region about the past climate and environment changes. We used wavelet analysis to examine periodic temperature and precipitation oscillations over the past 1700 years recorded in the Guliya ice core. The results show non-linear oscillations in the ice-core records, with multiple timescales. Temperature records indicate persistent oscillations with periodicities of approximately 200, 150 and 70 years. Precipitation records show significant periodicities at 200, 100, 150 and 60 years. However, the amplitude modulation and frequency vary with time. Wavelet analysis can explore these time series in greater detail and furnish additional useful information.

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