scholarly journals Ice-core evidence for widespread Arctic glacier retreat in the Last Interglacial and the early Holocene

2002 ◽  
Vol 35 ◽  
pp. 19-24 ◽  
Author(s):  
Roy M. Koerner ◽  
David A. Fisher
Keyword(s):  
Ice Core ◽  
Canadian Arctic ◽  
Ice Cores ◽  
Early Holocene ◽  
Interglacial Period ◽  
Russian Arctic ◽  
Last Interglacial ◽  
Ice Caps ◽  
Ice Cap ◽  
Thermal Maximum

AbstractAn early study of the various components of the Greenland, Antarctic and Canadian Arctic ice-cap cores (Koerner, 1989) suggested that during the last interglacial period, the Greenland ice sheet suffered massive retreat and Canadian ice caps melted completely. Since then, modeling has helped support this interpretation (Cuffey and Marshall, 2000). Ice-core records of stable isotopes, melt layering and chemistry from the same Canadian ice cores, and others from the Russian Arctic islands, Svalbard and Greenland are presented as evidence for a more modest, but still substantial, retreat in the early Holocene. the sections representing the first half of the Holocene in many cores have less negative δ18O values (d values) and a higher percentage of melt layers than recently deposited ice, suggesting that temperatures were 1.3–3.5˚C warmer than today. Given that glacier balances are slightly negative today, they must have been substantially more negative during the early-Holocene thermal maximum, leading to retreat of the circumpolar ice caps. Evidence is presented to suggest that, with the exception of Academii Nauk ice cap, the ice in the Russian Arctic islands and Svalbard must have almost disappeared. In the Canadian Arctic, the larger Canadian ice caps retreated but survived. the cooling trend that followed this thermal maximum promoted re-expansion and new growth of most of the ice caps in the Russian Arctic islands and Svalbard.

scholarly journals Some comments on climatic reconstructions from ice cores drilled in areas of high melt

1997 ◽  
Vol 43 (143) ◽  
pp. 90-97 ◽  
Author(s):  
Roy M. Koerner
Keyword(s):  
Time Scales ◽  
Ice Core ◽  
Ice Cores ◽  
The Holocene ◽  
Ice Caps ◽  
Ice Cap ◽  
Thermal Maximum ◽  
Devon Ice Cap ◽  
Seasonal Signals ◽  
Cross Correlations

AbstractPoor consideration has been given in many Arctic circum-polar ice-core studies to the effect of summer snow melt on chemistry, stable-isotope concentrations and time-scales. Many of these corps are drilled close to the firn line where melt is intense. Some come from below the firn line where accumulation is solely in the form of super-imposed ice. In all cases, seasonal signals are reduced or removed and, in some, time gaps develop during periods of excessive melting which situate the drill site in the ablation zone. Consequently, cross correlations of assumed synchronous events among the cores are invalid, so that time-scales along the same cores differ between authors by factors of over 2. Many so-called climatic signals are imaginary rather than real. By reference to published analyses of cores from the superimposed ice zone on Devon Ice Cap (Koerner, 1970) and Meighen Ice Cap (Koerner and Paterson, 1974), it is shown how melt affects all the normally well-established ice-core proxies and leads to their misinterpretation. Despite these limitations, the cores can give valuable low-resolution records for all or part of the Holocene. They show that the thermal maximum in the circum-polar Arctic occurred in the early Holocene. This maximum, effected negative balances on all the ice caps and removed the smaller ones. Cooler conditions in the second half of the Holocene have caused the regrowth of these same ice caps.

scholarly journals Some comments on climatic reconstructions from ice cores drilled in areas of high melt

1997 ◽  
Vol 43 (143) ◽  
pp. 90-97 ◽  
Author(s):  
Roy M. Koerner
Keyword(s):  
Time Scales ◽  
Ice Core ◽  
Ice Cores ◽  
The Holocene ◽  
Ice Caps ◽  
Ice Cap ◽  
Thermal Maximum ◽  
Devon Ice Cap ◽  
Seasonal Signals ◽  
Cross Correlations

AbstractPoor consideration has been given in many Arctic circum-polar ice-core studies to the effect of summer snow melt on chemistry, stable-isotope concentrations and time-scales. Many of these corps are drilled close to the firn line where melt is intense. Some come from below the firn line where accumulation is solely in the form of super-imposed ice. In all cases, seasonal signals are reduced or removed and, in some, time gaps develop during periods of excessive melting which situate the drill site in the ablation zone. Consequently, cross correlations of assumed synchronous events among the cores are invalid, so that time-scales along the same cores differ between authors by factors of over 2. Many so-called climatic signals are imaginary rather than real. By reference to published analyses of cores from the superimposed ice zone on Devon Ice Cap (Koerner, 1970) and Meighen Ice Cap (Koerner and Paterson, 1974), it is shown how melt affects all the normally well-established ice-core proxies and leads to their misinterpretation. Despite these limitations, the cores can give valuable low-resolution records for all or part of the Holocene. They show that the thermal maximum in the circum-polar Arctic occurred in the early Holocene. This maximum, effected negative balances on all the ice caps and removed the smaller ones. Cooler conditions in the second half of the Holocene have caused the regrowth of these same ice caps.

scholarly journals Natural and anthropogenic levels of tritium in a Canadian Arctic ice core, Agassiz Ice Cap, Ellesmere Island, and comparison with other radionuclides

2000 ◽  
Vol 46 (152) ◽  
pp. 35-40 ◽  
Author(s):  
Thomas G. Kotzer ◽  
Akira Kudo ◽  
James Zheng ◽  
Wayne Workman
Keyword(s):  
Ice Core ◽  
Canadian Arctic ◽  
Fission Products ◽  
Ellesmere Island ◽  
Anthropogenic Radionuclides ◽  
Ice Caps ◽  
Nuclear Bomb ◽  
Ice Cap ◽  
Nuclear Weapons Testing ◽  
Arctic Ice

AbstractNumerous studies of the ice caps in Greenland and Antarctica have observed accumulations of transuranic radionuclides and fission products from nuclear weapons testing, particularly during the period 1945–75. Recently, the concentrations of radionuclides in the annually deposited surface layers of Agassiz Ice Cap, Ellesmere Island, Canadian Arctic, from 1945 to the present have been measured and have demonstrated a continuous record of deposition of 137Cs and 239,240Pu in ice and snow. In this study, 3He-ingrowth mass spectrometry has been used to measure the low levels of tritium (3H) in some of these samples. Pre-nuclear-bomb tritium levels in ice-core samples were approximately 12 TU in high-latitude meteoric waters and 3–9 TU in mid-latitude meteoric waters. Comparisons of 3H levels and 3H/137Cs + 239,240Pu ratios, which were quite low during the earliest fission-bomb detonations (1946–51) and substantially higher during thermonuclear hydrogen-fusion bomb testing (1952–64), provide a clear indication of the type of nuclear device detonated. This finding accords with the results from other ice-core studies of the distribution of anthropogenic radionuclides from bomb fallout.

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.

scholarly journals Holocene climate variability archived in the Puruogangri ice cap on the central Tibetan Plateau

2006 ◽  
Vol 43 ◽  
pp. 61-69 ◽  
Author(s):  
Lonnie G. Thompson ◽  
Yao Tandong ◽  
Mary E. Davis ◽  
Ellen Mosley-Thompson ◽  
Tracy A. Mashiotta ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ice Core ◽  
Ice Cores ◽  
The Tibetan Plateau ◽  
Climate History ◽  
Ice Caps ◽  
Ice Cap ◽  
Monsoon System ◽  
The Tropics ◽  
Ice Core Records

AbstractTwo ice cores (118.4 and 214.7 m in length) were collected in 2000 from the Puruogangri ice cap in the center of the Tibetan Plateau (TP) in a joint US-Chinese collaborative project. These cores yield paleoclimatic and environmental records extending through the Middle Holocene, and complement previous ice-core histories from the Dunde and Guliya ice caps in northeast and northwest Tibet, respectively, and Dasuopu glacier in the Himalaya. The high-resolution Puruogangri climate record since AD 1600 details regional temperature and moisture variability. The post-1920 period is characterized by above-average annual net balance, contemporaneous with the greatest 18O enrichment of the last 400 years, consistent with the isotopically inferred warming observed in other TP ice-core records. On longer timescales the aerosol history reveals large and abrupt events, one of which is dated ∼4.7 kyr BP and occurs close to the time of a drought that extended throughout the tropics and may have been associated with centuries-long weakening of the Asian/Indian/African monsoon system. The Puruogangri climate history, combined with the other TP ice-core records, has the potential to provide valuable information on variations in the strength of the monsoon across the TP during the Holocene.

scholarly journals A brief history of ice core science over the last 50 yr

2013 ◽  
Vol 9 (6) ◽  
pp. 2525-2547 ◽  
Author(s):  
J. Jouzel
Keyword(s):  
Time Scales ◽  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Future Research ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Last Interglacial Period ◽  
History Of ◽  
Scientific Results

Abstract. For about 50 yr, ice cores have provided a wealth of information about past climatic and environmental changes. Ice cores from Greenland, Antarctica and other glacier-covered regions now encompass a variety of time scales. However, the longer time scales (e.g. at least back to the Last Glacial period) are covered by deep ice cores, the number of which is still very limited: seven from Greenland, with only one providing an undisturbed record of a part of the last interglacial period, and a dozen from Antarctica, with the longest record covering the last 800 000 yr. This article aims to summarize this successful adventure initiated by a few pioneers and their teams and to review key scientific results by focusing on climate (in particular water isotopes) and climate-related (e.g. greenhouse gases) reconstructions. Future research is well taken into account by the four projects defined by IPICS. However, it remains a challenge to get an intact record of the Last Interglacial in Greenland and to extend the Antarctic record through the mid-Pleistocene transition, if possible back to 1.5 Ma.

scholarly journals Sensitivity of interglacial Greenland temperature and δ<sup>18</sup>O: ice core data, orbital and increased CO<sub>2</sub> climate simulations

2011 ◽  
Vol 7 (3) ◽  
pp. 1041-1059 ◽  
Author(s):  
V. Masson-Delmotte ◽  
P. Braconnot ◽  
G. Hoffmann ◽  
J. Jouzel ◽  
M. Kageyama ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Interglacial Period ◽  
Orbital Forcing ◽  
Last Interglacial ◽  
Core Data ◽  
Climate Simulations ◽  
The Impact

Abstract. The sensitivity of interglacial Greenland temperature to orbital and CO2 forcing is investigated using the NorthGRIP ice core data and coupled ocean-atmosphere IPSL-CM4 model simulations. These simulations were conducted in response to different interglacial orbital configurations, and to increased CO2 concentrations. These different forcings cause very distinct simulated seasonal and latitudinal temperature and water cycle changes, limiting the analogies between the last interglacial and future climate. However, the IPSL-CM4 model shows similar magnitudes of Arctic summer warming and climate feedbacks in response to 2 × CO2 and orbital forcing of the last interglacial period (126 000 years ago). The IPSL-CM4 model produces a remarkably linear relationship between TOA incoming summer solar radiation and simulated changes in summer and annual mean central Greenland temperature. This contrasts with the stable isotope record from the Greenland ice cores, showing a multi-millennial lagged response to summer insolation. During the early part of interglacials, the observed lags may be explained by ice sheet-ocean feedbacks linked with changes in ice sheet elevation and the impact of meltwater on ocean circulation, as investigated with sensitivity studies. A quantitative comparison between ice core data and climate simulations requires stability of the stable isotope – temperature relationship to be explored. Atmospheric simulations including water stable isotopes have been conducted with the LMDZiso model under different boundary conditions. This set of simulations allows calculation of a temporal Greenland isotope-temperature slope (0.3–0.4‰ per °C) during warmer-than-present Arctic climates, in response to increased CO2, increased ocean temperature and orbital forcing. This temporal slope appears half as large as the modern spatial gradient and is consistent with other ice core estimates. It may, however, be model-dependent, as indicated by preliminary comparison with other models. This suggests that further simulations and detailed inter-model comparisons are also likely to be of benefit. Comparisons with Greenland ice core stable isotope data reveals that IPSL-CM4/LMDZiso simulations strongly underestimate the amplitude of the ice core signal during the last interglacial, which could reach +8–10 °C at fixed-elevation. While the model-data mismatch may result from missing positive feedbacks (e.g. vegetation), it could also be explained by a reduced elevation of the central Greenland ice sheet surface by 300–400 m.

scholarly journals Moderate Greenland ice sheet melt during the last interglacial constrained by present-day observations and paleo ice core reconstructions

2016 ◽  
Author(s):  
P.M. Langebroek ◽  
K.H. Nisancioglu
Keyword(s):  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Atmospheric Temperature ◽  
Lapse Rate ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Temperature Lapse Rate

Abstract. During the last interglacial period (LIG, ~ 130–115 ka before present, ka = 1000 yr) summer temperatures over Greenland were several degrees higher than today. It is likely that the Greenland ice sheet (GIS) was smaller than today, contributing to the reconstructed sea-level highstand of the LIG. However, the range of simulated GIS melt is large, and the location of the melt is uncertain. Here, we use temperature and precipitation patterns simulated by the Norwegian Earth System Model (NorESM) to investigate the volume, extent and stability of the GIS during the LIG. Present-day observations of ice sheet size, elevation and stability, together with paleo elevation information from five deep ice cores, are used to evaluate our ensemble of GIS simulations. Accepted simulations indicate a maximum GIS reduction equivalent to a global mean sea-level rise of 0.8–2.2 m compared to today, with most of the melt occurring in the southwest. The timing of the maximum ice melt over Greenland is simulated between 124 and 122 ka. We furthermore suggest a preferred mean value for the basal sliding parameter, relatively high PDD factors and an average to high atmospheric temperature lapse rate based on training the SICOPOLIS ice sheet model to observations and available LIG proxy data.

scholarly journals Pollen Analysis and Discussion of Time-Scales in Canadian Ice Cores

1988 ◽  
Vol 10 ◽  
pp. 85-91 ◽  
Author(s):  
R.M. Koerner ◽  
J.C. Bourgeois ◽  
D.A. Fisher
Keyword(s):  
Flow Line ◽  
Ice Cores ◽  
Bulk Sample ◽  
High Arctic ◽  
Interglacial Period ◽  
Drilling Process ◽  
Last Interglacial ◽  
Ice Cap ◽  
Last Interglacial Period ◽  
Pollen Concentrations

Previous pollen analyses of ice cores from Devon and Ellesmere islands have contributed considerably to our knowledge of past climate in the Canadian High Arctic. In this case, in 1979, bulk (35–83 litres) water samples were melted down a hole 139 m deep, drilled to bedrock, 1.2 km from the top of the flow line in Agassiz Ice Cap in northern Ellesmere Island. Analysis of ten of these samples, plus some taken in very dirty ice from the melt tank during drilling 7 years ago, has yielded pollen concentrations that, together with the oygen-isotope (6) signatures, suggest the Agassiz Ice Cap began its growth during the last interglacial period. A discrepancy between melt-tank and bulk-sample pollen concentrations is believed to be due to a loss of pollen from the melt-tank samples during the drilling process.

Eastern Alpine summit mass balances as complementary indicators of local climate change 

2021 ◽  
Author(s):  
Andrea Fischer ◽  
Pascal Bohleber ◽  
Martin Stocker-Waldhuber
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Ice Core ◽  
Ice Cores ◽  
Time Lapse ◽  
Mass Balances ◽  
Local Climate ◽  
Ice Caps ◽  
Ice Cap ◽  
Research Perspectives

&lt;p&gt;Eastern Alpine Mountain Glaciers are threatened by current climate change, for which they are visible and prominent indicators. This makes them an important part of climate communication pushing our commitment for mitigation efforts. At the same time, this requires the scientific community to thoroughly understand and communicate the ongoing processes.&lt;/p&gt;&lt;p&gt;From a scientific viewpoint, the link between classical in-situ mass balance data and the climate and environmental records potentially preserved in the so-called cold &amp;#8220;miniature ice caps&amp;#8221; sparks novel research perspectives. Summit stake measurements and ice core drillings are both rare, although the comparison of today&amp;#8217;s stake mass balance records with the variance of annual accumulation preserved in ice cores offers an intriguing hub to unravelling past processes.&lt;/p&gt;&lt;p&gt;We implemented summit stake mass balance measurements on two summits in the Austrian Alps, Wei&amp;#223;seespitze (3500 m) in &amp;#214;tztal Alps and Gro&amp;#223;venediger (3600 m) in Hohe Tauern National Park. At Wei&amp;#223;seespitze summit ice cap, two ice cores were drilled recently to bedrock and subsequently micro-radiocarbon dated. A stake network is complemented by a continuous monitoring of point thickness changes and a time lapse cam to monitor patterns of snow cover distribution. An energy balance station offers information on wind, air and ice temperatures and radiation.&lt;/p&gt;&lt;p&gt;The results from the first two years of monitoring at Wei&amp;#223;seespitze indicate that the remaining ice cap of about 10 m thickness will be gone within two decades even under current conditions. In view of present melt rates of about 0.6 m/year, a dated ice core record could eventually shed light on the question if similar conditions as today have occurred earlier in the past 6000 years of glacier cover at the summit. Learning more about (sub)seasonal patterns of accumulation is extremely import for the interpretation of these ice cores, as main accumulation takes place during early and late accumulation season, whereas the accumulation during colder periods is lost by wind erosion. The so far rarely studied miniature ice caps therefore open windows to complementary climate information, different from summer temperatures and winter precipitation which are widely accepted to be represented in total glacier mass balances.&lt;/p&gt;

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