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

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.

Download Full-text

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

Annals of Glaciology ◽

10.3189/172756402781817338 ◽

2002 ◽

Vol 35 ◽

pp. 19-24 ◽

Cited By ~ 34

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.

Download Full-text

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

Annals of Glaciology ◽

10.3189/172756406781812375 ◽

2006 ◽

Vol 43 ◽

pp. 132-136 ◽

Cited By ~ 4

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.

Download Full-text

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

Annals of Glaciology ◽

10.3189/172756406781812357 ◽

2006 ◽

Vol 43 ◽

pp. 61-69 ◽

Cited By ~ 89

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.

Download Full-text

Holocene atmospheric iodine evolution over the North Atlantic

Climate of the Past ◽

10.5194/cp-15-2019-2019 ◽

2019 ◽

Vol 15 (6) ◽

pp. 2019-2030 ◽

Cited By ~ 2

Author(s):

Juan Pablo Corella ◽

Niccolo Maffezzoli ◽

Carlos Alberto Cuevas ◽

Paul Vallelonga ◽

Andrea Spolaor ◽

...

Keyword(s):

North Atlantic ◽

Ice Core ◽

First Record ◽

Atmospheric Composition ◽

The Holocene ◽

Holocene Thermal Maximum ◽

Ice Cap ◽

The North ◽

Thermal Maximum ◽

The North Atlantic

Abstract. Atmospheric iodine chemistry has a large influence on the oxidizing capacity and associated radiative impacts in the troposphere. However, information on the evolution of past atmospheric iodine levels is restricted to the industrial period while its long-term natural variability remains unknown. The current levels of iodine in the atmosphere are controlled by anthropogenic ozone deposition to the ocean surface. Here, using high-resolution geochemical measurements from coastal eastern Greenland ReCAP (REnland ice CAP project) ice core, we report the first record of atmospheric iodine variability in the North Atlantic during the Holocene (i.e., the last 11 700 years). Surprisingly, our results reveal that the highest iodine concentrations in the record were found during the Holocene Thermal Maximum (HTM; ∼ 11 500–5500 years before-present). These high iodine levels could be driven by marine primary productivity resulting in an Early Holocene “biological iodine explosion”. The high and stable iodine levels during this past warm period are a useful observational constraint on projections of future changes in Arctic atmospheric composition and climate resulting from global warming.

Download Full-text

Continuous Non-Marine Inputs of Per- and Polyfluoroalkyl Substances to the High Arctic: A Multi-Decadal Temporal Record

10.5194/acp-2017-1009 ◽

2017 ◽

Cited By ~ 1

Author(s):

Heidi M. Pickard ◽

Alison S. Criscitiello ◽

Christine Spencer ◽

Martin J. Sharp ◽

Derek C. G. Muir ◽

...

Keyword(s):

Solid Phase ◽

Ice Core ◽

High Arctic ◽

The Arctic ◽

Ice Caps ◽

Ice Cap ◽

Devon Ice Cap ◽

Pollutant Sources ◽

Arctic Ice ◽

Changes Over Time

Abstract. Perfluoroalkyl acids (PFAAs) are persistent, bioaccumulative compounds found ubiquitously within the environment. They can be formed from the atmospheric oxidation of volatile precursor compounds and undergo long-range transport through the atmosphere and ocean to remote locations. Ice caps preserve a temporal record of PFAA deposition making them useful in studying the atmospheric trends in LRT of PFAAs as well as understanding major pollutant sources and production changes over time. A 15 m ice core representing 38 years of deposition (1977–2015) was collected from the Devon Ice Cap in Nunavut, providing us with the first multi-decadal temporal ice record in PFAA deposition to the Arctic. Ice core samples were concentrated using solid phase extraction and analyzed by liquid and ion chromatography methods. Both perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) were detected in the samples, with fluxes ranging from

Download Full-text

Survival of the Mýrdalsjökull ice cap through the Holocene thermal maximum: evidence from sulphur contents in Katla tephra layers (Iceland) from the last ∽8400 years

Annals of Glaciology ◽

10.3189/172756407782282516 ◽

2007 ◽

Vol 45 ◽

pp. 183-188 ◽

Cited By ~ 11

Author(s):

Bergrun A. Oladottir ◽

Thor Thordarson ◽

Gudrun Larsen ◽

Olgeir Sigmarsson

Keyword(s):

Melt Inclusions ◽

Explosive Activity ◽

Mean Values ◽

The Holocene ◽

Holocene Thermal Maximum ◽

Ice Caps ◽

Ice Cap ◽

Thermal Maximum ◽

Tephra Layers ◽

External Water

AbstractThe climate in Iceland was drier and warmer during the Holocene thermal maximum than it is today and it has been suggested that ice caps disappeared entirely. Katla, a volcano covered by the Mýrdalsjökull ice cap in southern Iceland, has erupted rather steadily throughout the Holocene. Pre-and post-eruption sulphur concentrations in its products have been determined in previous studies, through melt inclusions trapped in phenocrysts (pre-eruption mean values of 2155±165 ppm) and fully degassed magmatic tephra (post-eruption mean values of 445±130 ppm). The phreatomagmatic tephra has much more variable S contents (550–1775 ppm) and spans the compositional gap between magmatic tephra and melt inclusions. These variable sulphur values are attributed to arresting of degassing as the magma is quenched upon contact with external water in the shallow levels of the volcano conduit. Sulphur in Katla tephra can thus be used to evaluate whether Mýrdalsjökull survived the warm spells of the Holocene. In this study, sulphur concentrations in tephra layers representing the last ∽8400 years of the volcano’s eruption history were measured, revealing concentrations in the phreatomagmatic range (600–1600 ppm). Hence, we conclude that over the last ∽8400 years, explosive activity at Katla has been dominated by phreatomagmatic eruptions, implying that the Mýrdalsjökull ice cap has been present throughout the Holocene.

Download Full-text

Are there multiple scaling regimes in Holocene temperature records?

Earth System Dynamics Discussions ◽

10.5194/esdd-6-1201-2015 ◽

2015 ◽

Vol 6 (2) ◽

pp. 1201-1235 ◽

Cited By ~ 1

Author(s):

T. Nilsen ◽

K. Rypdal ◽

H.-B. Fredriksen

Keyword(s):

Time Scales ◽

Ice Core ◽

Null Model ◽

Ice Cores ◽

The Holocene ◽

Scaling Model ◽

Temperature Records ◽

Glacial Time ◽

Temperature Time ◽

Scale Break

Abstract. The concept of multiple scaling regimes in temperature time series is examined, with emphasis on the question whether or not a mono-scaling model can be rejected from the data at hand. A model with only one regime is simpler and is preferred if this explains the observed variability. Our analysis of spectra from reconstructed air temperature from Greenland and Antarctica ice cores shows that a scale break around centennial time scales is evident for the last glacial period, but not for the Holocene. Nor by analysing a number of late Holocene multiproxy temperature reconstructions can a significant scale break be identified. Our results indicate that a mono-scaling model cannot be rejected as a null model for the Holocene climate up to at least millennial time scales, although it can be rejected for the glacial climate state. The scale break observed from the glacial time ice core records is likely caused by the influence of Dansgaard–Oeschger events and teleconnections to the Southern Hemisphere on centennial time scales. From our analysis we conclude that the two-regime model is not sufficiently justified for the Holocene to be used for temperature prediction on centennial time scales.

Download Full-text

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

10.5194/egusphere-egu21-8686 ◽

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

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.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 &#8220;miniature ice caps&#8221; sparks novel research perspectives. Summit stake measurements and ice core drillings are both rare, although the comparison of today&#8217;s stake mass balance records with the variance of annual accumulation preserved in ice cores offers an intriguing hub to unravelling past processes.We implemented summit stake mass balance measurements on two summits in the Austrian Alps, Wei&#223;seespitze (3500 m) in &#214;tztal Alps and Gro&#223;venediger (3600 m) in Hohe Tauern National Park. At Wei&#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.The results from the first two years of monitoring at Wei&#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.

Download Full-text

Do Greenland Ice Cores Reflect NW European Interglacial Climate Variations?

Quaternary Research ◽

10.1006/qres.1995.1014 ◽

1995 ◽

Vol 43 (2) ◽

pp. 125-132 ◽

Cited By ~ 29

Author(s):

Eiliv Larsen ◽

Hans Petter Sejrup ◽

Sigfus J. Johnsen ◽

Karen Luise Knudsen

Keyword(s):

Western Europe ◽

Ice Core ◽

Greenland Ice Sheet ◽

Ice Cores ◽

High Amplitude ◽

Atlantic Water ◽

Polar Front ◽

Norwegian Sea ◽

The Holocene ◽

Climatic Evolution

AbstractThe climatic evolution during the Eemian and the Holocene in western Europe is compared with the sea-surface conditions in the Norwegian Sea and with the oxygen-isotope-derived paleotemperature signal in the GRIP and Renland ice cores from Greenland. The records show a warm phase (ca. 3000 yr long) early in the Eemian (substage 5e). This suggests that the Greenland ice sheet, in general, recorded the climate in the region during this time. Rapid fluctuations during late stage 6 and late substage 5e in the GRIP ice core apparently are not recorded in the climatic proxies from western Europe and the Norwegian Sea. This may be due to low resolution in the terrestrial and marine records and/or long response time of the biotic changes. The early Holocene climatic optimum recorded in the terrestrial and marine records in the Norwegian Sea-NW European region is not found in the Summit (GRIP and GISP2) ice cores. However, this warm phase is recorded in the Renland ice core. Due to the proximity of Renland to the Norwegian Sea, this area is probably more influenced by changes in polar front positions which may partly explain this discrepancy. A reduction in the elevation at Summit during the Holocene may, however, be just as important. The high-amplitude shifts during substage 5e in the GRIP core could be due to Atlantic water oscillating closer to, and also reaching, the coast of East Greenland. During the Holocene, Atlantic water was generally located farther east in the Norwegian Sea than during the Eemian.

Download Full-text