scholarly journals Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events

2020 ◽  
Vol 6 (42) ◽  
pp. eabb6546
Author(s):  
Jannik Martens ◽  
Birgit Wild ◽  
Francesco Muschitiello ◽  
Matt O’Regan ◽  
Martin Jakobsson ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Cores ◽  
Early Holocene ◽  
The Arctic ◽  
Last Deglaciation ◽  
Siberian Arctic ◽  
Carbon Release ◽  
Order Of Magnitude ◽  
Global Sea Level ◽  
Carbon Remobilization

Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO2 levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores—(i) Dansgaard-Oeschger event 3 (~28 ka B.P.), (ii) Bølling-Allerød (14.7 to 12.9 ka B.P.), and (iii) early Holocene (~11.7 ka B.P.)—caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.

scholarly journals Pervasive Arctic lead pollution suggests substantial growth in medieval silver production modulated by plague, climate, and conflict

2019 ◽  
Vol 116 (30) ◽  
pp. 14910-14915 ◽  
Author(s):  
Joseph R. McConnell ◽  
Nathan J. Chellman ◽  
Andrew I. Wilson ◽  
Andreas Stohl ◽  
Monica M. Arienzo ◽  
...  
Keyword(s):  
Middle Ages ◽  
Large Scale ◽  
Industrial Revolution ◽  
Atmospheric Transport ◽  
Pollution Abatement ◽  
Early Modern Period ◽  
Ice Cores ◽  
The Arctic ◽  
Lead Pollution ◽  
Lower Growth

Lead pollution in Arctic ice reflects large-scale historical changes in midlatitude industrial activities such as ancient lead/silver production and recent fossil fuel burning. Here we used measurements in a broad array of 13 accurately dated ice cores from Greenland and Severnaya Zemlya to document spatial and temporal changes in Arctic lead pollution from 200 BCE to 2010 CE, with interpretation focused on 500 to 2010 CE. Atmospheric transport modeling indicates that Arctic lead pollution was primarily from European emissions before the 19th-century Industrial Revolution. Temporal variability was surprisingly similar across the large swath of the Arctic represented by the array, with 250- to 300-fold increases in lead pollution observed from the Early Middle Ages to the 1970s industrial peak. Superimposed on these exponential changes were pronounced, multiannual to multidecadal variations, marked by increases coincident with exploitation of new mining regions, improved technologies, and periods of economic prosperity; and decreases coincident with climate disruptions, famines, major wars, and plagues. Results suggest substantial overall growth in lead/silver mining and smelting emissions—and so silver production—from the Early through High Middle Ages, particularly in northern Europe, with lower growth during the Late Middle Ages into the Early Modern Period. Near the end of the second plague pandemic (1348 to ∼1700 CE), lead pollution increased sharply through the Industrial Revolution. North American and European pollution abatement policies have reduced Arctic lead pollution by >80% since the 1970s, but recent levels remain ∼60-fold higher than at the start of the Middle Ages.

Dominant diatom species in the Canada Basin in summer 2003, a reported serious melting season

Polar Record ◽  
2010 ◽  
Vol 47 (3) ◽  
pp. 244-261 ◽  
Author(s):  
Shuxian Zheng ◽  
Guizhong Wang ◽  
Fang Zhang ◽  
Minghong Cai ◽  
Jianfeng He
Keyword(s):  
Diversity Index ◽  
Algal Species ◽  
Ice Cores ◽  
Distribution Patterns ◽  
Canada Basin ◽  
Algal Community ◽  
The Arctic ◽  
Species Number ◽  
Diatom Species ◽  
Order Of Magnitude

ABSTRACTDuring the second Chinese National Arctic Research Expedition in summer 2003, sea ice cores and the underlying water were sampled from seven stations in the pack ice zone of the Canada Basin and were examined with a phase contrast microscope. A total of 102 and 78 algal species were identified for the ice cores and the underlying water, respectively, ranking in the middle range among the surveys of the Arctic Ocean up to the present despite seasonal variability. The Shannon-Wiener indices ranged from 1.40 to 4.88 with an average of 3.58 ± 0.68. Diatom species, especially pennate species, dominated in all the samples. A large number of algal spores were contained in every layer (abundance percentage > 1%). The microalgal abundances ranged from 1.4 × 104 to 8.73 × 105 cells L−1 and the biomass ranged from 0.56 to 89.49 μg L−1. They were correlated with the number of algal species (P < 0.05) but not with the diversity index (P > 0.05). Ice algal maxima were observed in various layers (bottom, interior and near the surface of the ice floes). The phytoplankton biomass in the ice-water interface was one order of magnitude lower than that in the bottom ice (P < 0.05). The species number and the diversity index in water samples, with much less biomass (P < 0.01), were comparative with the ice samples (P > 0.05). Spatial heterogeneity in both horizontal and vertical directions was the main characteristic of the algal community structure, which was demonstrated by the cluster analysis result and the distribution patterns.

scholarly journals Ice stratigraphy at the Pâkitsoq ice margin, West Greenland, derived from gas records

2009 ◽  
Vol 55 (191) ◽  
pp. 411-421 ◽  
Author(s):  
Hinrich Schaefer ◽  
Vasilii V. Petrenko ◽  
Edward J. Brook ◽  
Jeffrey P. Severinghaus ◽  
Niels Reeh ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Core ◽  
Three Dimensional ◽  
Ice Cores ◽  
Early Holocene ◽  
Dimensional Structure ◽  
Glacier Surface ◽  
Climatic Fluctuations ◽  
West Greenland ◽  
Geochemical Parameters

AbstractHorizontal ice-core sites, where ancient ice is exposed at the glacier surface, offer unique opportunities for paleo-studies of trace components requiring large sample volumes. Following previous work at the Pâkitsoq ice margin in West Greenland, we use a combination of geochemical parameters measured in the ice matrix (δ18Oice) and air occlusions (δ18Oatm, δ15N of N2 and methane concentration) to date ice layers from specific climatic intervals. The data presented here expand our understanding of the stratigraphy and three-dimensional structure of ice layers outcropping at Pâkitsoq. Sections containing ice from every distinct climatic interval during Termination I, including Last Glacial Maximum, Bølling/Allerød, Younger Dryas and the early Holocene, are identified. In the early Holocene, we find evidence for climatic fluctuations similar to signals found in deep ice cores from Greenland. A second glacial–interglacial transition exposed at the extreme margin of the ice is identified as another outcrop of Termination I (rather than the onset of the Eemian interglacial as postulated in earlier work). Consequently, the main structural feature at Pâkitsoq is a large-scale anticline with accordion-type folding in both exposed sequences of the glacial–Holocene transition, leading to multiple layer duplications and age reversals.

scholarly journals The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis

2016 ◽  
Author(s):  
Célia J. Sapart ◽  
Natalia Shakhova ◽  
Igor Semiletov ◽  
Joachim Jansen ◽  
Sönke Szidat ◽  
...  
Keyword(s):  
Water Column ◽  
Large Scale ◽  
Age Determination ◽  
Arctic Shelf ◽  
Climate Feedback ◽  
The Arctic ◽  
Small Contribution ◽  
Isotope Data ◽  
Siberian Arctic ◽  
Subsea Permafrost

Abstract. Methane (CH4) is a strong greenhouse gas emitted by human activity and natural processes that are highly sensitive to climate change. The Arctic Ocean, especially the East Siberian Arctic Shelf (ESAS) overlays large areas of subsea permafrost that is degrading. The release of large amount of CH4 originally stored or formed there could create a strong positive climate feedback. Large scale CH4 super-saturation has been observed in the ESAS waters, pointing to leakages of CH4 through the sea floor and possibly to the atmosphere, but the origin of this gas is still debated. Here, we present CH4 concentration and triple isotope data analyzed on gas extracted from sediment and water sampled over the shallow ESAS from 2007 to 2013. We find high concentrations (up to 500 μM) of CH4 in the pore water of the partially thawed subsea permafrost of this region. For all sediment cores, both hydrogen and carbon CH4 isotope data reveal the predominant presence of CH4 that is not of thermogenic/natural gas origin as it has long been thought, but resultant from microbial CH4 formation using as primary substrate glacial water and old organic matter preserved in the subsea permafrost or below. Radiocarbon data demonstrate that the CH4 present in the ESAS sediment is of Pleistocene age or older, but a small contribution of highly 14C-enriched CH4, from unknown origin, prohibits precise age determination for one sediment core and in the water column. Our data suggest that at locations where bubble plumes have been observed, CH4 can escape anaerobic oxidation in the surface sediment. CH4 will then rapidly migrate through the very shallow water column of the ESAS to escape to the atmosphere generating a positive radiative feedback.

scholarly journals Impurities in Snow: Effects on Albedo and Snowmelt (Review)

1984 ◽  
Vol 5 ◽  
pp. 177-179 ◽  
Author(s):  
Stephen G. Warren
Keyword(s):  
Large Scale ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Surface Energy Budget ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
West Antarctica ◽  
Snow Albedo ◽  
The North ◽  
Long Term Effect

Very small (ppm) amounts of soil dust in snow can significantly reduce snow albedo and thereby affect the snow-surface energy budget. Ice cores from Greenland show enhanced dust concentrations in ice from the last glacial maximum, in amounts capable of causing measurable effects on snow albedo. This enhanced dust is probably due in part to the expanded desert areas at that time.Volcanic ash layers visible in the Byrd station core reduced the snow albedo in West Antarctica when they were on the surface. The ash is unlikely to have had a long-term effect on albedo because of the episodic nature of volcanic eruptions.Very large amounts of dust on snow can inhibit snow-melt by insulating the snow. A debris cover probably slowed the melting of parts of the North American ice sheet during its most recent decay phase.Snow in the Arctic Ocean is presently suffering large-scale contamination by carbon soot from anthropogenic sources. Preliminary estimates indicate that soot concentrations in Arctic snow are sufficient to reduce snow albedo measurably.

scholarly journals Ice core evidence for decoupling between mid-latitude atmospheric water cycle and Greenland temperature during the last deglaciation

2018 ◽  
Author(s):  
Amaëlle Landais ◽  
Emilie Capron ◽  
Valérie Masson-Delmotte ◽  
Samuel Toucanne ◽  
Rachael Rhodes ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Last Deglaciation ◽  
Sequence Of Events ◽  
Decadal Scale ◽  
Abrupt Changes ◽  
The Last Deglaciation

Abstract. The last deglaciation represents the most recent example of natural global warming associated with large-scale climate changes. In addition to the long-term global temperature increase, the last deglaciation onset is punctuated by a sequence of abrupt changes in the Northern Hemisphere. Such interplay between orbital- and millennial-scale variability is widely documented in paleoclimatic records but the underlying mechanisms are not fully understood. Limitations arise from the difficulty in constraining the sequence of events between external forcing, high- and low- latitude climate and environmental changes. Greenland ice cores provide sub-decadal-scale records across the last deglaciation and contain fingerprints of climate variations occurring in different regions of the Northern Hemisphere. Here, we combine new ice d-excess and 17O-excess records, tracing changes in the mid-latitudes, with ice δ18O records of polar climate. Within Heinrich Stadial 1, we demonstrate a decoupling between climatic conditions in Greenland and those of the lower latitudes. While Greenland temperature remains mostly stable from 17.5 to 14.7 ka, significant change in the mid latitudes of northern Atlantic takes place at ~ 16.2 ka, associated with warmer and wetter conditions of Greenland moisture sources. We show that this climate modification is coincident with abrupt changes in atmospheric CO2 and CH4 concentrations recorded in an Antarctic ice core. Our coherent ice core chronological framework and comparison with other paleoclimate records suggests a mechanism involving two-step freshwater fluxes in the North Atlantic associated with a southward shift of the intertropical convergence zone.

scholarly journals Annual Greenland accumulation rates (2009–2012) from airborne Snow Radar

2015 ◽  
Vol 9 (6) ◽  
pp. 6697-6731 ◽  
Author(s):  
L. S. Koenig ◽  
A. Ivanoff ◽  
P. M. Alexander ◽  
J. A. MacGregor ◽  
X. Fettweis ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
The Arctic ◽  
Accumulation Rates ◽  
Surface Mass ◽  
Automated Method

Abstract. Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet (GrIS) through increasing surface melt, emphasizing the need to closely monitor surface mass balance (SMB) in order to improve sea-level rise predictions. Here, we quantify accumulation rates, the largest component of GrIS SMB, at a higher spatial resolution than currently available, using Snow Radar stratigraphy. We use a semi-automated method to derive annual-net accumulation rates from airborne Snow Radar data collected by NASA's Operation IceBridge from 2009 to 2012. An initial comparison of the accumulation rates from the Snow Radar and the outputs of a regional climate model (MAR) shows that, in general, the radar-derived accumulation matches closely with MAR in the interior of the ice sheet but MAR estimates are high over the southeast GrIS. Comparing the radar-derived accumulation with contemporaneous ice cores reveals that the radar captures the annual and long-term mean. The radar-derived accumulation rates resolve large-scale patterns across the GrIS with uncertainties of up to 11 %, attributed mostly to uncertainty in the snow/firn density profile.

Sediment archives from the Arctic Ocean provide evidence for massive remobilization of permafrost carbon in Siberia during the last glacial termination

2020 ◽  
Author(s):  
Jannik Martens ◽  
Birgit Wild ◽  
Tommaso Tesi ◽  
Francesco Muschitiello ◽  
Matt O’Regan ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Large Scale ◽  
Sediment Cores ◽  
The Arctic ◽  
Last Deglaciation ◽  
Central Arctic Ocean ◽  
Last Glacial ◽  
The Arctic Ocean ◽  
Siberian Shelf ◽  
The Last Glacial

&lt;p&gt;Environmental archives and carbon cycle models suggest that climate warming during the last deglaciation (the transition from the last glacial to the Holocene) caused large-scale thaw of Arctic permafrost, followed by the release of previously freeze-locked carbon. In addition to changing oceanic circulation and outgassing of CO&lt;sub&gt;2 &lt;/sub&gt;trapped in the deep glacial ocean, organic carbon (OC) release from thawing permafrost might have contributed to the rise in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; by 80 ppmv or ~200 Pg C between 17.5 and 11.7 kyr before present (BP). The few Arctic sediment cores to date, however, lack either temporal resolution or reflect only regional catchments, leaving most of the permafrost OC remobilization of the deglaciation unconstrained.&lt;/p&gt;&lt;p&gt;Our study explores the flux and fate of OC released from permafrost to the Siberian Arctic Seas during the last deglaciation. The Arctic Ocean is the main recipient of permafrost material delivered by river transport or collapse of coastal permafrost, providing an archive for current and past release of OC from thawing permafrost. We studied isotopes (&amp;#916;&lt;sup&gt;14&lt;/sup&gt;C-OC, &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-OC) and terrestrial biomarkers (CuO-derived lignin phenols, &lt;em&gt;n&lt;/em&gt;-alkanes, &lt;em&gt;n&lt;/em&gt;-alkanoic acids) in a number of sediment cores from the Siberian Shelf and Central Arctic Ocean to reconstruct source and fate of OC previously locked in permafrost.&lt;/p&gt;&lt;p&gt;The composite record of three cores from the Laptev, East Siberian and Chukchi Seas suggest a combination of OC released by deepening of permafrost active layer in inland Siberia and by thermal collapse of coastal permafrost during the deglaciation. Coastal erosion of permafrost during the deglaciation suggests that sea-level rise and flooding of the Siberian shelf remobilized OC from permafrost deposits that covered the dry shelf areas during the last glacial. A sediment core from the Central Arctic Ocean demonstrates that this occurred in two major pulses; i) during the B&amp;#248;lling-Aller&amp;#248;d (14.7-12.9 kyr BP), but most strongly ii) during the early Holocene (11-7.6 kyr BP). In the early Holocene, flooding of 80% of the Siberian shelf amplified permafrost OC release to the Arctic Ocean, with peak fluxes 10-9 kyr BP one order of magnitude higher than at other times in the Holocene.&lt;/p&gt;&lt;p&gt;It is likely that the remobilization of permafrost OC by flooding of the Siberian shelf released climate-significant amounts of dormant OC into active biogeochemical cycling and the atmosphere. Previous studies estimated that a pool of 300-600 Pg OC was held in permafrost covering Arctic Ocean shelves during the last glacial maximum; one can only speculate about its whereabouts after the deglaciation. Present und future reconstructions of historical remobilization of permafrost OC will help to understand how important permafrost thawing is to large-scale carbon cycling.&lt;/p&gt;

scholarly journals Antarctic precipitation and its contribution to the global sea-level budget

1998 ◽  
Vol 27 ◽  
pp. 220-226 ◽  
Author(s):  
David H. Bromwich ◽  
Richard I. Cullather ◽  
Michael L. Van Woert
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Weather Forecasting ◽  
Polar Regions ◽  
Weather Forecasts ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Order Of Magnitude ◽  
Global Sea Level ◽  
Antarctic Precipitation

Antarctic precipitation estimations derived from several new sources are examined in comparison to results found previously. The availability of analyzed atmospheric datasets has been a significant and beneficial tool for atmospheric and climate research for a broad range of research interests. This is particularly true for the polar regions, where the observational arrays are sparsely distributed. in high southern latitudes, a comprehensive assimilation of all available observations, including satellite data, is necessary for an accurate depiction of the atmospheric circulation. Recent st udies have found the operational analyses of the European Centre for Medium-range Weather Forecasts to be superior to those of other weather-forecasting centers in depicting the large-scale atmospheric circulation patterns over Antarctica. “Re-analysis” programs at major weather-forecasting centers have produced atmospheric numerical analyses using a “frozen” data-assimilation system. These projects have also derived precipitation and evaporation fields using an ensemble of short-term forecasts. From these new sources, Antarctic Ρ - E (precipitation minus evaporation/sublimation) is compared and evaluated against the long-term glaciological synthesis, as well as results from previous studies. The comparisons indicate significant regional disagreements exist between P — E from the re-analysis forecasts and the glaciological data. For the ensemble forecasting method, the continental-average evaporation is the largest area of uncertainty and differs by an order of magnitude between the rc-analysis datasets. This finding supports the use of the atmospheric moisture budget for determining P — E collectively in atmospheric diagnostic studies for Antarctica.

scholarly journals Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation

2018 ◽  
Vol 14 (10) ◽  
pp. 1405-1415 ◽  
Author(s):  
Amaëlle Landais ◽  
Emilie Capron ◽  
Valérie Masson-Delmotte ◽  
Samuel Toucanne ◽  
Rachael Rhodes ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Last Deglaciation ◽  
Sequence Of Events ◽  
Decadal Scale ◽  
Abrupt Changes ◽  
The Last Deglaciation

Abstract. The last deglaciation represents the most recent example of natural global warming associated with large-scale climate changes. In addition to the long-term global temperature increase, the last deglaciation onset is punctuated by a sequence of abrupt changes in the Northern Hemisphere. Such interplay between orbital- and millennial-scale variability is widely documented in paleoclimatic records but the underlying mechanisms are not fully understood. Limitations arise from the difficulty in constraining the sequence of events between external forcing, high- and low- latitude climate, and environmental changes. Greenland ice cores provide sub-decadal-scale records across the last deglaciation and contain fingerprints of climate variations occurring in different regions of the Northern Hemisphere. Here, we combine new ice d-excess and 17O-excess records, tracing changes in the midlatitudes, with ice δ18O records of polar climate. Within Heinrich Stadial 1, we demonstrate a decoupling between climatic conditions in Greenland and those of the lower latitudes. While Greenland temperature remains mostly stable from 17.5 to 14.7 ka, significant change in the midlatitudes of the northern Atlantic takes place at ∼16.2 ka, associated with warmer and wetter conditions of Greenland moisture sources. We show that this climate modification is coincident with abrupt changes in atmospheric CO2 and CH4 concentrations recorded in an Antarctic ice core. Our coherent ice core chronological framework and comparison with other paleoclimate records suggests a mechanism involving two-step freshwater fluxes in the North Atlantic associated with a southward shift of the Intertropical Convergence Zone.

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