scholarly journals Holocene atmospheric iodine evolution over the North Atlantic

2019 ◽  
Vol 15 (6) ◽  
pp. 2019-2030 ◽  
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.

scholarly journals Holocene atmospheric iodine evolution over the North Atlantic

2019 ◽  
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 ◽  
The North ◽  
Thermal Maximum ◽  
Radiative Impacts

Abstract. Atmospheric iodine chemistry has a large influence on oxidizing capacity and associated radiative impacts in the troposphere. However, information on the evolution of 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 ice core measurements from coastal eastern Greenland (ReCAP ice core), we report the first record of atmospheric iodine variability during the Holocene (last 11,700 years). Surprisingly, our results reveal that the highest iodine concentrations in the record, found during the Holocene Thermal Maximum (~ 11,500-–5,500 years before -present). These high iodine levels could be driven by ocean primary productivity resulting in an Early Holocene “Biological Iodine Explosion”. The iodine trend during this past warm period is a useful observational constraint on projections of future changes in Arctic atmospheric composition and climate resulting from global warming.

Luminescence age constraints on the Pleistocene-Holocene transition recorded in loess sequences

2020 ◽  
Author(s):  
Daniela Constantin ◽  
Stefana-Madalina Sacaciu ◽  
Viorica Tecsa ◽  
Anca Avram ◽  
Robert Begy ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
North Atlantic ◽  
Ice Core ◽  
Soil Formation ◽  
Luminescence Dating ◽  
The Holocene ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
The Last Glacial

<p>Here we investigate the timing of the last glacial loess - Holocene soil transition recorded in loess-paleosol sequences across the Chinese Loess Plateau, the SE European loess belt and the Central Great Plains, Nebraska, USA by applying comparative luminescence dating techniques on quartz and feldspars. Equivalent dose measurements were carried out using the single-aliquot regenerative-dose (SAR) protocol on silt (4–11 μm) and sand-sized (63–90 μm and coarser fraction when available) quartz. Feldspar infrared stimulated luminescence (IRSL) emitted by 4–11 μm polymineral grains was measured using the post IR-IRSL<sub>290</sub> technique.</p><p>The paleoenvironmental transition from the last glacial loess to the current interglacial soil was characterized using magnetic susceptibility and its frequency dependence. Based on the OSL ages and the threshold of the magnetic signal enhancement the onset of soil formation started around Termination 1 (~17 ka in the North Atlantic) as observed in radiocarbon-dated regional benthic δ<sup>18</sup>O stacks (Stern and Lisiecki, 2014) but before the stratigraphic Pleistocene/Holocene transition dated at 11.7 ka in ice core records (Svensson et al., 2008).</p><p>No major hiatuses in ages are identified in the investigated sites. A change in the sedimentation rate is generally observed at the Pleistocene-Holocene transition and no significant sedimentation change during the Holocene. Sedimentation rates of around 6 cm/ka are determined for the Holocene soil in most of the sites investigated.</p><p>The magnetic susceptibility indicates a gradual increase in pedogenesis after Termination 1 (∼17 ka in the North Atlantic). Based on this, we infer that the upbuilding soil formation prevailed over topdown soil formation during the Pleistocene-Holocene transition in the investigated sites (Roberts, 2008).</p><p> </p><p>References</p><p>Roberts, H.M., 2008. The development and application of luminescence dating to loess deposits: a perspective on the past, present and future. Boreas 37, 483-507.</p><p>Svensson, A., Andersen, K.K., Bigler, M., Clausen, H.B., Dahl-Jensen, D., Davies, S.M., Johnsen, S.J., Muscheler, R., Parrenin, F., Rasmussen, S.O., Röthlisberger, R., Seierstad, I., Steffensen, J.P., Vinther, B.M., 2008.A 60 000 year Greenland stratigraphic ice core chronology. Climate of the Past 4, 47-57.</p><p>Stern, J.V., Lisiecki, L.E., 2014. Termination 1 timing in radiocarbon-dated regional benthic δ18O stacks. Paleoceanography 29, 1127-1142.</p><p> </p><p>This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme ERC-2015-STG (grant agreement No [678106]).</p>

First record of the deep-water whalefish Cetichthys indagator (Actinopterygii: Cetomimidae) in the North Atlantic Ocean

2012 ◽  
Vol 81 (3) ◽  
pp. 1133-1137 ◽  
Author(s):  
R. P. Vieira ◽  
B. Christiansen ◽  
S. Christiansen ◽  
J. M. S. Gonçalves
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
First Record ◽  
The North ◽  
The North Atlantic

scholarly journals Centennial-to-millennial hydrologic trends and variability along the North Atlantic Coast, USA, during the Holocene

2014 ◽  
Vol 41 (12) ◽  
pp. 4300-4307 ◽  
Author(s):  
Paige E. Newby ◽  
Bryan N. Shuman ◽  
Jeffrey P. Donnelly ◽  
Kristopher B. Karnauskas ◽  
Jeremiah Marsicek
Keyword(s):  
North Atlantic ◽  
Atlantic Coast ◽  
The Holocene ◽  
The North ◽  
The North Atlantic

First record of the rare deep-sea polychaete Rhamphobrachium (Rhamphobrachium) agassizii (Annelida: Onuphidae) in European waters

2020 ◽  
Vol 100 (5) ◽  
pp. 719-724
Author(s):  
Andrés Arias ◽  
Hannelore Paxton
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
North Atlantic Ocean ◽  
First Record ◽  
Polychaete Species ◽  
Azores Archipelago ◽  
The North ◽  
Deep Water Species ◽  
The North Atlantic ◽  
Water Species

AbstractRhamphobrachium (Rhamphobrachium) agassizii is reported from the Cantabrian Sea, Spain, from depths of 925–1207 m. This is its first record off the Iberian Peninsula and in European waters, representing its northernmost distribution in the North Atlantic Ocean to date. Previous reports of R. (R.) agassizii from the eastern and western North Atlantic demonstrate its apparent amphi-Atlantic distribution, which appears consistent with the distribution of the main Atlantic currents. It is a typical deep-water species with its deepest record at 2165 m from the Azores archipelago. The specimens were collected singly at two stations, attesting to the rarity of the species in contrast to its congener R. (Spinigerium) brevibrachiatum which was the most dominant polychaete species in a previous study.

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 A 120 000-year record of sea ice in the North Atlantic?

2019 ◽  
Vol 15 (6) ◽  
pp. 2031-2051 ◽  
Author(s):  
Niccolò Maffezzoli ◽  
Paul Vallelonga ◽  
Ross Edwards ◽  
Alfonso Saiz-Lopez ◽  
Clara Turetta ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Ice Core ◽  
Arctic Sea Ice ◽  
First Year ◽  
Sea Ice Extent ◽  
Nordic Seas ◽  
The North ◽  
Arctic Sea ◽  
The North Atlantic

Abstract. Although it has been demonstrated that the speed and magnitude of the recent Arctic sea ice decline is unprecedented for the past 1450 years, few records are available to provide a paleoclimate context for Arctic sea ice extent. Bromine enrichment in ice cores has been suggested to indicate the extent of newly formed sea ice areas. Despite the similarities among sea ice indicators and ice core bromine enrichment records, uncertainties still exist regarding the quantitative linkages between bromine reactive chemistry and the first-year sea ice surfaces. Here we present a 120 000-year record of bromine enrichment from the RECAP (REnland ice CAP) ice core, coastal east Greenland, and interpret it as a record of first-year sea ice. We compare it to existing sea ice records from marine cores and tentatively reconstruct past sea ice conditions in the North Atlantic as far north as the Fram Strait (50–85∘ N). Our interpretation implies that during the last deglaciation, the transition from multi-year to first-year sea ice started at ∼17.5 ka, synchronously with sea ice reductions observed in the eastern Nordic Seas and with the increase in North Atlantic ocean temperature. First-year sea ice reached its maximum at 12.4–11.8 ka during the Younger Dryas, after which open-water conditions started to dominate, consistent with sea ice records from the eastern Nordic Seas and the North Icelandic shelf. Our results show that over the last 120 000 years, multi-year sea ice extent was greatest during Marine Isotope Stage (MIS) 2 and possibly during MIS 4, with more extended first-year sea ice during MIS 3 and MIS 5. Sea ice extent during the Holocene (MIS 1) has been less than at any time in the last 120 000 years.

scholarly journals Decadal-scale progression of the onset of Dansgaard–Oeschger warming events

2019 ◽  
Vol 15 (2) ◽  
pp. 811-825 ◽  
Author(s):  
Tobias Erhardt ◽  
Emilie Capron ◽  
Sune Olander Rasmussen ◽  
Simon Schüpbach ◽  
Matthias Bigler ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Ice Core ◽  
Sea Salt ◽  
Meridional Overturning Circulation ◽  
Proxy Records ◽  
The North ◽  
Decadal Scale ◽  
The North Atlantic ◽  
North Greenland

Abstract. During the last glacial period, proxy records throughout the Northern Hemisphere document a succession of rapid millennial-scale warming events, called Dansgaard–Oeschger (DO) events. A range of different mechanisms has been proposed that can produce similar warming in model experiments; however, the progression and ultimate trigger of the events are still unknown. Because of their fast nature, the progression is challenging to reconstruct from paleoclimate data due to the limited temporal resolution achievable in many archives and cross-dating uncertainties between records. Here, we use new high-resolution multi-proxy records of sea-salt (derived from sea spray and sea ice over the North Atlantic) and terrestrial (derived from the central Asian deserts) aerosol concentrations over the period 10–60 ka from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores in conjunction with local precipitation and temperature proxies from the NGRIP ice core to investigate the progression of environmental changes at the onset of the warming events at annual to multi-annual resolution. Our results show on average a small lead of the changes in both local precipitation and terrestrial dust aerosol concentrations over the change in sea-salt aerosol concentrations and local temperature of approximately one decade. This suggests that, connected to the reinvigoration of the Atlantic meridional overturning circulation and the warming in the North Atlantic, both synoptic and hemispheric atmospheric circulation changes at the onset of the DO warming, affecting both the moisture transport to Greenland and the Asian monsoon systems. Taken at face value, this suggests that a collapse of the sea-ice cover may not have been the initial trigger for the DO warming.

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