Toward an improved characterisation of climate and environmental changes during warm periods of the past: First results from the MOPGA HOTCLIM project 

2021 ◽  
Author(s):  
Etienne Legrain ◽  
Emilie Capron ◽  
Frederic Parrenin
Keyword(s):  
Carbon Cycle ◽  
Ocean Circulation ◽  
Environmental Changes ◽  
Temporal Structure ◽  
Ice Cores ◽  
Environmental Data ◽  
Interglacial Period ◽  
Climate Projections ◽  
The Past ◽  
First Results

<p>The current and future anthropogenic-induced high-latitude warming will have global climatic implications due to polar ice mass loss, sea level rise and ocean circulation changes. However, uncertainty remains on future climate projections mainly due to an incomplete understanding of climate, cryosphere and carbon cycle feedback processes occurring at centennial to millennial- timescales. Progress can be achieved by exploring climate and environmental changes that occurred in the past. In the HOTCLIM project, we are studying past warm periods, also referred to as interglacials, which exhibit a polar warming comparable to that projected by 2100 due to specific combinations of orbital and CO<sub>2</sub> forcing. Especially, we are investigating the link between the carbon cycle dynamics and climate changes. To do so, we are combining (i) new analyses on the air trapped in Antarctic deep ice cores to inform on past changes in Antarctic climate and atmospheric CO2 concentrations (ii) climate and environmental data synthesis looking into the lower latitudes using terrestrial and oceanic archives (sea surface temperature, hydrological cycles, ocean circulation) (iii) an evaluation of outputs from climate models using the new comparison of the paleoclimatic datasynthesis and models output. The HOTCLIM project will improve our understanding of the natural climate variability and the processes involved during past periods associated with temperature changes comparable to projected future warming, hence helping improve climate projections</p><p>Here, we present the first results from the HOTCLIM project which is a multi-archive synthesis focused on the warm interval occurring between 190 and 243 ka BP, also refered to as Marine Isotopic Stage 7 (MIS 7). This warm period is of special interest because it follows the fastest transition between a cold (glacial) and a hot (interglacial) period of the last 800 000 ka, with a polar warming of 10 degrees in less than 5ka. We have compiled more than 30 oceanic cores, 9 speleothems and 3 ice cores covering the MIS 7 period. To compare them, we are now building a common chronology to these records. The use of combined continental (ice cores, speleothems) and oceanic (sediment cores) archives located on the whole surface of the Earth will allows to characterize (i) the amplitude and the temporal structure of the surface warming across the globe (ii) the contrast between oceanic and continental warming.</p>

PMIP-carbon: towards a multi-models comparison of climate-carbon interactions at the Last Glacial Maximum

2020 ◽  
Author(s):  
Nathaelle Bouttes ◽  
Ruza Ivanovic ◽  
Ayako Abe-Ouchi ◽  
Hidetaka Kobayashi ◽  
Laurie Menviel ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Isotopes ◽  
Last Glacial Maximum ◽  
Ocean Circulation ◽  
Ice Cores ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Intercomparison Project ◽  
The Last Glacial Maximum ◽  
The Last Glacial

<p>More and more climate models now include the carbon cycle, but multi-models studies of climate-carbon simulations within the Climate Model Intercomparison Project (CMIP) are limited to present and future time periods. In addition, the carbon cycle is not considered in the simulations of past periods analysed within the Paleoclimate Modelling Intercomparison Project (PMIP). Yet, climate-carbon interactions are crucial to anticipate future atmospheric CO<sub>2</sub> concentrations and their impact on climate. Such interactions can change depending on the background climate, it is thus necessary to compare model results among themselves and to data for past periods with different climates such as the Last Glacial Maximum (LGM).</p><p>The Last Glacial Maximum, around 21,000 years ago, was about 4°C colder than the pre-industrial, and associated with large ice sheets on the American and Eurasian continents. It is one of the best documented periods thanks to numerous paleoclimate archives such as marine sediment cores and ice cores. Despite this period having been studied for years, no consensus on the causes of the lower atmospheric CO<sub>2</sub> concentration at the time (around 180 ppm) has been reached and models still struggle to simulate these low CO<sub>2</sub> values. The ocean, which contains around 40 times more carbon than the atmosphere, likely plays a key role, but models tend to simulate ocean circulation changes in disagreement with proxy data, such as carbon isotopes.</p><p>This new project aims at comparing, for the first time, the carbon cycle representation at the Last Glacial Maximum from general circulation models and intermediate complexity models. We will explain the protocol and present first results in terms of carbon storage in the main reservoirs (atmosphere, land and ocean) and their link to key climate variables such as temperature, sea ice and ocean circulation. The use of coupled climate-carbon models will not only allow to compare changes in the carbon cycle in models and analyse their causes, but it will also enable us to better compare to indirect data related to the carbon cycle such as carbon isotopes.</p>

scholarly journals The importance of Northern Peatlands in global carbon systems during the Holocene

2009 ◽  
Vol 5 (2) ◽  
pp. 1231-1258 ◽  
Author(s):  
Y. Wang ◽  
N. T. Roulet ◽  
S. Frolking ◽  
L. A. Mysak
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Ice Cores ◽  
Deep Ocean ◽  
Interglacial Period ◽  
The Holocene ◽  
The Past ◽  
C Cycle ◽  
Carbon Dioxide Co2 ◽  
Northern Peatlands ◽  
Global Carbon

Abstract. We applied an inverse model to simulate global carbon (C) cycle dynamics during the Holocene period using atmospheric carbon dioxide (CO2) concentrations reconstructed from Antarctic ice cores and prescribed C accumulation rates of Northern Peatlands (NP) as inputs. Previous studies indicated that different sources could contribute to the 20 parts per million by volume (ppmv) atmospheric CO2 increase over the past 8000 years. These sources of C include terrestrial release of 40–200 petagram C (PgC, 1 petagram=1015 gram), deep oceanic adjustment to a 500 PgC terrestrial biomass buildup early in this interglacial period, and anthropogenic land-use and land-cover changes of unknown magnitudes. Our study shows that the prescribed peatland C accumulation significantly modifies our previous understanding of Holocene C cycle dynamics. If the buildup of the NP is considered, the terrestrial pool becomes the C sink of about 160–280 PgC over the past 8000 years, and the only C source for the terrestrial and atmospheric C increases is presumably from the deep ocean due to calcium carbonate compensation. Future studies need to be conducted to constrain the basal times and growth rates of the NP C accumulation in the Holocene. These research endeavors are challenging because they need a dynamically-coupled peatland simulator to be constrained with the initiation time and reconstructed C reservoir of the NP. Our results also suggest that the huge reservoir of deep ocean C explains the major variability of the glacial-interglacial C cycle dynamics without considering the anthropogenic C perturbation.

scholarly journals Utilizing sponge spicules in taxonomic, ecological and environmental reconstructions: a review

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10601
Author(s):  
Magdalena Łukowiak
Keyword(s):  
Ocean Circulation ◽  
Environmental Data ◽  
Silicon Isotope ◽  
Structural Elements ◽  
Climate Conditions ◽  
The Past ◽  
Sponge Spicules ◽  
Silica Cycle ◽  
Taxonomic Assignments ◽  
Water Depths

Most sponges produce skeletons formed by spicules, structural elements that develop in a wide variety of sizes and tridimensional shapes. The morphologies of spicules are often unique to clade- or even species-level taxa which makes them particularly useful in taxonomic assignments. When dead sponge bodies disintegrate, spicules become incorporated into sediments and sometimes accumulate into enormous agglomerations called spicule mats or beds, or fossilize to form special type of rocks called the spiculites. The record of fossil and subfossil sponge spicules is extraordinarily rich and often serves as a basis for far-reaching reconstructions of sponge communities, though spicules are also bearers of significant ecological and environmental information. Specific requirements and preferences of sponges can be used to interpret the environment in which they lived, and reconstruct oscillations in water depths, pH, temperatures, and other parameters, providing snapshots of past climate conditions. In turn, the silicon isotope compositions in spicules (δ30Si) are being increasingly often used to estimate the level of silicic acid in the marine settings throughout the geological history, which enables to reconstruct the past silica cycle and ocean circulation. This contribution provides a review of the use of sponge spicules in reconstructions of sponge communities, their ecology, and environments, and aims to detect the pertinent gaps in their utilization. Even though spicules are well known for their significance as bearers of taxonomic, ecological, and environmental data, their potential remains to be fully exploited.

scholarly journals Post-bubble close-off fractionation of gases in polar firn and ice cores: effects of accumulation rate on permeation through overloading pressure

2015 ◽  
Vol 15 (24) ◽  
pp. 13895-13914 ◽  
Author(s):  
T. Kobashi ◽  
T. Ikeda-Fukazawa ◽  
M. Suwa ◽  
J. Schwander ◽  
T. Kameda ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Accumulation Rate ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Significant Negative Correlation ◽  
Orbital Parameters ◽  
The Past ◽  
Pressure Sensitive ◽  
Core Project

Abstract. Gases in ice cores are invaluable archives of past environmental changes (e.g., the past atmosphere). However, gas fractionation processes after bubble closure in the firn are poorly understood, although increasing evidence indicates preferential leakages of smaller molecules (e.g., neon, oxygen, and argon) from the closed bubbles through the ice matrix. These fractionation processes are believed to be responsible for the observed millennial δO2/N2 variations in ice cores, linking ice core chronologies with orbital parameters. In this study, we investigated high-resolution δAr/N2 of the GISP2 (Greenland Ice Sheet Project 2), NGRIP (North Greenland Ice Core Project), and Dome Fuji ice cores for the past few thousand years. We find that δAr/N2 at multidecadal resolution on the "gas-age scale" in the GISP2 ice core has a significant negative correlation with accumulation rate and a positive correlation with air contents over the past 6000 years, indicating that changes in overloading pressure induced δAr/N2 fractionation in the firn. Furthermore, the GISP2 temperature and accumulation rate for the last 4000 years have nearly equal effects on δAr/N2 with sensitivities of 0.72 ± 0.1 ‰ °C−1 and −0.58 ± 0.09 ‰ (0.01 m ice year−1)−1, respectively. To understand the fractionation processes, we applied a permeation model for two different processes of bubble pressure build-up in the firn, "pressure sensitive process" (e.g., microbubbles: 0.3–3 % of air contents) with a greater sensitivity to overloading pressures and "normal bubble process". The model indicates that δAr/N2 in the bubbles under the pressure sensitive process are negatively correlated with the accumulation rate due to changes in overloading pressure. On the other hand, the normal bubbles experience only limited depletion (< 0.5 ‰) in the firn. Colder temperatures in the firn induce more depletion in δAr/N2 through thicker firn. The pressure sensitive bubbles are so depleted in δAr/N2 at the bubble close-off depth that they dominate the total δAr/N2 changes in spite of their smaller air contents. The model also indicates that δAr/N2 of ice cores should have experienced several per mil of depletion during the storage 14–18 years after coring. Further understanding of the δAr/N2 fractionation processes in the firn, combined with nitrogen and argon isotope data, may lead to a new proxy for the past temperature and accumulation rate.

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.

10 Be and 14 C in the Earth system

1987 ◽  
Vol 323 (1569) ◽  
pp. 45-56 ◽  
Keyword(s):  
Ocean Circulation ◽  
Ice Core ◽  
Ice Cores ◽  
Solar Modulation ◽  
Isotope Production ◽  
Polar Ice ◽  
Climatic Effects ◽  
The Past ◽  
Short Period ◽  
Ocean Sediment

In a very short period of time, 10 Be data have significantly improved our knowledge in various fields of Earth and planetary sciences. Examples are: (a) solar modulation of isotope production, revealed in 10 Be ice-core profiles; (b)geomagnetic m odulation of isotope production, revealed in 10 Be ice-core (from the past 10 ka) and ocean-sediment profiles (geomagnetic reversals); (c) climatic effects reflected in 10 Be profiles in loess and polar ice cores ( 10 Be behaviour in atmosphere); (d) comparison of 10 Be and 14 C variations (tree rings) from carbon-cycle models and inform ation on ocean circulation history from 14 C m easurements on benthic and planktonic Foram inifera in ocean sediments. An overview on work in collaboration with the Zurich AMS facility (with Professor W. Wolfli) is given.

Eemian and early Weichselian environmental changes at the Jałówka site, NE Poland, and their correlation with marine and ice records

2021 ◽  
pp. 1-20
Author(s):  
Mirosława Kupryjanowicz ◽  
Magdalena Fiłoc ◽  
Barbara Woronko ◽  
Tomasz Mirosław Karasiewicz ◽  
Joanna Rychel ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Ice Cores ◽  
Sensu Stricto ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Last Glacial Period ◽  
Ne Poland ◽  
Last Interglacial Period ◽  
Mis 5E ◽  
The Last Glacial

Abstract Vegetation changes were documented across the last interglacial period (MIS 5e, Eemian) and continuing through the older part of the last glacial period (MIS 5d–a, early Weichselian). This study was based on pollen data collected at the Jałówka site, NE Poland. Two cold oscillations appeared within warm periods during this stage of the upper Pleistocene. The older oscillation was the temporary intra–interglacial cooling at the end of the Eemian. The younger one was the intra–interstadial cooling that occurred within the oldest interstadial of the early Weichselian (MIS 5c, Brørup). This last event corresponds well to the stadial separating both the Amersfoort and Brørup sensu stricto interstadials in the Netherlands and to the Montaigu event as recognized in France. The development of a pollen sequence allows speculation as to potential correlations with Greenland ice cores and marine records. We suggest that the Eemian in NE Poland may comprise not only MIS 5e, but also a part of MIS 5d. This supposition could shed light on potential for non-synchrony in upper boundaries of the MIS 5e and terrestrial Eemian in Europe. We await the development of more precise independent dating controls to validate our theory more assiduously.

scholarly journals The importance of Northern Peatlands in global carbon systems during the Holocene

2009 ◽  
Vol 5 (4) ◽  
pp. 683-693 ◽  
Author(s):  
Y. Wang ◽  
N. T. Roulet ◽  
S. Frolking ◽  
L. A. Mysak
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Ice Cores ◽  
Deep Ocean ◽  
Interglacial Period ◽  
The Holocene ◽  
The Past ◽  
C Cycle ◽  
Carbon Dioxide Co2 ◽  
Northern Peatlands ◽  
Global Carbon

Abstract. We applied an inverse model to simulate global carbon (C) cycle dynamics during the Holocene period using atmospheric carbon dioxide (CO2) concentrations reconstructed from Antarctic ice cores and prescribed C accumulation rates of Northern Peatlands (NP) as inputs. Previous studies indicated that different sources could contribute to the 20 parts per million by volume (ppmv) atmospheric CO2 increase over the past 8000 years. These sources of C include terrestrial release of 40–200 petagram C (PgC, 1 petagram=1015 gram), deep oceanic adjustment to a 500 PgC terrestrial biomass buildup early in this interglacial period, and anthropogenic land-use and land-cover changes of unknown magnitudes. Our study shows that the prescribed peatland C accumulation significantly modifies our previous understanding of Holocene C cycle dynamics. If the buildup of the NP is considered, the terrestrial pool becomes the C sink of about 160–280 PgC over the past 8000 years, and the only C source for the terrestrial and atmospheric C increases is presumably from the deep ocean due to calcium carbonate compensation. Future studies need to be conducted to constrain the basal times and growth rates of the NP C accumulation in the Holocene. These research endeavors are challenging because they need a dynamically-coupled peatland simulator to be constrained with the initiation time and reconstructed C reservoir of the NP. Our results also suggest that the huge reservoir of deep ocean C explains the major variability of the glacial-interglacial C cycle dynamics without considering the anthropogenic C perturbation.

scholarly journals Late Pleistocene Expansion of Small Murid Rodents across the Palearctic in Relation to the Past Environmental Changes

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 642
Author(s):  
Katarzyna Kozyra ◽  
Tomasz M. Zając ◽  
Hermann Ansorge ◽  
Heliodor Wierzbicki ◽  
Magdalena Moska ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Climatic Changes ◽  
Interglacial Period ◽  
Demographic Changes ◽  
Distribution Models ◽  
Genetic Analyses ◽  
The Past ◽  
Asian Clade ◽  
Historical Distribution ◽  
Murid Rodents

We investigated the evolutionary history of the striped field mouse to identify factors that initiated its past demographic changes and to shed light on the causes of its current genetic structure and trans-Eurasian distribution. We sequenced mitochondrial cyt b from 184 individuals, obtained from 35 sites in central Europe and eastern Mongolia. We compared genetic analyses with previously published historical distribution models and data on environmental and climatic changes. The past demographic changes displayed similar population trends in the case of recently expanded clades C1 and C3, with the glacial (MIS 3–4) expansion and postglacial bottleneck preceding the recent expansion initiated in the late Holocene and were related to environmental changes during the upper Pleistocene and Holocene. The past demographic trends of the eastern Asian clade C3 were correlated with changes in sea level and the formation of new land bridges formed by the exposed sea shelf during the glaciations. These data were supported by reconstructed historical distribution models. The results of our genetic analyses, supported by the reconstruction of the historical spatial distributions of the distinct clades, confirm that over time the local populations mixed as a consequence of environmental and climatic changes resulting from cyclical glaciation and the interglacial period during the Pleistocene.

Environmental changes in the Wehntal Valley in Northern Switzerland

2020 ◽  
Author(s):  
Johannes Miocic ◽  
Ruth Drescher-Schneider ◽  
Hans Rudolf Graf ◽  
Marlu Kühn ◽  
Frank Preusser ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Environmental Data ◽  
Luminescence Dating ◽  
Last Interglacial ◽  
Plant Macroremains ◽  
Last Glacial Period ◽  
Northern Switzerland ◽  
First Results ◽  
Near Shore

&lt;p&gt;Quaternary deposits within the glacially overdeepened trough of the Wehntal Valley in Northern Switzerland, record glacial and interglacial conditions from the Beringen Glaciation (MIS 6) through to the Holocene. The area is well known for the Niederweningen site, with its rich Late Pleistocene mammal remains found in a buried peat deposit. In addition to this famous &amp;#8220;mammoth peat&amp;#8221;, more deeply buried peat layers, part of which have previously been attributed to the final part of the Last Interglacial, also include a wealth of environmental data.&lt;/p&gt;&lt;p&gt;Here, we present the first results of an investigation, including sedimentology, geochemistry, palaeobotany (pollen, wood and plant macroremains), malacology, and luminescence dating, of two 16 meter drill cores taken close to the Niederweningen site. The analysed sedimentary successions in both cores show a transition from a series of laminated silts typical of a lake environment to a several meter-thick succession of well-developed organic silts, tufaceous silts and peat layers characteristic of near shore and shore conditions. The presence of dropstones and a lack of organic material in the lower part of the lake sediments indicate glacial conditions, while the peat-rich succession formed during a relatively warm period followed by a time of fluctuating climate. Preliminary results indicate that the organic-rich units represent the Last Interglacial, followed by warm interstadials during the early part of the Last Glacial period. The &quot;mammoth peat&quot; appears to be missing from the studied cores. Erosive surfaces within the peaty succession impede a straightforward interpretation.&lt;/p&gt;

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