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- Sequential changes in ocean circulation and biological export productivity
during the last glacial–interglacial cycle: a model–data study
Abstract: Sequential changes in ocean circulation and biological export productivity during the last glacial–interglacial cycle: a model–data study
Cameron M. O'Neill, Andrew McC. Hogg, Michael J. Ellwood, Bradley N. Opdyke, and Stephen M. Eggins
Clim. Past, 17, 171–201, https://doi.org/10.5194/cp-17-171-2021, 2021
We undertake a model–data study of the last glacial–interglacial cycle of atmospheric CO2, spanning 0–130 ka. We apply a carbon cycle box model, constrained with glacial–interglacial observations, and solve for optimal model parameter values against atmospheric and ocean proxy data. The results indicate that the last glacial drawdown in atmospheric CO2 was delivered mainly by slowing ocean circulation, lower sea surface temperatures and also increased Southern Ocean biological productivity.
PubDate: Fri, 15 Jan 2021 15:38:42 +010
- DeepMIP: model intercomparison of early Eocene climatic optimum (EECO)
large-scale climate features and comparison with proxy data
Abstract: DeepMIP: model intercomparison of early Eocene climatic optimum (EECO) large-scale climate features and comparison with proxy data
Daniel J. Lunt, Fran Bragg, Wing-Le Chan, David K. Hutchinson, Jean-Baptiste Ladant, Polina Morozova, Igor Niezgodzki, Sebastian Steinig, Zhongshi Zhang, Jiang Zhu, Ayako Abe-Ouchi, Eleni Anagnostou, Agatha M. de Boer, Helen K. Coxall, Yannick Donnadieu, Gavin Foster, Gordon N. Inglis, Gregor Knorr, Petra M. Langebroek, Caroline H. Lear, Gerrit Lohmann, Christopher J. Poulsen, Pierre Sepulchre, Jessica E. Tierney, Paul J. Valdes, Evgeny M. Volodin, Tom Dunkley Jones, Christopher J. Hollis, Matthew Huber, and Bette L. Otto-Bliesner
Clim. Past, 17, 203–227, https://doi.org/10.5194/cp-17-203-2021, 2021
This paper presents the first modelling results from the Deep-Time Model Intercomparison Project (DeepMIP), in which we focus on the early Eocene climatic optimum (EECO, 50 million years ago). We show that, in contrast to previous work, at least three models (CESM, GFDL, and NorESM) produce climate states that are consistent with proxy indicators of global mean temperature and polar amplification, and they achieve this at a CO2 concentration that is consistent with the CO2 proxy record.
PubDate: Fri, 15 Jan 2021 15:38:42 +010
- El Niño–Southern Oscillation and internal sea surface temperature
variability in the tropical Indian Ocean since 1675
Abstract: El Niño–Southern Oscillation and internal sea surface temperature variability in the tropical Indian Ocean since 1675
Maike Leupold, Miriam Pfeiffer, Takaaki K. Watanabe, Lars Reuning, Dieter Garbe-Schönberg, Chuan-Chou Shen, and Geert-Jan A. Brummer
Clim. Past, 17, 151–170, https://doi.org/10.5194/cp-17-151-2021, 2021
The dominant modes of climate variability on interannual timescales in the tropical Indian Ocean are the El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole. El Niño events have occurred more frequently during recent decades, and it has been suggested that an asymmetric ENSO teleconnection (warming during El Niño events is stronger than cooling during La Niña events) caused the pronounced warming of the western Indian Ocean. In this study, we test this hypothesis using coral Sr∕Ca records from the central Indian Ocean (Chagos Archipelago) to reconstruct past sea surface temperatures (SSTs) in time windows from the mid-Little Ice Age (1675–1716) to the present. Three sub-fossil massive Porites corals were dated to the 17–18th century (one coral) and the 19–20th century (two corals). Their records were compared with a published modern coral Sr∕Ca record from the same site. All corals were subsampled at a monthly resolution for Sr∕Ca measurements, which were measured using a simultaneous inductively coupled plasma optical emission spectrometer (ICP-OES). Wavelet coherence analysis shows that interannual variability in the four coral records is driven by ENSO, suggesting that the ENSO–SST teleconnection in the central Indian Ocean has been stationary since the 17th century. To determine the symmetry of El Niño and La Niña events, we compiled composite records of positive and negative ENSO-driven SST anomaly events. We find similar magnitudes of warm and cold anomalies, indicating a symmetric ENSO response in the tropical Indian Ocean. This suggests that ENSO is not the main driver of central Indian Ocean warming.
PubDate: Fri, 15 Jan 2021 15:38:42 +010
- Evaluating the utility of qualitative personal diaries in precipitation
reconstruction in the eighteenth and nineteenth centuries
Abstract: Evaluating the utility of qualitative personal diaries in precipitation reconstruction in the eighteenth and nineteenth centuries
Alice Harvey-Fishenden and Neil Macdonald
Clim. Past, 17, 133–149, https://doi.org/10.5194/cp-17-133-2021, 2021
This paper evaluates the utility of personal diaries in precipitation reconstruction and value of multiple overlapping diaries for producing a more objective record. Through analysis of>27 500 daily weather descriptions, we demonstrate that indices derived from such qualitative sources can create valuable precipitation records, with potential for this methodology to be applied to earlier material or in areas without extant instrumental records to address spatial and temporal gaps in knowledge.
PubDate: Thu, 14 Jan 2021 15:38:42 +010
- FYRE Climate: A high-resolution reanalysis of daily precipitation
and
temperature in France from 1871 to 2012
Abstract: FYRE Climate: A high-resolution reanalysis of daily precipitationand temperature in France from 1871 to 2012
Alexandre Devers, Jean-Philippe Vidal, Claire Lauvernet, and Olivier Vannier
Clim. Past Discuss., https//doi.org/10.5194/cp-2020-156,2021
Preprint under review for CP (discussion: open, 0 comments)
This article presents FYRE Climate, a dataset providing daily precipitation and temperature spanning the 1871–2012 period at 8-km resolution over France. FYRE Climate has been obtained through the combination of daily/yearly observations and a gridded reconstruction already available through a statistical technique called data assimilation. Results highlight the quality of FYRE Climate in terms of both long-term variations and reproduction of extreme events.
PubDate: Wed, 13 Jan 2021 15:38:42 +010
- Impact of mid-glacial ice sheets on deep ocean circulation and global
climate
Abstract: Impact of mid-glacial ice sheets on deep ocean circulation and global climate
Sam Sherriff-Tadano, Ayako Abe-Ouchi, and Akira Oka
Clim. Past, 17, 95–110, https://doi.org/10.5194/cp-17-95-2021, 2021
We perform simulations of Marine Isotope Stage 3 and 5a with an atmosphere–ocean general circulation model to explore the effect of the southward expansion of mid-glacial ice sheets on the Atlantic Meridional Overturning Circulation (AMOC) and climate. We find that the southward expansion of the mid-glacial ice sheet causes a surface cooling over the North Atlantic and Southern Ocean, but it exerts a small impact on the AMOC due to the competing effects of surface wind and surface cooling.
PubDate: Tue, 12 Jan 2021 15:38:42 +010
- Can we reconstruct the formation of large open-ocean polynyas in the
Southern Ocean using ice core records'
Abstract: Can we reconstruct the formation of large open-ocean polynyas in the Southern Ocean using ice core records'
Hugues Goosse, Quentin Dalaiden, Marie G. P. Cavitte, and Liping Zhang
Clim. Past, 17, 111–131, https://doi.org/10.5194/cp-17-111-2021, 2021
Polynyas are ice-free oceanic areas within the sea ice pack. Small polynyas are regularly observed in the Southern Ocean, but large open-ocean polynyas have been rare over the past decades. Using records from available ice cores in Antarctica, we reconstruct past polynya activity and confirm that those events have also been rare over the past centuries, but the information provided by existing data is not sufficient to precisely characterize the timing of past polynya opening.
PubDate: Tue, 12 Jan 2021 15:38:42 +010
- Co-evolution of terrestrial and aquatic ecosystem structure
with
hydrological change in the Holocene Baltic Sea
Abstract: Co-evolution of terrestrial and aquatic ecosystem structure withhydrological change in the Holocene Baltic Sea
Gabriella M. Weiss, Julie Lattaud, Marcel T. J. van der Meer, and Timothy I. Eglinton
Clim. Past Discuss., https//doi.org/10.5194/cp-2020-163,2021
Preprint under review for CP (discussion: open, 0 comments)
Here we study the elemental signatures of plant wax compounds as well as molecules from algae and bacteria to understand how water sources changed over the last 11,000 years in the northeastern part of Europe surrounding the Baltic Sea. Our results show diversity in plant and aquatic microorganisms following the melting of the large ice sheet that covered Northern Europe which caused the regional climate to warm.
PubDate: Tue, 12 Jan 2021 15:38:42 +010
- Large-scale features of Last Interglacial climate: results from evaluating
the lig127k simulations for the Coupled Model Intercomparison Project
(CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4)
Abstract: Large-scale features of Last Interglacial climate: results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4)
Bette L. Otto-Bliesner, Esther C. Brady, Anni Zhao, Chris M. Brierley, Yarrow Axford, Emilie Capron, Aline Govin, Jeremy S. Hoffman, Elizabeth Isaacs, Masa Kageyama, Paolo Scussolini, Polychronis C. Tzedakis, Charles J. R. Williams, Eric Wolff, Ayako Abe-Ouchi, Pascale Braconnot, Silvana Ramos Buarque, Jian Cao, Anne de Vernal, Maria Vittoria Guarino, Chuncheng Guo, Allegra N. LeGrande, Gerrit Lohmann, Katrin J. Meissner, Laurie Menviel, Polina A. Morozova, Kerim H. Nisancioglu, Ryouta O'ishi, David Salas y Mélia, Xiaoxu Shi, Marie Sicard, Louise Sime, Christian Stepanek, Robert Tomas, Evgeny Volodin, Nicholas K. H. Yeung, Qiong Zhang, Zhongshi Zhang, and Weipeng Zheng
Clim. Past, 17, 63–94, https://doi.org/10.5194/cp-17-63-2021, 2021
The CMIP6–PMIP4 Tier 1 lig127k experiment was designed to address the climate responses to strong orbital forcing. We present a multi-model ensemble of 17 climate models, most of which have also completed the CMIP6 DECK experiments and are thus important for assessing future projections. The lig127ksimulations show strong summer warming over the NH continents. More than half of the models simulate a retreat of the Arctic minimum summer ice edge similar to the average for 2000–2018.
PubDate: Mon, 11 Jan 2021 15:38:42 +010
- A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice
data compilation and model differences
Abstract: A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice data compilation and model differences
Masa Kageyama, Louise C. Sime, Marie Sicard, Maria-Vittoria Guarino, Anne de Vernal, Ruediger Stein, David Schroeder, Irene Malmierca-Vallet, Ayako Abe-Ouchi, Cecilia Bitz, Pascale Braconnot, Esther C. Brady, Jian Cao, Matthew A. Chamberlain, Danny Feltham, Chuncheng Guo, Allegra N. LeGrande, Gerrit Lohmann, Katrin J. Meissner, Laurie Menviel, Polina Morozova, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, Ryouta O'ishi, Silvana Ramos Buarque, David Salas y Melia, Sam Sherriff-Tadano, Julienne Stroeve, Xiaoxu Shi, Bo Sun, Robert A. Tomas, Evgeny Volodin, Nicholas K. H. Yeung, Qiong Zhang, Zhongshi Zhang, Weipeng Zheng, and Tilo Ziehn
Clim. Past, 17, 37–62, https://doi.org/10.5194/cp-17-37-2021, 2021
The Last interglacial (ca. 127 000 years ago) is a period with increased summer insolation at high northern latitudes, resulting in a strong reduction in Arctic sea ice. The latest PMIP4-CMIP6 models all simulate this decrease, consistent with reconstructions. However, neither the models nor the reconstructions agree on the possibility of a seasonally ice-free Arctic. Work to clarify the reasons for this model divergence and the conflicting interpretations of the records will thus be needed.
PubDate: Mon, 11 Jan 2021 15:38:42 +010
- Hydroclimatic variability of opposing late Pleistocene climates in the
Levant revealed by deep Dead Sea sediments
Abstract: Hydroclimatic variability of opposing late Pleistocene climates in the Levant revealed by deep Dead Sea sediments
Yoav Ben Dor, Francesco Marra, Moshe Armon, Yehouda Enzel, and Efrat Morin
Clim. Past Discuss., https//doi.org/10.5194/cp-2020-161,2021
Preprint under review for CP (discussion: open, 0 comments)
Laminated sediments from the deepest part of the Dead Sea were studied in order to configure how climate change has affected hydrological phenomena in the eastern Mediterranean during past global climate changes. This study demonstrates the importance of geological archives in complementing modern hydrological measurements that likely do not capture the extent of natural hydroclimatic variability, which is necessary to configure the impacts of climate change on the hydrological cycle.
PubDate: Mon, 11 Jan 2021 15:38:42 +010
- Overcoming model instability in tree-ring-based temperature
reconstructions using a multi-species method: A case study from the
Changbai Mountains, northeastern China
Abstract: Overcoming model instability in tree-ring-based temperature reconstructions using a multi-species method: A case study from the Changbai Mountains, northeastern China
Liangjun Zhu, Shuguang Liu, Haifeng Zhu, David J. Cooper, Danyang Yuan, Yu Zhu, Zongshan Li, Yuandong Zhang, Hanxue Liang, Xu Zhang, Wenqi Song, and Xiaochun Wang
Clim. Past Discuss., https//doi.org/10.5194/cp-2021-2,2021
Preprint under review for CP (discussion: open, 0 comments)
In this study, we take the temperature reconstruction for Changbai Mountains in northeast China as an example to illustrate a novel tree-species mixing reconstruction method, which clearly improve the accuracy of tree-ring-based reconstructions in areas with unstable growth-climate relationships. Our reconstruction is more accurate than previous temperature reconstructions developed from a single species. The AMO plays a key role in modulating temperature in the northern Changbai Mountains.
PubDate: Mon, 11 Jan 2021 15:38:42 +010
- On the tuning of plateaus in atmospheric and oceanic 14C records to derive
calendar chronologies of deep-sea cores and records of 14C marine
reservoir age changes
Abstract: On the tuning of plateaus in atmospheric and oceanic 14C records to derive calendar chronologies of deep-sea cores and records of 14C marine reservoir age changes
Edouard Bard and Timothy J. Heaton
Clim. Past Discuss., https//doi.org/10.5194/cp-2020-164,2021
Preprint under review for CP (discussion: open, 0 comments)
As an extended comment on the paper by Sarnthein et al. (2020), we express strong reservations about the methodology of the so-called 14C plateau tuning (PT) technique used to date marine sediment records and its implications on the determination of 14C marine reservoir ages (MRA). The main problems are linked to: the assumption of constant MRA during 14C-age plateaus; the lack of consideration of foraminifera abundance changes coupled to bioturbation that can create spurious plateaus in marine sediments; the assumption that plateaus have the same shapes and durations in atmospheric and oceanic records; the implication that atmospheric 14C/12C peaked instantaneously from one plateau to the next; that the 14C plateaus represent 82 % of the total time spent between 14,000 and 29,000 cal yr BP, whereas during the remaining 18 % of the time, the radiocarbon clock was running almost 5 times too fast; that the sparsity, combined with the level of analytical uncertainties and additional noise, in both atmospheric and marine data do not currently allow one to reliably or robustly identify plateaus (should they exist) beyond 15,000 cal yr BP; and that the determination and identification of plateaus is reliant upon significant changes in sedimentation rate within the marine sediments which are, a priori, unknown and are not verified with an independent method. The concerns we raise are supported and strengthened with carbon cycle box-model experiments and statistical simulations of pseudo-atmospheric and pseudo-marine records, allowing us to test the ability to identify and tune 14C-age plateaus, in the context of noisy and sparse data.
PubDate: Fri, 08 Jan 2021 15:38:42 +010
- PMIP4/CMIP6 last interglacial simulations using three different versions
of MIROC: importance of vegetation
Abstract: PMIP4/CMIP6 last interglacial simulations using three different versions of MIROC: importance of vegetation
Ryouta O'ishi, Wing-Le Chan, Ayako Abe-Ouchi, Sam Sherriff-Tadano, Rumi Ohgaito, and Masakazu Yoshimori
Clim. Past, 17, 21–36, https://doi.org/10.5194/cp-17-21-2021, 2021
The last interglacial is known as the warmest period in the recent glacial–interglacial cycle. We carry out a last interglacial experiment using three versions of general circulation models to reproduce the warm climate indicated by geological evidence. Our result clearly shows that vegetation change in the last interglacial is a necessary factor to predict a strong warming in northern high latitudes, which is indicated by geological evidence.
PubDate: Wed, 06 Jan 2021 15:38:42 +010
- Mid-Holocene Antarctic sea-ice increase driven by marine ice sheet retreat
Abstract: Mid-Holocene Antarctic sea-ice increase driven by marine ice sheet retreat
Kate E. Ashley, Robert McKay, Johan Etourneau, Francisco J. Jimenez-Espejo, Alan Condron, Anna Albot, Xavier Crosta, Christina Riesselman, Osamu Seki, Guillaume Massé, Nicholas R. Golledge, Edward Gasson, Daniel P. Lowry, Nicholas E. Barrand, Katelyn Johnson, Nancy Bertler, Carlota Escutia, Robert Dunbar, and James A. Bendle
Clim. Past, 17, 1–19, https://doi.org/10.5194/cp-17-1-2021, 2021
We present a multi-proxy record of Holocene glacial meltwater input, sediment transport, and sea-ice variability off East Antarctica. Our record shows that a rapid Antarctic sea-ice increase during the mid-Holocene (~ 4.5 ka) occurred against a backdrop of increasing glacial meltwater input and gradual climate warming. We suggest that mid-Holocene ice shelf cavity expansion led to cooling of surface waters and sea-ice growth, which slowed basal ice shelf melting.
PubDate: Tue, 05 Jan 2021 15:38:42 +010
- Climate reconstructions based on GDGT and pollen surface datasets
from
Mongolia and Siberia: calibrations and applicability to
extremely
cold-dry environments over the Late Holocene
Abstract: Climate reconstructions based on GDGT and pollen surface datasetsfrom Mongolia and Siberia: calibrations and applicability toextremely cold-dry environments over the Late Holocene
Lucas Dugerdil, Sébastien Joannin, Odile Peyron, Isabelle Jouffroy-Bapicot, Boris Vannière, Boldgiv Bazartseren, Julia Unkelbach, Hermann Behling, and Guillemette Ménot
Clim. Past Discuss., https//doi.org/10.5194/cp-2020-154,2020
Preprint under review for CP (discussion: open, 0 comments)
Since the understanding of Holocene climate change appear to be a relevant issue for future climate change, the paleoclimate calibrations have to be improved. Here, surface samples from Mongolia and Siberia were analyzed to provide new calibrations for pollen and biomakers climate models. These calibrations appear to be more powerful than global calibrations, especially in Arid Central Asian context. These calibrations will improve the Monsoon Holocene oscillations understanding.
PubDate: Tue, 29 Dec 2020 15:38:42 +010
- OPTiMAL: a new machine learning approach for GDGT-based palaeothermometry
Abstract: OPTiMAL: a new machine learning approach for GDGT-based palaeothermometry
Tom Dunkley Jones, Yvette L. Eley, William Thomson, Sarah E. Greene, Ilya Mandel, Kirsty Edgar, and James A. Bendle
Clim. Past, 16, 2599–2617, https://doi.org/10.5194/cp-16-2599-2020, 2020
We explore the utiliity of the composition of fossil lipid biomarkers, which are commonly preserved in ancient marine sediments, in providing estimates of past ocean temperatures. The group of lipids concerned show compositional changes across the modern oceans that are correlated, to some extent, with local surface ocean temperatures. Here we present new machine learning approaches to improve our understanding of this temperature sensitivity and its application to reconstructing past climates.
PubDate: Wed, 23 Dec 2020 15:38:42 +010
- Plateaus and jumps in the atmospheric radiocarbon record – potential
origin and value as global age markers for glacial-to-deglacial
paleoceanography, a synthesis
Abstract: Plateaus and jumps in the atmospheric radiocarbon record – potential origin and value as global age markers for glacial-to-deglacial paleoceanography, a synthesis
Michael Sarnthein, Kevin Küssner, Pieter M. Grootes, Blanca Ausin, Timothy Eglinton, Juan Muglia, Raimund Muscheler, and Gordon Schlolaut
Clim. Past, 16, 2547–2571, https://doi.org/10.5194/cp-16-2547-2020, 2020
The dating technique of 14C plateau tuning uses U/Th-based model ages, refinements of the Lake Suigetsu age scale, and the link of surface ocean carbon to the globally mixed atmosphere as basis of age correlation. Our synthesis employs data of 20 sediment cores from the global ocean and offers a coherent picture of global ocean circulation evolving over glacial-to-deglacial times on semi-millennial scales to be compared with climate records stored in marine sediments, ice cores, and speleothems.
PubDate: Wed, 23 Dec 2020 15:38:42 +010
- Holocene vegetation dynamics in response to climate change and
hydrological processes in the Bohai region
Abstract: Holocene vegetation dynamics in response to climate change and hydrological processes in the Bohai region
Chen Jinxia, Shi Xuefa, Liu Yanguang, Qiao Shuqing, Yang Shixiong, Yan Shijuan, Lv Huahua, Li Jianyong, Li Xiaoyan, and Li Chaoxin
Clim. Past, 16, 2509–2531, https://doi.org/10.5194/cp-16-2509-2020, 2020
In this study, we present pollen and grain size data obtained from the Bohai Sea. The results reveal that soil development and salinity gradients are the main factors determining the vegetation dynamics of coastal wetland. Moreover, our pollen-based temperature index revealed a warm Early Holocene, a cool Middle Holocene and then a relatively warm Late Holocene. The main driving factors of temperature variation in this region are insolation, greenhouse gases and ENSO.
PubDate: Wed, 23 Dec 2020 15:38:42 +010
- The middle to late Eocene greenhouse climate modelled using the CESM 1.0.5
Abstract: The middle to late Eocene greenhouse climate modelled using the CESM 1.0.5
Michiel Baatsen, Anna S. von der Heydt, Matthew Huber, Michael A. Kliphuis, Peter K. Bijl, Appy Sluijs, and Henk A. Dijkstra
Clim. Past, 16, 2573–2597, https://doi.org/10.5194/cp-16-2573-2020, 2020
Warm climates of the deep past have proven to be challenging to reconstruct with the same numerical models used for future predictions. We present results of CESM simulations for the middle to late Eocene (∼ 38 Ma), in which we managed to match the available indications of temperature well. With these results we can now look into regional features and the response to external changes to ultimately better understand the climate when it is in such a warm state.
PubDate: Wed, 23 Dec 2020 15:38:42 +010
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