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- Synthetic weather diaries: concept and application to Swiss weather in
1816
Abstract: Synthetic weather diaries: concept and application to Swiss weather in 1816
Stefan Brönnimann
Clim. Past, 16, 1937–1952, https://doi.org/10.5194/cp-16-1937-2020, 2020
Scientists often reconstruct climate from proxy data such as tree rings or historical documents. Here, I do the reverse and produce a weather diary from historical numerical weather data. Such "synthetic weather diaries" may be useful for historians, e.g. to compare with other sources or to study the weather experienced during a journey or a military operation. They could also help train machine-learning approaches, which could then be used to reconstruct weather from historical diaries.
PubDate: 2020-10-21T23:49:38+02:00
- Simulated stability of the AMOC during the Last Glacial Maximum
under
realistic boundary conditions
Abstract: Simulated stability of the AMOC during the Last Glacial Maximumunder realistic boundary conditions
Frerk Pöppelmeier, Jeemijn Scheen, Aurich Jeltsch-Thömmes, and Thomas F. Stocker
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-135,2020
Preprint under review for CP (discussion: open, 0 comments)
The stability of the Atlantic Meridional Overturning Circulation (AMOC) critically depends on its mean-state. We simulate the response of the AMOC to North Atlantic freshwater perturbations under different glacial boundary conditions. We find that a closed Bering Strait greatly increases the AMOCs sensitivity to freshwater hosing. Further, the shift from mono- to bistability strongly depends on the chosen boundary conditions, with weaker circulation states exhibiting more abrupt transitions.
PubDate: 2020-10-21T23:49:38+02:00
- Reassessing long-term drought risk and societal impacts in Shenyang,
Liaoning Province, north-east China (1200–2015)
Abstract: Reassessing long-term drought risk and societal impacts in Shenyang, Liaoning Province, north-east China (1200–2015)
LingYun Tang, Neil Macdonald, Heather Sangster, Richard Chiverrell, and Rachel Gaulton
Clim. Past, 16, 1917–1935, https://doi.org/10.5194/cp-16-1917-2020, 2020
A historical drought series (since 1200 CE) for Shenyang, NE China, shows 20th century droughts comparable in magnitude to recent severe droughts. Drought resilience driven by early 20th century societal/cultural changes reduced loss of life compared with the 1887 and 1891 droughts. A longer temporal analysis from integrated precipitation and historical records shows an earlier onset to droughts. Regional standardised precipitation indices could provide early warnings for drought development.
PubDate: 2020-10-20T23:49:38+02:00
- Quantifying paleo-reconstruction skill of the Southern Annular
Mode in a
model framework
Abstract: Quantifying paleo-reconstruction skill of the Southern AnnularMode in a model framework
Willem Huiskamp and Shayne McGregor
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-133,2020
Preprint under review for CP (discussion: open, 0 comments)
This study investigates the reliability of paleo-reconstructions of the Southern Annular Mode (SAM) using climate model data. We find that reconstructions are able to, at best, capture ~ 60 % of SAM variability, with poorer reconstructions managing only 35 %. Reconstructions perform best when they use a larger number of proxies, sourced from the entire Southern Hemisphere land mass. Future reconstructions should endeavour to address both sampling and proxy-SAM correlation stability uncertainties.
PubDate: 2020-10-20T23:49:38+02:00
- Sampling density and date along with species selection influence spatial
representation of tree-ring reconstructions
Abstract: Sampling density and date along with species selection influence spatial representation of tree-ring reconstructions
Justin T. Maxwell, Grant L. Harley, Trevis J. Matheus, Brandon M. Strange, Kayla Van Aken, Tsun Fung Au, and Joshua C. Bregy
Clim. Past, 16, 1901–1916, https://doi.org/10.5194/cp-16-1901-2020, 2020
We found that increasing the density of chronologies in the tree-ring network resulted in estimated soil moisture conditions that better matched the spatial variability of the values that were instrumentally recorded for droughts and, to a lesser extent, pluvials. By sampling trees in 2010 compared to 1980, the sensitivity of tree rings to soil moisture decreased in the southern portion of our region, where severe drought conditions have been absent over recent decades.
PubDate: 2020-10-19T23:49:38+02:00
- Life and death in the Chicxulub impact crater: a record of the
Paleocene–Eocene Thermal Maximum
Abstract: Life and death in the Chicxulub impact crater: a record of the Paleocene–Eocene Thermal Maximum
Vann Smith, Sophie Warny, Kliti Grice, Bettina Schaefer, Michael T. Whalen, Johan Vellekoop, Elise Chenot, Sean P. S. Gulick, Ignacio Arenillas, Jose A. Arz, Thorsten Bauersachs, Timothy Bralower, François Demory, Jérôme Gattacceca, Heather Jones, Johanna Lofi, Christopher M. Lowery, Joanna Morgan, Noelia B. Nuñez Otaño, Jennifer M. K. O'Keefe, Katherine O'Malley, Francisco J. Rodríguez-Tovar, Lorenz Schwark, and the IODP–ICDP Expedition 364 Scientists
Clim. Past, 16, 1889–1899, https://doi.org/10.5194/cp-16-1889-2020, 2020
A rare tropical record of the Paleocene–Eocene Thermal Maximum, a potential analog for future global warming, has been identified from post-impact strata in the Chicxulub crater. Multiproxy analysis has yielded evidence for increased humidity, increased pollen and fungi input, salinity stratification, bottom water anoxia, and sea surface temperatures up to 38 °C. Pollen and plant spore assemblages indicate a nearby diverse coastal shrubby tropical forest resilient to hyperthermal conditions.
PubDate: 2020-10-19T23:49:38+02:00
- CH4 and N2O fluctuations during the penultimate deglaciation
Abstract: CH4 and N2O fluctuations during the penultimate deglaciation
Loïc Schmidely, Christoph Nehrbass-Ahles, Jochen Schmitt, Juhyeong Han, Lucas Silva, Jinwha Shin, Fortunat Joos, Jérôme Chappellaz, Hubertus Fischer, and Thomas F. Stocker
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-131,2020
Preprint under review for CP (discussion: open, 0 comments)
Using ancient gas trapped in polar glaciers, we reconstructed the atmospheric concentrations of methane and nitrous oxide over the penultimate deglaciation to study their response to major climate changes. We show this deglaciation to be characterized by fluctuations in concentration correlated to varying strength of the meridional circulation in the Atlantic Ocean, which is believed to have modulated methane and nitrous oxide emissions during the penultimate deglaciation.
PubDate: 2020-10-19T23:49:38+02:00
- Dust record in an ice core from tropical Andes (Nevado Illimani –
Bolivia), potential for climate variability analyses in the Amazon basin
Abstract: Dust record in an ice core from tropical Andes (Nevado Illimani – Bolivia), potential for climate variability analyses in the Amazon basin
Filipe Gaudie Ley Lindau, Jefferson Cardia Simões, Rafael da Rocha Ribeiro, Patrick Ginot, Barbara Delmonte, Giovanni Baccolo, Stanislav Kutuzov, Valter Maggi, and Edson Ramirez
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-129,2020
Preprint under review for CP (discussion: open, 1 comment)
Glaciers are important freshwater sources in the Tropical Andes. Their retreat has been accelerating since the 1980s. This exposes fresh glacial sediments and facilitates the transport of coarse dust particles to the Nevado Illimani summit. Both the glacial area of Illimani and its ice core record of coarse dust particles respond to warmer conditions across the southern tropical Andes, and drier conditions over the Amazon basin.
PubDate: 2020-10-15T23:49:38+02:00
- Extending and understanding the South West Western Australian rainfall
record using a snowfall reconstruction from Law Dome, East Antarctica
Abstract: Extending and understanding the South West Western Australian rainfall record using a snowfall reconstruction from Law Dome, East Antarctica
Yaowen Zheng, Lenneke M. Jong, Steven J. Phipps, Jason L. Roberts, Andrew D. Moy, Mark A. J. Curran, and Tas D. van Ommen
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-124,2020
Preprint under review for CP (discussion: open, 1 comment)
South West Western Australia has experienced a prolonged drought in recent decades. The causes of this drought are unclear. We use an ice core from East Antarctica to reconstruct changes in rainfall over the past 2,000 years. We find that the current drought is unusual, with only two other droughts of similar severity having occurred during this period. Climate modelling shows that greenhouse gas emissions during the industrial era are likely to have contributed to the recent drying trend.
PubDate: 2020-10-13T23:49:38+02:00
- Climate indices in historical climate reconstructions: A global
state-of-the-art
Abstract: Climate indices in historical climate reconstructions: A global state-of-the-art
David J. Nash, George C. D. Adamson, Linden Ashcroft, Martin Bauch, Chantal Camenisch, Dagomar Degroot, Joelle Gergis, Adrian Jusopović, Thomas Labbé, Kuan-Hui Elaine Lin, Sharon D. Nicholson, Qing Pei, María del Rosario Prieto, Ursula Rack, Facundo Rojas, and Sam White
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-126,2020
Preprint under review for CP (discussion: open, 0 comments)
Qualitative evidence contained within historical sources provides an important record of climate variability for periods prior to the onset of systematic meteorological data collection. Before such evidence can be used for climate reconstructions, it needs to be converted to quantitative data. A common approach used is the generation of ordinal-scale climate indices. This review, written by members of the PAGES CRIAS Working Group, provides a global synthesis of the use of the index approach.
PubDate: 2020-10-09T23:49:38+02:00
- Snapshots of mean ocean temperature over the last 700,000 yr using noble
gases in the EPICA Dome C ice core
Abstract: Snapshots of mean ocean temperature over the last 700,000 yr using noble gases in the EPICA Dome C ice core
Marcel Haeberli, Daniel Baggenstos, Jochen Schmitt, Markus Grimmer, Adrien Michel, Thomas Kellerhals, and Hubertus Fischer
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-127,2020
Preprint under review for CP (discussion: open, 0 comments)
Using the temperature dependent solubility of noble gases in ocean water, we reconstruct global mean ocean temperature (MOT) over the last 700 kyr using noble gas ratios in air enclosed in polar ice cores. Our record shows that glacial MOT was about 3 °C cooler compared to the Holocene. Interglacials before 450 kyr ago were characterized by about 1.5 °C lower MOT than the Holocene. In addition, some interglacials show transient maxima in ocean temperature related to changes in ocean circulation.
PubDate: 2020-10-08T23:49:38+02:00
- Comparison of Holocene temperature reconstructions based on GISP2
multiple-gas-isotope measurements
Abstract: Comparison of Holocene temperature reconstructions based on GISP2 multiple-gas-isotope measurements
Michael Döring and Markus Christian Leuenberger
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-132,2020
Preprint under review for CP (discussion: open, 0 comments)
We analyze Holocene temperatures reconstructed from gas-stable-isotope species measured on ancient air extracted from a Greenland ice core. Also, we compare two state of the art firn-models which are needed for the inversion of the gas-isotope data to paleo-temperature and provide detailed uncertainty estimations for the reconstructed temperature estimates. Finally, we compare our reconstructed temperatures to two recent reconstructions based on the same gas-isotope data as used here.
PubDate: 2020-10-07T23:49:38+02:00
- Climate records in ancient Chinese diaries and their application in
historical climate reconstruction – a case study of Yunshan Diary
Abstract: Climate records in ancient Chinese diaries and their application in historical climate reconstruction – a case study of Yunshan Diary
Siying Chen, Yun Su, Xiuqi Fang, and Jia He
Clim. Past, 16, 1873–1887, https://doi.org/10.5194/cp-16-1873-2020, 2020
Private diaries are important sources of historical data for research on climate change. Through a case study of Yunshan Diary, authored by Bi Guo of the Yuan dynasty of China, this article demonstrates how to delve into climate information in ancient diaries, mainly including species distribution records, phenological records and daily weather descriptions. This article considers how to use these records to reconstruct climate change and extreme climatic events on various timescales.
PubDate: 2020-10-06T23:49:38+02:00
- Optimizing sampling strategies in high-resolution paleoclimate records
Abstract: Optimizing sampling strategies in high-resolution paleoclimate records
Niels de Winter, Tobias Agterhuis, and Martin Ziegler
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-118,2020
Preprint under review for CP (discussion: open, 0 comments)
The aim of paleoclimate studies to resolve climate variability from noisy proxy records can in essence be reduced to a statistical problem. The challenge is to isolate meaningful information on climate events from these records by reducing measurement uncertainty through a combination of proxy data while retaining the temporal resolution needed to assess the timing and duration of the event. In this study, we explore the limits of this compromise by testing different methods for combining proxy data (smoothing, binning and sample size optimization) on a particularly challenging paleoclimate problem: resolving seasonal variability in stable isotope records. We test and evaluate the effects of changes in the seasonal temperature and hydrology cycle as well as changes in accretion rate of the archive and parameters such as sampling resolution and age model uncertainty on the reliability of seasonality reconstructions based on clumped and oxygen isotope analyses in 33 real and virtual datasets. Our results show that strategic combinations of clumped isotope analyses can significantly improve the accuracy of seasonality reconstructions if compared with conventional stable oxygen isotope analyses, especially in settings where the isotopic composition of the water is poorly constrained. Smoothing data using a moving average often leads to a dampening of the seasonal cycle, significantly reducing the accuracy of reconstructions. A statistical sample size optimization protocol yields more precise results than smoothing. However, the most accurate results are obtained through monthly binning of proxy data, especially in cases where growth rate or water composition cycles dampen the seasonal temperature cycle. Our analysis of a wide range of natural situations reveals that the effect of temperature seasonality on isotope records almost invariably exceeds that of changes in water composition. Thus, in most cases, isotope records allow reliable identification of growth seasonality as a basis for age modelling and seasonality reconstructions in absence of independent chronological markers in the record. These specific findings allow us to formulate general recommendations for sampling and combining data in paleoclimate research and have implications beyond the reconstruction of seasonality. We discuss the implications of our results for solving common problems in paleoclimatology and stratigraphy, including cyclostratigraphy, strontium isotope dating and event stratigraphy.
PubDate: 2020-10-06T23:49:38+02:00
- How precipitation intermittency sets an optimal sampling distance
for
temperature reconstructions from Antarctic ice cores
Abstract: How precipitation intermittency sets an optimal sampling distancefor temperature reconstructions from Antarctic ice cores
Thomas Münch, Martin Werner, and Thomas Laepple
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-128,2020
Preprint under review for CP (discussion: open, 0 comments)
We analyse Holocene climate model simulation data to find the locations ofAntarctic ice cores which are best suited to reconstruct local-to-regional scaletemperatures. We find that the spatial decorrelation scales of the temperaturevariations and of the noise from precipitation intermittency set an effectivesampling length scale. Following this, a single core should be located at thetarget site for the temperature reconstruction, a second one optimally lies morethan 500 km away.
PubDate: 2020-10-05T23:49:38+02:00
- Deoxygenation dynamics above the western Nile deep-sea fan during sapropel
S1 at seasonal to millennial time-scales
Abstract: Deoxygenation dynamics above the western Nile deep-sea fan during sapropel S1 at seasonal to millennial time-scales
Cécile L. Blanchet, Rik Tjallingii, Anja M. Schleicher, Stefan Schouten, Martin Frank, and Achim Brauer
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-114,2020
Preprint under review for CP (discussion: open, 0 comments)
The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial time scales.
PubDate: 2020-10-02T23:49:38+02:00
- Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene
simulations
Abstract: Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations
Chris M. Brierley, Anni Zhao, Sandy P. Harrison, Pascale Braconnot, Charles J. R. Williams, David J. R. Thornalley, Xiaoxu Shi, Jean-Yves Peterschmitt, Rumi Ohgaito, Darrell S. Kaufman, Masa Kageyama, Julia C. Hargreaves, Michael P. Erb, Julien Emile-Geay, Roberta D'Agostino, Deepak Chandan, Matthieu Carré, Partrick J. Bartlein, Weipeng Zheng, Zhongshi Zhang, Qiong Zhang, Hu Yang, Evgeny M. Volodin, Robert A. Tomas, Cody Routson, W. Richard Peltier, Bette Otto-Bliesner, Polina A. Morozova, Nicholas P. McKay, Gerrit Lohmann, Allegra N. Legrande, Chuncheng Guo, Jian Cao, Esther Brady, James D. Annan, and Ayako Abe-Ouchi
Clim. Past, 16, 1847–1872, https://doi.org/10.5194/cp-16-1847-2020, 2020
This paper provides an initial exploration and comparison to climate reconstructions of the new climate model simulations of the mid-Holocene (6000 years ago). These use state-of-the-art models developed for CMIP6 and apply the same experimental set-up. The models capture several key aspects of the climate, but some persistent issues remain.
PubDate: 2020-10-01T23:49:38+02:00
- Cosmogenic isotope measurements from recently deglaciated bedrock as a new
tool to decipher changes in Greenland Ice Sheet size
Abstract: Cosmogenic isotope measurements from recently deglaciated bedrock as a new tool to decipher changes in Greenland Ice Sheet size
Nicolás E. Young, Alia J. Lesnek, Josh K. Cuzzone, Jason P. Briner, Jessica A. Badgeley, Alexandra Balter-Kennedy, Brandon L. Graham, Allison Cluett, Jennifer L. Lamp, Roseanne Schwartz, Thibaut Tuna, Edouard Bard, Marc W. Caffee, Susan R. H. Zimmerman, and Joerg M. Schaefer
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-111,2020
Preprint under review for CP (discussion: open, 0 comments)
Retreat of the Greenland Ice Sheet (GrIS) margin is exposing a bedrock landscape that holds clues regarding the timing and extent of past ice-sheet minima. We present cosmogenic nuclides measurements from recently deglaciated bedrock surfaces (the last few decades), combined with a refined chronology of southwestern Greenland deglaciation and model simulations of GrIS change. Results suggest that inland retreat of the southwestern GrIS margin was likely minimal in the middle to late Holocene.
PubDate: 2020-09-30T23:49:38+02:00
- Comparison of the oxygen isotope signatures in speleothem records and
iHadCM3 model simulations for the last millennium
Abstract: Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium
Janica Carmen Bühler, Carla Roesch, Moritz Kirschner, Louise Sime, Max D Holloway, and Kira Rehfeld
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-121,2020
Preprint under review for CP (discussion: open, 1 comment)
We present three new isotope-enabled simulations for the last millennium (850–1850 CE) and compare them to records from a global speleothem database. Offsets between the simulated and measured oxygen isotope ratios are fairly small. While modeled oxygen isotope ratios are more variable on decadal timescales, proxy records are more variable on (multi-)centennial timescales. This could be due to a lack of long-term variability in complex model simulations, but proxy biases cannot be excluded.
PubDate: 2020-09-29T23:49:38+02:00
- Nutrient utilization and diatom productivity changes in the low-latitude
SE Atlantic over the past 70 kyr: Response to Southern Ocean leakage
Abstract: Nutrient utilization and diatom productivity changes in the low-latitude SE Atlantic over the past 70 kyr: Response to Southern Ocean leakage
Katharine Hendry, Oscar Romero, and Vanessa Pashley
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-115,2020
Preprint under review for CP (discussion: open, 0 comments)
Productive Eastern boundary upwelling systems (EBUs) are characterised by abundant siliceous algae, diatoms, and play a key role in carbon fixation. Understanding past shifts in diatom production is critical for predicting the impact of future climate change. We combine existing sediment archives from the Benguela EBU with new diatom isotope analyses and modelling to reconstruct Late Quaternary silica cycling, which we suggest depends on both upwelling intensity and surface utilisation.
PubDate: 2020-09-29T23:49:38+02:00
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