CL1.2.4 | Studying the climate of the last two millennia
EDI
Studying the climate of the last two millennia
Co-sponsored by PAGES 2k
Convener: Andrea SeimECSECS | Co-conveners: Hugo Beltrami, Nikita KaushalECSECS, Steven Phipps, Stefan Bronnimann
Orals
| Tue, 25 Apr, 16:15–18:00 (CEST)
 
Room 0.31/32
Posters on site
| Attendance Tue, 25 Apr, 14:00–15:45 (CEST)
 
Hall X5
Orals |
Tue, 16:15
Tue, 14:00
This session aims to place recently observed climate change in a long-term perspective by highlighting the importance of paleoclimate research spanning the past 2000 years. We invite presentations that provide insights into past climate variability, over decadal to millennial timescales, from different paleoclimate archives (ice cores, marine sediments, terrestrial records, historical archives and more). In particular, we are focussing on quantitative temperature and hydroclimate reconstructions, and reconstructions of large-scale modes of climate variability from local to global scales. This session also encourages presentations on the attribution of past climate variability to external drivers or internal climate processes, data syntheses, model-data comparison exercises, proxy system modelling, and novel approaches to producing multi-proxy climate field reconstructions such as data assimilation or machine learning.

Orals: Tue, 25 Apr | Room 0.31/32

Chairpersons: Andrea Seim, Nikita Kaushal, Stefan Bronnimann
16:15–16:20
16:20–16:30
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EGU23-16901
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solicited
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On-site presentation
Gregory Hakim, Anna Black, and Kyle Armour

Many aspects of climate change are related to the net energy imbalance at top of Earth's atmosphere. This measures the difference between incoming solar radiation and outgoing radiation from emission and reflected solar radiation; the net imbalance must be reflected in changes to global energy storage. While the net imbalance has been measured by satellites in recent decades and constrained by ocean heat-content estimates from Argo floats, long-term changes are poorly constrained, even in the 20th century. Here we test the hypothesis that the planetary energy imbalance can be estimated from observations, and proxies, of surface temperature using data assimilation over the Common Era.

We present and evaluate a method for reconstructing outgoing radiation at the top of the atmosphere from assimilation of surface temperature observations. The method is first tested during the satellite era by assimilating HadCRUT surface temperature observations using prior estimates drawn from historical climate-model simulations outside the validation period. Results show higher skill in the reconstructions compared to AMIP simulations for interannual variability in both the outgoing infrared, and reflected solar radiation fields, when compared to CERES measurements. Over longer periods of time, the effective radiative forcing (ERF) from changing greenhouse gases and aerosols must be considered since ERF is, by definition, the radiative response independent of surface temperature changes. Adding estimates of ERF from climate simulations to the reconstructed radiation fields shows good agreement with AMIP simulations over the historical period. We extend the method to the Common Era using PAGES2K temperature-sensitive proxies and the Last Millennium Reanalysis assimilation framework.

How to cite: Hakim, G., Black, A., and Armour, K.: Reconstructing Earth Energy Imbalance over the Common Era, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16901, https://doi.org/10.5194/egusphere-egu23-16901, 2023.

16:30–16:40
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EGU23-3587
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ECS
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Highlight
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On-site presentation
Pedro Roldán, Jesús Fidel González-Rouco, Jason Smerdon, and Félix García-Pereira

Global changes have been found in simulated and reconstructed temperatures during the Last Millennium (LM), mainly associated to changes in the Earth’s energy balance like those during the periods of the Medieval Climate Anomaly (MCA; ca. 950-1250 CE) and the Little Ice Age (LIA; ca. 1450-1850 CE), respectively characterized by warmer and cooler conditions over many regions. Even if the impact of these changes in the hydroclimate is not fully understood, evidences of coordinated changes in the hydroclimate of distant regions can be also found in reconstructions from areas of North America, Europe and the Mediterranean basin, South America, Eastern Africa and Monsoon Asia. The timing of such changes suggests a link to the MCA and the LIA, while other areas like Southeast Asia and the Indo-Pacific also show coordinated changes in the hydroclimate of the LM, but without a patent link to the periods of MCA and LIA.

To better assess these coordinated changes in the hydroclimate of distant regions, and whether they also extend to other periods of the LM different from the MCA and the LIA, evidences from reconstructions and simulations have been compiled, including: a compilation of 92 reconstructions reporting changes from wetter to drier or from drier to wetter conditions in the transition from MCA to LIA; reconstruction-based products like the Drought Atlases for Europe (OWDA), North America (NADA), Asia (MADA), Mexico (MXDA) and Eastern Australia and New Zealand (ANZDA); hybrid products like the Paleo Hydrodynamics Data Assimilation product (PHYDA) and the Last Millennium Reanalysis (LMR); and model simulations from the Community Earth System Model - Last Millennium Ensemble (CESM-LME) and the Coupled Model Intercomparison Project Phase 5 (CMIP5) and 6 (CMIP6).

The comparison between proxy-based datasets and model simulations has allowed to obtain robust conclusions regarding the behavior of the hydroclimate of different regions and to deeply analyze the impact of external forcing and internal variability on hydroclimate changes. In tropical areas, changes have been mainly associated to alterations in the position and intensity of the Intertropical Convergence Zone (ITCZ), while in extratropical areas the alteration of variability modes like the Northern (NAM) and Southern Annular Modes (SAM) may have had a major role in the response of hydroclimate to changes in external forcing.

 

How to cite: Roldán, P., González-Rouco, J. F., Smerdon, J., and García-Pereira, F.: Global changes in the hydroclimate of the Last Millennium: Evidences from reconstructions and simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3587, https://doi.org/10.5194/egusphere-egu23-3587, 2023.

16:40–16:50
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EGU23-654
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On-site presentation
Beyrem Jebri and Myriam Khodri

Proxy records (corals, marine sediments, etc.) documenting the last 2000 years (2K) provide evidences for the wide range of natural variability not captured by recent direct observations. Assessing climate models ability to reproduce such natural variations is crucial to understand climate sensitivity and impacts of future climate change. The length of record is relatively short for investigating slow climate features, especially when considering coupled ocean-atmosphere variability. In order to extend the information contained in proxies from the locations and times to which they pertain, additional information is needed to create a climate field reconstruction. Paleoclimate data assimilation offers a powerful way to extend the instrumental period and better characterize the decadal to secular natural ocean variability by optimally combining the physics described by climate models with information from available observations while taking into account their uncertainties. Here we present a new Proxy Data Assimilation product based on a sequential importance resampling particle filter (PF-SIR) that uses Linear Inverse Modeling as an emulator of GCMs, providing dynamical ocean memory and improving the reconstruction of low-frequency climate variability. The climate reconstructions include robust uncertainty quantification and a set of physically consistent spatial fields useful for dynamical inquiry beyond what is feasible from proxies or climate models alone. We use these new results to explore low-frequency aspects of main coupled variability modes and provide some constrains on climate model simulations for the last millennium.

How to cite: Jebri, B. and Khodri, M.: Large ensemble particle filter for proxy-based spatial reconstructions of the last 2000-years climate variability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-654, https://doi.org/10.5194/egusphere-egu23-654, 2023.

16:50–17:00
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EGU23-386
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On-site presentation
Jörg Franke, Valler Veronika, Ralf Hand, Eric Samakinwa, Angela-Maria Burgdorf, Elin Lundstad, Yuri Brugnara, Laura Hövel, and Stefan Brönnimann

The Modern Era Reanalysis (ModE-RA) extends current re-analysis back until the year 1420 CE at monthly resolution. It combines our understanding of physics coming from an ensemble of atmospheric model simulations with all available direct and indirect climate observations of monthly to annual resolution. A 20-member ensemble of atmospheric model simulations (ModE-Sim) driven by an ensemble of external forcings and an ensemble of new sea surface temperature reconstructions serves as a prior estimate of the possible climate states at each assimilation time step. After the entire simulations were completed, we assimilated multiple data sources using an offline Kalman filtering technique. We include up to ~100000 monthly to annual observations per year. These consist of thousands of existing and newly digitised instrumental measurements of temperature, precipitation, wet days per months, and pressure, including measurements made on ships over the ocean and in harbours. Earliest instrumental station data go back to the year 1658. Additionally, we collected and digitised climate information from historical documents, including phenological data. These are especially valuable for the autumn, winter and spring season and go back to the year 1420. Finally, we assimilate annually resolved climate proxies. The vast majority are tree-ring observations, which represent growing season conditions on the continents. In otherwise data sparse regions, we supplemented ice and coral data at high latitudes and the tropical oceans, respectively. ModE-RA offers especially  insides into interannual to multidecadal variability such as phases of accelerated warming, monsoon strength or subtropical droughts as well as rare events such as volcanic eruptions. 

How to cite: Franke, J., Veronika, V., Hand, R., Samakinwa, E., Burgdorf, A.-M., Lundstad, E., Brugnara, Y., Hövel, L., and Brönnimann, S.: ModE-RA - the Modern Era Reanalysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-386, https://doi.org/10.5194/egusphere-egu23-386, 2023.

17:00–17:10
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EGU23-13169
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On-site presentation
Martin Werner and Alexandre Cauquoin

Stable water isotopes are widely used to reconstruct past temperature and precipitation variations in many regions of the Earth. While the general physical processes of how isotope variations are controlled by temperature and water amounts is well understood, quantifying past isotope changes as a proxy for temperature and precipitation is much more difficult. An explicit simulation of water isotopes in current Earth system models is one possibility to approach this problem.
In this study we present new results of a transient fully-coupled simulation of the climate of the last two millennia, using the isotope-enabled model MPI-ESM-wiso. We analyze long-term trends, variability and extremes of the simulated isotope changes in precipitation, compare model results to available data compilations (e.g. PAGES Iso2k) and quantify the relations with associated temperature and hydrological changes. Our analyses show that for many regions of the Earth, the surface warming starting with the beginning of the industrialization period is clearly imprinted in the oxygen-18 isotope signal of precipitation, e.g., over Greenland, North America, and the Atlantic Ocean. However, in some regions recent temperature, precipitation and isotope changes seem to be decoupled, e.g., over West Antarctica, Oceania, and the Indian Ocean. In our presentation, we will discuss this regional varying imprint of the Anthropocene on the water isotope signal in detail. Further analyses focus on changes in isotope variability in different regions over the last two millennia, as well as the possible detection of past climate extremes in different isotope records.

How to cite: Werner, M. and Cauquoin, A.: Climate trends, variability and extremes recorded by water isotopes during the last two millennia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13169, https://doi.org/10.5194/egusphere-egu23-13169, 2023.

17:10–17:20
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EGU23-13374
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On-site presentation
Dominik Fleitmann, Anamaria D. Häuselmann, Hai Cheng, Markus Leuenberger, and Stèphane Affolter

Almost all of the Central European temperature reconstructions covering the last two millennia reflect summer rather than mean annual air or cold season temperatures. To address the seasonal bias, we developed highly resolved 2000 year-long calcite isotope (δ18O) and fluid inclusion water isotope (δ2O and δ18O) records from a stalagmite from Milandre Cave in the Swiss Jura Mountains. Present-day climate in this region is strongly influenced by westerly air masses, making it an ideal site to record climate variability in the North Atlantic and European realm. Calibration of the Milandre Cave isotope records with historical and observational temperature and isotope data enables us to reconstruct mean annual air temperatures.  Our new temperature reconstruction shows temperature variations of approximately 2°C during the past two millennia, the temperature difference between the warmest decade of the Medieval Climate Anomaly (950–1250 CE) and the coldest decade of the Little Ice Age (1400–1700 CE) is around ~1.7°C. In general, higher central European temperatures were reconstructed in the periods 450–600 CE and 1000–1150 CE, and relatively low temperatures were recorded in the intervals 650–900 CE and 1350–1700 CE. Modelled cold season temperatures for the past millennium compare remarkably well with our reconstruction, and confirm the importance of both solar and internal forcing on Central European temperature.

How to cite: Fleitmann, D., Häuselmann, A. D., Cheng, H., Leuenberger, M., and Affolter, S.: Central European temperature variations over the past two millennia recorded in a stalagmite from western Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13374, https://doi.org/10.5194/egusphere-egu23-13374, 2023.

17:20–17:30
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EGU23-3407
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Highlight
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On-site presentation
Martin Stendel and Adam Jon Kronegh

The project ROPEWALK, funded by the AP Møller Mærsk Fund, is a joint initiative of the Danish National Archive and the Danish Meteorological Institute over the period 2023-2026. The aim of the project is to digitize and transcribe all weather observations in ship journals and logbooks stored in the Danish National Archive.

The collection in the archive is remarkable for several reasons. A huge amount of data (more than 750 shelf metres) is stored, beginning as early as the 1680s. With the exception of the Napoleonic wars and the Danish state bankruptcy in 1814, the data is complete. In particular, there were no losses during the Second World War.

In the archive, logbooks from Danish ships over large parts of Northern Hemisphere are found. Of particular interest are observations from two regions, the Øresund and Greenland.

In connection with the Sound duties which every ship passing the sound or belts had to pay between 1426 and 1857, weather observations were made on board of war ships placed at strategic locations near Copenhagen, Helsingør and Nyborg. These ships had to ensure that no one passed without paying the duties. Probably for practical reasons, weather observations were tabulated as early as the first half of the 18th century. In several cases, observations were conducted every time the ship bell was struck, resulting in 48 observations in the course of one day. The early part of the logbook collection is from the Little Ice Age, and numerous ice observations in the Danish waters have been preserved.

The other group of logbooks which are of particular interest are from voyages to the colonies, in particular to (western) Greenland. The Greenlandic Trade Company had a monopoly for commerce with Greenland for nearly 200 years, and foreign ships would not be allowed to call a port. These "Greenland Voyages" were conducted several times per year. In many cases, detailed sea ice observations have been made.

The original logbooks are being scanned by the National Archive in highest possible resolution. The scans will then be transcribed by means of machine learning. This is possible, since the political system in Denmark was absolutistic between 1660 and 1848, and logbooks from different periods resemble each other much more than is the case for the nautical heritage in other seafaring nations. Where this is not possible, the data will be transcribed with the help of volunteers. For the oldest logbooks, which are in free text rather than in tabular form, we could locate older transcriptions which are much easier to read tahn the original data, either by machine or manually.

All transcribed data will be made publicly available. They can be used for future research or as input for reanalysis projects. We will present first results of our analysis.

How to cite: Stendel, M. and Kronegh, A. J.: ROPEWALK (Rescuing Old data with People's Efforts: Weather and climate Archives from LogbooK records) - a digitization project for three centuries of weather observations on board of Danish ships, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3407, https://doi.org/10.5194/egusphere-egu23-3407, 2023.

17:30–17:40
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EGU23-2148
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On-site presentation
Fredrik Charpentier Ljungqvist, Bo Christiansen, Lea Schneider, and Peter Thejll

Wine is a particularly climate-sensitive crop for which long documentary series are available in much of Europe. Most studies of climate–wine growth relationships have hitherto utilised grape harvest date series. We instead investigate the climatic signature, and impact from volcanic forcing, on two long annual wine harvest quantity records from the Moselle Valley, in present-day Luxembourg, close to the latitudinal limit of commercial wine agriculture in Europe. A strong positive relationship between reconstructed temperature, especially summer temperature, and wine production quantities is found in our data that extend from the mid-fifteenth century until the end of the eighteenth century. Extremely cold or wet years show clear imprints on the wine harvest quantities. Large declines in the wine harvest – sometimes even total harvest failures – occurred after volcanic forcing events. The most significant decline in wine production quantities occurred during the first year after a volcanic forcing event. However, persistent wine production decline is evident over several consecutive years following larger volcanic forcing events. We compare the signature of Moselle Valley wine production declines following volcanic forcing events with corresponding tree-ring growth declines in different regions of Europe. It is evident that wine production shows a stronger and more distinct downturn following volcanic forcing events, even more minor ones, than tree-ring growth does in central Europe. Possible mechanisms for this behaviour are explored and discussed.

How to cite: Charpentier Ljungqvist, F., Christiansen, B., Schneider, L., and Thejll, P.: Strong volcanic and climatic shocks on early modern wine production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2148, https://doi.org/10.5194/egusphere-egu23-2148, 2023.

17:40–17:50
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EGU23-3969
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ECS
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Highlight
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On-site presentation
Martin Skoglund

For the region of central Scandinavia, there exists high-quality tree-ring based temperature reconstructions that cover the last 1200 years. This paper utilizes climate reconstructions in tandem with historical sources to estimate the relationships between climatic variability and agriculture in central Scandinavia between the 16th and 20th centuries, with a specific focus on temperatures, harvests and agricultural dates. Using historical sources on agriculture importantly allows for evaluation of different climate reconstructions before the era of instrumental measurements. Thus, this paper not only sheds light on the societal relevance of past and present climatic change and variability, but also provides insights into the climate of the past.

While historical harvest dates in many parts of Europe have been employed to reconstruct growing season temperatures, this paper also includes virtually unique long time-series of sowing and hay-cutting dates going back to the late 17th and 18th century, respectively, and shows how these type of agricultural dates also had significant relationships with temperature variability in central Scandinavia. Furthermore, agriculture in this region, located in the northern boreal zone, was heavily constrained by growing season temperatures, and harvests exhibits much clearer relationships with climatic variability compared with less marginal regions of Europe. Climate-harvest relationships are studied at a local level, allowing for spatial anlaysis of micro-climatological differences within the larger regional context.

How to cite: Skoglund, M.: Agroclimatic relationships in Central Scandinavia, c. 1560–1920, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3969, https://doi.org/10.5194/egusphere-egu23-3969, 2023.

17:50–18:00
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EGU23-12593
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ECS
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On-site presentation
Xiaoxing Wang, Kinya Toride, Mika Ichino, and Kei Yoshimura

Daily atmospheric conditions before 1900 have been rarely investigated due to the limited availability of instrumental meteorological records. The documentary evidence is an alternative source that archives the atmospheric state. In Japan, the Historical Weather Database (HWDB, accessible by: http://tk2-202-10627.vs.sakura.ne.jp) provides descriptive daily weather information recorded in diaries at many stations since the 1660s. We utilize data assimilation to achieve high-temporal reconstructions by optimally combining observations with climate model forecasts. This study reconstructs daily weather conditions in the 1810s by assimilating diary weather information for the first time. We first categorize the descriptive records into “sunny”, “cloudy”, and “rainy”, and then assimilate these diary-based weather categories into the Global Spectral Model (GSM) through a local ensemble transform Kalman filter (LETKF) scheme. The reconstructed precipitation corresponds well with the daily synoptic pattern illustrated by documentary evidence in Japan. In a single-day case in August, 80% of non-assimilated diary categories are consistent with precipitation results. The atmospheric characteristics are also well reproduced in the Meiyu-Baiu season. Our results show better accuracy than the Twentieth Century Reanalysis (20CR) dataset due to their weak constraint in the Japan region. In addition, the Tambora eruption in April 1815 was among the largest in recent history, leading to the temperature decrease in Europe in the following year, commonly known as the “Year Without a Summer”. In our results, the surface air temperature anomaly indicates significant cooling also occurred in Japan in the summer of 1816, demonstrating the climate response to the Tambora eruption. This study shows the capability of diary data assimilation to reproduce daily atmospheric conditions, providing the basis to understand the cause of short-term variability in the past climate.

How to cite: Wang, X., Toride, K., Ichino, M., and Yoshimura, K.: Atmospheric Analysis in the 1810s by Assimilating Diary-based Weather Category, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12593, https://doi.org/10.5194/egusphere-egu23-12593, 2023.

Posters on site: Tue, 25 Apr, 14:00–15:45 | Hall X5

Chairpersons: Andrea Seim, Hugo Beltrami, Steven Phipps
X5.169
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EGU23-8871
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ECS
Georgina Falster, Hussein Sayani, Anais Orsi, Helen McGregor, Nikita Kaushal, Lukas Jonkers, Matthew Jones, Benjamin Henley, Sarah Eggleston, and Alyssa Atwood

The climate of the past two thousand years (2k) provides context for current and future changes, and as such is vital for developing our understanding of the modern climate system. Building on previous phases of the PAGES 2k network, Phase 4 of the PAGES 2k Network paves the way for a new level of understanding of the global water cycle, including enhanced science-policy integration. 

Previous PAGES 2k network phases emphasised temperature reconstructions, fundamentally improving our understanding of global climate changes over the Common Era. These reconstructions received widespread recognition and were featured in the Summary for Policymakers of the IPCC’s Sixth Assessment Report. Integration of this data with state-of-the-art Earth systems models, proxy system models and data assimilation yielded a more comprehensive understanding of the associated physical drivers and climate dynamics.  

Phase 4 challenges our community to turn its focus towards hydroclimate. Our aim is to reconstruct hydroclimatic variability over the Common Era, from local to global spatial scales, at sub-annual to multi-centennial time scales, developing a process-level understanding of past hydroclimate events and variability. Our multi-faceted approach includes (1) developing new hydroclimate syntheses that are well-suited for data-model comparisons, (2) improving the interoperability and scope of existing data and model products, and (3) facilitating the translation of our science into evidence-based policy outcomes. In this presentation, we report on our activities and progress to date, particularly highlighting the early stages of our data synthesis efforts.

How to cite: Falster, G., Sayani, H., Orsi, A., McGregor, H., Kaushal, N., Jonkers, L., Jones, M., Henley, B., Eggleston, S., and Atwood, A.: Phase 4 of PAGES 2k: Hydroclimate of the Common Era, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8871, https://doi.org/10.5194/egusphere-egu23-8871, 2023.

X5.170
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EGU23-6648
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ECS
Nora Hirsch, Maria Hörhold, and Thomas Laepple

Understanding natural climate variability, its fluctuations throughout the Holocene, and its dependency on the mean climate state can provide valuable insights into driving mechanisms and potentially allow for a better prediction of a plausible range of future climates. However, polar climate variability and its changes remain uncertain due to a lack of thorough analysis across the Holocene. Ice core water isotope records are a temperature proxy which covers both high resolutions as well as long timescales and thus enable us to resolve variability changes across a large range of frequencies. By consolidating a multitude of such records from Greenland and Antarctica and using our knowledge how the ice-core signal is recorded, we distinguish signal from noise in the spectral domain. Based on this, we examine spatial and temporal changes of the polar climate signal variability, its relationships to earth system processes and its representation in climate models.

How to cite: Hirsch, N., Hörhold, M., and Laepple, T.: Polar climate variability during the Holocene as archived in ice core water isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6648, https://doi.org/10.5194/egusphere-egu23-6648, 2023.

X5.171
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EGU23-4841
Stefan Bronnimann and Angela-Maria Burgdorf

Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climate. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations particularly for the temperature sensitive series. Correlations are somewhat lower for precipitation sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.

How to cite: Bronnimann, S. and Burgdorf, A.-M.: DOCU-CLIM: A global documentary climate dataset for climate reconstructions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4841, https://doi.org/10.5194/egusphere-egu23-4841, 2023.

X5.172
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EGU23-322
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ECS
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Neele Sander, Caroline C. Ummenhofer, Bastian Münch, and Timothy D. Walker

Historical wind patterns in the North Atlantic are assessed using U.S. whaling logbooks of voyages from the 19th century, a time when instrumental wind observations were not widely available. The recordings from whaling ship logbooks provide systematic daily to sub-daily information about wind force, wind direction, and other weather observations (e.g., precipitation, sea state) over a period from ca. 1785-1915 and are housed in the New England archives by the New Bedford Whaling Museum, Nantucket Historical Association, and Providence Public Library. The extracted data from the whaling logbooks is quality checked, and the qualitative wind descriptions transferred to the Beaufort wind force scale to better compare it to the 20th-Century-Reanalysis.  Specifically, the whaling ship logbook-sourced wind recordings are used in conjunction with several indices of North Atlantic climate variability, such as North Atlantic Oscillation, East Atlantic Pattern, and Atlantic Multidecadal Oscillation, to explore variations and change in predominant North Atlantic wind patterns in the past. Here we demonstrate that the wind data from the whaling ship logbooks agrees with mean wind patterns and climate variability reconstructed for the North Atlantic and therefore provides valuable insights into the past wind patterns in this area complementing existing reanalysis products. We further demonstrate how qualitative descriptive wind information can be turned into quantitative information that can be directly compared with numerical data from reanalysis models. Since the comparison of the historical logbook data with the 20th-Century-Reanalysis data shows overall good agreement, it can be used to gain a further understanding of the dominant climate patterns in the North Atlantic and might aid development of improved indices of North Atlantic climate variability, such as the North Atlantic Oscillation or Azores High index.

How to cite: Sander, N., Ummenhofer, C. C., Münch, B., and Walker, T. D.: Assessing North Atlantic climate variability since the early 1800s through historical New England whaling ship logbooks and reanalyses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-322, https://doi.org/10.5194/egusphere-egu23-322, 2023.

X5.173
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EGU23-5734
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ECS
Thomas Pliemon and Ulrich Foelsche

The Austrian National Library has digitized several volumes of the newspaper "Grätzer Zeitung", which contains daily measurements (morning, noon and evening) of temperature, pressure, short simple weather descriptions, wind direction, and wind strength, recorded in the historic center of Graz by Mr. Rospini (and later by his son and grandsons). Other volumes of the newspaper are available on microfilm or have been found in archives. The measurement series of the Rospini family started as early as 1781, and have been continuously published in the "Grätzer Zeitung" from 1795 onwards. However, in the first years only temperature and pressure data were published and the first publications of wind directions began in March 1822. Thus, we analyze an almost uninterrupted record of wind directions from 1822 to 1850. The measurement times for this period are given as 7 a.m., 3 p.m. and 10 p.m. To assert the validity of the data, we compare it with modern data as well as with the other measurements of the Rospinis. Initial analysis reveal an improvement in measurement accuracy during the measurement period. I.e. the year-round seasonal distributions of the main wind directions differ significantly in the 1820s with respect to modern data, whereas those of the 1840s are comparable.

How to cite: Pliemon, T. and Foelsche, U.: Analysis of wind direction measurements made by the Rospini family in Graz (Austria), 1822-1850 CE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5734, https://doi.org/10.5194/egusphere-egu23-5734, 2023.

X5.174
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EGU23-10323
Mika Ichino, Kooiti Masuda, and Takehiko Mikami

The impact of climate change on human society has been a significant issue in historical studies and is also vital for future adaptation to climate change. To understand climate change and its devastating impacts on societies in the past, before the start of meteorological observations, the spatial patterns of climate variation must be reconstructed with a higher temporal resolution than those provided by the annual data. Japan has a large volume of records, including those related to daily weather conditions (e.g., "fine", "cloudy", and "rainy"), from the 17th to 19th century.

This study has developed a method for estimating solar radiation using daily weather descriptions recorded. Using this method and the daily weather records in historical diaries of Tokyo, Japan, we reconstructed solar radiation fluctuations for the period 1720–1912, pertaining to the Little Ice Age. We compared our estimations with the observed sunshine duration records of the Japan Meteorological Agency to validate our findings. This method is effective in reconstructing solar radiation for all seasons and allows for the reconstruction of historical climate fluctuations with higher temporal resolution compared with that reconstructed using other methods or proxy data often used previously. In addition, solar radiation is a fundamental factor for not only the energy balance of the Earth but also the hydrological cycle and agricultural productivity.

Here, we created a long-time series of solar radiation for the period 1720–2022 in Tokyo, thereby providing insights into low and high solar radiation for this practical 300-year period. Furthermore, the reconstruction of historical solar radiation fluctuations could enable the exploration of the correlation between climate variations and social changes.

How to cite: Ichino, M., Masuda, K., and Mikami, T.: Reconstruction of solar radiation in Tokyo since 1720 based on historical weather records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10323, https://doi.org/10.5194/egusphere-egu23-10323, 2023.

X5.175
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EGU23-6604
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ECS
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Laura Hövel, Ralf Hand, Jörg Franke, and Stefan Brönnimann

The decade 1531-1540 was characterized by a high number of dry summer episodes making it the driest summer decade of the past 500 years in some areas of Central Europe. In addition to established climate reconstructions, we use the ModE-RA (Modern Era Reanalysis) and ModE-Sim (Modern Era Simulations) data sets which provide gridded climate information of the past 600 years to analyse the summers of 1531-1540 and compare it with other decadal dry spells over Europe.

While most previous studies focus on the variability of individual drought events or multi-decadal mega droughts, our aim is to identify decadal scale dry spells similar to the 1531-1540 decade. With our three-dimensional reanalysis and the model simulations forced with observed volcanic forcings and prescribed SST we can then investigate the atmospheric and oceanic drivers of such events as well as the influence of the volcanic forcings.

Our first results show that the magnitude and distribution of observed decadal dry spells in ModE-RA is realistic and comparable to other climate reconstructions. In the ModE-Sim ensemble mean the drying signal for the 1531-1540 event is less strong but still visible. Overall, with our ongoing analysis we contribute to the evaluation of past and future decadal dry spells over Europe that are driven by both natural and anthropogenic forcings.

How to cite: Hövel, L., Hand, R., Franke, J., and Brönnimann, S.: The 1531-1540 dry summers in Europe - Identifying potential drivers of decadal dry spells using climate reconstructions and ensemble simulations of the past 600 years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6604, https://doi.org/10.5194/egusphere-egu23-6604, 2023.

X5.176
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EGU23-9075
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ECS
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Mingyue Zhang, Eva Hartmann, Sebastian Wagner, Muralidhar Adakudlu, and Elena Xoplaki

The interactions and feedbacks between climate stress and social systems are currently the focus of interest for the scientific community and the general public. Understanding how paleo societies responded to extreme climate conditions is important for gaining insight into current and future climate concerns. The East Mediterranean (EM) and the Nile River basin (NR) are ideal areas for scientific and historical studies and modelling experiments due to the abundance of proxy and historical data. The 6th century AD is of particular interest from both a historical and scientific perspective, as it coincides with a period of prosperity for the Eastern Byzantine Empire and political stability, but which also experienced a plague pandemic and significant climate variability in parallel or as a result of a major cluster of volcanic eruptions. To investigate these events and the climate variability in the 6th century in more detail, a transient paleo-simulation is carried out with the appropriately adjusted regional climate model COSMO-CLM (COSMO 5.0 clm16). The regional climate model is driven by the global MPI-ESM-LR at 0.44° for the last 2500 years. The state-of-the-art external forcings of the CMIP6 compliant Earth System Model comprise of volcanic (stratospheric aerosol optical depth), orbital (eccentricity, obliquity, longitude), solar (irradiance), land-use (leaf area index and plant coverage) and greenhouse-gas (CO2 equivalent) changes, implemented in the regional climate model. The simulated temperature and precipitation will be compared with those of other CMIP6 models, and proxy records. This research will provide a comprehensive interpretation of the regional climate and its impacts during the 6th century AD in the Mediterranean.

 

Reference

Jungclaus, J. H., Bard, E., Baroni, M., Braconnot, P., Cao, J., Chini, L. P., Egorova, T., Evans, M., González-Rouco, J. F., Goosse, H., Hurtt, G. C., Joos, F., Kaplan, J. O., Khodri, M., Klein Goldewijk, K., Krivova, N., LeGrande, A. N., Lorenz, S. J., Luterbacher, J., Man, W., Maycock, A. C., Meinshausen, M., Moberg, A., Muscheler, R., Nehrbass-Ahles, C., Otto-Bliesner, B. I., Phipps, S. J., Pongratz, J., Rozanov, E., Schmidt, G. A., Schmidt, H., Schmutz, W., Schurer, A., Shapiro, A. I., Sigl, M., Smerdon, J. E., Solanki, S. K., Timmreck, C., Toohey, M., Usoskin, I. G., Wagner, S., Wu, C.-J., Yeo, K. L., Zanchettin, D., Zhang, Q., and Zorita, E.: The PMIP4 contribution to CMIP6 – Part 3: The last millennium, scientific objective, and experimental design for the PMIP4 past1000 simulations, Geoscientific Model Development, 10, 4005–4033, https://doi.org/10.5194/gmd-10-4005-2017, 2017.

How to cite: Zhang, M., Hartmann, E., Wagner, S., Adakudlu, M., and Xoplaki, E.: Climate of the 6th Century based on the Fully Forced Regional Climate Model COSMO-CLM over the Eastern Mediterranean and the Nile Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9075, https://doi.org/10.5194/egusphere-egu23-9075, 2023.

X5.177
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EGU23-3976
Mariano Barriendos, Josep Barriendos, María Hernández, Salvador Gil-Guirado, and Jorge Olcina-Cantos

The current climate change scenario is increasing concerns about the frequency of droughts in the Mediterranean region and the management of water resources. For this reason, it is interesting to study the most severe droughts of the recent past in order to better characterise the current phenomenon and future adaptive strategies.

One of these episodes of great magnitude and significant impact on economic and social activity were the droughts that occurred in the first third of the 19th century in the Mediterranean basins of the Iberian Peninsula. This relatively brief period, placed at the end of the Little Ice Age, contains up to four episodes of drought that affected the Spanish Mediterranean Basins. Their occurrence can be linked to known climatic forcing factors. On the one hand, the effects of the Dalton Solar Minimum (1790-1830). On the other hand, the effects of three different volcanic eruptions produced in the intertropical latitudes with a VEI equal or greater than 5: the Unknown eruption of 1809, the Tambora eruption of 1815 and the Galunggung eruption of 1822.

The climatic characterisation of the drought in this period is proposed with the use of historical proxy-data based on rogation ceremonies to monitor situations of rainfall deficit at high temporal resolution (daily/monthly). For drought assessment, a drought information classification system is proposed based on an index that takes into account the basic characteristics of each episode (duration, extent and severity). This classification will be tested to determine the behaviour of the droughts that affected the Spanish Mediterranean Basin during the period of the Dalton Solar Minimum.

The results obtained from the application of these methodologies and materials allow the identification of severe droughts that affected the Spanish Mediterranean Basin during this period. Some of these years with severe droughts are 1807, 1812, 1817-1818, the most severe drought in the overall of the series, and 1822-1825. The description and cartographic representation of the historical data about these droughts allows us to assess their severity due to the extraordinary persistence of the rainfall deficits and their capacity to affect simultaneously distant regions.

Finally, in order to compare the results obtained from the historical data recorded in Barcelona about rainfall deficits, we use the instrumental meteorological series of Barcelona. This data series begun in 1780 recording data on temperature and pressure and begun recording precipitation in 1786. The information from those records allows the comparison with the historical data.

How to cite: Barriendos, M., Barriendos, J., Hernández, M., Gil-Guirado, S., and Olcina-Cantos, J.: Drought variability in the Spanish Mediterranean Basin during the Dalton Solar Minimum period (1790-1830), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3976, https://doi.org/10.5194/egusphere-egu23-3976, 2023.

X5.178
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EGU23-14248
Monica Ionita-Scholz, Viorica Nagavciuc, Catalin Roibu, Andrei Mursa, Marian-Ionut Stirbu, and Ionel Popa

Paleoclimate reconstructions are increasingly used to characterize climate variability and change prior to the instrumental record, in order to improve our estimates of climate extremes and to provide a baseline for climate change projections. Most of these reconstructions are focused on temperature, precipitation, and/or drought indices and, to a lesser extent, reconstruct streamflow variability. In this study, the first regional tree-ring width chronology (i.e. Quercus sp.), from the Caraorman forest (Danube Delta, Romania), was used to reconstruct the last ~250 years of annual (from November previous year to July of the current year) streamflow of the Lower Danube River. The obtained results indicate a stable and significant correlation between the tree-ring width index from the Caraorman forest and the Danube streamflow at the Ceatal Izmail hydrologic station situated in the southeastern part of Europe. Interannual streamflow variation for the analyzed period indicates 14 extremely high flow years, with streamflow greater than 8780 m3/s (1770, 1771, 1799, 1836, 1838, 1839, 1871, 1876, 1877, 1879, 1940, 1941, 1997 and 2010) and 14 extremely low flow years, with streamflow lower than 5300 m3/s (1741, 1745, 1750, 1753, 1773, 1794, 1812, 1832, 1843, 1882, 1899, 1921, 1964 and 1994). Periods characterized by pluvials in the lower Danube Delta are associated with a low-pressure system centered over Europe, positive sea surface temperature (SST) anomalies over the Atlantic Ocean, and negative SST anomalies over the Baltic, North, and Mediterranean Seas. These large-scale conditions favor the advection of moist air from the Mediterranean and the Black Sea towards the southeastern part of Romania, which in turn leads to high precipitation rates over this region. Opposite to this, low streamflow years are associated with a high-pressure system centered over Europe, characterized by a northward shift of the storm tracks and negative SST anomalies over the Atlantic Ocean, and positive SST anomalies over the Baltic, North, and Mediterranean Seas. Based on our results, we argue that the reconstruction of river streamflow data based on the tree-ring width has important scientific and practical implications for a better understanding of the streamflow variation of the past, necessary for water resource management and environmental-hydrological protection.

How to cite: Ionita-Scholz, M., Nagavciuc, V., Roibu, C., Mursa, A., Stirbu, M.-I., and Popa, I.: The first tree-ring reconstruction of streamflow variability over the last ~250 years in the Lower Danube, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14248, https://doi.org/10.5194/egusphere-egu23-14248, 2023.

X5.179
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EGU23-574
Paulo Silva, Ilana Wainer, and Myriam Khodri

In the Tropics, the Hadley Cell plays a key role in controlling precipitation patterns, since it is related to the position of the ITCZ, which is also a main component of the South America Monsoon System (SAMS). Several studies have documented a poleward expansion of the Hadley Cell over the historical period and a shift in the position of its subsiding branches and the expansion of the subtropical dry zones. This widening has largely been attributed to anthropogenic forcing, such as greenhouse gases (GHG) and stratospheric ozone depletion. However, prior to the industrial period, the extent of the Hadley Cell is dominated by internal variability and the radiative effects of volcanic eruptions. Understanding this natural variability is key to better predict the possible combined effects with anthropogenic external forcing. Thus, in this study we to investigate the variability of the Hadley Cell during the Last Millennium and its response to volcanic eruptions. We rely on the simulations of the Last Millennium provided by the Paleoclimate Modeling Intercomparison Project (PMIP4) contribution to the Climate Model Intercomparison Project phase 6 (CMIP6).

How to cite: Silva, P., Wainer, I., and Khodri, M.: Hadley Cell Variability during the Last Millenium and response to volcanism in the PMIP4/CMIP6 models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-574, https://doi.org/10.5194/egusphere-egu23-574, 2023.

X5.180
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EGU23-2170
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ECS
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Jiawei Jiang, Lin Chen, Aifeng Zhou, and Zhonghui Liu

The East Asia summer monsoon variability and changes in monsoonal rainfall are critical for hydrology and ecology conditions in water-stressed regions of northern China. Due to complex interactions of monsoonal and westerlies circulation, hydroclimatic conditions at the boundary between two circulation systems, commonly defined as the 300 mm annual rainfall line, remain poorly understood. Here we report alkenone records (UK'37, %C37:4, and RIK37) from Lake Eastern Juyanze in northern China to assess temperature and hydrological changes in marginal monsoon region over the last millennium. Our records show wet conditions during the Medieval Warm Period, with the presence of alkenone C37:3 isomer at the interval of ~ 700-1,050 AD and thus evident freshening of lake water, and dry conditions during the Little Ice Age. The paired records follow the warm-wet and cold-dry association in monsoonal regions over the last millennium, opposite to the warm-dry and cold-wet association in westerlies region, although Lake Eastern Juyanze is located to the northwest of current monsoonal limit. Our results, together with other hydrological records from marginal monsoon regions, collectively indicate northwestward migration of East Asia monsoonal limit during the Medieval Warm Period associated with relatively high solar irradiance and enhanced summer monsoon circulation. Findings in this study highlight the complexity of hydroclimatic changes in marginal monsoonal regions, and further investigations focusing on the Holocene epoch are highly recommended.

 

How to cite: Jiang, J., Chen, L., Zhou, A., and Liu, Z.: Northwestward migration of the East Asian monsoonal limit during the Medieval Warm Period, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2170, https://doi.org/10.5194/egusphere-egu23-2170, 2023.

X5.181
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EGU23-8040
Pierre Francus, Antoine Gagnon-Poiré, and François Lapointe

Grand Lake, Labrador, is a 245-m deep and 55 km long fjord lake deglaciated c.a. 8000 years ago, located at the eastern margin of North America in the high boreal forest ecozone. The lake is fed by two large rivers that transport a substantial amount of sediments, mainly during the snowmelt season. As a result, up to 13 mm thick varves are preserved in the proximal zone of the two main tributaries, while distal varves are 1.26 mm thick on average. Proximal and distal varves can be correlated thanks to cross-correlation of distinctive varves. Varve counts were made from high-resolution images of thin sections at the scanning electron microscope, and from 100 µm-resolution µXRF profiles. The age model was validated by 210Pb, 137Cs and 14C dating. The proximal varves are composed of 3 distinct laminae, while the distal varves contain 2 layers. This paper outlines how the proximal and distal sequences were combined to produce a 1523-year-long record allowing a very long reconstruction of past river mean discharge (Q-mean). The river discharge was higher during the Medieval Climate Anomaly (1050–1225 CE) and lower during the Little Ice Age (15th–19th centuries). The reconstructed Q-mean shows a significant co-variability with Atlantic Multidecadal Variability reconstructions and with reconstructed summer Northern Hemisphere temperature based on tree rings. This suggests that river discharge in Labrador was influenced by ocean-atmosphere interactions across the North Atlantic, and that a longer varved record from Grand Lake has the potential to reconstruct the supra-regional modes of climatic variability for most of the Holocene.

How to cite: Francus, P., Gagnon-Poiré, A., and Lapointe, F.: A new 1523-year-long varve sequence reveals the influence of the Atlantic Multidecal Variability on Eastern Canada hydroclimate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8040, https://doi.org/10.5194/egusphere-egu23-8040, 2023.

X5.182
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EGU23-222
The Indian monsoon variability during the last two millennia and links to the tropical equatorial Pacific
(withdrawn)
Naveen Gandhi, Aannpureddy P. Reddy, Madhusudan G. Yadava, and Raghavan Krishnan
X5.183
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EGU23-2600
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ECS
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Mathurin A. Choblet, Janica C. Bühler, Nathan J. Steiger, Valdir F. Novello, and Kira Rehfeld

Data Assimilation in paleoclimatology (PaleoDA) is a method that has been used in several climate reconstructions for the last millennium. By fusing information from both climate proxies and general circulation models (GCMs), PaleoDA provides statistical estimates of climate fields that are dynamically consistent. However, existing reconstructions mostly rely on calibrated tree ring data and assimilate proxy records on a single, annual time scale. Ice cores and speleothems, which record past variations in the oxygen isotope ratio of precipitation, often have a lower and irregular time resolution, but reliably record climate variations on decadal to centennial time scales. 

Here, we implemented a computationally efficient DA algorithm that enables the assimilation of proxy records on multiple timescales. The algorithm has been applied to speleothem and ice core records from the SISALv2 and Iso2k database and five isotope-enabled GCMs. Reconstructions of global mean temperature changes during the last millennium compare well in both amplitude and uncertainty to recent studies. The potential of incorporating speleothems is shown with a reconstruction of hydroclimatic changes in tropical South America, where speleothems represent the most abundant type of hydroclimate archive. The experiments performed suggest an increased reconstructed decadal to centennial variability by using proxy records on multiple timescales. Making use of different climate models shows the influence of model biases on the reconstructions. Future PaleoDA reconstructions could be improved from more proxy records and the multiple time scale approach to provide a globally complete picture of past climate changes. 

How to cite: Choblet, M. A., Bühler, J. C., Steiger, N. J., Novello, V. F., and Rehfeld, K.: Reconstructing climate fields with terrestrial climate archives, isotope-enabled GCMs and Data Assimilation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2600, https://doi.org/10.5194/egusphere-egu23-2600, 2023.