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Earth's climate and environmental dynamics

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State and timescale-dependency of climate variability from the last Glacial to present day

The central aim of the group is to explore and quantify changes of climate variability in the past, the role (global) mean temperature played them, and to assess how well climate models can reflect them. We focus predominantly on the time period from the last Glacial period to the present day (~130,000 years ago to today). In our work we combine the statistical analysis of climate proxy and model data, the modeling of palaeoclimate proxy archive signal formation and climate models (from the very simple to coupled general circulation models), to improve scientific understanding of climate variability changes in a warming world.

Key research questions

  1. How does climate variability depend on the general Earth system state, and global mean temperature?
  2. How is variability on short timescales (in other words: weather) linked to variability on long timescales (up to Glacial-Interglacial timescales)?
  3. How does the Earth system's sensitivity to disturbances (for example volcanic eruptions, or massive ice melt) change under mean-state changes?

Our group is step-by-step moving to Tübingen, where Kira is the new professor for Climatology and the Biosphere. Our new homepage is here. We can sadly no longer offer supervision on site in Heidelberg.

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  1. 12/21 New paper by Moritz, Nils, and Kira published in Paleoceanography and Paleoclimatology! We study spatio-temporal vegetation variations during the last deglaciation and compare the results with transient simulations.
  2. 12/21 Elisa and Janica received the prize for best tutorial to the "Introduction of climate modeling and analysis" in the winter semester 2020/21.
  3. 11/21 New discussion paper in Climate of the Past comparing multiple isotope-enabled GCMs to speleothems from the last millennium lead by Janica: https://doi.org/10.5194/cp-2021-152.
  4. 09/21 Starting from September 2021, Kira is the new professor for Climatology and the Biosphere at the Geo- and Environmental Research Center (GUZ), University of Tübingen. Congratulations!!! The STACY group is step-by-step moving to Tübingen. You can find our new website here.
  5. 08/21 Successful summer: It started great with lively discussion and scientific exchange at our CVAS PingPong workshop. Julian, Christian, Maximilian took this momentum to finish their Master's thesis, congratulations! And in the meantime, two new studies by Kira and colleagues on "Past abrupt changes" and "Solar hydrogen production" were published  in Nature and Energy & Environmental Science, respectively.
  6. 05/21 Two published papers: one in Climate of the Past and the other in Geoscientific Model Development with first authors Janica and Elisa, respectively. Congratulations!!
  7. 04/21 Successful student! Yannick Heiser successfully passed the Bachelor colloquium and exam. He will soon present his work on the "Comparison of isotopic signatures in ice core and speleothem records to an isotope enabled climate model simulation for the last millennium" at vEGU 2021. Congratulations!
  8. 02/21 - Bessac et al. (including Nils) developed a new scale-aware stochastic parameterization method for sea surface fluxes in weather and climate models. The paper is published in the Journal of Advances in Modeling Earth Systems.
  9. 02/21 - New preprint out by Bea, presenting her latest work on the time-scale dependent stability of global and local temperature.
  10. 01/21 -  Stacy goes Twitter! We launched our @weather2climate account to provide you with the latest news about #paleoclimate, #climatedynamics, and #climateresearch. Furthermore, Anna Sommani successfully finished her M.Sc. thesis. Congratulations!
  11. 12/20 - Elisa and Nils presented their work at the virtual AGU. Elisa's poster is about first results on climate variability since the Last Glacial Maximum from experiments with a transient model of the Earth’s energy balance. Nils presented the heterogeneous global structure of Dansgaard-Oeschger events in paleoclimate archives and climate simulations. Well done and a big thanks to all collaborators!
  12. 11/20 -  Looking forward to the CVAS lecture series on "Climate variability across scales: from the butterfly’s wings to the age of the Earth" that will take us from surface climate variability on timescales of seconds all the way to millennia. More information, and how to register, can be found here.
  13. 10/20 - How far can simple models go? The paper documenting the revised implementation of a classic two-dimensional energy balance model for transient simulations of Earth's climate is now under public review at Geoscientific Model Development Discussions. 
  14. 09/20 - A new paper documenting comparison of the oxygen isotope signatures in speleotherm and iHadCM3 model simulations for the last millennium, has been accepted for review and is now under discussion. The paper documenting the speleothem database SISAL v.2. with new age models automatically constructed and screened by experts has been accepted for publication. Moreover, a new article showing "The impact of climate change on astronomical observations" was published in Nature Astronomy.
  15. 08/20 - Shirin Ermis and Simon Rosenkranz, who spent the COVID-19 summer working with the STACY group, are on their way to new academic achievements in the UK and France, respectively. Good luck!
  16. 07/20 - Successful student: Jakob Pfannschmidt successfully passed the Bachelor colloquium and exam. Congratulations!
  17. 06/20 - Successful student: Nadine Theisen successfully passed the Bachelor colloquium and exam. Congratulations!
  18. 05/20 - New paper on the variability of surface climate in simulations of past and future published in Earth System Dynamics.
  19. 04/20 - #ResearchAcrossBorders: only by working together and sharing scientific knowledge and scientifc data can we address the current challenges. One example is the new temperature database for the last 12000 years . This effort was led by Darrell Kaufman in the US, and more than 80 colleagues from all over the world contributed along with Kira. Therefore, a big thank you to data contributors, data cleaners and a heads up: there is a new large temperature dataset that now awaits exploration. Stay safe, and let's tackle the challenges from home for now.
  20. 03/20 - More than a year of hard work and finally the SISAL database version 2 is online for discussion. It includes data for 691 records worldwide. Carla and Kira contributed, in particular to the age modeling effort. Big thanks go to the speleothem community and in particular Laia Comas Bru! Nils' paper is now under review at Climate Dynamics, the preprint can be found here. The MitigationHub contribution to the wirvsvirus hackathon can be found here.
  21. 02/20 - February updates: Three successful students: Carla Roesch and Moritz Kirschner finished their M.Sc. theses, and Shirin Ermis passed the Bachelor colloquium and exam. Congratulations! And a new paper led by Kira on the variability of surface climate in simulations of past and future  and coming out of the PMIP Past2Future/Paleovar working group, went into discussion in Earth System Dynamics.
  22. 01/20 - Project start: Jean-Philippe Baudouin joined the group to tackle data-model comparison in the project PALMOD II. Welcome! Also a big thanks to Marie-France Loutre from PAGES who visited us and gave a highly informative talk on orbital forcing of climate!
  23. 11/19 - One of this year's EGU Outstanding Student Poster and PICO (OSPP) Award went to Elisa Ziegler for her M.Sc. thesis work on climate variability using energy balance models, congratulations! The poster can be found here. Welcome to Beatrice Ellerhoff, who successfully applied for an 18-month fellowship for her PhD work from the Heidelberg Graduate School of Fundamental Physics (HGSFP). Congratulations and a thank you to the HGSFP!
  24. 10/19 - STACY on the road: Carla presented her results on the automatized construction of speleothem growth reconstructions at the 2019 Climate Informatics workshop in Paris, supported by a full travel grant thanks to the organizers. The 4-page short paper can be found here. Kira gave a talk on networks and climate at the IWCSN, and Moritz A., Elisa and Janica presented their work at the REKLIM conference in Berlin. Moritz K. presented a poster at the YES Congress in Berlin. Well done, everyone!
  25. 8/19 - The SISAL big picture paper on `Evaluating model outputs using integrated global speleothem records of climate change since the last glacial' is now online in Climate of the Past. Big thanks to the community for the great efforts!
  26. 7/19 - Exciting new paper this week: Using seven methods for climate reconstruction, the PAGES2k consortium - including colleagues from Switzerland, Costa Rica, the US, China, the UK, Australia, Sweden with us in Germany - showed that multidecadal variability is consistent in global temperature reconstructions and simulations over the Common Era, and that there are clear relationships to volcanic forcing. A view-only version to be found here, and more details at the PAGES info page.
  27. 7/19 - Save the date for the workshop "Beyond Palaeoclimate Ping Pong - Improving estimates of past climate variability by consistent model-data comparison'' from 2nd to 5th of June 2020 at the beautiful IWH in Heidelberg, which is possible due to the Hengstberger prize 2019!
  28. 7/19 - Successful student! Moritz Adam passed the colloquium and exam and presented the results of his Bachelor thesis on complex network approaches for testing coherency of climate variability in a pollen network. Congratulations!
  29. 4/19 - April highlights before Easter: The EGU conference 2019 is over, where we presented the first results of the STACY group work: Elisa Ziegler showed first results from her 100k EBM simulations, and Kira showed results of her work with Carla Roesch and the SISAL chronology team that aims at new age models for 400+ speleothems (Abstract), which was a PICO.
  30. 3/19 - Highlights in March: We hosted Heather Andres from Memorial University of Newfoundland, who gave a talk on deglacial climate variability, and Carla Roesch presented promising results from her M.Sc. project at the DPG spring meeting; and we hosted Martina Stebich from Senckenberg research station Weimar and discussed ongoing work on Glacial climate and ecological variability as recorded by pollen.
  31. 2/19 - Successful student: Benjamin Schmiedel successfully passed the colloquium and exam and presented the results of his Bachelor thesis on one-dimensional energy balance models. An example of his work can be found here. Congratulations!
  32. 1/19 - Four highlights in January for the STACY group: Martin Werner from AWI Bremerhaven visited us and gave a seminar talk on water isotopes, Janica Bühler started her PhD on speleothem forward modeling, Nils Weitzel will tackle the pollen-based climate reconstruction challenges and there is a new publication from earlier work: May, M. M. and Rehfeld, K.: ESD Ideas: Photoelectrochemical carbon removal as negative emission technology, Earth Syst. Dynam., 10, 1-7, https://doi.org/10.5194/esd-10-1-2019, 2019.
  33. 12/18 - Chris Brierley from University College London visited the STACY group for three days and gave a talk in the IUP seminar on Climate variability diagnostics for PMIP4/CMIP6. Thanks!
  34. 9/18 - Group start: Thanks to the Deutsche Forschungsgemeinschaft for funding the Emmy Noether junior research group STACY: State and timescale-dependency of surface climate variability from the last Glacial to present day!

Gruppenfoto Stacy


Dr. Kira Rehfeld
Dr. Jean-Philippe Baudouin
Moritz Adam (BSc)
Laura Braschoß (BSc)
Janica Bühler (MSc)
Dr. Mathieu Casado (guest at AWI)
Beatrice Ellerhoff (MSc)
Dr. Olga Erokhina
Jakob Kruse (MSc)
Dr. Markus Maisch
Jonah Mende
Franka Neumann
Leoni Rath (BSc)
Maybritt Schillinger (BSc, co-supervised with Robert Scheichl)
Patrizia Schoch (BSc)
Stephan Sprinz
Dr. Nils Weitzel
Jonathan Wider (BSc, co-supervised with Ullrich Koethe)
Elisa Ziegler (MSc)

Student assistants:

Mathurin Choblet (BSc)
Laura Fink (BSc)
Muriel Racky (BSc)
Irene Trombini (BSc)
Eric Walter (BSc)


Oliver Mehling (MSc 2021)
Christian Wirths (MSc 2021)
Claudia Schiavini
Maximilian May (MSc 2021)
Julian Schäfer (MSc 2021)
Yannick Heiser (BSc 2021)
Anna Sommani (MSc 2021)
Simon Rosenkranz (BSc 2020)
Shirin Ermis (BSc 2020)
Nadine Theisen (BSc 2020) (co-supervised with Prof. Dr. Ullrich Köthe, IWR)
Moritz Kirschner (MSc 2020)
Carla Roesch (MSc 2020) - Now PhD student at the University of Edinburgh
Benjamin Schmiedel (BSc 2019) - Results and new developments here

Project opportunities

Please contact us if you are interested in our work. Please enclose a short CV as well as an overview of your course of studies, detail experience/expectations you have relating to climate, data analysis and programming, and why you are interested in joining this group in particular.


The workshop "Beyond Palaeoclimate Ping Pong: Improving estimates of climate variability by consistent data-model comparison" took place on 4-7 July 2021 on behalf of CVAS thanks to the 2019 Hengstberger Prize awarded to Kira Rehfeld. A report is published in the PAGES Magazine.


Dr. Kira Rehfeld
Universität Heidelberg
Institut für Umweltphysik
Im Neuenheimer Feld 229 (room 402)
69120 Heidelberg

Office: +49 6221 54 6353
kira.rehfeld ( at ) iup.uni-heidelberg.de

Funding through the Emmy Noether programme of the German Research foundation, and the Federal Ministry of Education and Research, is gratefully acknowledged.
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