Current Projects


Hail Risk Model for Europe

Tokio Millennium Re is developing a probabilistic hail risk model for Europe (HAMLET) in conjunction with the Karlsruhe Institute of Technology (KIT).

The model will permit estimations of the monetary damages to an insurer's building and car portfolio for past hail events, but also probabilities of future losses. More information on the model can be found here.



Publications


Articles in Peer-Reviewed Journals

  • Pfister, P. L., T. F. Stocker, J. Rempfer, and S. P. Ritz, Influence of the Central American Seaway and Drake Passage on ocean circulation and Neodymium isotopes: a model study, Paleoceanography, 29, doi:10.1002/2014PA002666, 2014 [PDF].
  • Roth, R., S. P. Ritz, and F. Joos, Burial-nutrient feedbacks amplify the sensitivity of carbon dioxide to changes in organic matter remineralisation, Earth System Dynamics, 5, 321–343, 2014 [PDF].
  • Wanner, H., L. Mercolli, M. Grosjean, and S. P. Ritz, Holocene climate variability and change – a data based review, Journal of the Geological Society, doi:10.1144/jgs2013-101, 2014 [PDF].
  • Bakker, P., V. Masson-Delmotte, B. Martrat, S. Charbit, H. Renssen, M. Gröger, U. Krebs-Kanzov, G. Lohmann, D. J. Lunt, M. Pfeiffer, S. J. Phipps, M. Prange, S. P. Ritz, M. Schulz, B. Stenni, E. J. Stone, and V. Varma, Temperature trends during the present and last interglacial periods – a multi-model-data comparison, Quaternary Science Reviews, 99, 224–243, 2014 [PDF].
  • Bakker, P., E. J. Stone, S. Charbit, M. Gröger, U. Krebs-Kanzow, S. P. Ritz, V. Varma, V. Khon, D. J. Lunt, U. Mikolajewicz, M. Prange, H. Renssen, B. Schneider, and M. Schulz, Last interglacial temperature evolution - a model inter-comparison, Climate of the Past, 9, 605–619, 2013 [PDF].
  • Ritz, S. P., T. F. Stocker, J. O. Grimalt, L. Menviel, and A. Timmermann, Estimated strength of the Atlantic overturning circulation during the last deglaciation, Nature Geoscience, 6, 208–212, 2013 [PDF] [Supplementary Information] [Data].
  • Menviel, L., F. Joos, and S. P. Ritz, Atmospheric CO2, 13C and the marine carbon cycle during the last glacial-interglacial cycle: results from transient simulations with the Bern3D model, Quaternary Science Reviews, 56, 46–68, 2012 [PDF].
  • Ritz, S. P., T. F. Stocker, and J. P. Severinghaus, Noble gases as proxies of mean ocean temperature: sensitivity studies using a climate model of reduced complexity, Quaternary Science Reviews, 30, 3728–3741, 2011 [PDF].
  • Wanner, H., O. Solomina, M. Grosjean, S. P. Ritz, and M. Jetel, Structure and origin of Holocene cold events, Quaternary Science Reviews, 30, 3109–3123, 2011 [PDF][Data].
  • Ritz, S. P., T. F. Stocker and F. Joos, A coupled dynamical ocean - energy balance atmosphere model for paleoclimate studies, Journal of Climate, 24, 349–375, 2011 [PDF].
  • Ritz, S. P., T. F. Stocker, and S. A. Müller, Modeling the effect of abrupt ocean circulation change on marine reservoir age, Earth and Planetary Science Letters, 268/1–2, 202–211, 2008 [PDF].
  • Siddall, M., T. F. Stocker, G. M. Henderson, F. Joos, M. Frank, N. R. Edwards, S. P. Ritz, and S. A. Müller, Modeling the relationship between 231Pa/230Th distribution in North Atlantic meridional overturning circulation, Paleoceanography, 22, PA2214, 2007 [PDF].

Other Publications

  • Stone, E. J., P. Bakker, S. Charbit, S. P. Ritz, and V. Varma, Insights into paleoclimate modeling, PAGES news, 21, 10–11, 2013 [PDF].
  • Stone, E. J., P. Bakker, S. Charbit, S. P. Ritz, and V. Varma, A climate model inter-comparison of Last Interglacial peak warmth, PAGES news, 21, 32–33, 2013 [PDF].
  • Wanner, H., and S. P. Ritz, Holocene Climate Atlas (HOCLAT), supplement to Wanner et al., 2011, Quaternary Science Reviews, 2011 [PDF][Data].

Ph.D. Thesis

  • Ritz, S. P., 2011, Development of a reduced complexity climate model and applications on glacial-interglacial timescales, Ph.D. thesis, Climate and Environmental Physics, University of Bern, Bern, Switzerland [PDF].

Masters Thesis

  • Ritz, S. P., 2007, Global distribution of radiocarbon during changes of the Atlantic meridional overturning circulation, Masters thesis, Climate and Environmental Physics, University of Bern, Bern, Switzerland [PDF].


Awards

  • Award of the faculty of physics of the University of Bern for excellent masters thesis, 2008.



The Bern3D Earth System Model


The Bern3D Earth System Model of Intermediate Complexity is designed to perform transient simulations on glacial-to-interglacial timescales and large ensemble simulations of future climate projections. The model contains a 3D ocean component (Edwards et al., 2005; Müller et al., 2006), a 2D energy and moisture balance atmosphere model (Ritz et al., 2011a), a dynamical vegetation model (Stocker et al., submitted; Steinacher et al., submitted), a marine carbon cycle module (Müller et al., 2008; Tschumi et al., 2008; Parekh et al., 2008), an optional marine ecosystem module (Gangsø et al., 2011) and a marine sediment diagenesis module for long timescale carbon cycle simulations (Tschumi et al., 2011). Next to the tracers calculated by the carbon cycle module (dissolved inorganic and organic carbon including their isotopes DIC, DIC-13, DIC-14, DOC, DOC-13, DOC-14, alkalinity, oxygen, phosphate, silicate, and iron), the model includes a number of physical tracers. These are the radiocarbon-to-carbon ratio R-14, protactinium and thorium (Siddall et al., 2007), neodymium isotopes Nd-143 and Nd-144 (Rempfer et al., 2011), chlorofluorocarbons CFC-11 and CFC-12 (Müller et al., 2006), and noble gases argon, krypton, xenon, as well as the radioactive argon isotope Ar-39, and molecular N-2 (Ritz et al., 2011b).

Transient Simulation of the Past 450,000 Years


Transient simulation of the last 450,000 years with the Bern3D Earth System Model.
Click to display the movie.

Downloads of Data

Data of publications Wanner et al., (2011) and Holocene Climate Atlas (HOCLAT)

FileDescription
wanner11qsr_Figs2and3_data.zipData to Wanner et al., (2011) Figures 2 and 3
wanner11qsr_original_data.zipOriginal temperature and precipitation time series data
wanner11qsr_standardized_data.zipStandardized temperature and precipitation time series data

Transient simulations described in Ritz et al., (2011a) with orbital, greenhouse gas, and ice-sheet forcing

Note that the model version described in Ritz et al., (2011b) was used for these simulations.
The time in the data files is given in years AD.

TimeDescriptionKind
130 kyr - 120 kyr BPFull model output every 1 kyrNetCDF document
130 kyr - 120 kyr BPTimeseries output every 1 yrNetCDF document
6 kyr - 1 kyr BPFull model output every 1 kyrNetCDF document
6 kyr - 0.5 kyr BPTimeseries output every 1 yrNetCDF document
800 kyr - 0.5 kyr BPTimeseries output every 1 yrNetCDF document