Geo- und Umweltnaturwissenschaften

Climate variability and extremes

Statistics and mechanisms of climate variability and their implications on extremes and projections

Investigating the causes and structure of climate variability across spatial and temporal scales is a key mission of the SPACY group and the focus of the team variability and extremes.

We investigate:

  • the reliability of climate variability estimates from paleoclimate archives and observations across temporal scales from years to several thousand of years

  • the causes of climate variability and its dependency on the mean climate state

  • the ability of climate models to reliably simulate local to global climate variability in the past and future

  • the role of climate variability in future projections, including the impact on extremes

The left panel shows the main components (hydrosphere, atmosphere, biosphere, lithosphere, and cryosphere) and drivers (volcanic aerosols, solar irradiance, greenhouse gas emissions, and orbital forcing) of Earth’s climate system. The right panel highlights characteristic timescales for some system-inherent processes (orange) and external drivers (blue). The figure uses estimates from the PALAEOSENS Project Members, 2012; Peixoto & Oort, 1992, and Rohling et al., 2018, as well as icons from flaticon.com.

To progress on these research questions, we

  • study the temperature, precipitation, d180 and vegetation variability using large observational, reconstruction and simulation data sets

  • develop statistical tools and idealized modeling approaches to study climate variability

  • use mathematical models to quantify the link between variability, extremes, and the losses and damages they cause

Among others, we offer thesis projects on the following topics:

  • Can paleoclimate studies of long-term variability inform future projections of extremes?

  • How will possible future changes in variability impact the frequency and magnitude of extremes?

  • Pseudo-proxy experiments to investigate the changes in distribution of temperature and precipitation during the Last Deglaciation

Topics covered are (see also the work of our linked team members):

  • Hydroclimate variability

  • Variability in model simulations of the past, present and future and in models of varying complexity, role of variability in modeling of climate impact

  • Spatial structure of millennial- and orbital-scale climate and vegetation variability

  • Monsoon variability and tropical extra-tropical interactions

  • Effects of carbon dioxide removal on the statistics of climate

If you are interested in joining our research team see here for contact information.

It would be helpful if you bring some experience / knowledge in programming, statistics, data analysis, and/or climate physics, but this is not a necessary requirement. We are looking forward to learning about your ideas!

For publications from the SPACY group related to this team’s work see, for example:

  • Rehfeld, K., Münch, T., Ho, S. L., & Laepple, T. (2018). Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene. Nature, 554(7692), 356–359. https://doi.org/10.1038/nature25454

  • Rehfeld, K., Hébert, R., Lora, J., Lofverstrom, M., & Brierley, C. (2020). Variability of surface climate in simulations of past and future. Earth System Dynamics, 1–30. https://doi.org/10.5194/esd-2019-92

  • Ellerhoff, B., Kirschner, M. J., Ziegler, E., Holloway, M. D., Sime, L., & Rehfeld, K. (2022). Contrasting State‐Dependent Effects of Natural Forcing on Global and Local Climate Variability. Geophysical Research Letters, 49(10). https://doi.org/10.1029/2022GL098335

  • Adam, M., Weitzel, N., & Rehfeld, K. (2021). Identifying Global‐Scale Patterns of Vegetation Change During the Last Deglaciation From Paleoclimate Networks. Paleoceanography and Paleoclimatology, 36(12). https://doi.org/10.1029/2021PA004265

  • Bühler, J. C., Roesch, C., Kirschner, M., Sime, L., Holloway, M. D., & Rehfeld, K. (2021). Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium. Climate of the Past, 17(3), 985–1004. https://doi.org/10.5194/cp-17-985-2021