Climatology and the Biosphere Research
Feedbacks between geosphere, biosphere, atmosphere and ocean lead to timescale and state-dependent Earth system sensitivity and climate variability. These feedbacks have operated in the past, and led to substantial changes in surface temperature, precipitation, and topography, partly mediated by volcanism.
We investigate the cross-scale impacts of changes in boundary conditions on weather, climate and the carbon cycle by simulations with Earth system models of varying complexity. Generally, different models are employed for deep-time periods than for close-to-present-day conditions, with a varying range of feedbacks. We aim to test the impacts of this by experiments across a range of boundary conditions and levels of model complexity. A key element in our working philosophy are tracers for water isotope changes, and vegetation. These allow us to bridge between models (i.e. our understanding of the physical, biological, chemical interactions written down in formulae) and what actually can be observed in our one and only Earth system. The abundance of stable water isotopologues (i.e. water molecules with different molecular masses for the hydrogen and oxygen atoms) is affected by the movement and phase changes of water through the Earth system. This isotope variability can be measured on natural palaeoclimate archives (ice, speleothems, trees, foraminifera), as well as modeled by isotope-enabled general circulation models. Similarly, vegetation affects weather and climate, and is impacted by it at different timescales. We combine tracers and models to evaluate to what extent feedbacks can indeed be taken to operate on individual scales, and at which temporal and spatial scales isotopic tracers can inform on changes in boundary conditions and climate.
Major Research Topics
State- and timescale-dependency of Climate Variability
https://www.iup.uni-heidelberg.de/research/paleoclimate-dynamics
Data-model comparison in palaeoclimate and palaeoenvironmental research
Sustainable Pathways, Carbon Cycle Dynamics, and Climate Change Impacts
Climate–carbon cycle–biosphere interactions, Carbon dioxide removal, Societal transformation, Decarbonization, Economic consequences of climate change
Contributing to sustainable pathways into the future is a key mission of the SPACY group. In this research area, we focus on a key aspect of sustainable development under climate change: interactions between the carbon cycle, the climate and the Earth-Society system.
Main research questions
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How can artificial carbon dioxide removal from the atmosphere support sustainable transformations? How can it impede development goals?
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How accurate are Earth system models in capturing the response of vegetation to climate and carbon dioxide changes and how can we improve their description of the biosphere?
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How do climate change and climate variability affect societies and economies?
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Could new plant species combinations help to increase the CO2 fixation from the atmosphere?
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:
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the reliability of climate variability estimates from paleoclimate archives and observations across temporal scales from years to several thousand of years
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the causes of climate variability and its dependency on the mean climate state
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the ability of climate models to reliably simulate local to global climate variability in the past and future
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the role of climate variability in future projections, including the impact on extremes
Climate Modeling
Model development and evaluation, simulation setup and execution, application of machine learning methods to climate science
Climate models represent the climate system’s components and mechanisms numerically. They rest upon physical principles and approximations for hardly resolvable process chains (“parametrizations“). As such, they provide a laboratory for investigating climate at all times during Earth’s past and future.
We employ models of varying complexity to analyze the climate system on various scales in time and space. Our model development focuses on including new processes or modeling processes in more detail, especially for simulating land use and isotopes. These developments help us improve the quality of simulations since they implement processes that are crucial for future projections (land use, carbon dioxide removal) and because they provide a direct way of comparing simulations of climate’s past to past climate data. We carry out experiments simulating conditions at varying times in Earth’s history and future as well as idealized experiments aimed at furthering the understanding of the Earth System.
The variety of topics that can be explored with models is immense. As such, they contribute to all other research areas in our group.
Isotopes
With aims to understand the paleoclimate, atmospheric dynamics, and geochemical processes in caves we study oxygen isotopes in precipitation, cave dripwater and speleothems; and multiproxies in sediments and secondary carbonates.
Water isotopologues, i.e. the ratio between the more abundant H216O and the heavier H218O, are an important tracer of the hydrological cycle. These ratios change at phase changes along the moisture path of water parcels and can reveal important information on the dynamics of the climate system. One key research in the SPACY group is to decipher the diverse influences on these ratios from climate archives, such as speleothems, ice cores, shelf ice, and wood, but also from precipitation and drip water monitoring.
Main research topics
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Paleoclimate and paleoenvironmental reconstructions based on speleothems and other cave materials
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Effects of climate on the isotopic composition of rainwater from Tübingen and other sites in Southern Germany
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We study the atmospheric dynamics and trace (extreme) weather events by studding isotopic composition in precipitation
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We monitor the microclimate and geochemical conditions of cave environment and its surroundings
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We explore worldwide isotope data in databases (SISAL, Iso2k, etc) and comparison with climate models
Participation in Research Projects
Joining the SPACY group for thesis projects
You got excited about one of our research areas and want to contribute to our group’s work on sustainable pathways under climate variability (SPACY)? That is amazing, we are happy to discuss any project ideas with you! Just contact us (Prof. Kira Rehfeld and the SPACY group). Please include a brief statement on what topic(s)/research area(s) you are interested in, your subject(s) of study and the rough timing you envisage. You might want to include a CV or further documents, but this is not at all a prerequisite.
Some of our thesis ideas involve a lot of modeling/programming whereas others are more oriented towards lab work. Courses which prepare you well cover, for example, climate dynamics, time series analysis, or programming (check out the courses offered by the SPACY group here). However, you can also always contact us if you want to develop skills in your thesis work that you don’t already have – research is about learning new exciting things and skills. We are keen on finding a thesis topic that interests you, provides a decent learning potential for you and suits your skills well.
From time to time we also offer an info session on our research and on thesis opportunities. Check out if one will happen soon here. No matter if there is an info session happening or not, you can always contact us as described above.