UFZ Environmental Modeling & Monitoring Lectures
Lectures in this series were paused in 2020.
JAKOB RUNGE: "Inferring causation from time series with perspectives in Earth system sciences", 22 October 2019
JAKOB RUNGE, Institute of Data Science, Data Management and Analysis, German Aerospace Center (DLR)
Inferring causation from time series with perspectives in Earth system sciences
The heart of the scientific enterprise is a rational effort to understand the causes behind the phenomena we observe. In disciplines dealing with complex dynamical systems, such as the Earth system, replicated real experiments are rarely feasible. However, a rapidly increasing amount of observational and simulated data opens up the use of novel data-driven causal inference methods beyond the commonly adopted correlation techniques. The key idea shared by several approaches is that, while the truism “correlation does not imply causation” holds, causal relations among variables can be estimated from their joint probability distribution given some assumptions. Causal inference is indeed a rapidly growing field with enormous potential to help answer long-standing scientific questions. Unfortunately, many methods are still little known and therefore rarely adopted in Earth system sciences. In this talk I will give an overview over causal inference methods and identify key tasks and major challenges where causal methods have the potential to greatly advance the state-of-the-art. Several methods will be illustrated by `success' examples where causal inference methods have already led to novel insights and I will close with an outlook of this relatively new and exciting field.
JOHN L. CASTI: "Complexity, Extreme Events and Human Social Progress, or Why the Trend is Not Your Friend", 5 September 2018
JOHN L. CASTI, The X-Center, Vienna, Austria | X-Event Dynamics, LLC, San Jose, CA, USA
Complexity, Extreme Events and Human Social Progress, or Why the Trend is Not Your Friend
Major movements in human social progress are almost without exception driven by extreme events ("X-events") that wipe away existing power and social structures that have outlived their usefulness. Example: The asteroid that wiped out the dinosaurs 65 million years ago. Bad news for the dinosaurs but good news for us humans, as that X-event opened up many eco-niches that our ancient ancestors exploited to create the humans of today.
In this presentation, I will make the point that such X-events are a *necessary* condition for major human progress (or regress!). I also argue that the drivers of these rare, surprising and high-impact events are mostly mismatches in the complexity levels of the different subsystems that compose the overall living systems of the time. That ancient asteroid had a much higher level of complexity than the dinosaur society, with the result that that complexity gap or mismatch created a stress that the system was unable to accommodate. Result: Extinction of the dinosaurs and opportunity for other organisms not so vulnerable to that kind of impact.
During the course of this presentation, I will make the argument that virtually all social advances and declines are the end result of just such a complexity mismatch. In modern (i.e., human) times, the mismatch is accompanied by major shifts in the mood of the population (their beliefs about the future, positive or negative). These two factors combine to create not only the X-event, but also the most likely new state that the human system will take in the next major epoch.
These theoretical arguments will be supported by examples taken from areas as disparate as popular culture (the shifts in musical tastes and fashion) to medium timescales events such as the outbreak of war and shifts in political ideology to very long timescale events like the rise and fall of a civilization.
ALLEN G. HUNT, Department of Physics, Wright State University, Dayton, Ohio (USA)
Spatio-temporal Scaling of Soil Formation and Vegetation Growth
At the scale of a single pore, advection, diffusion, and reaction times may be similar, making modeling complicated. With increasing scale, advective processes should gain in importance. The advective solute velocity for conservative, but non-Gaussian, solute transport is a theoretical proxy for surface reactions in porous media, and its scaling with fluid flow rates, time, and space match both experimental and field results, including those of chemical weathering and soil formation. In an analogy, we find that vegetation growth is limited by the topology of the optimal paths in the soil surface, related both to mechanics of root development (energy expenditure) and to dominant nutrient fluxes. Both scaling relationships are rooted in the tendency for flow to follow optimal paths. Each gives a different scaling power, producing an enormous difference in time scales, at large enough length scales. While soil formation is proportional to infiltration, the vegetation growth rate is proportional to the transpiration.
WERNER LEO KUTSCH: "In-situ observations of the European Carbon Cycle: The Integrated Carbon Observation System (ICOS)", 5 June 2018
WERNER LEO KUTSCH, Integrated Carbon Observation System (ICOS), Director General, ICOS ERIC Head Office (Helsinki, Finland)
In-situ observations of the European Carbon Cycle: The Integrated Carbon Observation System (ICOS)
The Integrated Carbon Observation System (ICOS) is a European Research Infrastructure. The mission of the ICOS is to facilitate research to understand the carbon and greenhouse gas (GHG) budgets and perturbations. ICOS provides high-precision, standardized long-term observations required to understand the present state and predict future behaviour of the global carbon cycle and GHG emissions. Technological developments and implementations, related to GHGs, will be promoted by linking research, education and innovation. ICOS is a distributed research infrastructure. The backbones of ICOS are the national measurement stations such as ICOS atmosphere, ecosystem and ocean stations. Together they form national measurement networks.
MARTYN CLARK: "The evolution of process-based hydrologic models: historical challenges and the collective quest for physical realism", 30 May 2018
MARTYN CLARK, Research Applications Laboratory, National Center for Atmospheric Research, NCAR (Colorado, USA)
The evolution of process-based hydrologic models: historical challenges and the collective quest for physical realism
The diversity in hydrologic models has historically led to great controversy on the “correct” approach to process-based hydrologic modeling, with debates centered on the adequacy of process parameterizations, data limitations and uncertainty, and computational constraints on model analysis. In this presentation, we revisit key modeling challenges on requirements to (1) define suitable model equations, (2) define adequate model parameters, and (3) cope with limitations in computing power. We outline the historical modeling challenges, provide examples of modeling advances that address these challenges, and define outstanding research needs. We illustrate how modeling advances have been made by groups using models of different type and complexity, and we argue for the need to more effectively use our diversity of modeling approaches in order to advance our collective quest for physically realistic hydrologic models.
FRANK HILKER: "Dynamics and tipping points of exploited biological resources: Insights from mathematical modelling", 25 January 2018
FRANK HILKER, Institute of Environmental Systems Research, Osnabrück University
Dynamics and tipping points of exploited biological resources: Insights from mathematical modelling
The exploitation of biological resources is a pertinent issue in fisheries, forestry, grazing systems, wildlife management and pest control. Anthropogenic impact is increasingly recognized to put pressure on ecosystems, which is why there are different types of harvesting and management strategies aimed at sustainable exploitation. At the same time, ecological systems are inherently complex in themselves, giving rise to tipping points and unpredictable dynamics for example. How do management strategies interact with ecosystem dynamics and prevent –or even drive– ecological regime shifts? In this lecture, I will address this question with mathematical models that represent the dynamics of a biological resource in generic form (e.g., simple difference equations for fish stock or population size), but account for complexities like inherent oscillations and alternative stable states. I will pull together insights gained from mathematical analysis and simulations, and synthesize how different management strategies and intervention timing affect the persistence, constancy stability and resilience of the exploited resource.
RUTH DELZEIT: "Global economic-biophysical assessment of midterm scenarios for agricultural markets", 28 November 2017
RUTH DELZEIT, Kiel Institute for the World Economy (Germany)
Global economic-biophysical assessment of midterm scenarios for agricultural markets - biofuel policies, dietary patterns, cropland expansion, and productivity growth
Land-use decisions are made at the local level. They are influenced both by local factors and by global economic and political drivers and trends. These will most likely change over time e.g. due to political shocks, market developments or climate change. Hence, their influence should be taken into account when analysing and projecting local land-use decisions. We provide a set of mid-term scenarios of global drivers (until 2030) for use in regional and local studies on agriculture and land-use. In a participatory process, four important drivers are identified by experts from globally distributed regional studies: biofuel policies, increase in preferences for meat and dairy products in Asia, cropland expansion into uncultivated areas, and changes in agricultural productivity growth. Their impact on possible future developments of global and regional agricultural markets, food production and food prices are analysed with a modelling framework consisting of a global computable general equilibrium model and a crop growth model. Global trends as shown in the Business As Usual (BAU) scenario lead to an increasing scarcity of fertile land with rising prices for primary agricultural products as well as a shift towards the production of vegetable oils. It also leads to a conversion of pasture land to cropland. Under different scenarios, global crop price changes range between -42 and +4% in 2030 compared to the BAU. The comparison of the scenario simulations with the BAU highlights the impact of specific policy as well as supply- and demand-side changes. It turns out that supply-side effects have a stronger impact than changes on the demand side.
THORSTEN WAGENER: "Some thoughts on building parsimonious models of complex environmental systems", 12 October 2017
THORSTEN WAGENER, Department of Civil Engineering, University of Bristol (UK)
Some thoughts on building parsimonious models of complex environmental systems
“How can we build environmental and earth system models that are more integrated, more detailed and covering larger domains, while also being parsimonious? How can we assess what additional data we should collect to better evaluate these models and to reduce the uncertainty in their predictions? These are questions we are currently wrestling with across a range of application areas linked to understanding the water environment under current and potential future climate and land use conditions. Our approach to this problem is a focus on understanding dominant controls on relevant variables across space and time scales using both empirical and model-based strategies. Variables we currently investigate include those from hydrology, like groundwater recharge, and others that are partially controlled by hydrologic processes, such as infectious disease risk. In this talk I will describe the modelling-based strategies we use to understand these controls. These strategies are centred around our Global Sensitivity Analysis Toolbox, SAFE (www.safetoolbox.info), which has already been adopted by over 1000 researchers worldwide. I will use examples in which we try to understand the impact of subsurface heterogeneity on groundwater recharge, attempt to understand the impact of different uncertain data sources on flood inundation predictions, and (briefly) try to understand hydrologic controls on liver fluke infection risk in the UK.” (Prof. Thorsten Wagener)
SANDER VAN DER LEEUW: "Integrated Modelling of the Future of Socio-Environmental Dynamics", 20 June 2017
SANDER VAN DER LEEUW, Center for Biosocial Complex Systems, Arizona State University & Sante Fe Institute (USA)
Integrated Modeling of the Future of Socio-environmental Dynamics
"As part of an effort to develop tools that may help us further the above agenda, I held a workshop at IASS Potsdam in March 2017 that was the third in a series of workshops on integrated modeling of socio-environmental phenomena. Aim was to bring together an open source community striving to develop, in particular, approaches to model transitions in complex systems, considering decisions concerning land use as the interface between societal and environmental dynamics. In this lecture, I will discuss the general approach, some conceptual and methodological challenges as well as ways forward to reach this goal."