KlimaCampus Colloquium

Diversity and interdisciplinarity – these two keywords are the core of our research at the KlimaCampus Hamburg as well as of our seminar series “KlimaCampus Colloquium”: During the academic term we invite international renowned scientists from various disciplines to present and discuss current challenges in climate research.

The lectures are held in English, and everybody interested is welcome to attend. Please note that the Colloquium is an in-person event.

Time: on Thursdays at 3:15 pm during the academic term. From 2:45 pm onwards some welcome coffee and cake will be served in room 024.

Location: room 022/023, Bundesstrasse 53, 20146 Hamburg

Scientific organizing committee:Simone Rödder (UHH), Dirk Notz (UHH) and Victor Brovkin (MPI-M)




Upcoming talks

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Donnerstag 04. Juli 2024

Es spricht: Stephen Sitch, University of Exeter

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Donnerstag 20. Juni 2024

Es spricht: Moritz Drupp (UHH)

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The technology deleting photobombs can do climate research? The chat bot writing poems can do climate analysis?

Donnerstag 30. Mai 2024

Es spricht: Christopher Kadow, DKRZ

Climate change research today relies on climate information from the past. Historical climate records of temperature observations form global gridded datasets that are examined, for example, in IPCC reports. However, the datasets combining measurement records are sparse in the past. Even today, they contain missing values. We found that recently successful image inpainting technologies, such as those found on smartphones to get rid of unwanted objects or people in photos, are useful here. The derived AI networks are able to reconstruct artificially cropped versions in the grid space for any given month using the missing values observation mask. So herewith we have found with AI a technique that gives us data from the past that we never measured with instruments.  Other important datasets used in the Assessment Report 6 of the IPCC to study climate change, as well as advanced applications such as downscaling in atmosphere and ocean, a hybrid (AI&ESM) data assimilation approach within ICON, or precipitation in broken radar fields are shown in this presentation.

Climate research, including the study mentioned in the previous paragraph, often requires substantial technical expertise. This involves managing data standards, various file formats, software engineering, and high-performance computing. Translating scientific questions into code that can answer them demands significant effort. The question is, why? Data analysis platforms like Freva (Kadow et al. 2021, e.g., gems.dkrz.de) aim to enhance user convenience, yet programming expertise is still required. In this context, we introduce a large language model setup and chat bot interface based on GPT-4/ChatGPT, which enables climate analysis without technical obstacles, including language barriers. This approach is tailored to the needs of the broader climate community, which deals with massive data sets from kilometer-scale modeling and requires a processing environment utilizing modern technologies, but addressing society after all - such as those in the Earth Virtualization Engines (EVE eve4climate.org).

Kadow, C., Hall, D.M. & Ulbrich, U. Artificial intelligence reconstructs missing climate information. Nat. Geosci. 13, 408-413 (2020). https://doi.org/10.1038/s41561-020-0582-5

Kadow, C., Illing, S., Lucio-Eceiza, E. E., Bergemann, M., Ramadoss, M., Sommer, P. S., Kunst, O., Schartner, T., Pankatz, K., Grieger, J., Schuster, M., Richling, A., Thiemann, H., Kirchner, I., Rust, H. W., Ludwig, T., Cubasch, U., and Ulbrich, U.: Introduction to Freva – A Free Evaluation System Framework for Earth System Modeling, Journal of Open Research Software, 9, p. 13, https://doi.org/10.5334/jors.253, 2021


Thinking Through Planetary Commons Governance

Donnerstag 23. Mai 2024

Es spricht: Louis Kotzé (THE NEW INSTITUTE)

The Anthropocene signifies the start of a no-analogue trajectory of the Earth system that is fundamentally different from the Holocene. This new trajectory is characterized by rising risks of triggering irreversible and unmanageable shifts in Earth system functioning. We urgently need a new global approach to safeguard critical Earth system regulating functions more effectively and comprehensively. The global commons framework is the closest example of an existing approach with the aim of governing biophysical systems on Earth upon which the world collectively depends. Derived during stable Holocene conditions, the global commons framework must now evolve in the light of new Anthropocene dynamics. This requires a fundamental shift from a focus only on governing shared resources beyond national jurisdiction, to one that secures critical functions of the Earth system irrespective of national boundaries. We propose a new framework—the planetary commons—which differs from the global commons framework by including not only globally shared geographic regions but also critical biophysical systems that regulate the resilience and state, and therefore livability, on Earth. The new planetary commons should articulate and create comprehensive stewardship obligations through Earth system governance aimed at restoring and strengthening planetary resilience and justice.


The Incredible Lightness of Water Vapor

Donnerstag 11. April 2024

Es spricht: Da Yang, University of Chicago

Conventional wisdom suggests that warm air rises while cold air sinks. However, recent satellite observations show that, on average, rising air is colder than sinking air in the tropical free troposphere. This is due to the buoyancy effect of water vapor: the molar mass of water vapor is less than that of dry air, making humid air lighter than dry air at the same temperature and pressure. Unfortunately, this vapor buoyancy effect has been considered negligibly small and thereby overlooked in large-scale climate dynamics. Here we use theory, reanalysis data, and a hierarchy of climate models to show that vapor buoyancy has a similar magnitude to thermal buoyancy in the tropical free troposphere. As a result, cold air rises in the tropical free troposphere. We further show that vapor buoyancy enhances thermal radiation, increases subtropical stratiform low clouds, favors convective aggregation, and stabilizes Earth’s climate. However, some state-of-the-art climate models fail to represent vapor buoyancy properly. This flaw leads to inaccurate simulations of cloud distributions—the largest uncertainty in predicting climate change. Implications of our results on paleoclimate and planetary habitability will also be discussed.


Archive of Lectures: Videos and Abstracts

Did you miss a talk? We provide videos of the lectures in cooperation with the central video portal Lecture2Go at Universität Hamburg.

Just choose an academic term below and start a video ...

All hands on deck! Improved ocean carbon sink estimates by combining models and data

Donnerstag 01. Februar 2024

Es spricht: Galen McKinley, Columbia University and Lamont-Doherty Earth Observatory

Since the preindustrial era, the ocean has removed about 40% of fossil CO2 from the atmosphere, and it will eventually absorb at least 80% of human CO2 emissions. There is no doubt that the ocean is a critical player in the global carbon cycle, but many questions remain. Critically, these uncertainties reduce confidence in projections of the future global carbon cycle and climate. In this talk, I demonstrate how multiple approaches can be used together to reduce these uncertainties. Specifically, I introduce a machine-learning approach that merges observations and models to improve skill against independent data. With this approach, air-sea CO2 fluxes for 1959-2022 can be estimated and, at the same time, large-scale model biases are revealed. These biases propagate directly into future projections under both high and low-emission scenarios. The clearest paths to improving quantification of the ocean carbon sink are (1) targeted observations to fill identified gaps and (2) reduced mean-state biases in modeled circulation and biogeochemistry.


Climate Informed Engineering: An Essential Pillar of Industry 4.0 Transformation

Donnerstag 7. Dezember 2023

Es spricht: Nima Shokri, Institute of Geo-Hydroinformatics, Hamburg University of Technology (TUHH)

Breakthroughs in computing have led to development of new generations of Earth Systems Models providing detailed information on how our planet may locally respond to the ongoing global warming. This presents an unprecedented opportunity for engineers to make tangible contributions to climate adaptation through integration of climate information in their products and designs. This is precisely the key focus of Climate Informed Engineering (CIE) Research Initiative founded at TUHH in collaboration with MPI-M and United Nations University. The concept behind CIE is to enable engineers to build infrastructure, devices, sensors or develop new materials and processes that are informed by climate information, thus contributing to concepts like resilience and climate change adaptation. We believe CIE will be an increasingly important dimension of Engineering Science resonating with engineers and scientists with different backgrounds (1) with the details discussed in this talk.

(1) Shokri, N., Stevens, B., Madani, K., Grabe, J., Schlüter, M., Smirnova, I. (2023), Climate Informed Engineering: An essential pillar of Industry 4.0 transformation, ACS Eng. Au, 3, 1, 3–6.


Fast upper-level jet stream winds get faster under climate change

Donnerstag 23. November 2023

Es spricht: Tiffany A. Shaw, University of Chicago and currently at MPI-M as a Friedrich Wilhelm Bessel Research Award holder by the Alexander von Humboldt Foundation

Earth's upper-level jet streams influence the speed and direction of travel of weather systems and commercial aircraft and are linked to severe-weather occurrence. Climate change is projected to accelerate the average upper-level jet stream winds. However, little is known about how fast (> 99th percentile) upper-level jet stream winds will change. Here we show fast upper-level jet stream winds get faster under climate change using daily data from climate model projections across a hierarchy of physical complexity. Fast winds also increase ~2.5 times more than the average wind response. We show the multiplicative increase underlying the fast-get-faster response follows from the non-linear Clausius-Clapeyron relation (moist-get-moister response). The signal is projected to emerge across both hemispheres by 2050 when considering scenario uncertainty. The results can be used to explain projected changes in commercial flight times, record-breaking winds, clear-air turbulence, and a potential increase in severe-weather occurrence under climate change.


Millennial scale climate variability and ice age cycle

Donnerstag 16. November 2023

Es spricht: Ayako Abe-Ouchi, University of Tokyo

Glacial periods were punctuated by abrupt millennial scale climate changes, such as Dansgaard-Oeschger events, Boeling-Allerod and Younger Dryas. Although glacial abrupt climate changes were shown to have a strong link to the Atlantic Meridional overturning circulation (AMOC) changes and the glacial background climate, simulating the millennial scale climate change and understanding its condition with fully coupled ocean-atmosphere GCM have been challenging. Here we present several cases of millennial scale climate variability simulated with our Japanese Atmosphere Ocean coupled GCM, MIROC4m. A series of long transient experiments (> 10,000 years) were performed systematically with different steady glacial conditions (CO2 level, obliquity, precession, ice sheet size and meltwater amount) in order to study the dependence of millennial scale variability on the background climate and summarize the results as phase diagrams. We found that a sweet spot of millennial scale oscillation exists under a certain condition, while the AMOC is in a stable strong (weak) mode of about 18 (10) Sv (Sverdrup) without the oscillation. In the sweet spot, self-sustained oscillation with bipolar seesaw pattern appears and shifts between interstadials with strong AMOC and stadials with weak AMOC occur. The interval between abrupt events ranges from 1000 years to more than 5000 years, while an abrupt shift from stadial to interstadial mode occurs in about 100 years, just like geological evidence, ice core analysis and the deep-sea cores. The mechanism of the millennial scale climate variability as well as its threshold of occurrence, which is likely related to the thermal condition of global climate, can be now discussed. 


29. Juni 2023 | Isla Simpson, NCAR

Humidity trends in dry regions are inconsistent with climate models

Arid and semi-arid regions of the world are particularly vulnerable to greenhouse gas driven hydroclimate change. The American Southwest is a particularly clear example where recent drought has led to unprecedented water shortages in the Colorado River, and some of the most extreme wildfire seasons in recent history, and this has almost certainly been exacerbated by the substantial warming and aridification that has resulted from rising greenhouse gases. Climate models are our primary tool for projecting the future hydroclimate that society in these regions must adapt to, but here a concerning discrepancy between observed and model-based historical hydroclimate trends will be discussed. While observations of many of the processes of relevance to the hydroclimate, such as soil moisture and evapotranspiration, are limited, we do have a reasonably complete network of station-based near surface atmospheric humidity measurements as well as reanalysis-based estimates of atmospheric water vapor. Here, we will use these datasets along with CMIP6 models to demonstrate a rather drastic difference in the nature of near surface humidity trends over the period 1980 to 2020.  Where and when this discrepancy occurs is closely tied to climatological aridity, with it being most apparent in arid/semi-arid regions of the world, but also visible in the most arid seasons of more humid regions. It will be shown that models tend to exhibit increases in atmospheric water vapor that are close to those expected from Clausius Clapeyron scaling, while atmospheric humidity in reality has stayed roughly constant over arid and semi-arid regions of the world. This suggests that the availability of moisture to satisfy the increased atmospheric demand is lower in reality than in models in arid and semi-arid regions and it indicates a major gap in our understanding and modeling capabilities, which could have severe implications for hydroclimate projections, including fire hazard, moving forward.


22. Juni 2023, 15:15 Uhr | Wilco Hazeleger, Dean of the Faculty of Geosciences and professor of Climate System Science at Utrecht University

Perspectives on Digital Twin Earth

Digital twins are a hype in many scientific domains. A digital twin of the Earth is envisaged in leading programs, such as Europe’s Destination Earth. While some see this as a continuous development towards km-scale global non-hydrostatic modelling enabled by increasing computational capabilities, others regard this as paradigmatic leading to fundamental new workflows in weather and climate research and services. I will present a perspective on the latter and will discuss digital twins in the weather and climate domain related to emerging digital technologies and data sciences up to considerations from social sciences and humanities.


08. Juni 2023 | Edwin Gerber, Professor at the Courant Institute NYU

Revealing the statistics of extreme events hidden in short weather forecast data: A case study of Sudden Stratospheric Warmings

Climate change will be felt primarily through changes in extreme weather: intense storms, precipitation events, and temperature anomalies.  Extreme events in the stratosphere, namely Sudden Stratospheric Warmings (SSWs), are known to impact surface weather extremes, driving an equatorward shift of the storm tracks and associated jet streams.  Efforts to quantify potential changes in SSWs in response to anthropogenic forcing, both their frequency and their surface impact, however, have been hampered by the large uncertainty in the observational record.  The problem becomes more acute for the most extreme SSWs, which are known to have a stronger surface impact. A once-in-a-century event takes, on average, 100 years of observations or simulation time to appear just once.  This is far beyond the typical integration length of our most accurate weather models, which provide the best representation of stratosphere-troposphere coupling, so the task is often left to cheaper, but less accurate, low-resolution or statistical models.  One reduces the sampling error (aleatoric uncertainty) at the expense of increased model error (epistemic uncertainty).

In this work, we propose methods to extract climatological information from subseasonal forecast ensembles.  Despite being short in duration, weather forecast ensembles are produced multiple times a week, collectively, adding up to thousands of years of data.  Using ensemble hindcasts produced by the European Center for Medium-range Weather Forecasting (ECMWF) archived in the subseasonal-to-seasonal (S2S) database, we compute multi-centennial return times of extreme SSW events. Consistent results are found between alternative methods, including basic counting strategies and Markov state modeling. By combining different trajectories together in a statistically rigorous way, we obtain estimates of SSW frequencies and their seasonal distributions that are consistent with reanalysis-derived estimates for moderately rare events, but can be extended to events of unprecedented severity that have not yet been observed historically. The same methods hold potential for assessing extreme events throughout the climate system, beyond the example of stratospheric extremes presented here, and could be adopted in the context of climate change integrations to quantify the impact of anthropogenic forcing on extreme weather.


25. Mai 2023 | Kerry A. Emanuel, Professor Emeritus of Atmospheric Science, MIT

What Sets the Climatology of High CAPE?

Severe convective storms are a significant source of weather-related losses and injury, worldwide. Yet very little is known about what sets their climatology in the current climate, and why climate models generally indicate increased severe storm activity as the climate warms. In this talk, I will focus on one of the main ingredients in severe convective storms: Convective Available Potential Energy (CAPE). The global climatology of CAPE differs significantly from that of deep convection in general; for example, high CAPE values are quite rare over the ocean. Using both an observational analysis and a 1-D model coupled to a model of soil and vegetation, I will argue that high CAPE results when air masses that have been significantly modified by passage over dry, lightly vegetated soils are advected over moist soils with moderate to extensive vegetation. This suggests that widespread agricultural practices may significantly modify the climatology of severe convection and points to how climate change might affect the prevalence and intensity of severe convective storms.


19. January 2023 | Leonie Wenz, Potsdam Institute for Climate Impact Research

The economic cost of climate change

Changing climate conditions and weather extremes can affect various fundamental elements of our economies such as labor productivity or agricultural yields – thereby posing a threat to economic prosperity and societal welfare. Estimates of the macroeconomic costs of climate change hence play an important role in climate policy debates and decisions. However, current estimates differ strongly – partly because it is unclear how resilient regions, sectors and communities are and how persistently weather extremes can thus affect them. In this talk, I will give an overview of some recent findings in this research area. Specifically, I will present insights gained from a novel data set comprising subnational income data from the past 40 years and more than 1500 regions worldwide. Based on these granular data, we have empirically estimated historic temperature and precipitation impacts at different time scales, from daily fluctuations and extremes to changes in the long-term mean. Our findings show that economic productivity is strongly affected by rainfall and temperature changes but that these effects display large spatial heterogeneity. Whereas low-income, low-latitude regions are most vulnerable to rising and erratic temperatures, increases in the number of rainy days and extreme rainfall events are most harmful in wealthy, industrialized countries. In our economically interconnected world, these local impacts can have repercussions in other parts of the work as well. I will conclude by presenting preliminary results on such spill-over effects in firm networks.


12. Januar 2023 | Laure Zanna, Professor of Mathematics & Atmosphere/Ocean Science [she/her] Courant Institute, NYU

Transforming Climate Modeling for Machine Learning: Hype or Reality?

Climate simulations remain one of the best tools to understand and predict global and regional climate change. Uncertainties in climate predictions originate partly from the poor or lacking representation of processes, such as ocean turbulence and clouds, that are not resolved in global climate models but impact the large-scale temperature, rainfall, sea level, etc. The representation of these unresolved processes has been a bottleneck in improving climate simulations and projections. The explosion of climate data and the power of machine learning (ML) algorithms are suddenly offering new opportunities: can we deepen our understanding of these unresolved processes and simultaneously improve their representation in climate models to reduce climate projections uncertainty? In this talk, I will discuss the advantages and challenges of using machine learning for climate projections. I will focus on our recent work in which we leverage ML tools to learn representations of unresolved ocean processes - in particular, learning symbolic expression. Some of our work suggests that machine learning could open the door to discovering new physics from data and enhance existing climate modeling. Yet, many questions remain unanswered, making the next decade exciting and challenging for ML + climate modeling for robust and actionable climate projections. The work presented is part of M²LInES – an international effort to improve climate models with scientific machine learning. 


15. Dezember 2022 | Michael Byrne, Reader in Earth & Environmental Sciences – University of St Andrews Marie Skłodowska-Curie Research Fellow – University of Oxford

Extreme tropical temperatures in a changing climate: theory and simulations

Understanding the future of extreme temperatures is a critical goal for science and society. Simulations with coupled climate models suggest that hot days over tropical land will warm substantially more than the average day. For example, averaged across models, warming of the hottest 5% of days is projected to be approximately 20% larger than the annual-mean warming. Amplified warming of extreme temperatures implies severe impacts on humans and ecosystems, yet the physical mechanisms underpinning this emergent behaviour of numerical models remain unclear. Here, I interpret the response of extreme temperatures over tropical land to climate change using a theory based on convective coupling and the weak temperature gradient approximation. According to the theory, warming is amplified for hot land days because those days are dry: this is termed the ‘drier get hotter’ mechanism and can be predicted given properties of the current climate. Changes in near-surface relative humidity further increase tropical land warming, with decreases in land relative humidity particularly important. The theory advances understanding of extreme weather in the tropics, and highlights land-surface dryness as a key factor determining how hot days will respond to climate change. 

Ideas for generalising the theory beyond the tropics will be discussed.


08. Dezember 2022 | Timo Goeschl, Heidelberg University, Department of Economics and Research Centre for Environmental Economics

Attribution to anthropogenic causes helps prevent adverse events

The science of extreme event attribution (EEA) has rapidly established itself as a popular tool for quantifying - ex post - the anthropogenic contribution to recent adverse events in the climate system. Yet, whether backward-looking causal attribution can lead to future behavioral change is conceptually unclear, and evidence that it can reduce anthropogenic stress on these systems is lacking. Our online experiment with 3,031 participants in three treatment conditions provides a proof of principle. There, adverse events can arise either as a result of excess stress on the system by participants’ pursuit of individual material benefits (anthropogenic cause) or as a result of chance (natural cause). We examine both the impact on future anthropogenic stress of making past adverse events causally attributable and the demand for attributability. We find that whether an adverse event can be causally attributed is behaviorally relevant: Attribution to an anthropogenic cause reduces future anthropogenic stress and leads to fewer adverse events compared to no attributability and compared to attribution to a natural cause. Joint causation has no effect. There is demand for ex-post event attribution in the population of participants, even when costly. The conjecture that attribution science can be behaviorally impactful, socially valuable, and in demand therefore rests on promising experimental foundations.


03. November 2022 | Steven Yearley, University of Edinburgh, School of Social and Political Science

Has the climate crisis put an end to green ambivalence about science?

The idea at the heart of this colloquium presentation is that there is an elective affinity between environmental campaign organisations/the environmental movement and scientific claims that is, to a large degree, distinctive among social movements. This gives environmentalists and green campaigning bodies an urgent interest in science communication issues and has turned many of them into significant science-communication actors. However, these ties to science have – as is well known – not been problem-free. Demands for scientific “proof” of environmental problems have often been used by governments or regulators as grounds for inaction. Green campaigners have themselves been sceptical about scientific arguments in relation to GMOs and – before that – nuclear safety. At the same time, environmentalists’ opponents have learned to deploy doubt and uncertainty as ways to counter science-based claims. Scientific claims have also typically stemmed from the “Global North”, giving rise to concerns about their applicability or sensitivity to issues in the Global South. Finally, scientific claims are typically presented as empirical assertions and thus non-normative; this may be beneficial when identifying problems but tells one less about solutions and the ways we should live with environmental change. The urgency of the climate crisis intensifies these questions about the environmental movement’s attachment to science: has the climate crisis put an end to green ambivalence about science?


13. Juli 2022 | Dr. Maike Sonnewald, Princeton University and NOAA/Geophysical Fluid Dynamics Laboratory

Understanding the response of the ocean's global overturning to global warming: A robust blueprint for trustworthy AI for climate analysis

The global ocean overturning is central to the health of the planet, but open questions about what drives the circulation hinder our understanding and ability to monitor changes. Climate models suggest that the circulation is changing, but the physical drivers are poorly constrained. Here, artificial intelligence is used to both construct hypotheses to gain new theoretical understanding of the upwelling and to design a monitoring framework. Explicitly transparent, the monitoring method Tracking global Heating with Ocean Regimes (THOR), reveals key mechanisms and is used to track changes in dynamics associated with the overturning using only the sea surface height, wind stress curl and depth. Here, we will focus on the North Atlantic and Southern Ocean, specifically the location of the Gulf Stream, Trans Atlantic Current and downwelling regions, as well as the gyre-like circulation that modulates upwelling in the Southern Ocean. With abrupt CO2 quadrupling, the North Atlantic overturning circulation weakens due to a shift in deep water formation regions, a northward shift of the Gulf Stream and an eastward shift in the Trans Atlantic Current. In the Southern Ocean, the overturning increases with an expansion of the dynamical regime associated with upwelling. If CO2 is increased 1% yearly, similar but weaker patterns emerge influenced by natural variability. THOR demonstrates a path to progress in oceanographic problems that have resisted classical analysis. Beyond a black box approach, THOR is engineered to elucidate its source of predictive skill rooted in physical understanding, and the talk concludes with an outlook on the inherently transparent THOR methodology with its demonstrable rooting in physics. THOR constitutes a blueprint and a step toward trustworthy artificial intelligence called for within oceanography and beyond.


07. Juli 2022 | Prof. Sarah Kang, Ulsan National Institute of Science and Technology

Role of Southern Ocean in shaping the tropical Pacific climate pattern

Excessive precipitation over the southeastern tropical Pacific is a major common bias that persists through generations of global climate models. While recent studies suggested an overly warm Southern Ocean as the cause, models disagree on the quantitative importance of this remote mechanism in light of ocean circulation feedback. Here, using a multi-model experiment in which the Southern Ocean is radiatively cooled, we reveal a teleconnection from the Southern Ocean to the tropical Pacific that is mediated by a shortwave subtropical cloud feedback. Cooling the Southern Ocean preferentially cools the southeastern tropical Pacific, thereby shifting the eastern tropical Pacific rainbelt northward with the reduced precipitation bias. Regional cloud locking experiments confirm that the teleconnection efficiency depends on the subtropical stratocumulus cloud feedback. This subtropical cloud feedback is too weak in most climate models, suggesting that teleconnections from the Southern Ocean to the tropical Pacific are stronger than widely thought. We also identify the Southern Ocean-to-tropical Pacific teleconnection in future climate projections.


01. Juli 2022 | Axel Andersson, DWD Hamburg

Measuring the Climate on the Oceans - 150 Years of Weather Observations at Sea

In the middle of the 19th century, merchant ships leaving the harbour of Hamburg started to take meteorological instruments with them to conduct systematic meteorological observations at sea. The data was collected on behalf of the "Deutsche Seewarte" and significantly improved the knowledge about the weather and the climatic conditions on the oceans allowing safer and faster voyages. This system of "Voluntary Observing Ships" still exists and nowadays a fleet of several hundred vessels regularly sends weather reports to Deutscher Wetterdienst (DWD) in Hamburg. Apart from their use in operational weather forecasting, the observations are an important contribution for climatological archives such as marine in-situ database of DWD's Marine Climate Data Centre. Apart from recent data received through operational data streams, the database consists of a large amount of historic data, which is continuously growing by digitization from old meteorological ship logbooks.
As part of the international data exchange, data is regularly integrated in the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) and is used for a variety of application such as input for climate reanalyses, operational climate monitoring and the calibration of satellite observations. In this talk, I will give an overview of the history of marine meteorological observations in Hamburg from the 19th century sailing ship era to modern automated observation systems. The data rescue project will be highlighted as well as the evolution of the international data exchange and recent climate related applications.


12. Mai 2022 | Prof. Dr. Daniela Domeisen

Linking the dynamics and predictability of extreme weather in a changing climate

Extreme events such as e.g. heatwaves and precipitation extremes can have devastating consequences for society and ecosystems. Furthermore, many extremes tend to become more frequent under climate change, and are therefore crucial to better understand and predict. Despite the importance of anticipating such extremes, it remains challenging to predict them, especially on timescales of days to weeks, a crucial planning timescale. However, the analysis of the predictability of extreme events and their evolution in a changing climate does not only yield benefits for emergency management, but it also provides insights into the origins and the dynamics of these events. Extremes can be caused by a range of localized and remote dynamical mechanisms from local to global scales, including links established by remote connections between the tropics, midlatitudes, the polar regions, as well as the Earth’s land and ocean surface and the upper atmosphere. These dynamical mechanisms within the Earth system can be understood through a broad hierarchy of methods and models. An improved understanding of extremes can then feed back towards an improved prediction of extremes, which in turn helps to protect lives and livelihoods. This presentation provides an overview of the current state of extreme event predictability on a range of timescales in a changing climate, while linking to the dynamical origins of extreme weather.


24. März 2022 | Jochem Marotzke, Hans von Storch, Erland Källén, Michael Werz, Cathrin Zengerling, Moderation: Barbara Hans

Wissenschaft. Macht. Politik. ― Klimadiskurs und Gesellschaft

Sonderkolloquium mit der Helmut und Loki Schmidt Stiftung


Die großen Herausforderungen unserer Zeit lassen sich nur lösen, wenn politische Entscheidungen von aktuellen wissenschaftlichen Erkenntnissen ausgehen. Wenn die Forschungslage sehr eindeutig ist, wie bei der Frage nach der menschlichen Verantwortung für den Klimawandel, müssen verantwortungsvolle Politikerinnen und Politiker ihr Handeln an diesen Erkenntnissen ausrichten. Gleichzeitig braucht demokratische Debatte Alternativen und Wahlfreiheiten, die die ergebnisoffene Abwägung unterschiedlicher Interessenlagen und Argumente zulassen. Am Beispiel der Klimapolitik wird das Spannungsverhältnis zwischen wissenschaftlicher Erkenntnis und politischer Entscheidungsfindung mit besonderer Brisanz deutlich.

June 24th | Jörg Knieling, HCU Hamburg

Climate Adaptation Governance of "Water from 4 Sides": Of wicked problems and metropolitan complexities in urban systems

"Water from 4 Sides" is one of the projects of CLICCS. In an interdisciplinary team of researchers it looks at climate adaptation in urban systems with regard to different water issues: river flooding, storm surges, heavy rain events, and ground water. For handling these challenges in the societal and political context the governance research provides a broad range of analytical and conceptual approaches including different steering modes and reaching from regulative and informal to economic instruments. However, governance arrangements are challenged by phenomena which complicate 'simple solutions', such as uncertaintiy, multi-level-responsibilities or diverging stakeholder rationalities. The presentation explores how those wicked problems and complexities refer to climate adaptation governance and could be considered in metropolitan strategies.


June 17th | Johanna Baehr, Universität Hamburg

Back to the future: a guided journey through Earth system predictions

Skilful Earth system predictions for a season or a decade ahead remain in many cases a formidable challenge. I will present recent progress in predicting climate and Earth system variability using prediction systems based on the Max-Planck-Institute Earth System Model (MPI-ESM). I will also challenge the current practice to focus on the ensemble mean and suggest a less-is-more approach instead.


June 10th | Grischa Perino, Universität Hamburg

Climate Protest Mobilization is a Strategic Game: Theory, Econometric Application, and Experimental Evidence from the Field

Considering private and collective goods supplied by political mass protest, we model how beliefs regarding the participation of others are critical in protest formation. We test the hypotheses with data from a field experiment that uses an information treatment to identify the effect of beliefs on participation. The study was conducted around the “Third Global Climate Strike” (20.9.19) with adults from the largest four German cities, which was the first attempt to reach out beyond the youth. We find robust evidence that participation decisions are causally related to beliefs about participation of others in a way consistent with “free riding”.


June 3rd | Hartmut Graßl, MPI-M Hamburg

Scientific highlights and major structural changes at MPI for Meteorology since 1975

(as seen by Hartmut Graßl)

Starting in 1975 as a small MPI with one director of (Klaus Hasselmann) and one director at (Hans Hinzpeter), our institute is now among the leading Earth system modelling centres worldwide and also adds new observations for the improvement of models. When I started as a group leader in 6/1976 the scientists and technicians of the institute occupied less than 2 floors in Geomatikum, in close cooperation with the Meteorological Institute of the University of Hamburg. Now we can look back to many early achievements, here mentioning only very few: First coupled atmosphere/ocean/land-model in Europe, first global satellite-based energy flux climatology at the ocean surface, detection of the anthropogenic climate signal. I will also include the stories about the structural changes (foundation of the German Climate Computing Centre in Hamburg) and the threat to close the institute at the turn of the century.


May 27th | Corinna Schrum, HZG Geesthacht

Between Climate Change and fairway deepening: How do models contribute to the development of sustainable future scenarios for the Elbe estuary and the region?

How will climate change impact the Elbe estuary and what are the implications for the city of Hamburg and the port? This is a central question for long-term planning and climate adaptation measures of Hamburg. The Elbe estuary and the harbor is a system, that is influenced by different socio-economic and climate drivers. Climate drivers control the dynamics of the estuary through the water balance in the catchment area and through sea level at the river mouth. Biogeochemical dynamics and sediment transport are moreover controlled by temperature and nutrient loads.  However, climate pressures are not the only drivers of the Elbe estuary, the estuary is also a massively engineered system. Substantial fairway deepening over more than a century but also coastal protection, dikes, punctures and changes of the course of the estuary represent an even stronger control of the Elbe estuarine dynamics.

Today`s management of the estuary takes place in a framework characterized by different federal-state responsibilities. In addition to coastal protection needs and economic objectives it also needs to serve ecological objectives. Conflicting interests and trade-offs often exist and the complex and sometimes unpredicted behavior of the estuarine system complicates management and implementation of climate adaptation measures.      

We here present a model framework that can support the exploration of adaptation options.

The framework couples a global climate model with regional focus and additional sea level rise contributions to a high-resolution estuary model. The framework resolves the most important drivers and feedbacks and meets the level of detail and accuracy requirements needed for planning processes.  

This event was not recorded.



May 20th | Martin Wickel, HCU Hamburg

The German Climate Protection Law after the Decision of the Federal Constitutional Court

Das Bundesverfassungsgericht hat mit seinem Beschluss zum Klimaschutzgesetz den verfassungsrechtlichen Kerngehalt des Klimaschutzrechts konkretisiert. Stichworte sind die grundrechtlichen Schutzpflichten, das Staatsziel Umweltschutz und vor allem die intertemporale Freiheitssicherung durch die Grundrechte. Damit ändern sich die (verfassungs-)rechtlichen Rahmenbedingungen für den Klimaschutz in Deutschland. Der Vortrag wird beleuchten, welche Erwägungen hinter dem Beschluss stehen, welche Schlussfolgerung das Gericht zieht und wie der Gesetzgeber darauf reagieren muss.

This event took place as a CLICCS Convent instead of the KlimaCampus Colloquium. The recording will be published soon.



April 22nd | Lars Kutzbach, Universität Hamburg

Methane flux dynamics in permafrost landscapes of the Arctic

Increased methane release from a warming Arctic is expected to be a major feedback on the global climate. However, due to the complex effects of climate change on arctic permafrost landscapes, projections of future land-atmosphere fluxes of methane are highly uncertain. At the same time, empirical data covering the pronounced spatio-temporal variability of methane fluxes is rare due to the logistic and technical difficulties associated with experimental investigations in the Arctic. In this talk, I will present our studies on methane flux variability on spatial and temporal scales conducted in the Siberian Lena River Delta (72.4° N, 126.5° E) between 2002 and 2019.



April 8th | Guy Brasseur, MPI-M

An unintended worldwide experiment: Impact of COVID-19 on the global chemical composition of the atmosphere

The reduction in the emissions of greenhouse gases and air pollutants during COVID-19 offers a glimpse into a potential future in which air quality would be improved. With a global Earth system model, we assess the response of primary and secondary chemical species of the atmosphere to this global atmospheric experiment. We highlight the nonlinear behavior of the chemical system, which makes air pollution mitigation policies difficult to implement. Meteorological variability produces anomalies, sometimes larger than the perturbations attributed to changes in the emissions. This worldwide experiment provides information that should help improve air quality on the different continents.



February 18th | Stefan Aykut, Universität Hamburg

Global climate summits, international cooperation, and the prospects of collective action on the climate crisis

Since the 1990s, global climate summits federate each year delegates from virtually all countries on the planet. They produced a series of treaties, from the 1992 Climate Convention to the 2015 Paris agreement. Increasingly, they also try to facilitate and orchestrate decentralized climate action by firms, investors or municipalities. But what are the results of almost 30 years of global ‘summitry’ in terms of forging an international response to the climate problem? And how do social scientists observe, analyze and assess transnational mega-events that gather tens of thousands of delegates, activists, lobbyists and journalists? In this talk, I present a social science perspective on global climate politics, explain with which methods we study global climate summits, and share some insights from ongoing research.



February 4th | Bjorn Stevens, MPI-M Hamburg

Clouds, Circulation and Climate Sensitivity — EUREC4A!

The response of shallow clouds over the tropical oceans to warming has proven pivotal for assessments of Earth's equilibrium climate sensitivity.  Models that project a strong future warming invariably show a marked reduction in clouds in the trades.  Studies over the past decades have not only helped identify the important role of these clouds for a model's response to radiative forcing (i.e., greenhouse gases), but also the mechanisms underpinning such responses.  By exploiting advances in measurement science, EUREC4A, a Barbadian-German-French led field campaign, collected observations to test these mechanisms.  By demonstrating an ability to measure both clouds, and the circulations in which they were embedded, EUREC4A also made it possible to also address a wide range of additional questions related to the physics that regulate cloud amount in the trades, and to provide benchmark measurements for a new generation of climate models. In this talk, I will present the science behind EUREC4A, its execution, and some snapshots of results emerging less than one year since the campaign's conclusion.



January 28th | Daniela Jacob, GERICS Geesthacht |

Challenges for Climate Services

The need to adapt to climate change has led to the establishment of a new research and service field, called Climate Services, encompassing a variety of activities and formats. It is clear that Climate Services need to be context specific, non-uniform and often cross-sectoral, ‘fit for purpose’ with science-society dialog as a key to develop usable climate services. However, Climate Services still face some challenges. They do not exist in all sectors, exchange with practitioners could be enhanced, sharing experiences world-wide is difficult and clear carrier paths to climate service experts are lacking. The talk will elaborate on these challenges and the needs for climate service in an era of transformation! 





January 30th | Felix Riede, University of Aarhus, Denmark.

Felix Riede is guest of the MPI-M.

Volcanoes, climate and societal change in the prehistory of northern Europe – does the past hold lessons for the future?

Climate change and extreme or compound events are today recognized as major societal challenges yet they play little role in classic ideas of how societies changed in the past. In my presentation, I will present the results of recent research investigating the long-range impacts of volcanic eruptions on climate and, importantly, also on societies in northern Europe. Moving from the still rather close-to-home eruption of the Laacher See volcano in the Eifel to more distant eruptions in the Mediterranean to those located in the far-away reaches of Alaska and Central America, these case studies range from the Late Pleistocene Stone Age to the Bronze and Iron Ages. While covering different sorts of interactions between volcanism, climate and society, we may ask: Does the past hold lessons for the future?





December 19th | Felix Landerer, NASA’s Jet Propulsion Laboratory

Felix Landerer is guest of the MPI-M.

Weight-Watching from Space – tracking changes in Earth’s groundwater, glaciers, ice sheets and sea level rise in the last two decades

Earth's distribution of water - in the form of ice, snow, soil moisture, groundwater, lake and sea level - is undergoing profound changes as the climate changes over seasons to decades. The original Gravity Recovery and Climate Experiment (GRACE) mission, launched in early 2002, has enabled a unique and valuable data record to study changes in our global water cycle, and allowed precise determination of sea-level rise, polar ice-cap mass loss in Greenland and Antarctica, and large-scale water storage changes over land. By measuring small month-to-month changes in Earth's gravity field, these observations provide a unique window into Earth's evolving climate and water stores, and a glimpse into possible future impacts. The twin satellites of the GRACE Follow-On mission, in operation since early 2018, continue and extend this valuable data record. I will describe the fascinating technology behind gravity measurements from space, and present some first new science findings from the new joint US-German GRACE Follow-On mission, such as the variable ice mass loss over Greenland in 2018 and 2019, and the record-low land water storage in Europe during the 2018 drought.



December 12th |  Caroline Ummenhofer, Woods Hole Oceanographic Institution [Abstract]

Caroline Ummenhofer is guest of the MPI-M.

Extreme climate events with ecological relevance: from droughts and floods on land to marine heat waves along the coast

Mounting evidence points towards an increase in intensity and frequency of extreme weather and climate events over recent decades. These changes are being linked to human-induced climate change, while impacts on individual extreme climate events are more difficult to quantify. Limitations in the observational network, both for physical climate system parameters and even more so for long-term ecological monitoring, have hampered progress in understanding the effect of extreme climate events on bio-physical interactions. However, recent advances open new opportunities for developing a mechanistic understanding of how extreme climate events affect human and natural systems. This is illustrated with hydroclimatic extremes, such as droughts and floods, and their effect on terrestrial ecosystems for tropical rainforests, in semi-arid regions, as well as for marine heat waves in the coastal environment.

The hydroclimatic conditions in Australia are used as an example: in 2010/11, severe flooding in northeastern Australia occurred, as well as a rare filling of Lake Eyre and record terrestrial carbon uptake. The severity of the conditions across Australia was unusual, even considering that it was a strong La Niña event. Long-term ocean warming has resulted in 0.5°C warmer sea surface temperatures around the Australian continent over the past 60 years. It is demonstrated that the warmer ocean background state increased the likelihood of the extreme rainfall response and relevant mechanisms are identified. The unusual conditions of the 2010/11 La Niña also had severe implications on the coastal environment around Australia, including prolonged marine heat wave conditions off Western Australia. Using high-resolution ocean model sensitivity experiments, the upper-ocean structure of the marine heat wave is investigated and contributions from wind and buoyancy forcing are quantified.




December 5th | Trude Storelvmo, University of Oslo

Trude Storelvmo is guest of the MPI-M.

State-dependent cloud feedbacks make equilibrium climate sensitivities > 5°C plausible

For decades, global climate models (GCMs) have produced equilibrium climate sensitivities (ECSs) between 2 and 4.5°C, but interestingly that is now about to change: a subset of state-of-the-art GCMs participating in the 6th coupled model intercomparison project is producing ECSs well above 5°C. Here, I present analyses based on one such high-ECS model. In the past, it has been assumed that such very high simulated ECSs would make it practically impossible for GCMs to reproduce the historical temperature record, but that turns out not to be the case. This is because the model in question has a net positive cloud-climate feedback that grows with warming - in other words: the warmer it gets, the more clouds change in a way that further amplifies the warming, while for modest warming the amplification is much smaller. In this presentation I will explain the underlying physical mechanism responsible for the simulated state transition and discuss its general validity and broader implications.






November 14th | Ricarda Winkelmann, Potsdam-Institut für Klimaforschung

Ricarda Winkelmann is Guest of the MPI-M.

Beyond gradual change – Antarctic ice dynamics and tipping points

The Antarctic Ice Sheet is by far the largest potential source of future sea-level change, holding enough water to raise global sea level by 58 m. To this day, the complex dynamics of the ice sheet and its surrounding ice shelves are one of the key challenges for sea-level projections. Recent observations show that part of the West Antarctic Ice Sheet is rapidly retreating, and that this retreat is likely irreversible on human timescales. Other regions are currently protected by ice plugs, hindering the onset of a dynamic instability.

In her talk, Ricarda will discuss the underlying mechanisms and critical thresholds for triggering persistent ice discharge from Antarctic basins. As a consequence, sea-level might continue to rise for centuries or even millennia to come. This long-term perspective illustrates that policy decisions made in the next years to decades will have profound impacts on global climate and sea-level - not just for this century, but for the next millennia and beyond.



November 7th | Elizabeth Barnes, Colorado State University

Elizabeth Barnes is guest of the MPI-M.

Viewing Climate Signals through an AI Lens

Much of climate science is viewed as a signal-to-noise problem and the field has many statistical methods for extracting the signal of interest. Here, we argue that artificial neural networks (ANNs) are an additional useful tool for the “climate toolbox”. As an example, we demonstrate their utility for extracting forced climate patterns from model simulations and observations whereby the ANN identifies patterns that are complex, non-linear combinations of signal and noise. While neural networks are often viewed as black boxes, we further demonstrate how to visualize what the network has learned using recent advances in visualization tools within the computer science community. This approach suggests that viewing climate patterns through an AI lens has the power to uncover new insights into climate variability and change

April 18th | Adam Scaife, Met Office, UK

Adam Scaife is guest of Johanna Baehr (Uni HH).

Seasonal predictability of the winter North Atlantic Oscillation

The last few winters continue to suggest that the winter NAO and hence winter average weather over large areas of Europe is predictable at seasonal lead times with a good level of correlation skill.   I will show mechanisms for this predictability and argue that it originates from predictable variations in tropical rainfall and initial conditions in the stratosphere.  High predictability of tropical rainfall is first demonstrated for current prediction systems and this is shown to lead to predictable changes in seasonal vorticity sources.  These are associated with stationary Rossby waves that propagate polewards and eastwards into the extratropics, including the Atlantic sector, where the connection to tropical rainfall can explain around half of the forecast variance in the NAO.  We also show that initial atmospheric conditions are important for seasonal prediction of the NAO.  Initial anomalies in stratospheric winds at the start of winter propagate downwards into the troposphere where they lead to anomalies in the winter mean surface conditions.  Together, these mechanisms may explain the majority of forecast variance in the winter NAO.  Finally, we discuss some of the remaining errors in these ensemble forecasts, including the unresolved signal-to-noise paradox which means that current seasonal forecasts are better at predicting the real world than they are at predicting their own forecast members.

Unfortunately, no recording could be made due to technical difficulties.


May 9th | Alexander Proelß, Juristische Fakultät, Uni Hamburg

Alexander Proelß is guest of Hauke Schmidt

International Environmental Law and the Challenge of Climate Change

In view of the epochal challenges of climate change, international environmental law stands at a crossroad. Current regulatory principles and strategies mostly focus on the protection of individual environmental goods and are often distinguished by their fragmentary, or general, character. This also applies for the 2015 Paris Agreement, which pursues the aim of halting the increase in the global average temperature to well below 2°C above pre-industrial levels, and of pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels. Notwithstanding all efforts that have been taken so far, it seems highly questionable whether this objective can be achieved by the present (but partly unsuccessful) attempts to drastically reduce global carbon dioxide emissions. Against this background, international environmental law will also have to address the implementation of supplementary (“secondary”) climate measures in future. This does not only imply the need to improve the implementation and enforcement of the law as it stands today, but also to develop it further in order to provide an effective as well as legitimate normative answer to the “grand challenges” of international environmental politics.


May 23rd | Amanda Maycock, University of Leeds, UK

Amanda Maycock is guest of Jochem Marotzke (MPI-M).

ENSO teleconnections to the extratropics: role of El Niño amplitude and seasonal cycle

ENSO is a key driver of interannual climate variability in many regions of the world. However, disentangling the dependence of ENSO teleconnections on the specific characteristics of events is challenging given the relatively small number of observed events and multiple sources of internal variability.

In this talk I will present recent work from my group using targeted climate model experiments to investigate the mechanisms underpinning ENSO teleconnections to two extratropical regions spanning both hemispheres: the North Atlantic and the Amundsen sea low. I will focus on how the tropical-extratropical teleconnections vary as a function of ENSO amplitude and the role of the seasonal cycle.

In contrast to some previous studies, we show that the influence of El Niño on the winter North Atlantic Oscillation (NAO) is approximately linear over the range of observed El Niño amplitudes. The NAO response is tied to a weakening of the stratospheric polar vortex and an increase in the frequency of major sudden stratospheric warmings. In the Southern hemisphere, the El Niño teleconnection to the Amundsen Sea region is largest in austral winter, despite the fact El Niño typically peaks in austral spring/summer. In austral winter, the region of strong absolute vorticity near ∼30°S provided by the subtropical jet, in combination with the changes to upper tropospheric divergence due to the El Niño perturbation, acts as an anomalous Rossby wave source that is largely absent in austral summer. Furthermore, in austral summer the poleward propagation of tropically-sourced Rossby waves into the Amundsen sea region is inhibited by the strong polar front jet in the south Pacific sector, which leads to Rossby wave reflection away from the Amundsen sea region.

I will conclude by giving some ideas for key outstanding questions in understanding ENSO teleconnections to the extratropics.


[CANCELLED]June 13th | Trude Storelvmo, University of Oslo, Norway

Trude Storelvmo is guest of Jochem Marotzke (MPI-M).

State-dependent cloud feedbacks make equilibrium climate sensitivities > 5°C plausible

For decades, global climate models (GCMs) have produced equilibrium climate sensitivities (ECSs) between 2 and 4.5°C, but interestingly that is now about to change: a subset of state-of-the-art GCMs participating in the 6th coupled model intercomparison project is producing ECSs well above 5°C. Here, I present analyses based on one such high-ECS model. In the past, it has been assumed that such very high simulated ECSs would make it practically impossible for GCMs to reproduce the historical temperature record, but that turns out not to be the case. This is because the model in question has a net positive cloud-climate feedback that grows with warming – in other words: the warmer it gets, the more clouds change in a way that further amplifies the warming, while for modest warming the amplification is much smaller. In this presentation I will explain the underlying physical mechanism responsible for the simulated state transition and discuss its general validity and broader implications.


June 20th | Julia Pongratz, University of Munich

Julia Pongratz is guest of Martin Claußen (MPI-M).

Managing climate by managing land

Three quarters of the ice-free land surface are under some form of land use — cleared for agriculture, grazed on, or used in forestry. Strong further changes are expected for the future, because land use has been assigned a prime role in the effort to limit global warming to 2 degrees. Recent years have seen a surge in Earth observations focused on land use effects on climate. But observations often disagree with model results, preventing trust in model projections. For example, changes in energy and water fluxes associated with a reduction in forest cover show warming in most regions in observations, but cooling in Earth system models. Further, carbon stocks and fluxes associated with historical land use change are generally larger in observations than in models. In this presentation I resolve these discrepancies, highlight the dual role of land use as adaptation and mitigation tool, and prove the need to account for land management in addition to land cover changes in climate and carbon cycle modeling.

October 18th | Oliver Fuhrer, Federal Office of Meteorology and Climatology Meteo Swiss

Oliver Fuhrer is guest of Bjorn Stevens (MPI-M).

High performance computing for weather and climate: Learning how to forget

The weather and climate community has set ambitious goals to reach global km-scale modeling capability on future exascale high-performance computing (HPC) systems. Reducing the horizontal resolution to the kilometer-scale holds the promise of reducing some of the long-standing biases and uncertainties. But how far are we from achieving this goal?

The weather and climate community is struggling to keep up with the fast-paced developments as HPC system designs strive towards the Exascale. Only few production-ready community codes are able to leverage emerging hardware architectures. This has become known as the software productivity gap.  While novel programming models - such as OpenACC or CUDA - are available to target these hardware architectures, they further increase the complexity of the code and thus exacerbate the problem.

In this talk, we give an introduction to some of the challenges we are facing. Further, we discuss the experience of a re-design effort for a regional weather and climate model to illustrate a possible alternative pathway. Significant parts of the code have been rewritten based on a domain-specific language (DSL) specifically targeted to the key algorithmic motifs in weather and climate models. The DSL allows a high-level, hardware agnostic formulation of the model which then can be compiled to different hardware targets. Finally, we will demonstrate the capability of the refactored code on the leadership-class heterogeneous HPC system Piz Daint and discuss the implications for global km-scale climate simulations.


November 8th | Philip Stier, Department of Physics, University of Oxford

Philip Stier ist guest of Bjorn Stevens (MPI-M).

Observational constraints on clouds, aerosols and their interactions

Clouds, aerosols and their interactions arguably remain the single greatest uncertainty in our understanding of Earth’s climate response to anthropogenic perturbations. In particular the effects of aerosol-cloud interactions on global and regional radiation budgets and the hydrological cycle remain highly uncertain.

This presentation will critically review some of the achievements made towards quantifying aerosol-cloud interactions, with a particular focus on the role of observations in the evaluation of models across scales.

Starting from the local scale, we will explore model-data synergies in the assessment of the representativeness of observations, an assessment of the suitability of remote-sensing retrievals as well as novel Lagrangian constraints from geostationary satellites.


November 15th | Erich Fischer, Institute for Atmospheric and Climate Science, ETH Zurich

Erich Fischer is guest of Nicola Maher (MPI-M) and Jochem Marotzke (MPI-M).

A plethora of noise: Quantifying changes in extremes in the presence of large internal variability

Decision makers express a need for reliable information on changes in climatic extremes in the coming decades. However, projections at these time scales involve large irreducible uncertainties due to internal variability. I will demonstrate that despite large uncertainties at local scale, projections in an aggregated spatial perspective are consistent even for the coming decades. Furthermore, models agree reasonably well on the forced response of temperature and heavy precipitation extremes, the pattern of change in the absence of internal variability. Thus, I argue that it is vital to specify whether model agreement refers to the forced response or for individual realization. However, ultimately our confidence in changes of extremes does not only depend model agreement but the consistency between different lines of evidence — the combination of process understanding, agreement across a hierarchy of models and the wealth of observational evidence.

December 6th | Alexis Hannart, Ouranos, Montreal, Canada

Alexis Hannart is guest of Sebastian Sonntag (MPI-M).

Climate change and causal attribution: an overview

Have human emissions been the dominant cause of the observed climate warming? Extremely likely so of course (IPCC, AR5) but what is this statement based upon? And also, what about last summer’s European heatwave? And the wildfires recently affecting western North America, are they also attributable to human influence? How certain are we? And what about the Montreal flood of spring 2017? And the progression of the Lyme disease in some regions? And the trend in agricultural yields? And the hurricane Florence hitting North Carolina last September? And so on.
Such causal questions are more and more frequently asked to scientists by various sectors of society. Answers partly condition adaptation measures, mitigation policy as well as legal liability. How does science approach them? This seminar will attempt to give an overview of this question.

January 24th | Stefan Kollet, FZ Jülich

Stefan Kollet is guest of Bjorn Stevens (MPI-M).

Groundwater-to-atmosphere simulations including human water use: sustainability concepts revisited

Groundwater-to-atmosphere simulations are useful for closing the terrestrial water and energy cycles at the continental scale and interrogating anthropogenic impacts at different space and time scales.  We want to understand how human water use, in this case groundwater pumping and irrigation, changes the natural terrestrial cycles over the  European continent including local effects, such as changes in water table depths, evapotranspiration, and air temperature, and non-local effects, such as base flow, continental discharge and precipitation. In particular, we study whether these changes are systematic in space and time, and ultimately impact and potentially redistribute water resources across the continent. We present technical aspects of our work related to model coupling and high-performance computing technologies, and results illustrating the significant impact of human water use beyond individual watersheds.

January 31st | Alberto Garabato, University of Southampton

Alberto Garabato is guest of Jochem Marotzke (MPI-M).

The power of the small: The emergent role of submesoscale turbulence in shaping ocean circulation and climate 

Submesoscale turbulence is made up of oceanic currents with horizontal scales on the order of 1 km and time scales similar to an inertial period. This class of ocean flows has been traditionally ignored, because it is often less energetic than other types of ocean currents, and because it has only just started being partially resolved by some ocean circulation models in the last few years. In this talk, I will argue that submesoscale turbulence is important in shaping ocean circulation in key places at the ocean’s boundaries, where the ocean interacts with other elements of the climate system. To do this, I will draw on three recent observational experiments at the ocean’s interface with the atmosphere, the cryosphere and the Earth’s topography – and show that, in all three cases, submesoscale turbulence governs a significant aspect of the ocean’s climatic role.

April 5th |Pierre Gentine, Department of Earth and Environmental Engineering, Columbia University

What do we need to know about weather and climate extremes in a warming world?

Pierre Gentine is a guest of Cathy Hohenegger (MPI-M).

With rising CO2 concentration, the continental hydrological and carbon dioxide cycles are going to become more coupled. Predicting whether we will live in a drier or wetter world, with more or less droughts, is a relatively simple question, which has however widespread implications. Yet, we are not in a position to clearly answer this simple question. Models predict that surface CO2 physiological effects will dominate the future continental hydrological cycle. Those effects appear critical to explain whether we will live in a drier or wetter world... Read the Abstract (PDF)

April 12th | Oliver Geden, German Institute for International and Security Affairs (SWP), Berlin - (Guest Researcher at the MPI-M and the CGG from April – October 2018)

The challenge of integrating carbon dioxide removal into the EU's climate policy paradigm

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Oliver Geden is a guest of Jochem Marotze (MPI-M).

Scenarios meeting the Paris Agreement’s temperature targets envisage a major and imminent deployment of technologies to remove carbon dioxide from the atmosphere, of which there has been almost no practical implementation to date. The talk explores the political dimensions and policy implications of expectations for ‘negative emissions’ in the European Union, considering its largely successful leadership role in mitigation action and corresponding low-carbon technology development and deployment...Read the Abstract (PDF).


April 19th |Christian Beer, Bolin Centre for Climate Research, Stockholm University

Importance of temporal and spatial variability of environmental conditions for land-atmosphere interactions in permafrost landscapes

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Christian Beeris a guest of Victor Brovkin (MPI-M).

Northern permafrost soils are a huge reservoir of carbon that has been accumulated during the Pleistocene and Holocene. Climate-change induced permafrost thawing will make this carbon available for decomposition, initiating a positive feedback mechanism. However, future projections of high-latitude greenhouse gas balances remain highly uncertain. This talk will review recent advancements of our understanding of vegetation and soil carbon turnover processes with a special focus on the production of methane versus carbon dioxide...Read the Abstract (PDF).

April 26th | Sharon Nicholson from the Department of Earth, Ocean & Atmospheric Science, Florida State University

The myth of the ITCZ over equatorial Africa and other myths concerning African climate

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Sharon Nicholson is guest of M. Claußen (MPI-M).

African climate is frequently a topic of discussion because of the devastating droughts that affect much of the continent.  Much of the discussion is in the lay press and rumors abound. Unfortunately, many have been believed by the scientific community and get repeated in journal articles.  This talk exposes some of the myths and makes the more serious claim that issues concerning the ITCZ should be included in the category of "myths".  The common explanation for the progression of the rainy season over Africa is the seasonal excursion of the ITCZ. The ITCZ paradigm stems from a time when tropical rainfall was assumed to be associated mainly with localized convection. Its development was also linked to the emergence of mid-latitude frontal concepts. The paradigm has numerous shortcomings, including the diversity of definitions and the large number of parameters used to identify the ITCZ... Read the Abstract (PDF)

May 3rd |Pierre Friedlingstein, University of Exeter

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Pierre Friedlingstein is a guest of Victor Brovkin (MPI-M).


The terrestrial carbon cycle plays a central role in the climate system. On the average, about 30 % of the anthropogenic emissions of CO2 are being absorbed by terrestrial ecosystems, the rest being taken by the ocean or remaining in the atmosphere and contributing to climate change. The land carbon sink is a complex combination of ingoing and outgoing natural fluxes (photosynthesis, respiration, fires, etc) as well as fluxes from land use changes. These processes are being affected by changes in environmental drivers, atmospheric CO2 being probably the main driver of land sink, modulated by climate, nutrient limitation...Read the Abstract (PDF)

May 17th |David Tyfield, Lancaster Environment Centre, Lancaster University

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

David Tyfield is guest of Anita Engels (Universität Hamburg).

Will Chinese (E-mobility) Innovation Lead in Global Low-Carbon Transition?

In the last couple of years, however, an alternative future has emerged into global consciousness, regarding a new and unlikely hero for global environmental challenges in the 21st century: China.  China’s severe environmental challenges, including those of GHG emissions and air pollution, have long had negative international public attention.  But more recently, spectacular developments in a number of domains of low-carbon technology have begun to seed a new celebratory narrative.  This sees Chinese low-carbon innovation as an exceptional force that will both continue an apparently exponential rate of improvement while simultaneously spreading rapidly around the world with unrivalled government support.  In short, China’s national project of ‘Ecological Civilization’, it is argued, may yet ‘save the planet’.
This talk will explore evidence from the key arena of urban mobility innovation – arguably the ‘hardest case’ for low-carbon transition and one in which the new narrative is particularly significant.  We will explore the confusing dynamics of low-carbon innovation China and how they illuminate profound social and (geo-) political changes that are taking place in parallel with the rise of Chinese environmental technologies… and which must be taken into account when forecasting their possible future impact, both environmentally and socially.
Full Abstract (PDF)

May 31st | Benjamin Murray, University of Leeds

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Benjamin Murray is guest of Bjorn Stevens (MPI-M).

The Seeds of Ice in Clouds

The formation of ice in clouds is fundamentally important to life on our planet since cold clouds play a central role in climate and the hydrological cycle. Despite the significance of ice formation, our quantitative understanding of sources, properties, mode of action and transport of Ice-Nucleating Particles (INP) is remarkably poor. In this seminar I will review some of the advances we have made over recent years, focusing on improving knowledge of mineral dust INPs from deserts through laboratory and modelling work as well as using aircraft and ground stations on either side of the tropical Atlantic. As part of this, I will illustrate how we cross scales from laboratory research where we can identify nanoscale ice nucleation sites through to planetary scale modelling of INP and interaction with cloud fields... Read the Abstract (PDF)

----- This talk was not recorded. -----

June 21st | Sarah Kang, Ulsan National Institute of Science and Technology, Korea

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Sarah Kang is a guest of Bjorn Stevens (MPI-M).

Distinct tropical climate response to subpolar energy perturbations from the Northern or Southern Hemisphere

The energetics framework predicts how climatic asymmetry develops in response to interhemispheric differences in energy flux into the coupled ocean-atmosphere system. Indeed, the late 20th century anthropogenic aerosol emissions, mostly concentrated in the Northern Hemisphere (NH), forced an interhemispheric Hadley circulation that displaces the Inter-Tropical Convergence Zone (ITCZ) southward. Confusions arise, however, from recent climate model experiments that utilize realistic dynamical oceans, in which radiative perturbations over the Southern Ocean fail to significantly displace the ITCZ. Using a hierarchy of coupled models, here we demonstrate a previously unrecognized sensitivity that the tropical response is intrinsically distinct depending on whether the subpolar energy perturbation comes from the NH or Southern Hemisphere (SH)... Read the Abstract (PDF)

July 12th | Douglas Maraun, Karl-Franzens-Universität, Graz

Douglas Maraun is guest of Hermann Held (Universität Hamburg).

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor).

Understanding regional weather extremes in a changing climate

Regional weather extremes often have severe impacts on society and ecosystems. There is evidence that the character of events such as heatwaves or heavy precipitation has been changing already in response to anthropogenic global warming, and will continue to change. Yet our ability to simulate these changes is limited. In particular regional information about future extremes is affected by substantial uncertainties. These uncertainties stem from mainly four sources: internal climate variability fundamentally limits the signal to noise ratio of climate projections, in particular at the regional scale. Current generation general circulation models have too coarse a resolution to realistically represent large-scale circulation features associated with extreme events, and their response to climate change... Read the Abstract (PDF)

November 2nd | Ben Marzeion, University of Bremen

Future sea-level change from past glacier mass loss commitments

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Ben Marzeion is a guest of Martina Neuburger (CEN)

Even though glaciers store less than 1% of the global ice mass, they have probably been the strongest contributor to sea-level change in the 20th century. While mass loss from the ice sheets and thermal expansion of the ocean water are quickly increasing, glaciers will continue to play an important role in sea-level change in the 21st century. Understanding the causes, mechanisms and time scales of glacier change is therefore of paramount importance for identifying successful strategies for mitigation of, and adaption to, climate change....Read the abstract (PDF).


November 9th |Jana Sillmann, CICERO Center for International Climate Research, Norway

What do we need to know about weather and climate extremes in a warming world?

Jana Sillmann is a guest of Detlef Stammer (CEN)

One of today’s major challenges in climate sciences is how to use our state-of-the-art models and climate system knowledge to inform decision making regarding societal responses to climate change. Among the five key reasons for concern, according to the Intergovernmental Panel on Climate Change (IPCC), are the risks from weather and climate extremes. Severe impacts could be prevented or alleviated through appropriate adaptation measures and better preparedness. Weather and climate extremes are influenced by a complex interplay of natural and anthropogenicfactors that determine their occurrence, frequency, and intensity. Adaptation planning is challenged to take into account near- and long-term variability and changes in weather and climate extremes and associated uncertainties... Read the Abstract (PDF)

November 16th | Andy Pitman, University of New South Wales, ARC Centre of Excellence for Climate System Science, Australia

Drought in climate models: what can we do about the uncertainty in climate projections?

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Andy Pitman is a guest of Martin Claußen and Victor Brovkin (MPI-M).

There is no agreement on how best to define droughts. They can occur over multiple temporal and spatial scales with significant Australian droughts lasting a decade. We name them in Australia: the Federation Drought, the World War II drought, the Millennium Drought and they are written into our music, literature and poetry.

No CMIP5 climate model simulated an event with the duration of the Millennium Drought; there is something missing in the models in terms of the large-scale forcing. In uncoupled simulations, land surface schemes tend to dry too quickly, and remain dry too long in comparison to observations. In short, CMIP5 simulations of long-term/large scale forcing and seasonal/regional scale forcing are inconsistent with observations. Projections of future interannual droughts are uncertain to a degree that the sign of the change in future drought is unknown reliably... Read the Abstract (PDF)

November 23rd |Piotr Smolarkiewicz,ECMWF, UK

A finite-volume module for cloud-resolving simulations of global atmospheric flows

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Piotr Smolarkiewicz is a guest of Peter Korn (MPI-M)

The talk highlights the development of the Finite-Volume Module (FVM) of the Integrated Forecasting System (IFS) at ECMWF. FVM represents an alternative dynamical core that enhances the spectral dynamical core of the IFS with new capabilities, such as a compact-stencil finite-volume discretisation, flexible meshes, conservative non-oscillatory MPDATA transport, and all-scale nonhydrostatic governing equations...Read the Abstract (PDF).

November 30th | Kirstin Krüger, University of Oslo, Norway

Does the ocean impact the ozone layer?

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Kirstin Krüger is a guest of Hauke Schmidt (MPI-M)

Natural, halogenated very short-lived substances (VSLS) with an atmospheric lifetime τ<0.5 yr play an important role in the stratospheric ozone budget besides the anthropogenic long-lived chlorine- and brominefluorocarbons. The tropical oceans are a known source of reactive iodine and bromine to the atmosphere such as the VSLS methyl iodide (CH3I), bromoform (CHBr3), and dibromomethane (CH2Br2). They contribute to the halogen loading of the stratosphere if they are transported fast enough within, i.e., deep tropical convection. The tropical West Pacific and Indian Ocean are of special interest since the oceanic compounds of the VSLS are projected to have hot spots for both their emissions and transport pathways to the stratosphere. This study will give an overview of 10 years of research work on VSLS sources in the tropical oceans and their transport pathways and contribution to the stratospheric halogen level to answer the question. Poster (PDF)

December 14th |Roda Verheyen, Rechtsanwälte Günther, Hamburg

Climate change impacts – the role of the law: who is liable?  The example of the case Lliuya ./. RWE

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Roda Verheyen is a guest of Martin Claußen (MPI-M)

In this talk, lawyer Dr. Roda Verheyen will present the case of the Peruvian farmer Saúl Luciano Lliuya who took legal action against the energy company RWE. In his lawsuit he argues that Lake Palcacocha which is located above his hometown Huaraz in the Andes is at risk to “spill over” caused by glacier melting. In such a case his property would be damaged. Lliuya claims that this melting is caused by climate change which in turn RWE has contributed to through its operations. To protect his house, Lliuya has already invested in appropriate safety precautions. He now requests RWE to cover parts of his expenses – proportionate to RWE’s level of impairment.
Poster (PDF)

January 18th |Friederike Otto, University of Oxford, Environmental Change Institute, UK

Changing climate hazards across timescales – combining extreme event attribution and medium term climate projections

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Friederike Otto is a guest of Detlef Stammer (CEN)

Increasing risks of extreme weather events are the most noticeable and damaging manifestation of anthropogenic climate change. In the aftermath of an extreme event, policymakers are often called upon to make timely and sensitive decisions about rebuilding and managing present and future risks. Information regarding whether, where, and how present day and future risks are changing is needed to adequately inform these decisions. But this information is often not available and when it is, it is often not presented in a systematic way. A seamless approach to extreme event attribution and future risk assessment using the same set of model ensembles could be used to provide such information on past, present and future hazard risk... Read the Abstract (PDF)

January 25th |Laurent Bopp, LSCE, IPSL, France

The ocean carbon sink, today and tomorrow

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Laurent Bopp is a guest of Tatiana Ilyina (MPI-M)

The ocean is currently absorbing one quarter of all anthropogenic carbon emissions due to fossil fuel combustion and deforestation, thus significantly limiting the pace of increasing atmospheric CO2 and anthropogenic climate change. For the next decades, ocean models indicate that ocean carbon uptake will continue under all scenarios to 2100 (very high confidence, IPCC, 2013). There is also high agreement between models that climate change, through ocean warming and circulation changes, will partially offset this increase caused by rising atmospheric CO2.

Yet, there are still some severe inconsistencies between model simulations and carbon cycle observations over the last decades, very large regional differences in future projections performed with ocean carbon cycle models, and important processes that are still missing in the models. In this presentation, I review some of these shortcomings and present some on-going work aiming at resolving these issues, focusing on (1) unrepresented processes related to marine ecosystems, (2) the contribution of coastal ocean processes, and (3) the potential large variability in air-sea carbon fluxes, as shown by observations and underestimated by ocean models.

February 1st | Kevin Heng, University of Bern, Center for Space and Habitability

Remote Sensing of Exoplanetary Atmospheres

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Kevin Heng is a guest of Bjorn Stevens (MPI-M).

Short of interstellar travel, understanding the nature of exoplanets and potential habitats beyond the Solar System must necessarily proceed via remote sensing.  Specifically, the problem reduces to measuring and interpreting spectra of exoplanetary atmospheres, which is currently one of the frontier topics in astronomy and astrophysics.  The specific format of the data measured implies that the traditional methods of the Earth and planetary sciences cannot be imported without modification and generalisation.  In the current talk, I will focus on the physics of radiative transfer concerning transmission spectroscopy, which quantifies the variations in the amount of starlight occulted by an exoplanet, across wavelength, due to the varying opacity of its atmospheric constituents.


April 6th | Ken Caldeira, Carnegie Institution for Science, Stanford

Coral reefs, ocean acidification, and transformation of the global energy system

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

This talk will discuss our recent field work in Australia’s Great Barrier Reef in the ocean, acidification in the broader context of the global climate system, and the need for the development of near-zero emission global energy and transportation systems.

We have conducted the first-ever experiments in which a plume of water with high carbon dioxide concentrations was allowed to flow over a natural coral reef community without any artificial confinement. Our preliminary results indicate that the carbon dioxide harmed coral reef growth by increasing the rate of dissolution of the calcium carbonate minerals that make up much of the coral reef....Read the abstract (PDF).


April 13th | Chris Bretherton, University of Washington

Insights from high-resolution simulation of cloud feedbacks

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Cloud feedbacks are a leading source of uncertainty in the climate sensitivity simulated by global climate models (GCMs). Low-latitude boundary-layer and cumulus cloud regimes are particularly problematic, because they are sustained by tight interactions between clouds and unresolved turbulent circulations.This talk reviews cloud feedbacks simulated by high-resolution models that simulate the dominant cloud-forming eddy motions in such regimes...Read the Abstract (PDF)


April 20th | David Keith, Harvard University

Assessing and Reducing the Risks of Solar Geoengineering

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

I will discuss new results suggesting it may be possible to implement solar geoengineering using stratospheric aerosols without ozone loss while significantly reducing some other important side effects....Read the Abstract (PDF)


May 4th | Carl Friedrich Gethmann, Universität Siegen

Please note: The talk will be held in German.

Einige wissenschaftsphilosophische Fragen zur epistemischen Qualitätssicherung von Klimamodellen

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)


Die Herausforderungen der Menschheit durch „kollektive Handlungsprobleme von globalem Zuschnitt“, zu denen neben einer Reihe von anderen auch die Folgen der anthropogenen Erderwärmung gehören, erfordern einen neuen Typ von Wissenschaft, der unter unterschiedlichen Stichwörtern schon mehrfach beschrieben worden ist. Dabei steht die Wissenschaft unter besonderen Bedingungen des Nichtwissens (durch Ungewißheit, Unsicherheit und systematische Beschränktheit), die eine besondere methodologische Sorgfalt bei der Hypothesenbildung erfordern... kompletter Abstract (PDF)


May 11th | Kaoru Sato, University of Tokyo

An interplay of Rossby waves and gravity waves in the general circulation of the middle atmosphere

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

No Video available

The meridional circulation of the middle atmosphere is maintained by angular momentum deposition associated with waves. The summer-to-winter circulation in the mesosphere is mainly driven by gravity-wave forcing (GWF). However, GWF is not uniformly distributed, reflecting source distribution and filtering by Rossby waves...Read the Abstract (PDF)


May 18th | Dania Achermann, University of Aarhus

Changing Cultures of Climate Understanding: A historical perspective on climate modelling

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)
Today, climate research is dominated by the use of computer models. Introduced in the 1950s and 60s they have since gained high epistemic authority in producing climate knowledge. As this talk will show, the emergence of climate modelling as a hegemonic research tool and the shaping of modern climate science was not a linear development but a result of a competition between various approaches from different disciplines and “cultures” within climate research... Read the Abstract (PDF)


June 15th | Georg Kaser, University of Innsbruck

Glaciers under climate change

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Slide no. 11 had to be deleted since it has not been published yet.

There are approximately 200.000 individual glaciers globally, scattered from low-latitude high mountains to high-latitude islands and to the fringes of the ice sheets. Each one adapts to changing climate conditions individually, not only causing effects of different kind and magnitude but also telling different stories about the drivers for their change... Read the Abstract (PDF)


June 22th | Robert J. Nicholls, University of Southampton, UK

Climate change and sea-level rise: impact and adaptation on the coast

Time: 3:15 PM, Room 22/23 Bundesstraße 53 (ground floor)

Global mean sea-level rise is resulting in a range of impacts including increased flood risk and submergence, salinisation of surface and ground waters, and morphological change, such as erosion and wetland loss. The potential human and ecosystem impacts in the 21st Century are significant but uncertain. Actual impacts will depend on a range of change factors in addition to the amount of sea-level rise and climate change, including a number of factors which are human-controlled such as coastal land use and management approaches...Read the Abstract (PDF)

June 29th | Toshiro Tanimoto, University of California, CA

Seismic and acoustic waves in the whole Earth system

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Our study of the Earth has been compartmentalized by traditional disciplines such as atmospheric science, ocean science, and solid-earth science. However, seismic and acoustic waves refract and propagate through the whole Earth system, not being confined to any one of the medium...Read the Abstract (PDF)


November 3rd | Guy Brasseur, Max Planck Institute for Meteorology

A Multi-Model Analysis and Prediction System for Chemical Weather in Asia

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Several meteorological centers have extended the concept of “weather forecasting” to “environmental forecasting” with an important component that includes the daily prediction of "chemical weather” at the global to regional to local scales. Such models include a procedure to assimilate space and surface observations and a detailed formulation of surface exchanges (emissions and deposition)...Read the abstract (PDF).


 November 23rd, Wednesday | Hisashi Nakamura, RCAST, Tokyo University

Midlatitude warm ocean currents as climatic hotspots

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

The midlatitude ocean has been long believed to respond passively to atmosphere fluctuations, including remote influence from tropical variability like El Niño. Recent studies have nevertheless revealed active roles of the midlatitude ocean in the climate system. Unlike in vast areas of midlatitude ocean basins, warm western boundary currents, such as the Gulf Stream and Kuroshio... Read the Abstract (PDF)


December 1st | Valérie Masson-Delmotte, LSCE, France

From water molecules to climate - making sense of Greenland and Antarctic ice core records

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Records of water stable isotope ratios in ice core records are commonly used as qualitative proxies for past changes in temperature and moisture source characteristics, and I have worked to extract quantitative signals.
Recent findings have emerged from new methodologies to monitor water vapour stable isotopes. They challenge the classical interpretation of ice core records as precipitation signals, and the ability of atmospheric models equiped with water stable istopes to correctly capture the spatial structure of boundary layer vapour isotopic composition in the North Atlantic.
...Read the abstract.(PDF)



December 8th | Michael Riemer, Institut für Physik der Atmosphäre, Universität Mainz

Hurricanes and Rossby waves: Dynamics and predictability in the middle latitudes

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

The midlatitude climate is characterized by the ever-changing weather associated with the alternation of high and low-pressure systems. These surface pressure systems are associated with undulations of the midlatitude jet stream, so-called Rossby waves. Understanding the dynamics of Rossby waves is therefore fundamental to understanding the midlatitude weather.
In this presentation, we will first focus on the weather timescale. It will be demonstrated that moist processes play an important role in the amplification of the Rossby wave pattern...read the abstract.(PDF)


January 12th | Thomas Birner, Colorado State University

The changing width of Earth’s tropical belt

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Earth’s tropical belt can be defined by the band of rainy equatorial regions bordered by the arid subtropics to the north and the south. Converging near-surface trade winds transport moisture into the so-called Intertropical Convergence Zone, a meandering front of convection that brings rain to the equatorial latitudes and heats tropical air through the condensation of water vapor. This heated air rises through the troposphere and diverges poleward into the upper troposphere of both hemispheres, eventually subsiding in the subtropics, where it dries and stabilizes the atmosphere against convection. Because of the strong latitudinal gradients in temperature and precipitation at the edges of the tropical belt, any shift in its edges could drive major local changes in surface climate... Read the Abstract (PDF)


January 19th | Ottmar Edenhofer, Potsdam Institute for Climate Impact Research

Climate Policy and Trumponomics

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

Ottmar Edenhofer is Professor of the Economics of Climate Change at the TU Berlin - Berlin Institute of Technology and Deputy Director as well as Chief Economist at the Potsdam Institute for Climate Impact Research.

His research work is concentrating on strategies to mitigate climate change, questions of growth- and development theory, public finance, questions of distributional effects of climate policy instruments, game theoretic aspects of designing international agreements and last but not least energy economic aspects. He specializes in the Economics of Atmospheric Stabilization, Social Cost-Benefit Analysis, Sustainability Theory, Economic Growth Theory, Environmental Economics, Welfare Theory and General Intertemporal Equilibrium Theory.

In addition to his teaching and research, he is actively involved in public policy and in the public debate in Germany and at EU level. Until 2009 he was key climate change advisor to federal foreign minister and deputy-chancellor Frank-Walter Steinmeier.

January 26th | Sami K. Solanki, Max Planck Institute for Solar System Research, Göttingen

The Sun's Magnetic Field and Variability

Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)


The single quantity responsible for the continuing unrest and activity of the Sun is its tangled and dynamic magnetic field. It produces many fascinating phenomena, including changes in the Sun's radiative output, which has been invoked as a driver of the Earth's climate and a contributor to global change. In this talk some aspects of the magnetic field of the Sun will be introduced and a few recent advances in our knowledge will be presented. Brief descriptions of the Sunrise and Solar Orbiter missions will also be provided. In the second half of the talk, measurements and magnetic field-based models of solar irradiance variability will be outlined and some recent advances will be presented. Abstract (PDF)

February 2nd | Gerald Haug, Max-Planck-Institut for Chemistry, Mainz


Time: 3:15 PM, Room 22/23 Bundestraße 53 (ground floor)

In the publication to be presented, we argue for a pervasive link between cold climates and polar ocean stratification (Haug et al., 1999; Sigman et al., 2004, 2007). In both the Subarctic North Pacific and the Antarctic Zone of the Southern Ocean, ice ages were marked by low productivity (Figs. 1 and 2, Jaccard et al. 2010, 2013). The accumulated evidence from sediment cores points to an increase in density stratification that reduced the supply of nutrients from the ocean interior into the sunlit surface in both of these regions. Read the Abstract (PDF)



April 7th | David W. J. Thompson, Colorado State University

"Quantifying the role of internal variability in climate change"

Internal climate variability gives rise to substantial uncertainty in projections of future climate change. One popular method for estimating the uncertainty in future climate due to internal climate variability is to run "large ensembles" of climate change simulations, in which all aspects of the experiment set-up are held fixed from one ensemble member to the next but for small changes in the initial atmospheric state...read the abstract


April 28th | Geoffrey Vallis, University of Exeter

"Response of the General Circulation of the Atmosphere to Global Warming"

Global warming is one of the least controversial phenomena in science. We are as sure that it is happening, and what the main cause is, as we are about almost anything. Unfortunately, this knowledge does not translate to being able to predict what will happen to the climate and weather. The thermodynamic response is well understood ...read the abstract


May 12th | Jack Katzfey, CSIRO - Oceans and Atmosphere

"Using Regional Climate Projections for Asia and the Pacific"

Access to scientifically credible climate change information and guidelines have been identified as strong impediments for the robust assessment of risks related to climate change and for effective adaptation planning. To support better knowledge of and adaptation to climate change risks, the Asian Development Bank funded a project for Indonesia, Philippines, and Thailand ...read the abstract


May 26th | John Broome, University of Oxford

"Climate change: life and death"

Climate change raises important and difficult issues of ethics. Broadly they fall into two classes. There are issues of justice concerned with how the effort of dealing with climate change should be shared among countries and people. And there are issues of value concerned with judging the harm that climate change will do, and the benefits of measures to control it ...read the abstract


June 30th | Weiqing Han, University of Colorado at Boulder

"Regional decadal sea level variability associated with internal climate modes"

Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Regionally, SLR can deviate considerably from the global mean due to various geophysical processes, including changes of ocean circulations, which can be partly attributed to natural, internal climate modes of the climate system. ...read the abstract


July 14th | Sonia Seneviratne, ETH Zürich

"Determining allowable CO2 emissions from regional- and impact-related climate targets: The role of land processes"

Global temperature targets, such as the widely accepted “2° target”, may fail to communicate the urgency of reducing CO2 emissions because they are disconnected from their implications. The translation of CO2 emissions into regional- and impact-related climate targets is more powerful because such targets are more directly aligned with individual national interests. ...read the abstract

October 29th | Prof. Alan Plumb, MIT, USA 

"Dynamical Climate Perturbations and the Fluctuation-Dissipation Theorem"

Models indicate that much of the dynamical response of the atmosphere to imposed perturbations displays the same spatial patterns as those that dominate temporal fluctuations of the unperturbed climate. E.g., model responses to both increased GHGs and Antarctic ozone depletion show a poleward shift of the midlatitude jet in the southern hemisphere, ...read the abstract.


November 12th | Prof. Matt McDonald, University of Queensland, Australia

"Ethics and Climate Security"

The way the relationship between climate change and security is understood in academic and policy circles varies significantly, with different discourses of climate security encouraging different policy responses. Given these differences, it becomes important to identify progressive security discourses: discourses underpinned by defensible ethical assumptions and encouraging effective practical responses to environmental change ...read the abstract.


November 26th | Prof. Rupert Klein, Freie Universität Berlin

"Multiscale asymptotics, balanced models and related numerics"

Atmospheric flows cover spatio-temporal scales from raindrops to the Madden-Julian-Oscillation. Theoretical meteorology offers reduced descriptions of scale-dependent phenomena that capture the underlying dominant balances and mechanisms. Part I of the lecture will cover a systematization of such reduced models based on asymptotic analysis ...read the abstract.


December 3rd | Prof. Peter Thorne, Maynooth University

"GAIA-CLIM: Improving the usefulness and utility of non-satellite data for satellite characterisation"

The aim of the Gap Analysis for Integrated Atmospheric ECV CLImate Monitoring (GAIA-CLIM) project is to improve our ability to use ground-based and sub-orbital observations to characterise
satellite observations for a number of atmospheric Essential Climate Variables (ECVs) ...read the abstract.


January 14th | Dr. Edwards, The Open University

"Quantifying uncertainty in Antarctic ice sheet instability"

Antarctic marine ice sheet instability (MISI) – a proposed self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes – may have the potential to cause substantial sea level rise ...read the abstract.


January 21st | Prof. Oschlies, GEOMAR

"Climate Engineering – research and responsibility"

The realization that mitigation efforts have, until now, been relatively ineffective in slowing down the speed of atmospheric CO2 increase, has led to an increasing interest in climate engineering as a possible means of preventing potentially dangerous consequences of climate change ...read the abstract.


January 28th | Prof. Joos, University of Bern

"The carbon cycle in the Earth System: a few research examples"

Ice core and other proxy records, modern measurements, and model projections show us the fascinating variability of the global carbon cycle in the Earth System. Variations in atmospheric CO2 provide a key feedback forcing glacial-interglacial climate swings ...read the abstract.

Dr. Dmitry Kovalevsky, Nansen International Environmental and Remote Sensing Centre, Russia | Lecture held on April 09th 2015

"Addressing Positive Feedbacks and Impacts of Abrupt Climate Change in Actor-Based System Dynamics Integrated Assessment Models"

The lecture presents an actor-based system dynamics approach to modelling the coupled climate–socioeconomic system. The evolution of the modeled economy is governed by the interactions of a few key aggregated actors (a firm, household, government, bank etc.) pursuing individual, often conflicting, goals. The economy is treated as a nonlinear system described by ...read the abstract.


Prof. Dong-Jiing Doong, National Cheng-Kung University in Tainan, Taiwan | Lecture held on April 16th 2015

"Typhoon Impacts on the Coast of Taiwan under Climate Change"

Taiwan, located in the Western Pacific between mainland China, Japan and Philippines, faces the impacts of typhoons frequently. The 1139 km long coastline is one of the vulnerable areas of the island, where more than 90% of the Taiwanese population lives. Scientific numbers show the warming trend in Taiwan is significant. The increase of mean temperature, rainfall intensity and sea level rise are higher than ...read the abstract.


Prof. David Marshall, University of Oxford, United Kingdom | Lecture held on April 23rd 2015

"The Fundamental Role of the Southern Ocean in Global Climate"

Over the past two decades, a paradigm shift has occurred in our under-standing of the global ocean circulation and its impact on global climate, with the Southern Ocean and its turbulent eddies playing pivotal roles. In this talk, I will explain how the simple dynamical balances in the Southern Ocean exert a ...read the abstract (PDF).


April 30th | Dr. Folkard Wittrock, IUP, Universität Bremen

 "Air Emissions from International Shipping"

This lecture provides an overview on the contribution of international shipping on air quality problems and climate change. The first part covers the current knowledge of this contribution on global scale and explains the current legislation to reduce these effects …read the abstract.




Dr. Cécile Blanchet, GEOMAR, Kiel | Lecture held on May 7th 2015

The Nile River during the Holocene: Environment, Climate and the Humans

As being one of the longest rivers on Earth, and having nurtured the development of highly complexhuman societies, the Nile River is a key location to study the environment-human interactions, and the response of the geosystem to climatic changes. In this regard, the Holocene period is a particularly relevant time interval as it encompasses large-scale environmental changes, such as the waxing and waning of the so-called Green Sahara as well as crucial evolutions in human populations ...read the abstract (PDF).


Prof. Vally Koubi,  ETH Zürich, Switzerland | Lecture held on May 21st 2015

Environmental Change and Migration

Environmentally induced migration has gained a lot of attention in the climate change context. While there is a broad consensus that environ-mental factors might play an important role on human mobility, the ex post empirical evidence is inconclusive. We contribute to the emerging empirical literature in this fi eld by focusing on the micro-level ...read the abstract (PDF).


Prof. Helmuth Thomas,  Dalhousie University, Canada | Lecture held on May 28th 2015

Regulation of CO2 air-sea fluxes and pH in the North Sea

In 2001, a large scale multiannual study of the CO2 and pH system of the North Sea has been initiated, comprising basinwide observations in 2001, 2002, 2005, 2008 and 2011, and complementing modelling activities. The ongoing studies have been carried out by an international consortium, comprising colleagues from Germany, The Netherlands, Belgium and Canada. These investigations describe the North Sea, as part of the NW European Shelf, as a strong continental shelf pump, facilitated through ...read the abstract.

18. Juni
Costs and Benefit of Climate Change Adaptation in Germany
Dr. Jesko Hirschfeld, Institut für ökologische Wirtschaftsforschung (IÖW) Berlin

Prof. Ted Shepherd,  University of Reading, United Kingdom | Lecture held on June 4th 2015

Atmospheric circulation as a source of uncertainty in climate change projections

The evidence for anthropogenic climate change continues to strengthen, and concerns about severe weather events are increasing. As a result, scientific interest is rapidly shifting from detection and attribution of global climate change to prediction of its impacts at the regional scale. However, nearly everything we have any confidence in when it comes to climate change is related to global patterns of ...read the abstract.


Dr. Christoph Krupp, Senatskanzlei Hamburg, Germany | Lecture held on June 25th 2015

Klimaforschung, Klimaschutz und die Politik in Hamburg und Berlin

Hamburg ist das wichtigste Zentrum der Klimaforschung in Deutschland und deshalb auch für den Hamburger Senat ein Schwerpunktbereich der Wissenschaftspolitik. Die Hamburger Klimaforscher haben aber auch immer wieder Anstöße für das politische Handeln gegeben und ...read the abstract.


Prof. Sarah Jones, Deutscher Wetterdienst, Germany | Lecture held on July 2nd 2015

Seamless Prediction from Minutes to Months: Recent Advances and Future Challenges

Advances in weather prediction during the last few decades have led to major changes in our ability to provide useful and timely warnings when high impact weather events threaten life, property, business or the environment. Skillful predictions can be made in some cases beyond ten days. Detailed forecasts of the structure ...read the abstract.


Dr. Scott St. George, University of Minnesota, USA | Lecture held on July 9th 2015

Large-Scale Dendrochronology and Low-Frequency Climate Variability

Large-scale Low-frequency variability has emerged as a priority for cli-mate research, but instrumental observations are not long enough to characterize this behavior or gage its impacts on dependent geophysical or ecological systems. As the leading source of high-resolution paleocli-mate information in the middle- and high-latitudes, tree rings are es-sential to ...read the abstract.



Prof. Dr. Konrad Ott, Christian-Albrechts-Universität Kiel | Lecture held on October 23rd 2014

The Ten Domains of Climate Ethics

The lecture provides an overview of the current state in climate ethics. It distinguishes different domains of climate ethics and ...read the abstract (PDF)



Prof. Brian Soden, Rosenstiel School of Marine and Atmospheric Science Miami | Lecture held on November 6th 2014

Mechanisms of Regional Precipitation Change from Anthropogenic Forcing

Few quantities are of greater importance in climate projections than regional precipitation. This talk will use a hierarchy of climate model simulations to examine key processes that control changes in regional precipitation ...read the abstract (PDF).


Prof. Tapio Schneider, ETH Zürich | Lecture held on November 13th 2014

Dynamics, Migrations an Bifurcations of the Intertropical Convergence Zone

Rainfall on Earth is most intense in the intertropical convergence zone (ITCZ), a narrow belt of clouds centered on average around six degrees north of the Equator. On seasonal and longer timescales, the ITCZ migrates, typically toward a warming hemisphere but with exceptions ...read the abstract (PDF).


Prof. Petra Schweizer-Ries, Hochschule Bochum | Lecture held on November 20th 2014

Conflict Resolution in the Field of Energy Transformation from an Environmental Psychological Perspective

The lecture will work on the three topics: (A) conflict solution in the (B) German energy transitions from (C) a mainly environmental psychological perspective. It will structure the issue of social acceptance of renewable energy production and use, including the discussions ...read the abstract (PDF).


Dr. Olivier Boucher, Laboratoire de Météorologie Dynamique | Lecture held on December 04th 2014

From Aerosol Forcing to Climate Sensitivity

The radiative forcing by aerosols remains a very uncertain quantity, which prevents an unambiguous estimate of the climate sensitivity from the observational record of surface temperature. In this talk we will revisit the radiative forcing by black carbon aerosols and explain ...read the abstract (PDF).


Prof. Mike Hulme, King's College London | Lecture held on December 11th 2014

The Dangers of Climate Emergencies

Emergencies are dramatic, crisis-fuelled constructions, and they can take on many shapes and guises: humanitarian, public health, security, environmental, political. Emergencies and the language and imagery they conjure shape the way we see the world, our place in it and the possibilities ...read the abstract (PDF).


Klaus Maurer, Leiter der Berufsfeuerwehr Hamburg, Behörde für Inneres und Sport der Stadt Hamburg | Lecture held on December 18th 2014

If Natural Disasters Wreak Havoc: The United Nations Assessment and Coordination Team (UNDAC) - Organisation, Methodology and Requirements for Support

Natural disasters such as earth quakes, volcano eruptions and hurricanes do not only claim dead or injured people, they also often damage the infrastructure. It is the task of the UNDAC team as the fi rst foreign rescue crew to go to the crisis area and ...read the abstract (PDF).


Prof. Darrel Moellendorf, Cluster of Excellence “Normative Orders”, Goethe Universität Frankfurt am Main | Lecture held on January 15th 2015

Energy Poverty and Dangerous Climate Change

The chief objective of the United Nations Framework Convention on Climate Change is to prevent “dangerous anthropogenic interference in the climate system” (Article 2). Attempts by natural and social scientists to identify dangerous climate change have failed to appreciate that danger ...read the abstract (PDF).


Prof. Gregory Flato, Canadian Centre for Climate Modelling and Analysis (Victoria, BC) | Lecture held on January 22nd 2015

The Changing Arctic: From Science to Scenarios

The Arctic is experiencing climate change that is much larger and more rapid than the global mean. This is having, and will continue to have, profound impacts on the ecology, inhabitants and industry. Adaptation will be necessary, and ...read the abstract (PDF).


Prof. Pavel Kabat, Director General and CEO of the International Institute for Applied Systems Analysis (IIASA), Austria | Lecture held on January 29th 2015

Principles and Benefits of Systems Science: The Case of the International Institute for Applied Systems Analysis (IIASA)

This International Institute for Applied Systems Analysis was created in the peak of the Cold War during the 1970s and it became a world leading institute for trans-disciplinary and cross-sectorial systems science applied towards multiple aspects of global and regional transformations ranging from environment, energy and climate to ...read the abstract (PDF).


15. August
Climate Risk Management in the Anthropocene:
From Basic Science to Decisionmaking (and Back)

Prof. Klaus Keller, FH Potsdam

10. Juli
Reconsidering the Relationship between Climate Science and Policy-Making
Dr. Oliver Geden, Stiftung Wissenschaft und Politik

03. Juli
Clouds, Aerosols and Climate
Dr. Andrew Gettelman, University of Washington

Dr. Philippe Ciais, Laboratoire des Sciences du Climat et de l'Environnement Paris | Lecture held on June  26th 2014

Attribution of Climate Change to Long-Lived and Short-Lived Forcers

A simple, but fully coupled model is used to attribute the climate feedbacks of temperature changes induced by emissions of a range of long-lived greenhouse gases and short-lived species, aerosols and tropospheric ozone precursors... read the abstract (PDF).



Prof. Dr. Frank Biermann, Vrije Universiteit Amsterdam | Lecture held on June 19th 2014

Earth System Governance: World Politics in the Anthropocene

The presentation critically discusses current conceptual developments in the field of global environmental governance, including new paradigms such as the “Anthropocene”, “planetary boundaries”, and “earth system governance”... read the abstract (PDF).



Prof. Dr. Yukio Tamura, Tokyo Polytechnic University | Lecture held on June 5th 2014

Wind Resistant Design of Tall Buildings and Relevant Emerging Issues

The lecture discusses various topics related to wind-resistant design of buildings and structures. Starting from some historical matters including statistics of economic and human losses... read the abstract. (PDF)


30. Januar
How geoengineering might work in practice
Prof. Piers Forster, University of Leeds

23. Januar
Ensemble Variational Assimilation and Bayesian Estimation
Prof. Olivier Talagrand, Directeur de Recherche Emerite au CNRS Laboratoire de Météorologie Dynamique École Normale Supérieure

09. Januar
From climate change to social change: Directions for future social science research and science-policy interactions
Prof. Dr. Peter P.J. Driessen, Utrecht University / Foundation Knowledge for Climate
Utrecht, The Netherlands

05. Dezember
Leviathan in the Greenhouse: controlling climate change without extending state
Prof. Myles Allen, University of Oxford, School of Geography and the Environment

21. November
Future Directions for the World Climate Research Programme:
Grand Challenges for the Decade Ahead

Prof. Antonio J. Busalacchi, University of Maryland

14. November
Balancing the needs for climate change mitigation and food security
Prof. Pete Smith, University of Aberdeen

07. November
The recent global surface temperature record and its implications for future changes
Prof. Jochem Marotzke, MPI-M

31. Oktober
Post IPCC AR5 – Where Next for Climate Science?
Prof. Dr. Julia Slingo, University of Reading

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