Description: Selecting a climate model subset to optimise key ensemble properties Nadja Herger, Gab Abramowitz, Reto Knutti, Oliver Angélil, Karsten Lehmann, and Benjamin M. Sanderson Earth Syst. Dynam., 9, 135-151, https://doi.org/10.5194/esd-9-135-2018, 2018 Users presented with large multi-model ensembles commonly use the equally weighted model mean as a best estimate, ignoring the issue of near replication of some climate models. We present an efficient and flexible tool that finds a subset of models with improved mean performance compared to the multi-model mean while at the same time maintaining the spread and addressing the problem of model interdependence. Out-of-sample skill and reliability are demonstrated using model-as-truth experiments.

Description: Tagging moisture sources with Lagrangian and inertial tracers: Application to intense atmospheric river events Vicente Pérez-Muñuzuri, Jorge Eiras-Barca, and Daniel Garaboa-Paz Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2018-8,2018 Manuscript under review for ESD (discussion: open, 1 comment) Two Lagrangian tracers tools are evaluated for studies on atmospheric moisture sources and pathways. Usual Lagrangian methods consider the initial moisture volume to remain constant and the particle follows flow path lines exactly. In a different approach, the initial volume can be considered to depend on time as it is advected by the flow, due to thermodynamic processes. Drag and buoyancy forces must be considered then.

Description: A framework for modelling the complexities of food and water security under globalisation Brian J. Dermody, Murugesu Sivapalan, Elke Stehfest, Detlef P. van Vuuren, Martin J. Wassen, Marc F. P. Bierkens, and Stefan C. Dekker Earth Syst. Dynam., 9, 103-118, https://doi.org/10.5194/esd-9-103-2018, 2018 Ensuring sustainable food and water security is an urgent and complex challenge. As the world becomes increasingly globalised and interdependent, food and water management policies may have unintended consequences across regions, sectors and scales. Current decision-making tools do not capture these complexities and thus miss important dynamics. We present a modelling framework to capture regional and sectoral interdependence and cross-scale feedbacks within the global food system.

Description: Assessing the Impact of a Future Volcanic Eruption on Decadal Predictions Sebastian Illing, Christopher Kadow, Holger Pohlmann, and Claudia Timmreck Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2018-5,2018 Manuscript under review for ESD (discussion: open, 0 comments) The likelihood of a large volcanic eruption in the future provides the largest uncertainty concerning the evolution of the climate system on the time scale of a few years; but also an excellent opportunity to learn about the behavior of the climate system, and our models thereof. So the question emerges how predictable is the response of the climate system to future eruptions? By this we mean, to what extent will the volcanic perturbation affect decadal climate predictions and how does the pre-eruption climate state influence the impact of the volcanic signal on the predictions? To address these questions, we performed decadal forecasts with the MiKlip prediction system in the low-resolution configuration for the initialization years 2012 and 2014, which differ in the Pacific Decadal Oscillation (PDO) phase among other things. Each forecast contains an artificial Pinatubo-like eruption starting in June of the first prediction year. For the construction of the aerosol radiative forcing, we used the global aerosol model ECHAM5-HAM in a version adapted for volcanic eruptions. We investigate the response of different climate variables, including near-surface air temperature, precipitation, frost days, and sea ice area fraction. Our results show that the average global cooling response over four years of about 0.2 K and the precipitation decrease of about 0.025 mm/day, is relatively robust throughout the different experiments and seemingly independent of the initialization state. However, on a regional scale, we find substantial differences between the initializations. The cooling effect in the North Atlantic and Europe lasts longer and the Arctic sea ice increase is stronger than in the simulations initialized in 2014. In contrast, the forecast initialized with a negative PDO shows a prolonged cooling in the North Pacific basin.

Description: Systematic Correlation Matrix Evaluation (SCoMaE) – a bottom–up, science-led approach to identifying indicators Nadine Mengis, David P. Keller, and Andreas Oschlies Earth Syst. Dynam., 9, 15-31, https://doi.org/10.5194/esd-9-15-2018, 2018 The Systematic Correlation Matrix Evaluation (SCoMaE) method applies statistical information to systematically select, transparent, nonredundant indicators for a comprehensive assessment of the Earth system state. We show that due to changing climate forcing, such as anthropogenic climate change, the ad hoc assessment indicators might need to be reevaluated. Within an iterative process, this method would allow us to select scientifically consistent and societally relevant assessment indicators.

Description: How Robust is Your System Resilience? Mehran Homayounfar, Rachata Muneepeerakul, and John M. Anderies Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2017-124,2018 Manuscript under review for ESD (discussion: open, 1 comment) For many complex social-ecological systems, robustness and resilience are difficult to quantify and the connections and trade-offs between them difficult to study. In this study, we present an analytical framework to address the linkage between robustness and resilience more systematically. The results reveal the tradeoffs between robustness and resilience. They also show how the nature of such tradeoffs varies with the choices of certain policies internal stresses and external disturbances.

Description: Earth system modelling with complex dynamic human societies: the copan:CORE World-Earth modeling framework Jonathan F. Donges, Jobst Heitzig, Wolfram Barfuss, Johannes A. Kassel, Tim Kittel, Jakob J. Kolb, Till Kolster, Finn Müller-Hansen, Ilona M. Otto, Marc Wiedermann, Kilian B. Zimmerer, and Wolfgang Lucht Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2017-126,2018 Manuscript under review for ESD (discussion: open, 0 comments) We present an open source software library for developing so-called World-Earth models that link physical, chemical and biological processes with social, economic and cultural processes to study the Earth system's future in the Anthropocene. Due to its modular structure, the software allows interdisciplinary studies of global change and sustainable development that combine stylized model components from Earth system science, climatology, economics, ecology, or sociology.

Description: Irreversible ocean thermal expansion under carbon dioxide removal Dana Ehlert and Kirsten Zickfeld Earth Syst. Dynam., 9, 197-210, https://doi.org/10.5194/esd-9-197-2018, 2018 This study uses a global climate model to explore the extent to which sea level rise due to thermal expansion of the ocean is reversible if the atmospheric concentration of carbon dioxide (CO 2 ) declines. It is found that sea level continues to rise for several decades after atmospheric CO 2 starts to decline and does not return to the pre-industrial level for over thousand years after atmospheric CO 2 is restored to the pre-industrial concentration.

Description: Contribution of atmospheric circulation to recent off-shore sea-level variations in the Baltic Sea and the North Sea Sitar Karabil, Eduardo Zorita, and Birgit Hünicke Earth Syst. Dynam., 9, 69-90, https://doi.org/10.5194/esd-9-69-2018, 2018 We analysed the contribution of atmospheric factors to interannual off-shore sea-level variability in the Baltic Sea region. We identified a different atmospheric circulation pattern that is more closely linked to sea-level variability than the NAO. The inverse barometer effect contributes to that link in the winter and summer seasons. Freshwater flux is connected to the link in summer and net heat flux in winter.The new atmospheric-pattern-related wind forcing plays an important role in summer.

Description: Causal dependences between the coupled ocean-atmosphere dynamics over the Tropical Pacific, the North Pacific and the North Atlantic Stéphane Vannitsem and Pierre Ekelmans Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2018-3,2018 Manuscript under review for ESD (discussion: open, 1 comment) The El-Nino-Southern-Oscillation phenomenon is a slow dynamics present in the coupled ocean-atmosphere tropical Pacific system which has important teleconnections with the northern extratropics. These teleconnections are usually believed to be the source of an enhanced predictability in the northern extratropics at seasonal to decadal time scales. This question is challenged by investigating the causality between these regions using an advanced technique known as Convergent Cross Mapping.