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Project: Literature - Literature e.g. grey literature Summary: The "Jahrbuch 2020-2021" gives an overview of DKRZ's activities in 2020 and 2021. It summarizes the results of important completed projects and takes a look at ongoing and newly started projects. The two main topics of the Yearbook 2020-2021 are the Nobel Prize in Physics 2021 for Prof. Klaus Hasselmann and his influence on the development of DKRZ, and DKRZ's new supercomputer "Levante" (HLRE-4), which was installed at the end of 2021. The pdf documents may be freely downloaded and used. Re-use of single parts (i.e. pictures) is only permitted for non-commercial purposes - except for those pictures that are copyrighted by commercial stock photo agencies. Details can be found in the corresponding picture credits ("Bildnachweis"). For any commercial use, a written agreement of DKRZ is required. Copyright: DKRZ (Creative Commons: CC BY-NC-ND 4.0). The yearbook is also available under the following link: https://www.dkrz.de/pdfs/downloads/dkrz_jahrbuch_2020-2021_web.pdf

The Scenario Model Intercomparison Project (ScenarioMIP) defines and coordinates the main set of future climate projections, based on concentration-driven simulations, within the Coupled Model Intercomparison Project phase 6 (CMIP6). This paper presents a range of its outcomes by synthesizing results from the participating global coupled Earth system models. We limit our scope to the analysis of strictly geophysical outcomes: Mainly global averages and spatial patterns of change for surface air temperature and precipitation. We also compare CMIP6 projections to CMIP5 results, especially for those scenarios that were designed to provide continuity across the CMIP phases, at the same time highlighting important differences in forcing composition, as well as in results. The range of future temperature and precipitation changes by the end of the century (2081-2100) encompassing the Tier 1 experiments based on the Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) and SSP1-1.9 spans a larger range of outcomes compared to CMIP5, due to higher warming (by close to 1.5-C) reached at the upper end of the 5 %-95% envelope of the highest scenario (SSP5-8.5). This is due to both the wider range of radiative forcing that the new scenarios cover and the higher climate sensitivities in some of the new models compared to their CMIP5 predecessors. Spatial patterns of change for temperature and precipitation averaged over models and scenarios have familiar features, and an analysis of their variations confirms model structural differences to be the dominant source of uncertainty. Models also differ with respect to the size and evolution of internal variability as measured by individual models' initial condition ensemble spreads, according to a set of initial condition ensemble simulations available under SSP3-7.0. These experiments suggest a tendency for internal variability to decrease along the course of the century in this scenario, a result that will benefit from further analysis over a larger set of models. Benefits of mitigation, all else being equal in terms of societal drivers, appear clearly when comparing scenarios developed under the same SSP but to which different degrees of mitigation have been applied. It is also found that a mild overshoot in temperature of a few decades around mid-century, as represented in SSP5-3.4OS, does not affect the end outcome of temperature and precipitation changes by 2100, which return to the same levels as those reached by the gradually increasing SSP4-3.4 (not erasing the possibility, however, that other aspects of the system may not be as easily reversible). Central estimates of the time at which the ensemble means of the different scenarios reach a given warming level might be biased by the inclusion of models that have shown faster warming in the historical period than the observed. Those estimates show all scenarios reaching 1.5-C of warming compared to the 1850-1900 baseline in the second half of the current decade, with the time span between slow and fast warming covering between 20 and 27 years from present. The warming level of 2-C of warming is reached as early as 2039 by the ensemble mean under SSP5-8.5 but as late as the mid-2060s under SSP1-2.6. The highest warming level considered (5-C) is reached by the ensemble mean only under SSP5-8.5 and not until the mid-2090s.

Project: Literature - Literature e.g. grey literature Summary: The issue 'Jahrbuch 2016-2017' focuses on the final phase of DKRZ's supercomputer 'Mistral' for the simulations of clouds and precipitation using weather and climate models (only available in German, published in July 2018). The pdf documents may be freely downloaded and used. Re-use of single parts (i.e. pictures) is only permitted for non-commercial purposes - except for those pictures that are copyrighted by commercial stock photo agencies. Details can be found in the corresponding picture credits ('Bildnachweis'). For any commercial use, a written agreement of DKRZ is required. Copyright: DKRZ (Creative Commons: CC BY-NC-ND 4.0). The yearbook is also available under the following link: https://www.dkrz.de/pdfs/downloads/dkrz-jahrbuch-2016-17?lang=de