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The increase in heatwave intensity, causing heat stress and crop failures in many regions is a concerning impact of global climate change. In northern Europe, significant interannual variability previously prevented robust assessments of trends in heat extremes. However, with a large-ensemble seasonal hindcasts and archived forecasts dataset covering 1981–2022 multiple realisations of weather patterns can be pooled and assessed. What are recent trends of extreme temperatures? Has the risk for a 100-year heatwave event increased in Northern Europe? We apply the UNSEEN (UNprecedented Simulated Extremes using ENsembles) approach to assess the credibility of the model ensemble and use non-stationary extreme value analysis to quantify recent trends in extreme 3-day heatwaves in late spring and early summer (May to July). We find significant non-stationarity and positive trends in annual maximum heatwave intensity. We also show that heatwave volatility, i.e. the risk of clearly outstanding heatwaves, is highest in central Scandinavia.

Purpose: A systematic literature review has neglected for years in both national and international vocational educational and training (VET) policy research. Recently, scholarly interest in and the need for such a review has increased rapidly. This review introduces the application of the systematic literature review method, with a focus on research work completed in European VET policy. Approach: To investigate the value and applicability of the systematic literature review method in European VET policy research, we conducted a pilot study following the guidelines and procedures presented by Gessler and Siemer. Findings: First, the process of conducting a literature review and its major methodological steps are described, followed by a descriptive analysis of the sample and characteristics of the studies reviewed. Second, initial insights into the research methodology and the topics that emerged during its application are presented. Altogether, we documented a first attempt to systematize research on European VET policy, including lessons learned from conducting a systematic literature review. Conclusion: The review revealed that although research on international European VET policy research has increased in recent years, hardly any systematization of the current research has been proposed. Instead, most research has been limited to identifying specific country-related factors. By comparison, we propose a systematic approach to reviewing research on European VET policy, being well aware of the strengths and limitations of the proposed method and the results. Thus, this systematic review presents a substantial starting point and research agenda for further studies on this topic.

The seven articles in this special issue represent a wide range of international comparative and review studies by international research teams from China, Germany, India, Russia, Switzerland and Mexico. The presented projects are part of the national program "Research on the Internationalisation of Vocational Education and Training", funded by the German Federal Ministry of Education and Research (BMBF). An adapted version of Urie Bronfenbrenner’s ecological systems theory forms the conceptual framework of the special issue. The four system levels (micro, meso, exo and macro) are addressed by one article each. The article on the microsystem level focuses on the intended and implemented curricula in a cross-country comparison of China and Russia. The article on the mesosystem level aims at the development of a quality management model for vocational education and training (VET) institutions in India. At the exolevel, the regional structures of the education and employment systems in Mexico, particularly the cooperation between schools and companies in the hotel industry, are investigated. At the macrosystem level, the social representation of non-academic labour in Mexico is examined in terms of cultural artefacts. Furthermore, three overarching review studies systematise relevant research developments and approaches. The topics of the three review studies are European VET policy, transfer of VET and VET research. The scope ranges from the development of a comparative research tool to a summary analysis of over 5,000 individual publications. Given the broad scope and heterogeneity of the findings, a summative conclusion would hardly be appropriate. Nevertheless, with regard to the model of the ‘triadic conception of purposes in comparative VET research’ that represents a heuristic for describing the purposes of international VET research, we conclude with an emphasis on a need of more criticality. In this context, one finding can be pointed out as an example: One review study found that most studies (here, with reference to VET transfer) refer to the recipient country without a comparative perspective. Thus, there is a clear demand for more comparative research following a critical-reflective approach.

There is a wide consensus within the polar science, meteorology, and oceanography communities that more in situ observations of the ocean, atmosphere, and sea ice are required to further improve operational forecasting model skills. Traditionally, the volume of such measurements has been limited by the high cost of commercially available instruments. An increasingly attractive solution to this cost issue is to use instruments produced in-house from open-source hardware, firmware, and postprocessing building blocks. In the present work, we release the next iteration of our open-source drifter and wave-monitoring instrument, which follows these solution aspects. The new design is significantly less expensive (typically by a factor of 5 compared with our previous, already cost-effective instrument), much easier to build and assemble for people without specific microelectronics and programming competence, more easily extendable and customizable, and two orders of magnitude more power-efficient (to the point where solar panels are no longer needed even for long-term deployments). Improving performance and reducing noise levels and costs compared with our previous generation of instruments is possible in large part thanks to progress from the electronics component industry. As a result, we believe that this will allow scientists in geosciences to increase by an order of magnitude the amount of in situ data they can collect under a constant instrumentation budget. In the following, we offer (1) a detailed overview of our hardware and software solution, (2) in situ validation and benchmarking of our instrument, (3) a fully open-source release of both hardware and software blueprints. We hope that this work, and the associated open-source release, will be a milestone that will allow our scientific fields to transition towards open-source, community-driven instrumentation. We believe that this could have a considerable impact on many fields by making in situ instrumentation at least an order of magnitude less expensive and more customizable than it has been for the last 50 years, marking the start of a new paradigm in oceanography and polar science, where instrumentation is an inexpensive commodity and in situ data are easier and less expensive to collect.

Arctic stratospheric ozone depletion is closely linked to the occurrence of low stratospheric temperatures. There are indications that cold winters in the Arctic stratosphere have been getting colder, raising the question if and to what extent a cooling of the Arctic stratosphere may continue into the future. We use meteorological reanalyses from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim and NASA's Modern-Era Retrospective-Analysis for Research and Applications (MERRA) for the past 32 yr together with calculations of the chemistry-climate model (CCM) ECHAM/MESSy Atmospheric Chemistry (EMAC) and models from the Chemistry-Climate Model Validation (CCMVal) project to infer radiative and dynamical contributions to long-term Arctic stratospheric temperature changes. For the past three decades the reanalyses show a warming trend in winter and cooling trend in spring and summer, which agree well with trends from the Radiosonde Innovation Composite Homogenization (RICH) adjusted radiosonde data set. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a residual radiatively induced cooling. Stratospheric radiatively induced cooling is detected throughout all seasons, being highly significant in spring and summer. This means that for a given dynamical situation, according to ERA-Interim the annual mean temperature of the Arctic lower stratosphere has been cooling by −0.41 ± 0.11 K decade−1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model qualitatively reproduce the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from reanalyses. There are indications that this discrepancy could be partly related to a possible underestimation of past Arctic ozone trends in the models. The models project a continued cooling of the Arctic stratosphere over the coming decades (2001–2049) that is for the annual mean about 40% less than the modeled cooling for the past, due to the reduction of ozone depleting substances and the resulting ozone recovery. This projected cooling in turn could offset between 15 and 40% of the Arctic ozone recovery.