The variability of results from different automated methods of detection and tracking of extratropical cyclones is assessed in order to identify uncertainties related to the choice of method. Fifteen international teams applied their own algorithms to the same dataset—the period 1989–2009 of interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERAInterim) data. This experiment is part of the community project Intercomparison of Mid Latitude Storm Diagnostics (IMILAST; see www.proclim.ch/imilast/index.html). The spread of results for cyclone frequency, intensity, life cycle, and track location is presented to illustrate the impact of using different methods. Globally, methods agree well for geographical distribution in large oceanic regions, interannual variability of cyclone numbers, geographical patterns of strong trends, and distribution shape for many life cycle characteristics. In contrast, the largest disparities exist for the total numbers of cyclones, the detection of weak cyclones, and distribution in some densely populated regions. Consistency between methods is better for strong cyclones than for shallow ones. Two case studies of relatively large, intense cyclones reveal that the identification of the most intense part of the life cycle of these events is robust between methods, but considerable differences exist during the development and the dissolution phases.

Wind and windstorms cause severe damage to natural and human-made environments. Thus, wind-related risk assessment is vital for the preparation and mitigation of calamities. However, the cascade of events leading to damage depends on many factors that are environment-specific and the available methods to address wind-related damage often require sophisticated analysis and specialization. Fortunately, simple indices and thresholds are as effective as complex mechanistic models for many applications. Nonetheless, the multitude of indices and thresholds available requires a careful selection process according to the target sector. Here, we first provide a basic background on wind and storm formation and characteristics, followed by a comprehensive collection of both indices and thresholds that can be used to predict the occurrence and magnitude of wind and storm damage. We focused on five key sectors: forests, urban areas, transport, agriculture and wind-based energy production. For each sector we described indices and thresholds relating to physical properties such as topography and land cover but also to economic aspects (e.g. disruptions in transportation or energy production). In the face of increased climatic variability, the promotion of more effective analysis of wind and storm damage could reduce the impact on society and the environment.

Extra-tropical cyclones in the subantarctic play a central role in the poleward transport of heat and moisture into Antarctica, with the latter being a key component of the mass balance of the Antarctic ice sheet. As the climate in this region undergoes substantial changes, it is anticipated that the character of these synoptic features will change. There are a number of different methods used to identify and track cyclones, which can potentially lead to different conclusions as to cyclone variability and trends, and mechanisms which drive these features. Given this, it is timely to assess the level of consensus among 14 state-of-the-art cyclone identification and tracking methods. We undertake this comparison with the ERA-Interim data-set for the period 1979–2008 and find large differences in the number of tracks identified by different methods, but the spatial patterns of the system density broadly agree. Links between large-scale modes of variability, such as the Southern Annular Mode (SAM), and subantarctic cyclones as suggested in the literature are confirmed by our analysis. Trends in the number of cyclone tracks show a more diverse picture. Robust trends are identified by almost all methods for austral summer over the region south to 60°S, mainly due to the strong relation to SAM, whereas in austral winter the methods disagree in the statistical significance of the trends. The agreement among the methods is greater when the comparison is confined to the stronger cyclones. This is confirmed by a moisture flux analysis associated with these strong synoptic systems. Our results indicate that multiple cyclone identification and tracking methods should be used to obtain robust conclusions for trends in cyclone characteristics as well as their relation to the large-scale circulation in the subantarctic region.

To manage Earth in the Anthropocene, new tools, new institutions, and new forms of international cooperation will be required. Earth Virtualization Engines is proposed as an international federation of centers of excellence to empower all people to respond to the immense and urgent challenges posed by climate change.

Europe frequently experiences a wide range of extreme events and natural hazards, including heatwaves, extreme precipitation, droughts, cold spells, windstorms, and storm surges. Many of these events do not occur as single extreme events but rather show a multivariate character, known as compound events. We investigate the interactions between extreme weather events, their characteristics, and changes in their intensity and frequency, as well as uncertainties in the past, present, and future. We also explore their impacts on various socio-economic sectors in Germany and central Europe. This contribution highlights several case studies with special focus on 2018, a year marked by an exceptional sequence of compound events across large parts of Europe, resulting in severe impacts on human lives, ecosystems, and infrastructure. We provide new insights into the drivers of spatially and temporally compound events, such as heat and drought, and heavy precipitation combined with extreme winds, and their adverse effects on ecosystems and society, using large-scale atmospheric patterns. We also examine the interannual influence of droughts on surface water and the impact of water scarcity and heatwaves on agriculture and forests. We assess projected changes in compound events at different current and future global surface temperature levels, demonstrating the need for improved quantification of future extreme events to support adaptation planning. Finally, we address research gaps and future directions, stressing the importance of defining composite events primarily in terms of their impacts prior to their statistical characterisation.