This study documents the dynamics behind the first occurrence of a multi-year negative Indian Ocean Dipole since the 1960s, which lasted for an unprecedented 19 months, and co-occurred with the triple-dip La Niña event of 2020–2022. The co-occurrence of such extremes is rare and can exacerbate the associated climate risk. We find that Indian Ocean conditions limited the impact of La Niña on the Indian Summer Monsoon, preventing excessive monsoonal rainfall.

Atmospheric deserts are air masses from the boundary layer of desert regions. This study tracked them from North Africa to Europe during a two-year period (May 2022–April 2024). They can occur up to 60 % of the time, and can span large parts of Europe. They typically last about a day, and can alter the atmosphere throughout the free troposphere. On its way from Africa the air either rises and may become even warmer and drier, or it stays at mid-altitudes and cools, or retains its properties.

Hurricane Ophelia of October 2017 is a rare example of a strong post-tropical cyclone impacting Europe, an event that is expected to occur more frequently as our climate warms. This study examines the changes in structure, behaviour, and extratropical transition of Hurricane Ophelia under alternate climate forcing using a regional model. We find that in warmer climates the storm becomes stronger, larger, and maintains the characteristics of a tropical cyclone for longer than in cooler climates.

Storm Boris led to record-breaking precipitation over central Europe in September 2024. By incorporating event-specific meteorological information, this work introduces a methodology to strengthen our comprehension of how global warming affects similar hazards. Furthermore, it contextualizes how the answer to the question "How will Boris-like storms change in a warmer climate?" depends on explicit and implicit methodological choices, with the aim to inform future attribution research.

Due to changes in atmospheric circulation some regions are warming quicker than others. Statistical methods are used to estimate how much of the local summer temperature changes are due to circulation changes. We evaluate these methods by comparing their estimates to special simulations representing only temperature changes related to circulation changes. By applying the methods to observations of 1979–2023 we find that half of the warming over parts of Europe is related to circulation changes.

By studying the variability of the trade winds during the Great Barrier Reef coral bleaching season, we show that ocean heating and a higher risk of coral bleaching are linked to the breakdown of the trade winds into either calm and clear conditions or a monsoon-like northerly flow. Years with mass coral bleaching are also associated with more "calm and clear" days in the warmest months and fewer strong trade wind days on the fringe months of the bleaching season.

This study presents three case studies of applying a newly developed method to quantify the uncertainty of the operational ensemble from the European Centre for Medium-Range Weather Forecasts in forecasting precipitation and wind extremes associated with Mediterranean cyclones. We find that the cyclones as well as their associated extremes are predicted well for lead times ≤ 48 h; however, for longer lead times there is large case-to-case variability in the ensemble performance.

Heat extremes are becoming more frequent and intense in southern South America. This study uses a storyline approach to explore how different climate drivers shape future summer temperature extremes. Using climate model simulations, we identified key drivers, such as soil moisture, sea surface temperature and atmospheric circulation, to build physically consistent scenarios that explain the sources of uncertainty in regional warming projections in southern South America.

The Wind Velocity Radar Nephoscope (WIVERN) mission will be the first space-based mission to provide global in-cloud wind, cloud and precipitation measurements. The mission is proposed as a candidate for the ESA Earth Explorer 11. Its data could be beneficial to several sectors, including numerical weather prediction performance enhancement. This paper aims to contribute to the last point by analyzing the impact that WIVERN would have in the case of a Tropical-like cyclone event.

The need for information about climate change is ever increasing. Therefore, it is important to have knowledge about climate change, along with an understanding of the uncertainties of climate model ensembles. Here, climate change in Sweden and neighbouring countries and its relation to global warming is described. Global warming results in higher temperature, more warm days and fewer cold days. The local and global warming suggest that climate change in Sweden may currently be at its fastest.

This study investigates the relationship between jet strength and storm track activity in the North Pacific and North Atlantic with a new approach that does not rely on monthly averaging. We find a consistent behaviour in the two basins, with two distinct relationships on seasonal and sub-monthly timescales emerging. This work underlines the importance of separating different timescales of variability to understand the interplay of jet characteristics and storm track activity.

We investigate the link between European meteorological droughts and persistent year-round weather regimes derived from mid-tropospheric circulation. Using a novel regionalization based on drought synchronicity and reanalysis data, we show that regime frequency anomalies partly explain drought occurrence, especially in western Europe and in winter, highlighting both the potential and limits of regime-based drought prediction.

Winds around the Antarctic coast have global importance. With influences from competing drivers, their structure is complex so it is hard to understand how they will change in the future. We develop a simple measure that identifies key features in the coastal winds, including their northern extent. Using climate models, we analyse future projections of this boundary and find that it will shift polewards, shrinking the Antarctic coastal wind region.

Severe warming and drying in the Eastern Mediterranean makes seasonal prediction of regional rain imperative. The study explores the observed relation of Mediterranean Sea variability to Levant winter precipitation. Ocean heat uptake in the Aegean Sea during summer is found to be a strong predictor of winter Levant precipitation. This connection is mediated by changes in the subtropical jet, which create more favorable conditions for precipitating storms in the Levant during winter.

Whether the zonal structure of a polar vortex matters for surface climate is an open question, with much observational work showing a role but with limited modeling work and demonstration of a causal influence. Here, we isolate this influence using a moist general circulation model. We find that the surface responses differ qualitatively depending on the zonal asymmetries of the shifted polar vortex and concurrently occurring wave reflection events, and provide a mechanistic explanation for why.

It has been suggested that resonant amplification of Rossby waves along a circumglobal jet may be responsible for the occurrence of extreme weather. Given that the recent literature has produced some conflicting results, the current paper revisits the issue with a particular focus on the meridional structure of the wave. It is found that generally no more than one zonal wavenumber can be expected to be associated with resonance. 

We used climate models to test how constant El Niño and La Niña ocean conditions shape the Madden-Julian Oscillation during northern winter. El Niño made this weather pattern move faster, while La Niña slowed it down. The Quasi-Biennial Oscillation, a repeating wind pattern high in the atmosphere, had little effect. This shows that long-lasting ocean conditions mainly drive the changes we found.

This study investigates how Svalbard's mountains modulate warm and moist air mass intrusions into the central Arctic, where such events are key drivers of warm extremes. Using atmospheric modeling, air parcel trajectories and observations from the MOSAiC expedition for a case in April 2020 and a climatological analysis for springtime in 2000–2022, we show that Svalbard can alter winds, temperatures, clouds and surface energy fluxes hundreds of kilometers downstream over sea ice.

We studied why some Mediterranean storms intensify and begin to resemble tropical cyclones, becoming especially damaging. By comparing many storms, we found that strong cyclones form when powerful disturbances high in the atmosphere are present. If this happens over warm seas, storms are more likely to develop tropical-like features, while the cooling of the sea by the storm itself helps limit its lifetime. These findings can help improve early warnings and reduce risks in the region.

Heatwaves are becoming more extreme in frequency and intensity. Yet running many climate simulations to find the rare worst-case events is slow and costly. We developed a method that tweaks initial weather conditions to target the most extreme heat scenarios at a fraction of the usual cost. For the 2021 Pacific Northwest heatwave, it found cases up to 3.7 °C hotter than any run in a 75-member ensemble, helping communities prepare for the worst.

Sudden Stratospheric Warmings (SSWs) are known to follow a sustained wave dissipation in the stratosphere, which depends on both the tropospheric and stratospheric states. However, the relative role of each state is still unclear. Using a new set of subseasonal to seasonal forecasts, we show that the stratospheric state does not drastically affect the precursors of three recent SSWs, but modulates the stratospheric wave activity, with impacts depending on SSW features.

Spring and summer heat extremes in Western Europe have intensified much faster than the global average since 1950. Spring warming is mainly driven by thermodynamical effects, while circulation changes explain over a third of local trends, with more frequent southerly flow patterns contributing. Climate models capture extreme trends in individual runs but underestimate observed warming. Open questions about forced change versus natural variability remain.