While overall the global warming with the causes and global processes connected to well-mixed CO2, and its impacts on global to continental scales are well understood with a high level of confidence, there are knowledge gaps concerning the impact of many other non-CO2 radiative forcers leading to low confidence in the conclusions. This relates mainly to specific anthropogenic and natural precursor emissions of short-lived GHGs and aerosols and their precursors. The anthropogenic origin is connected to large extent with the urban environment. These gaps and uncertainties also exist in their subsequent effects on atmospheric chemistry and climate, through direct emissions dependent on changes in e.g., agriculture production and technologies based on scenarios for future development as well as feedbacks of global warming on emissions, e.g., permafrost thaw.

The main goal of the EC Horizon Europe project FOCI, is to assess the impact of key radiative forcers, where and how they arise, the processes of their impact on the climate system, to find and test an efficient implementation of these processes into global Earth System Models and into Regional Climate Models coupled with CTMs, and finally to use the tools developed to investigate mitigation and/or adaptation policies incorporated in selected scenarios of future development targeted at Europe and other regions of the world, with final emphasis to selected cities environment in convection permitting scale. We will develop new regionally tuned scenarios based on improved emissions to assess the effects of non-CO2 forcers. Mutual interactions of the results and climate services producers and other end-users will provide feedbacks for the specific scenarios optimization and potential application to support the decision making, including climate policy.

Overall introduction to coupled RCM-CTM modelling experiment strategies and preliminary results will be presented in addition to the contemporary status of the project.

How to cite: Halenka, T., Sokhi, R., and Finardi, S.: Project FOCI - Non-CO2 Forcers and Their Climate, Weather, Air Quality and Health Impacts: Modelling of Chemistry-Climate Interactions Across the Scales, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-671, https://doi.org/10.5194/ems2025-671, 2025.

The main objective of the Horizon Europe project FOCI (non-CO₂ Forcers and their Climate, Weather, Air Quality and Health Impacts) is to improve our knowledge of individual and cumulative contribution of non-CO₂ radiative forcers and their precursors on climate and air quality. Due to their short lifetime and their non-uniform emission footprint, the short-lived climate forcers (SLCF) are expected to have different impacts at regional scale. To describe and assess the impact of SLCF, we have developed a framework of coupling global climate model, EC-Earth3, to regional climate models (RCMs), to conduct historical simulations over Europe using CEDS SLCF emissions and LUCAS land cover to maintain consistency with CMIP6 simulations. During the first phase of the project RCMs, consisting of meteorological and chemical transport models WRF+CMAQ and WRF+FARM, have been applied over the CORDEX European domain for years 2005 -19 driven by ERA5 meteorological and CAMS global atmospheric composition reanalyses to provide an historical baseline simulation to be compared and verified versus observations and existing meteorological and tracers’ concentration reanalyses. The verification of the modelling systems performances reconstructing meteorological variables, pollutants’ concentration and their variability observed during the historical period is necessary to validate their planned downstream use to downscale EC-Earth3 CMIP6 simulations under the SSP3.7.0 and SSP3.7.0-lowNCTF scenarios. Meteorological variables compared positively with METAR observations at selected locations. Temperature increasing trend shows intensity and spatial features coherent with those depicted by existing analyses, with a limited negative bias on the annual mean values with respect to both analyses and selected stations (BIAS=-0.7 − +0.3 K; RMSE=1.6 − 2.2 K; correlation=0.97 − 0.98). Wind speed shows positive comparison with mixed bias values at selected airport locations (BIAS=-0.8 − +0.4 m/s; RMSE=1.2 − 2.1 m/s; correlation=0.48 − 0.80) similarly to relative humidity (BIAS=-5.3 − +6.4 %; RMSE=9 − 16 %; correlation=0.71 − 0.85). Precipitation fields have structure coherent with that of other analyses with increased resolution and different biases with respect to different analyses. Wind and precipitation show varying trends on different areas of the continent. Climate stressors trends will be compared too. Concentrations of the main pollutants show space distribution and values range similar to those shown by existing reanalyses (e.g. CAMS global and CAMS regional ensemble median). Local differences and biases are preliminary attributed to the significant differences of the emission inventories supporting RCMs simulations and existing analyses. Historical atmospheric composition simulations will be completed by early summer and a thorough comparison with observations and reanalyses will be presented at the meeting.

How to cite: Finardi, S., Arghavani, S., Pepe, N., Alyuz, U., Silibello, C., and Sokhi, R.: Historical (2005-2019) reconstruction of regional scale climate and atmospheric composition over Europe, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-484, https://doi.org/10.5194/ems2025-484, 2025.

Biogenic Volatile Organic Compounds (BVOCs) are organic trace gases mainly composed by isoprenoids, alcohols, carbonyls and acids, released in the atmosphere by terrestrial plants. Since some isoprenoids react with OH radical and O3 much faster than many anthropogenic VOC, their emission can affect the tropospheric levels of O3, photochemical oxidants and secondary organic aerosols (SOA). Various tree species are characterized by quite different emission factors for BVOCs, ranging from neglectable to significant values. A plant-specific emission model (PSEM) based on a detailed mapping of the tree species of forest covered areas can produce a quite different BVOC emission flux, with respect to models based on a Plant Functional Type (PFT) approach. The impact of a species-specific estimate of BVOC emissions over Europe has been estimated through the comparison with PFT approach results to evaluate the impact of a detailed vegetation mapping to improve BVOC emissions estimate. The comparison showed that PSEM estimates lower isoprene than both MEGAN V2.1 and V3.2, potentially driving a smaller impact on ozone production, and terpenes emissions higher than MEGAN V2.1 but lower than V3.2, with possible larger/smaller impact on SOA production. The expected increase of BVOC emissions due to the climate change forcing has been estimated computing the percent variation of isoprene and monoterpenes emission over a decade period. Different geographic areas of significant extention show increases exceeding 25% of the mean values estimated during the 2000-2019 period, with larger increases over eastern continental Europe and parts of the Mediterranean basin. PSEM estimates larger increases than CAMS-GLOB-BIO v3.0. The expectable BVOC emission change under future climatic conditions has been estimated considering the meteorological conditions predicted by EC-Earth3 CMIP6 simulation of the SSP 3.7.0 scenario. The mean emissions predicted for 2045-2055 have been compared with those computed by PSEM over a coherent subset for the historical period covering the last 11 years (2009-2019). The space distribution of the emissions does not change in the future scenario and a general increase of emissions is predicted for all the considered chemical species, mainly due to the predicted increase of both temperature and radiation flux. The most significant increase of emissions is concentrated over central and eastern Mediterranean and over the Balkan peninsula for isoprene, while it appears more extended over eastern continental Europe and southern Scandinavia for monoterpenes and sesquiterpenes. 

How to cite: Finardi, S., Silibello, C., and Radice, P.: BVOC emissions in a changing climate: comparison of plant-specific and plat functional type emission models, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-708, https://doi.org/10.5194/ems2025-708, 2025.

In 2016, the World Meteorological Organization declared that lightning is an essential climate variable. To date, global change studies have only considered the effect of warming on lightning flash frequency and the global distribution of lightning activity. Furthermore, none of these studies considered the effects of climate change on lightning flash intensity. In our previous studies we suggested based on laboratory experiments that lightning intensity over water surfaces may be influenced by their chemical properties, including salinity (S), pH and total alkalinity (TA). In this study we tested the combined effects of changes in S, TA and pH in Mediterranean Sea surface water on the intensity of laboratory generated electrical sparks, which are considered to be analogous to cloud to sea-surface intensity of lightning discharges. The range of values tested in the lab correspond to changes in S, pH and TA of Mediterranean surface water that were caused by the anthropogenic climate change, ocean acidification and damming of the Nile in the 1960s. Where, the damming of the Nile is generally accepted to have caused nearly 30% of the total salination of Mediterranean surface water until now. The experimental results were used to develop a multivariate linear model of Lightning Flash Intensity (LFI) as a function of S, TA/S, which  and pH. The model was validated with wintertime (DJF) LFI measurements along a Mediterranean Sea zonal profile during the period 2009-2020 compared to corresponding climate model outputs of S, TA and pH. Based on this model, the combined effects of climate change, ocean acidification and the damming of the Nile, may have increased LFI in the Levantine Sea by 16±14% until now relative to the pre-Aswan Dam period. Furthermore, assuming that salinization and acidification of the Levantine Sea will continue at current trends, the LFI is predicted to increase by 25±13% by the year 2050.

How to cite: Asfur, M. and Silverman, J.:  Climate mediated changes in seawater chemistry and their potential effects on marine lightning intensity , EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-3, https://doi.org/10.5194/ems2025-3, 2025.