This special issue arose from the “6th Workshop on Parameterization of lakes in Numerical Weather Prediction and Climate Modelling”. The workshop was held on 22–24 October 2019 at Météo-France (Toulouse, France): http://www.meteo.fr/cic/meetings/2019/LAKE2019/ .

The special issue “Modelling inland waters in a changing climate” is inviting contributions related to the following aspects of research on inland waters.

• Modelling – lake–atmosphere interactions and coupling (parameterization of lakes in numerical models of the atmosphere, the impact of lakes on atmospheric processes, greenhouse gases transfers); processes in freshwater bodies (including studies related to biochemistry and water quality issues, in frozen and not frozen conditions).
• Parameters – external parameters (raw data sets and generation of external-parameter fields required to use lake parameterization schemes in atmospheric models, e.g. fields of lake depth and lake fraction).
• Data assimilation – snow and ice on lakes, reservoirs and other water bodies (data assimilation of observations and parameterization of snow and ice layers over water surfaces in numerical weather prediction and climate models, interaction air–snow–ice–water); assimilation of observational data on lake surface state (space-borne and in situ observations of lake surface state, assimilation of observational data into atmospheric models using lake parameterization schemes).
• Model validation and intercomparison – validation of numerical weather prediction and climate models that incorporate lake parameterization and lake data assimilation schemes; single-column studies; intercomparison of lake models, e.g. within the framework of the Lake Model Intercomparison Project.
• Remote sensing – remote sensing can offer valuable data for studying lake changes and their interaction with their environment and the impact and feedback of climate change; altimeters provide dense time series of water surface elevation measurements, and multispectral optical, thermal and radar sensors can be used to measure lake area, water quality, temperature and ice cover; time series of satellite products are available for studies on lake changes from local to global scale, e.g. within the framework of the ESA CCI LAKES.
• ISIMIP initiative – the aim of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) is to better understand climate impacts across sectors using a multi-impact model framework; the second phase of this international effort (ISIMIP2b) is designed to provide robust information about the impacts of 1.5°C and 2°C global warming, as highlighted by the IPCC’s special report on this topic; scientists contributing simulations and analyses to ISIMIP will find a forum to share their results in this special issue.

In recent years, there have been multiple community-level efforts to improve our scientific understanding of the possible effectiveness and effects of solar geoengineering, especially the Geoengineering Model Intercomparison Project (GeoMIP) and the Geoengineering Large Ensemble (GLENS). These projects have wide international participation among climate modeling centers and researchers, including developing country researchers participating in the Developing Country Impacts Modelling Analysis for SRM (DECIMALS) fund. By producing simulations available for any interested researcher, these two projects have been highly effective in advancing the state of knowledge of solar geoengineering.

Several of these projects are reaching critical stages. A new round of GeoMIP simulations has recently been released as part of CMIP6. The DECIMALS teams are maturing and are at the stage where they are ready to produce papers, with the possibility that the project will be extended. GLENS simulations are continuing to be analyzed and supplemented with simulations from additional research efforts. To capture the interrelated research amongst these projects, the special issue is set up jointly between Atmospheric Chemistry and Physics and Earth System Dynamics. In ACP, we invite papers that emphasize process-level understanding and stratospheric dynamics; in ESD, submissions on Earth system effects, feedbacks, and impacts (like agriculture or ecosystem responses) are invited.

This special issue is intended to be a comprehensive and up-to-date overview of the scientific topics which Baltic Earth had defined in 2013 as important fields for research. Baltic Earth is an international and interdisciplinary network of scientists and institutions around the Baltic Sea, striving for an improved understanding of the Earth system of the Baltic Sea region (baltic.earth). The research components of Baltic Earth encompass processes in the atmosphere, on land and in the sea, as well as processes and impacts related to the anthroposphere.

This special issue summarizes the current state of knowledge in regional climatology, oceanography, meteorology, hydrology and biogeochemistry, as defined by the Baltic Earth Science Plan and aims to identify gaps and inconsistencies in that knowledge. Hence, the special issue wraps together the currently available knowledge on the Grand Challenges and related topics, as defined in the Baltic Earth Science Plan 2017 (see baltic.earth).

The Baltic Earth Grand Challenges are currently the following:

• salinity dynamics in the Baltic Sea
• land–sea biogeochemical interlinkages in the Baltic Sea region
• natural hazards and extreme events in the Baltic Sea region
• sea level and coastal dynamics in the Baltic Sea
• regional variability of water and energy exchanges in the Baltic Sea region
• multiple drivers of regional Earth system changes in the Baltic Sea region.

Contributions should be in line or strongly related to the themes of the Baltic Earth Science Plan (2017) and must adhere to the following principles: BEAR wrap together the currently available published scientific knowledge. They do not document unpublished research results. The essence of the work is the synthesis of material drawn comprehensively from the available scientifically legitimate literature (e.g. peer-reviewed literature, conference proceedings and reports of scientific institutes). The work should encompass the knowledge about what scientists agree on but also identify cases of disagreement or knowledge gaps.

Volcanic eruptions are one of the major natural factors influencing climate variability at interannual to multidecadal timescales. However, simulating volcanically forced climate variability is a challenging task for climate models and one of the major uncertainties in near-term climate predictions. The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) is an endorsed contribution to the sixth phase of the Coupled Model Intercomparison Project. This multi-journal special issue on VolMIP aims at collecting relevant research results obtained within the VolMIP framework, and specifically concerning different aspects of the radiative and dynamical climatic response to volcanic forcing, detailed description of effects of different implementation of volcanic forcing in current climate models, aspects concerning the dynamical and chemical atmospheric response to volcanic aerosols simulated by global aerosol models, and comparison between reconstructed and simulated climate evolution after major eruptions.

Fire is an essential feature of terrestrial ecosystems and plays an important role in the Earth system. Fires are regulated by climate, vegetation characteristics, and human activity and also feedback to them in multiple ways. For example, fires can shape vegetation composition and structure; adjust land carbon, nutrient, water, and energy cycles; change atmospheric composition, chemistry, and physics; and affect air quality and human health. Elevated fire activity in 2019 across the arctic, Amazon, and other regions underscores the urgency of a quantitative understanding of fire as an Earth system process that interacts with vegetation, climate, and humans. The EGU2020 B3.17 session on the role of fire in the Earth system received the most abstracts in the Biogeosciences division this year and was highly attended during the live chat. The abstracts cover several aspects of interactions between fire and the biosphere, atmosphere, and humans across various temporal and spatial scales using modelling, field and laboratory observations, and remote sensing. Given that the topic is highly interdisciplinary and overarching, we propose an inter-journal (ESD/BG/ACP/GMD/NHESS) special issue for this session with ESD as the lead journal, and we also encourage the submission of topic-related studies outside the EGU fire session. The special issue will bring together new advances in understanding the feedbacks and interactions between fire and other components of the Earth system at all temporal and spatial scales using various methods, including (1) impacts of fire on weather, climate, and atmospheric chemistry; (2) interactions between fire, the biogeochemical cycle, vegetation composition and structure, and land water and energy budgets; (3) influence of humans on fire and vice versa; (4) fire characteristics (e.g., fire duration, emission factor, emission height, smoke transport); (5) spatial and temporal changes of fires in the past, present, and future; (6) fire products and models, their validation, and error/bias assessment; and (7) analytical tools designed to enhance situational awareness among fire practitioners and early warning systems, addressing specific needs of operational fire behaviour modelling.

Compound weather and climate events refer to combinations of multiple weather and climate drivers and/or hazards that lead to potentially large impacts. Compound events encompass a highly diverse set of events including concurrent climate extremes but also an array of nonstandard high-impact events. Consequently, research on compound events requires expertise from a variety of disciplines such as climate science, hydrology, impact modelling, engineering, and statistics, among others. The European COST Action DAMOCLES (http://damocles.compoundevents.org) provides a platform for compound event research and for generating synergies between the different research domains. This inter-journal special issue will serve as an outlet for the work within DAMOCLES and aims to advance our understanding of different aspects of compound events, including present-day and future risk assessments of such events, modelling of individual compound events, bottom-up approaches to identify new types of compound events, and novel model evaluation techniques. It is open for all submissions within its scope.

In recent years, there have been multiple community-level efforts to improve our scientific understanding of the possible effectiveness and effects of solar geoengineering, especially the Geoengineering Model Intercomparison Project (GeoMIP) and the Geoengineering Large Ensemble (GLENS). These projects have wide international participation among climate modeling centers and researchers, including developing country researchers participating in the Developing Country Impacts Modelling Analysis for SRM (DECIMALS) fund. By producing simulations available for any interested researcher, these two projects have been highly effective in advancing the state of knowledge of solar geoengineering.

Several of these projects are reaching critical stages. A new round of GeoMIP simulations has recently been released as part of CMIP6. The DECIMALS teams are maturing and are at the stage where they are ready to produce papers, with the possibility that the project will be extended. GLENS simulations are continuing to be analyzed and supplemented with simulations from additional research efforts. To capture the interrelated research amongst these projects, the special issue is set up jointly between Atmospheric Chemistry and Physics and Earth System Dynamics. In ACP, we invite papers that emphasize process-level understanding and stratospheric dynamics; in ESD, submissions on Earth system effects, feedbacks, and impacts (like agriculture or ecosystem responses) are invited.

This special issue arose from the “6th Workshop on Parameterization of lakes in Numerical Weather Prediction and Climate Modelling”. The workshop was held on 22–24 October 2019 at Météo-France (Toulouse, France): http://www.meteo.fr/cic/meetings/2019/LAKE2019/ .

The special issue “Modelling inland waters in a changing climate” is inviting contributions related to the following aspects of research on inland waters.

• Modelling – lake–atmosphere interactions and coupling (parameterization of lakes in numerical models of the atmosphere, the impact of lakes on atmospheric processes, greenhouse gases transfers); processes in freshwater bodies (including studies related to biochemistry and water quality issues, in frozen and not frozen conditions).
• Parameters – external parameters (raw data sets and generation of external-parameter fields required to use lake parameterization schemes in atmospheric models, e.g. fields of lake depth and lake fraction).
• Data assimilation – snow and ice on lakes, reservoirs and other water bodies (data assimilation of observations and parameterization of snow and ice layers over water surfaces in numerical weather prediction and climate models, interaction air–snow–ice–water); assimilation of observational data on lake surface state (space-borne and in situ observations of lake surface state, assimilation of observational data into atmospheric models using lake parameterization schemes).
• Model validation and intercomparison – validation of numerical weather prediction and climate models that incorporate lake parameterization and lake data assimilation schemes; single-column studies; intercomparison of lake models, e.g. within the framework of the Lake Model Intercomparison Project.
• Remote sensing – remote sensing can offer valuable data for studying lake changes and their interaction with their environment and the impact and feedback of climate change; altimeters provide dense time series of water surface elevation measurements, and multispectral optical, thermal and radar sensors can be used to measure lake area, water quality, temperature and ice cover; time series of satellite products are available for studies on lake changes from local to global scale, e.g. within the framework of the ESA CCI LAKES.
• ISIMIP initiative – the aim of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) is to better understand climate impacts across sectors using a multi-impact model framework; the second phase of this international effort (ISIMIP2b) is designed to provide robust information about the impacts of 1.5°C and 2°C global warming, as highlighted by the IPCC’s special report on this topic; scientists contributing simulations and analyses to ISIMIP will find a forum to share their results in this special issue.

Fire is an essential feature of terrestrial ecosystems and plays an important role in the Earth system. Fires are regulated by climate, vegetation characteristics, and human activity and also feedback to them in multiple ways. For example, fires can shape vegetation composition and structure; adjust land carbon, nutrient, water, and energy cycles; change atmospheric composition, chemistry, and physics; and affect air quality and human health. Elevated fire activity in 2019 across the arctic, Amazon, and other regions underscores the urgency of a quantitative understanding of fire as an Earth system process that interacts with vegetation, climate, and humans. The EGU2020 B3.17 session on the role of fire in the Earth system received the most abstracts in the Biogeosciences division this year and was highly attended during the live chat. The abstracts cover several aspects of interactions between fire and the biosphere, atmosphere, and humans across various temporal and spatial scales using modelling, field and laboratory observations, and remote sensing. Given that the topic is highly interdisciplinary and overarching, we propose an inter-journal (ESD/BG/ACP/GMD/NHESS) special issue for this session with ESD as the lead journal, and we also encourage the submission of topic-related studies outside the EGU fire session. The special issue will bring together new advances in understanding the feedbacks and interactions between fire and other components of the Earth system at all temporal and spatial scales using various methods, including (1) impacts of fire on weather, climate, and atmospheric chemistry; (2) interactions between fire, the biogeochemical cycle, vegetation composition and structure, and land water and energy budgets; (3) influence of humans on fire and vice versa; (4) fire characteristics (e.g., fire duration, emission factor, emission height, smoke transport); (5) spatial and temporal changes of fires in the past, present, and future; (6) fire products and models, their validation, and error/bias assessment; and (7) analytical tools designed to enhance situational awareness among fire practitioners and early warning systems, addressing specific needs of operational fire behaviour modelling.

This special issue is intended to be a comprehensive and up-to-date overview of the scientific topics which Baltic Earth had defined in 2013 as important fields for research. Baltic Earth is an international and interdisciplinary network of scientists and institutions around the Baltic Sea, striving for an improved understanding of the Earth system of the Baltic Sea region (baltic.earth). The research components of Baltic Earth encompass processes in the atmosphere, on land and in the sea, as well as processes and impacts related to the anthroposphere.

This special issue summarizes the current state of knowledge in regional climatology, oceanography, meteorology, hydrology and biogeochemistry, as defined by the Baltic Earth Science Plan and aims to identify gaps and inconsistencies in that knowledge. Hence, the special issue wraps together the currently available knowledge on the Grand Challenges and related topics, as defined in the Baltic Earth Science Plan 2017 (see baltic.earth).

The Baltic Earth Grand Challenges are currently the following:

• salinity dynamics in the Baltic Sea
• land–sea biogeochemical interlinkages in the Baltic Sea region
• natural hazards and extreme events in the Baltic Sea region
• sea level and coastal dynamics in the Baltic Sea
• regional variability of water and energy exchanges in the Baltic Sea region
• multiple drivers of regional Earth system changes in the Baltic Sea region.

Contributions should be in line or strongly related to the themes of the Baltic Earth Science Plan (2017) and must adhere to the following principles: BEAR wrap together the currently available published scientific knowledge. They do not document unpublished research results. The essence of the work is the synthesis of material drawn comprehensively from the available scientifically legitimate literature (e.g. peer-reviewed literature, conference proceedings and reports of scientific institutes). The work should encompass the knowledge about what scientists agree on but also identify cases of disagreement or knowledge gaps.

Compound weather and climate events refer to combinations of multiple weather and climate drivers and/or hazards that lead to potentially large impacts. Compound events encompass a highly diverse set of events including concurrent climate extremes but also an array of nonstandard high-impact events. Consequently, research on compound events requires expertise from a variety of disciplines such as climate science, hydrology, impact modelling, engineering, and statistics, among others. The European COST Action DAMOCLES (http://damocles.compoundevents.org) provides a platform for compound event research and for generating synergies between the different research domains. This inter-journal special issue will serve as an outlet for the work within DAMOCLES and aims to advance our understanding of different aspects of compound events, including present-day and future risk assessments of such events, modelling of individual compound events, bottom-up approaches to identify new types of compound events, and novel model evaluation techniques. It is open for all submissions within its scope.

Volcanic eruptions are one of the major natural factors influencing climate variability at interannual to multidecadal timescales. However, simulating volcanically forced climate variability is a challenging task for climate models and one of the major uncertainties in near-term climate predictions. The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) is an endorsed contribution to the sixth phase of the Coupled Model Intercomparison Project. This multi-journal special issue on VolMIP aims at collecting relevant research results obtained within the VolMIP framework, and specifically concerning different aspects of the radiative and dynamical climatic response to volcanic forcing, detailed description of effects of different implementation of volcanic forcing in current climate models, aspects concerning the dynamical and chemical atmospheric response to volcanic aerosols simulated by global aerosol models, and comparison between reconstructed and simulated climate evolution after major eruptions.