This special issue highlights the latest advances in our understanding of cryospheric ecosystems, drawing from research presented at the Cryospheric Ecosystems Conference (Poznań, Poland, 1–4 September, 2025) as well as global contributions from the broader scientific community. Cryospheric environments – including ice sheets, glaciers, snow cover, permafrost, and sea ice – are experiencing rapid changes under global warming with cascading effects on biodiversity, ecosystem dynamics, and climate feedbacks. Despite covering vast expanses of the Earth's surface, our understanding of these ecosystems and ongoing rapid changes remains limited.

The scope of the issue focusing on cryospheric ecosystems encompasses

• interactions and climate impacts: investigating physical and ecological connections between various cryospheric elements and their surroundings with an emphasis on climate-induced changes;
• biogeochemical, biodiversity and ecosystem resilience: examining the impact of cryosphere changes on nutrient cycles, biodiversity patterns, and ecosystem functioning;
• anthropogenic pressures and pollution: assessing the effects of pollutants and human activities on cryospheric environments;
• advances in technology and methods: showcasing new approaches in remote sensing, modelling, fieldwork, and data integration for monitoring and predicting cryospheric change;
• regional and comparative perspectives: highlighting studies that reveal unique adaptations and challenges in different geographic settings from polar regions to high-altitude environments.

The issue is jointly organized by Biogeosciences and The Cryosphere, reflecting the cross-disciplinary nature of the conference and the research community it serves. Submissions are welcome from all researchers working on cryospheric ecosystem topics regardless of conference attendance, thereby broadening the reach and relevance of the special issue. Both full-length original research articles and Review/Review and syntheses papers that integrate data across regions or disciplines will be considered for publication.

The glacial–interglacial cyclicity of the climate system varied in the past, most notably during the transition from a 40 ka to a 100 ka world in the mid-Pleistocene. Gases trapped in Antarctic ice are the most direct access available to investigate the composition of the paleo-atmosphere of that age and processes related to climate variability. The International Partnerships in Ice Core Sciences (IPICS) Oldest Ice endeavour aims at obtaining an undisturbed ice-core record older than 1 Ma. In addition to ice cores, time slices of paleo-records, available, for example, in Antarctic blue-ice fields, provide further valuable information, which complements continuous time series based on ice cores. This special issue will assemble contributions dedicated to the preparatory phase of this global effort to obtain ice samples and time series older than 700 000 years. This includes a consideration of glaciogical and geophysical settings which allow the presence of old ice, results from pre-site surveys and modelling studies, aspects of ice-core and other sampling techniques and analyses, and requirements for drilling and core handling.

SCAR INSTANT is a research programme of the Scientific Committee on Antarctic Research (SCAR) that focuses on understanding Antarctic ice sheet instabilities and their contribution to sea level changes, from the deep past to the future. The aim of INSTANT is to bridge communities, e.g. to try to bridge paleo-evidence and process-based development (for example, marine ice sheet instability (MISI), marine ice cliff instability (MICI), grounding line dynamics, ice–ocean interactions). The aim of the special issue is to reflect this process: what do we know from paleo-observations and present observations that can help to improve the physics; where are big modelling and observational gaps in ice sheet, ocean, and atmosphere physics; and what are the advances in paleo-proxies, present observations, methodologies, etc.? The various contributions should be community-driven and not single-author contributions. The papers should focus on the Antarctic system, thus focusing on atmosphere, the ocean, ice sheets, and bedrock and beneath and on the interactions between those components, from paleo-perspectives to the future. Global connections with Antarctica (teleconnections, inter-hemispheric processes) are also welcome. An important part of the SCAR INSTANT programme is the science-to-policy topic. As such, this special issue also welcomes policy-driven, actionable scientific contributions as well as social science studies.

This special issue highlights the latest advances in our understanding of cryospheric ecosystems, drawing from research presented at the Cryospheric Ecosystems Conference (Poznań, Poland, 1–4 September, 2025) as well as global contributions from the broader scientific community. Cryospheric environments – including ice sheets, glaciers, snow cover, permafrost, and sea ice – are experiencing rapid changes under global warming with cascading effects on biodiversity, ecosystem dynamics, and climate feedbacks. Despite covering vast expanses of the Earth's surface, our understanding of these ecosystems and ongoing rapid changes remains limited.

The scope of the issue focusing on cryospheric ecosystems encompasses

• interactions and climate impacts: investigating physical and ecological connections between various cryospheric elements and their surroundings with an emphasis on climate-induced changes;
• biogeochemical, biodiversity and ecosystem resilience: examining the impact of cryosphere changes on nutrient cycles, biodiversity patterns, and ecosystem functioning;
• anthropogenic pressures and pollution: assessing the effects of pollutants and human activities on cryospheric environments;
• advances in technology and methods: showcasing new approaches in remote sensing, modelling, fieldwork, and data integration for monitoring and predicting cryospheric change;
• regional and comparative perspectives: highlighting studies that reveal unique adaptations and challenges in different geographic settings from polar regions to high-altitude environments.

The issue is jointly organized by Biogeosciences and The Cryosphere, reflecting the cross-disciplinary nature of the conference and the research community it serves. Submissions are welcome from all researchers working on cryospheric ecosystem topics regardless of conference attendance, thereby broadening the reach and relevance of the special issue. Both full-length original research articles and Review/Review and syntheses papers that integrate data across regions or disciplines will be considered for publication.

SCAR INSTANT is a research programme of the Scientific Committee on Antarctic Research (SCAR) that focuses on understanding Antarctic ice sheet instabilities and their contribution to sea level changes, from the deep past to the future. The aim of INSTANT is to bridge communities, e.g. to try to bridge paleo-evidence and process-based development (for example, marine ice sheet instability (MISI), marine ice cliff instability (MICI), grounding line dynamics, ice–ocean interactions). The aim of the special issue is to reflect this process: what do we know from paleo-observations and present observations that can help to improve the physics; where are big modelling and observational gaps in ice sheet, ocean, and atmosphere physics; and what are the advances in paleo-proxies, present observations, methodologies, etc.? The various contributions should be community-driven and not single-author contributions. The papers should focus on the Antarctic system, thus focusing on atmosphere, the ocean, ice sheets, and bedrock and beneath and on the interactions between those components, from paleo-perspectives to the future. Global connections with Antarctica (teleconnections, inter-hemispheric processes) are also welcome. An important part of the SCAR INSTANT programme is the science-to-policy topic. As such, this special issue also welcomes policy-driven, actionable scientific contributions as well as social science studies.

The glacial–interglacial cyclicity of the climate system varied in the past, most notably during the transition from a 40 ka to a 100 ka world in the mid-Pleistocene. Gases trapped in Antarctic ice are the most direct access available to investigate the composition of the paleo-atmosphere of that age and processes related to climate variability. The International Partnerships in Ice Core Sciences (IPICS) Oldest Ice endeavour aims at obtaining an undisturbed ice-core record older than 1 Ma. In addition to ice cores, time slices of paleo-records, available, for example, in Antarctic blue-ice fields, provide further valuable information, which complements continuous time series based on ice cores. This special issue will assemble contributions dedicated to the preparatory phase of this global effort to obtain ice samples and time series older than 700 000 years. This includes a consideration of glaciogical and geophysical settings which allow the presence of old ice, results from pre-site surveys and modelling studies, aspects of ice-core and other sampling techniques and analyses, and requirements for drilling and core handling.