Ice cores provide a wealth of information about past climate and environmental conditions as well as direct records of the composition of the atmosphere on timescales from decades to hundreds of millennia. This comprises deep ice cores from both polar ice sheets and from high-altitude glaciers, with the latter responding most sensitively to human interaction with the Earth system.

In October 2022 the 3rd Open Science Conference of the International Partnerships of Ice Core Sciences (IPICS) takes place in Crans-Montana, Switzerland, providing the opportunity to document the status quo of ice core research including comparative studies on other climate archives and climate models in this joint special issue of Climate of the Past and The Cryosphere: "Ice core science at the three poles".

Potential topics of contributions include the latest results from polar and high-altitude ice cores, integrative science on ice cores, climate models and other climate archives, new proxies, and other ice-core-related technology developments. In particular, we invite ice-core-related contributions on the following themes.

1. Glacial–interglacial dynamics, interglacials, and sea level
2. Holocene and the last 2000-year climate forcings and variability
3. Progress in proxy development and interpretation
4. Ice dynamics, ice sheet instability, and geophysics
5. High-alpine ice cores
6. Ice biology, basal ice, and subglacial lakes
7. Pollution records
8. Advances in drilling engineering and borehole observations
9. Timescales and methods for ice dating
10. Rapid changes and teleconnections
11. Biogeochemical cycles in the Earth system – data and models
12. New ice archives
13. The Oldest Ice challenge and the preservation of climatic signals in the deepest ice.

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.

The reconstruction of ocean history, called palaeoceanography, is a relatively young scientific discipline initiated by the work of Cesare Emiliani and colleagues in the 50s of the last century by studying the stable oxygen and carbon isotopic composition of marine organisms. It had its climax in the 70s and 80s, for example in "The Fate of Fossil Fuel CO₂ in the Oceans", a visionary book edited by Andersen and Malahoff published in 1977. Here, seminal contributions by people like Wally Broecker and Wolfgang Berger document the importance of quantifying the magnitude and rate of climatic change as well as variability in the past to better understand the effect of human action on the climate system leading to ongoing global warming. A broad spectrum of studies have been performed since then, ranging from process and modelling studies as well as laboratory culturing of marine organisms to so-called high-resolution studies in time intervals of rapid climate change during the Cenozoic with a focus on the Pleistocene and Holocene. For the latter studies, sediment cores taken during the DSDP and IODP expeditions are a natural archive for the ocean history of the past 60 million years. Dick Kroon already realized all this as a student and spent his whole life dedicated to this field of science in a passionate way.

For this special issue (SI) we invite contributions from colleagues of Dick who cooperated with him in his numerous projects in teaching and research. Topics should be related to (palaeo)oceanography and cover time intervals from the Holocene to the Cenozoic.

We will add a special appendix to this SI, to which people can contribute personal memories and stories about Dick.

The global vegetation distribution determines the physical properties of the land surface, such as the roughness, albedo or water conductivity, and is a key player in the terrestrial carbon cycle. Hence, the vegetation directly affects the climate on Earth. In turn, the global climate controls the large-scale spatial vegetation distribution. Biogeophysical and biogeochemical interactions between vegetation and climate have contributed to past climate changes and will affect the future. Understanding past vegetation dynamics and their role in the climate system is thus of utmost importance.

The increasing publication of large-scale syntheses of vegetation reconstructions and the steadily growing ability to perform long-term transient and sophisticated past time-slice Earth system model simulations allow for more and more detailed analyses of the large-scale vegetation transitions and their effect on climate. However, previous studies also reveal that new metrics are needed to quantitatively compare the more complex reconstructions and model results.

With this special issue, we would like to bundle reconstructions, vegetation simulations and comparison tools. We invite all papers on the broad theme of past vegetation dynamics and their interaction with climate. This includes (a) vegetation simulations of various time intervals, (b) regional to global data–model or model–model comparison studies, (c) development of data–model comparison tools and techniques, and (d) vegetation–climate dynamics inferred from compilations of regional to global vegetation records. Any other related topic (past land use or past fire dynamics) is also welcome. Data compilation products may also be considered if the compiled data are integrated and used to address specific questions about past vegetation dynamics.

Sea ice is a critical component of the Earth system in that it regulates heat and gas exchange between the atmosphere and polar oceans; it modulates Southern Ocean upper and lower overturning cells and global ocean circulation; it influences surface ocean stratification, ocean productivity, and nutrient and carbon cycling; and it interacts with ice sheets and ice shelves. As Antarctic sea-ice cover is predicted to decrease in the next decades, it is essential for our Earth system models to be able to simulate the effects of this waning. However, currently both modern and paleo data–model intercomparisons display large differences in sea-ice extent and trends. This affects the ability of these models to project the effects of sea-ice changes on the atmosphere, deep-ocean circulation, and nutrient cycling. Reconstructions of changes in sea-ice concentrations are pivotal to understand how Antarctic sea ice changed in the past and how it influenced these physical and biogeochemical processes. Most previous paleoclimate reconstructions of Southern Ocean sea ice have focused on the Last Glacial Maximum time slice (CLIMAP, MARGO projects) or the Holocene and last interglacial periods (PAGES working group Sea Ice Proxies (SIP)).

This special issue arises from the efforts of an international PAGES working group called Cycles of Sea-Ice Dynamics in the Earth System (C-SIDE), which aims to (a) reconstruct sea-ice conditions in the Southern Ocean over the last 130 000 years, (b) compare these reconstructions with complementary paleo-environmental data documenting changes in the Southern Ocean, and (c) use these data along with model simulations to improve our understanding of Earth system processes. The C-SIDE working group has chosen the last glacial–interglacial cycle (or last 130 000 years) as a focus because this timescale allows us to evaluate the role of sea ice on major climate transitions including glacial inception, when carbon was sequestered in the ocean, and deglaciation, when ocean carbon reserves were released to the atmosphere. The time frame also encompasses the penultimate interglacial when Antarctica was c. 2 °C warmer than today – a useful “process” analogue for future warming scenarios. At this time, the working group has held two workshops (October 2018 in Vancouver, Canada, and August/September 2019 in Sydney, Australia) to achieve these goals.

This special issue invites papers on the topics of (a) new sea-ice reconstructions in the Southern Ocean using new and established proxies of changes in sea ice; (b) regional compilations of changes in sea-ice distributions during the last glacial–interglacial cycle; (c) studies comparing (new and published) sea-ice records with complementary records of changes in circulation, temperature, and nutrient or carbon cycling; and (d) model analysis and model–data comparison papers that provide insights into the key processes linking Southern Ocean sea-ice changes with ice sheet, atmosphere, and ocean dynamics, as well as biogeochemical cycling in the ocean. We strongly encourage submissions that focus on at least one full glacial–interglacial cycle but encourage submissions from other time spans as well.

The reconstruction of ocean history, called palaeoceanography, is a relatively young scientific discipline initiated by the work of Cesare Emiliani and colleagues in the 50s of the last century by studying the stable oxygen and carbon isotopic composition of marine organisms. It had its climax in the 70s and 80s, for example in "The Fate of Fossil Fuel CO₂ in the Oceans", a visionary book edited by Andersen and Malahoff published in 1977. Here, seminal contributions by people like Wally Broecker and Wolfgang Berger document the importance of quantifying the magnitude and rate of climatic change as well as variability in the past to better understand the effect of human action on the climate system leading to ongoing global warming. A broad spectrum of studies have been performed since then, ranging from process and modelling studies as well as laboratory culturing of marine organisms to so-called high-resolution studies in time intervals of rapid climate change during the Cenozoic with a focus on the Pleistocene and Holocene. For the latter studies, sediment cores taken during the DSDP and IODP expeditions are a natural archive for the ocean history of the past 60 million years. Dick Kroon already realized all this as a student and spent his whole life dedicated to this field of science in a passionate way.

For this special issue (SI) we invite contributions from colleagues of Dick who cooperated with him in his numerous projects in teaching and research. Topics should be related to (palaeo)oceanography and cover time intervals from the Holocene to the Cenozoic.

We will add a special appendix to this SI, to which people can contribute personal memories and stories about Dick.

Ice cores provide a wealth of information about past climate and environmental conditions as well as direct records of the composition of the atmosphere on timescales from decades to hundreds of millennia. This comprises deep ice cores from both polar ice sheets and from high-altitude glaciers, with the latter responding most sensitively to human interaction with the Earth system.

In October 2022 the 3rd Open Science Conference of the International Partnerships of Ice Core Sciences (IPICS) takes place in Crans-Montana, Switzerland, providing the opportunity to document the status quo of ice core research including comparative studies on other climate archives and climate models in this joint special issue of Climate of the Past and The Cryosphere: "Ice core science at the three poles".

Potential topics of contributions include the latest results from polar and high-altitude ice cores, integrative science on ice cores, climate models and other climate archives, new proxies, and other ice-core-related technology developments. In particular, we invite ice-core-related contributions on the following themes.

1. Glacial–interglacial dynamics, interglacials, and sea level
2. Holocene and the last 2000-year climate forcings and variability
3. Progress in proxy development and interpretation
4. Ice dynamics, ice sheet instability, and geophysics
5. High-alpine ice cores
6. Ice biology, basal ice, and subglacial lakes
7. Pollution records
8. Advances in drilling engineering and borehole observations
9. Timescales and methods for ice dating
10. Rapid changes and teleconnections
11. Biogeochemical cycles in the Earth system – data and models
12. New ice archives
13. The Oldest Ice challenge and the preservation of climatic signals in the deepest ice.

The global vegetation distribution determines the physical properties of the land surface, such as the roughness, albedo or water conductivity, and is a key player in the terrestrial carbon cycle. Hence, the vegetation directly affects the climate on Earth. In turn, the global climate controls the large-scale spatial vegetation distribution. Biogeophysical and biogeochemical interactions between vegetation and climate have contributed to past climate changes and will affect the future. Understanding past vegetation dynamics and their role in the climate system is thus of utmost importance.

The increasing publication of large-scale syntheses of vegetation reconstructions and the steadily growing ability to perform long-term transient and sophisticated past time-slice Earth system model simulations allow for more and more detailed analyses of the large-scale vegetation transitions and their effect on climate. However, previous studies also reveal that new metrics are needed to quantitatively compare the more complex reconstructions and model results.

With this special issue, we would like to bundle reconstructions, vegetation simulations and comparison tools. We invite all papers on the broad theme of past vegetation dynamics and their interaction with climate. This includes (a) vegetation simulations of various time intervals, (b) regional to global data–model or model–model comparison studies, (c) development of data–model comparison tools and techniques, and (d) vegetation–climate dynamics inferred from compilations of regional to global vegetation records. Any other related topic (past land use or past fire dynamics) is also welcome. Data compilation products may also be considered if the compiled data are integrated and used to address specific questions about past vegetation dynamics.

Sea ice is a critical component of the Earth system in that it regulates heat and gas exchange between the atmosphere and polar oceans; it modulates Southern Ocean upper and lower overturning cells and global ocean circulation; it influences surface ocean stratification, ocean productivity, and nutrient and carbon cycling; and it interacts with ice sheets and ice shelves. As Antarctic sea-ice cover is predicted to decrease in the next decades, it is essential for our Earth system models to be able to simulate the effects of this waning. However, currently both modern and paleo data–model intercomparisons display large differences in sea-ice extent and trends. This affects the ability of these models to project the effects of sea-ice changes on the atmosphere, deep-ocean circulation, and nutrient cycling. Reconstructions of changes in sea-ice concentrations are pivotal to understand how Antarctic sea ice changed in the past and how it influenced these physical and biogeochemical processes. Most previous paleoclimate reconstructions of Southern Ocean sea ice have focused on the Last Glacial Maximum time slice (CLIMAP, MARGO projects) or the Holocene and last interglacial periods (PAGES working group Sea Ice Proxies (SIP)).

This special issue arises from the efforts of an international PAGES working group called Cycles of Sea-Ice Dynamics in the Earth System (C-SIDE), which aims to (a) reconstruct sea-ice conditions in the Southern Ocean over the last 130 000 years, (b) compare these reconstructions with complementary paleo-environmental data documenting changes in the Southern Ocean, and (c) use these data along with model simulations to improve our understanding of Earth system processes. The C-SIDE working group has chosen the last glacial–interglacial cycle (or last 130 000 years) as a focus because this timescale allows us to evaluate the role of sea ice on major climate transitions including glacial inception, when carbon was sequestered in the ocean, and deglaciation, when ocean carbon reserves were released to the atmosphere. The time frame also encompasses the penultimate interglacial when Antarctica was c. 2 °C warmer than today – a useful “process” analogue for future warming scenarios. At this time, the working group has held two workshops (October 2018 in Vancouver, Canada, and August/September 2019 in Sydney, Australia) to achieve these goals.

This special issue invites papers on the topics of (a) new sea-ice reconstructions in the Southern Ocean using new and established proxies of changes in sea ice; (b) regional compilations of changes in sea-ice distributions during the last glacial–interglacial cycle; (c) studies comparing (new and published) sea-ice records with complementary records of changes in circulation, temperature, and nutrient or carbon cycling; and (d) model analysis and model–data comparison papers that provide insights into the key processes linking Southern Ocean sea-ice changes with ice sheet, atmosphere, and ocean dynamics, as well as biogeochemical cycling in the ocean. We strongly encourage submissions that focus on at least one full glacial–interglacial cycle but encourage submissions from other time spans as well.

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.