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.

Two closely coordinated groups (one from the USA and the other from Europe) are revisiting the Camp Century sub-ice sediment and the silty ice zone just above it using a wide variety of analytical techniques to make inferences about ice sheet behaviour, palaeo-climate, and palaeo-ecology as well as sediment transport and sourcing. The paper that kicked this off was in Proceedings of the National Academy of Sciences (PNAS) 2 years ago: "A multi-million-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century" (Christ et al., 2021).

Talking among the 20+ lead investigators, we decided that the papers coming out of multiple, coordinated investigations of this historic (and still unique) ice core would be very useful to the broader community if they could be gathered into a special issue. Having these papers together would increase their impact and accessibility. Because of the wide variety of investigations being conducted on the core materials, a combined special issue including papers from both The Cryosphere and Climate of the Past will generate the most contributions and the largest readership.

Reference:

Christ, A. J., Bieman, P. R., Schaefer, J. M., Dahl-Jensen, D., Steffensen, J. P, Corbett, L. B., Peteet, D. M., Thomas, E. K., Steig, E. J., Rittenour, T. M., Tison, J.-L., Blard, P.-H., Perdrial, N., Dethier, D. P., Lini, A., Hidy, A. J., Caffee, M. W., and Southon, J.: A multi-million-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century, P. Natl. Acad. Sci. USA, 118, e2021442118, https://doi.org/10.1073/pnas.2021442118, 2021.

Two closely coordinated groups (one from the USA and the other from Europe) are revisiting the Camp Century sub-ice sediment and the silty ice zone just above it using a wide variety of analytical techniques to make inferences about ice sheet behaviour, palaeo-climate, and palaeo-ecology as well as sediment transport and sourcing. The paper that kicked this off was in Proceedings of the National Academy of Sciences (PNAS) 2 years ago: "A multi-million-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century" (Christ et al., 2021).

Talking among the 20+ lead investigators, we decided that the papers coming out of multiple, coordinated investigations of this historic (and still unique) ice core would be very useful to the broader community if they could be gathered into a special issue. Having these papers together would increase their impact and accessibility. Because of the wide variety of investigations being conducted on the core materials, a combined special issue including papers from both The Cryosphere and Climate of the Past will generate the most contributions and the largest readership.

Reference:

Christ, A. J., Bieman, P. R., Schaefer, J. M., Dahl-Jensen, D., Steffensen, J. P, Corbett, L. B., Peteet, D. M., Thomas, E. K., Steig, E. J., Rittenour, T. M., Tison, J.-L., Blard, P.-H., Perdrial, N., Dethier, D. P., Lini, A., Hidy, A. J., Caffee, M. W., and Southon, J.: A multi-million-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century, P. Natl. Acad. Sci. USA, 118, e2021442118, https://doi.org/10.1073/pnas.2021442118, 2021.

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.