Hajo Eicken

Antarctica InSync is a global effort to synchronise research across Antarctica and the Southern Ocean, connecting ice, ocean, land, climate, and life to protect this vital region. This roadmap paper introduces the scientific and technological motivation and action plan to build an international programme for a coordinated field season in Antarctica and its surrounding seas. It lays out the international collaboration that is required to realise an ambitious action plan and the opportunities for the science community to address important scientific themes that identify current knowledge gaps. In the spirit of the Antarctic Treaty Consultative Meeting (ATCM), the planned scientific action mandates free data exchange, facilitates international collaboration, and derives expert scientific advice together with the Scientific Committee on Antarctic Research (SCAR). Aligned with challenges of the United Nation Ocean and Cryosphere Decades, we plan a shared global effort to better understand the role of Antarctica and its surrounding ocean for our global futures, building on decades of achievements in polar and ocean science. As a milestone leading up to the next International Polar Year in 2032/33 (IPY5), the ambition is to achieve a new level of cooperation, with opportunities for the next generation of polar scientists around the world by enhancing practices in sharing of ideas, infrastructure and information.

Antarctica InSync is a global effort to synchronise research across Antarctica and the Southern Ocean, connecting ice, ocean, land, climate, and life to protect this vital region. This roadmap paper introduces the scientific and technological motivation and action plan to build an international programme for a coordinated field season in Antarctica and its surrounding seas. It lays out the international collaboration that is required to realise an ambitious action plan and the opportunities for the science community to address important scientific themes that identify current knowledge gaps. In the spirit of the Antarctic Treaty Consultative Meeting (ATCM), the planned scientific action mandates free data exchange, facilitates international collaboration, and derives expert scientific advice together with the Scientific Committee on Antarctic Research (SCAR). Aligned with challenges of the United Nation Ocean and Cryosphere Decades, we plan a shared global effort to better understand the role of Antarctica and its surrounding ocean for our global futures, building on decades of achievements in polar and ocean science. As a milestone leading up to the next International Polar Year in 2032/33 (IPY5), the ambition is to achieve a new level of cooperation, with opportunities for the next generation of polar scientists around the world by enhancing practices in sharing of ideas, infrastructure and information.

Indigenous Peoples across the Arctic have adapted to environmental change since time immemorial, yet recent climate change has imposed unprecedented and abrupt changes that affect the land and sea upon which communities rely. Co-created community-based observing programs offer an opportunity to harness the holistic breadth of knowledge in communities with the goal of tracking Arctic change while simultaneously supporting community priorities and local-scale needs. The Alaska Arctic Observatory and Knowledge Hub (AAOKH) is a network of Iñupiaq observers from northern Alaska coastal communities working in partnership with academic researchers. Here, we describe five core functions that have emerged through AAOKH, which include tracking long-term environmental changes; communicating Indigenous-led observations of the environment and their meaning; place-based and culturally relevant education; enabling scientific and Indigenous Knowledge exchange; and supporting community-led responses to environmental change. We outline and discuss specific actions and opportunities that have been used to increase knowledge exchange of AAOKH observations, make space for the next generation of Indigenous scholars, and create locally relevant data products and syntheses that can inform resource management and community planning. We also discuss our ongoing efforts to increasingly shift toward a knowledge coproduction framework as we plan to sustain AAOKH into the future.

The timing of sea ice retreat and advance in Arctic coastal waters varies substantially from year to year. Various activities, ranging from marine transport to the use of sea ice as a platform for industrial activity or winter travel, are affected by variations in the timing of breakup and freeze-up, resulting in a need for indicators to document the regional and temporal variations in coastal areas. The primary objective of this study is to use locally based metrics to construct indicators of breakup and freeze-up in the Arctic and subarctic coastal environment. The indicators developed here are based on daily sea ice concentrations derived from satellite passive-microwave measurements. The “day of year” indicators are designed to optimize value for users while building on past studies characterizing breakup and freeze-up dates in the open pack ice. Relative to indicators for broader adjacent seas, the coastal indicators generally show later breakup at sites known to have landfast ice. The coastal indicators also show earlier freeze-up at some sites in comparison with freeze-up for broader offshore regions, likely tied to earlier freezing of shallow-water regions and areas affected by freshwater input from nearby streams and rivers. A factor analysis performed to synthesize the local indicator variations shows that the local breakup and freeze-up indicators have greater spatial variability than corresponding metrics based on regional ice coverage. However, the trends towards earlier breakup and later freeze-up are unmistakable over the post-1979 period in the synthesized metrics of coastal breakup and freeze-up and the corresponding regional ice coverage. The findings imply that locally defined indicators can serve as key links between pan-Arctic or global indicators such as sea ice extent or volume and local uses of sea ice, with the potential to inform community-scale adaptation and response.

Sea-ice pore microstructure constrains ice transport properties, affecting fluid flow relevant to oil-in-ice transport and biogeochemical processes. Motivated by a lack of pore microstructural data, in particular for granular ice and across the seasonal cycle, throat size, tortuosity, connectivity, and other microstructural variables were derived from X-ray computed tomography for brine-filled pores in seasonal landfast ice off northern Alaska. Data were obtained for granular and columnar ice during the ice growth, transition, and melt season. While granular ice exhibits a more heterogeneous pore space than columnar ice, pore and throat size distributions are comparable. The greater tortuosity of pores in granular (1.2 < τ_g < 1.7) compared to columnar ice (1.0 < τ_c < 1.1) compounded with a less interconnected pore space translates into lower permeability for granular ice during the growth season for a given porosity. The microstructural data explain findings of granular ice hindering vertical oil-in-ice transport during ice growth and transition stage. With granular ice more frequent in the changing Arctic, data from studies such as this are needed to inform improved modeling of porosity-permeability relationships.

Arctic coastal waters are characterized by seasonal retreat and advance of sea ice. The timing of advance and retreat varies substantially from year to year. Various activities, ranging from marine transport to the use of sea ice as a platform for industrial activity or winter travel, are affected by variations in the timing of break-up and freeze-up, resulting in a need for indicators to document the regional and temporal variations in coastal areas. Here we develop indicators based on daily sea ice concentrations derived from satellite passive microwave measurements. The “day of year” indicators are designed to optimize value for users while building on past studies characterizing break-up and freeze-up dates in the open pack ice. Relative to indicators for broader adjacent seas, the coastal indicators show later break-up at sites known to have extensive landfast ice, for which break-up typically lags retreat of the adjacent, thinner drifting ice. The coastal indicators also show an earlier freeze-up at some sites in comparison with freeze-up for broader offshore regions, likely tied to earlier freezing of shallow water regions and areas affected by freshwater input from nearby streams and rivers. A factor analysis performed to synthesize the local indicator variations shows that the local break-up and freeze-up indicators have greater spatial variability than corresponding metrics based on regional ice coverage. However, the trends towards earlier break-up and later freeze-up are unmistakable over the post-1979 period in the synthesized metrics of the coastal break-up/freeze-up and their corresponding regional ice coverage. The findings imply that locally defined indicators can serve as key links between pan-Arctic or global indicators such as sea-ice extent or volume and local uses of sea ice, with the potential to inform community-scale adaptation and response.

In this perspective on the future of the Arctic, we explore actions taken to mitigate warming and adapt to change since the Paris agreement on the temperature threshold that should not be exceeded in order to avoid dangerous interference with the climate system. Although 5 years may seem too short a time for implementation of major interventions, it actually is a considerable time span given the urgency at which we must act if we want to avoid crossing the 1.5 to <2 °C global warming threshold. Actions required include co-production of research exploring possible futures; supporting Indigenous rights holders’ and stakeholders’ discourse on desired futures; monitoring Arctic change; funding strategic, regional adaptation; and, deep decarbonization through transformation of the energy system coupled with negative carbon emissions. We are now in the decisive decade concerning the future we leave behind for the next generations. The Arctic’s future depends on global action, and in turn, the Arctic plays a critical role in the global future.

Rapid Arctic environmental change requires improved collaboration across observing activities that support adaptation and response from local to pan-Arctic scales. The Research Networking Activities in Support of Sustained Coordinated Observations of Arctic Change (RNA CoOBs), in partnership with the Food Security Working Group (FSWG), supports an Indigenous-led project on food security. These efforts tie into the broader goals of the Sustaining Arctic Observing Networks (SAON) Roadmap for Arctic Observing and Data Systems (ROADS). SAON is an open initiative of the International Arctic Science Committee and the Arctic Council, uniting Arctic and non-Arctic countries and Indigenous, regional, and global organizations that support improved observing network development and integration. SAON has been advancing a partnership development framework under ROADS that adds value to different observing activities by providing common context and identifying shared goals.

Weather and sea ice forecasts provided in support of the U.S. Navy's Ice Exercise winter 2020 campaign in the Beaufort Sea noted frequent storms in the absence of the climatological Beaufort High which coincided with anomalous eastward drift of the region's ice cover. To place the 2020 Beaufort‐Chukchi regional atmospheric conditions in historical context, we evaluated winter low sea‐level pressure (SLP) extremes and storm characteristics in the region over the 1948–2020 period. March 2020 SLP in the Beaufort‐Chukchi region was the lowest of the modern reanalysis era (1009.07 hPa) with record counts of passing storms and days with SLP at least two standard deviations below the climatological mean. The Beaufort High collapse in winter 2020 continued a recent pattern of Beaufort High collapses dating back to 2010. Unlike other recent collapses, such as 2017, most of the late‐winter 2020 cyclones originated locally over the western Arctic Ocean.