Introduction: Processes and Palaeo-Environmental Changes in the Arctic from Past to Present (PalaeoArc) special issue

PalaeoArc (Processes and Palaeo-Environmental Changes in the Arctic: From Past to Present) is an international network research programme, the aim of which is to understand and explain the climatically induced environmental changes in the Arctic that have taken place throughout the Quaternary and continue in the present-day (see http://www.palaeoarc.no/). This network builds on and extends the impressive legacy of previous palaeo-Arctic network programs and projects extending back to the 1980s. This began with the “Polar North Atlantic Margins—Late Cenozoic Evolution” project (PONAM: 1990–1994; Hjort and Persson 1994; Landvik and Salvigsen 1995; Elverhøi et al. 1998), which was followed by the “Quaternary Environment of the Eurasian North” project (QUEEN: 1996–2002; e.g., Larsen, Funder, and Thiede 1999; Thiede et al. 2001, 2004; Kjær et al. 2006). These were then followed by the “Arctic Palaeoclimate and Its Extremes” project (APEX: 2004–2012; Jakobsson et al. 2008, 2010, 2014) and the “Palaeo-Arctic Spatial and Temporal Gateways” project (PAST Gateways: 2012–2018; Ó Cofaigh et al. 2016, 2018). The latest incarnation of the network—PalaeoArc— was conceived at the final meeting of the PAST Gateways project in Durham, UK, in April 2019, when a new international steering committee was appointed to organize a series of activities and annual conferences for the following six years (2019–2024). The new international network held its first meeting in Poznań (20– 24 May 2019), hosted by the Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Poznań (see Lyså et al. 2019), comprising the usual mix of talks, posters, discussions, workshops, and a field excursion. The network planned to organize a conference hosted by the Department of Earth Sciences at the University of Pisa in May 2020, but this had to be postponed due to the COVID-19 pandemic and was eventually held online in May 2021, endorsed by the International Arctic Science Council, Italian Geological Society, and Italian Association for the Study of the Quaternary. The meeting proved incredibly popular and was “attended” by over 250 Arctic scientists from twenty-six different countries over a four-day period, allowing glacial and marine geologists, palaeoceanographers, palaeoecologists, and specialists in permafrost and numerical modeling to discuss records of Arctic environmental change over decadal to millennial timescales. The collection of articles in this special issue stems from this second PalaeoArc International Conference and encompasses the diverse range of topics presented at the meeting, each of which addresses the overarching aims of PalaeoArc (detailed below). The third international PalaeoArc conference took place (in person) in Rovaniemi in August 2022. The network has been extended for a year, with further meetings planned in Akureyri (2023), Stockholm (2024), and Tromsø (2025).