The Pan-Eurasian Experiment (PEEX) (www.atm.helsinki.fi/peex) is a multi-disciplinary, multi-scale and multi-component research infrastructure and capacity building programme. The PEEX originated from a bottom–up approach by the science communities in 2012. The programme aims to resolve the major uncertainties in Earth system science and global sustainability issues concerning the Arctic and boreal Pan-Eurasian regions as well as China. The PEEX solves interlinked global grand challenges influencing human well-being and societies in northern Eurasia and China by establishing and maintaining long-term, coherent and coordinated research activities as well as continuous, comprehensive research and educational infrastructures. The scientific issues covered by PEEX include climate change, air quality, biodiversity loss, chemicalization, food supply, freshwater and use of natural resources by mining, industry, energy production and transport. Our approach is integrative and interdisciplinary, recognizing the important role of the Arctic and boreal ecosystems in the Earth system.

The programme has had an open special issue in Atmospheric Chemistry and Physics in 2015–2019/2020 and has published 55 papers in total. A major part of the published papers originated from the PEEX collaboration, including organization of the PEEX science conferences, special sessions in the international conferences and on INAR Univ. Helsinki (PEEX-HQ) international collaboration, especially with the air quality research groups from China. The papers contributed to the large-scale research questions addressed by the PEEX Science Plan (www.atm.helsinki.fi/peex/images/PEEX_Science_Plan.pdf). PEEX is currently creating an overview of the research carried out during the last 5 years and is re-visiting its research agenda and large-scale research questions. PEEX continues organizing scientific conferences and workshops on a regular basis and is connected to the Arctic research community by U-Arctic thematic network "Arctic - boreal hub" (www.uarctic.org/organization/thematic-networks/arctic-boreal-hub/) coordinated by INAR Univ.Helsinki. The applied new PEEX- Part II special issue in ACP will be open for all submissions within these frameworks.