Special theme: "The Climate Action: Mathematics, Informatics and Socio-Economics Accelerating the Sustainability". This special issue provides a glimpse of the diverse research activities that focus on mobilizing the research-innovation and innovation commercialization ecosystem, towards producing solutions for the much-needed sustainability transition that aims to a sustainable interaction between the society the economy and the natural environment. ERCIM News (https://ercim-news.ercim.eu) is the magazine of the European Research Consortium for Informatics and Mathematics (https://www.ercim.eu). Each issue focuses on a special scientific theme presenting research activities carried out by research teams. ERCIM News is published quarterly.