This communication aims at testifying how individual commitments of researchers can be combined to engage a whole research lab – in this case INRAE RiverLy – in a carbon transition path. INRAE RiverLy is an interdsciplinary research unit for the management and restoration of river systems and their catchments. In 2020, a group of RiverLy people started questioning the downstream impacts of their research practices. An official internal action called RiverLy Downstream was thus launched to address these issues. A first lab-scale carbon accounting for the year 2019 was performed thanks to the GES 1point5 tool (https://apps.labos1point5.org/ges-1point5). It showed a large contribution of air travel to the total carbon footprint. Further carbon accounting for 2020 and 2021 however highlighted the even larger impact of purchases (equipment, consumables, etc.) thanks to newly implemented features in GES 1point5. An open “climate day” was organized in the lab in September 2022 for (1) raising awareness through a general-public-oriented tool, (2) provide live feedback from other research labs engaged in a carbon transition, and (3) collectively identify propositions of local actions on different themes: purchases, travels, premises, computing, food, and research activities. These propositions fed a lab-wide survey that will help defining a few carbon footprint reduction scenarios based on their social acceptability. These scenarios will then be submitted to the lab board for implementation. The whole process benefited from rich interactions with INRAE national to regional strategy for reducing its environmental footprint (https://www.inrae.fr/en/corporate-social-responsibility-inrae), and with the French national initiative Labos1point5 (https://labos1point5.org/).