Nowadays, many known celebrities use social media as a channel to promote positive narratives and support humanitarian work. This article offers an analysis of the argumentative strategies employed in Instagram by a Spanish actor Javier Bardem, an Antarctic ambassador for Greenpeace, in order to attract the attention of the public to the ecological problems of the Antarctic Ocean. I have studied 76 posts published in Instagram during the 2018-2019 period. Starting from the theoretical framework of argumentation, as well as of pragmatic linguistics, I analyze those linguistic mechanisms and discursive strategies that are used with the aim to achieve the persuasive purposes.