Climate change is one of the greatest challenges of modern times. Environmental organizations do their utmost to inform the public about environmental problems and to invite action to prevent them. To this direction, they run campaigns with posters that combine images and text and evoke emotions in the recipient about these issues. The study focuses on such multimodal texts and analyzes the multimodal resources used in environmental campaign posters from a visual rhetorical perspective with a focus on fear appeals and their expected persuasiveness. More specifically, the study examines how the environmental organizations WWF and Greenpeace use fear appeal as a rhetorical strategy in their campaigns. The visual and textual resources are analyzed to identify the purpose, arguments and emotional appeals of the posters that seek to increase people's awareness and power to act. The study also examines how the rhetorical strategies and effectiveness of the multimodal resources differ between the two organizations. The study shows that the two organizations make use of appeals to fear in a way that matches their different profiles to create awareness and encourage action concerning climate change.