While research shows different links between activism and science, little is known about activists engaging in science communication online. Demanding that decision-makers should “listen to the scientists”, the climate movements Fridays for Future (FFF) and Extinction Rebellion (XR) emphasize the role of scientific knowledge in democratic decision-making. Exploring the two movements' hyperlinking practices reveals a difference in the extent and selection of hyperlinks on their websites, pointing to influencer-based communication and focus on popularization of science by FFF and expert-based communication leaning on academic publications by XR, with both movements acting as amplifiers of existing science communication efforts.