In Germany, the Last Generation emerged as a new climate activist group at the end of 2021. The group is considered rather controversial due to their contested protest actions of for instance vandalizing artwork. This study examines the influence of their controversial protest actions on the online climate debate on Twitter, compared to actions of Fridays for Future Germany, which enjoy a less contested reputation. The three chosen activities per group were analyzed with the help of a case study approach using content and sentiment analysis. The analysis was then conducted based on the three following concepts: deliberation, on the one side, which fosters constructive debates, as well as communitarianism and liberal individualism, on the other side, which can foster polarization. The analysis revealed that polarization dominated the online climate debate generated by the posts of the two groups. As such, hostile attitudes, condescending language, as well as monologic statements fostered communitarianism and liberal individualism within the comment sections of the Twitter posts. Yet, also deliberation was visible, but to the greatest extend within the comment section of a non-controversial activity of Fridays for Future Germany. This, among others, led to the conclusion that the protest actions of activist groups do have an influence on the climate debate. As such, the controversial activities of both groups influenced the climate debate in so far as the debate shifted from the climate debate to the activity itself by for instance focusing on child protection instead of climate change/protection. This was supported by the use of negative sentiments expressed explicitly towards the action of the group(s).