How we, as societies, communicate about climate change shapes how we understand and possibly overcome this century-defining challenge — or fail to do so. In this dissertation, I argue that public discourse about climate change can face a social tipping point that is marked by a fundamental shift in public opinion, political parties’ positions, and media reporting. My empirical research, comparing Germany and the United States supports the view that the former has surpassed this crucial threshold: public controversy is predominantly focused on finding solutions, and the media overwhelmingly emphasise consensus around the need to reduce emissions by mid-century. In contrast, the US suffers from a disconnect between public opinion and how media report on the issue, likely aggravating public controversy and perceived differences between supporters of the two major parties. As my findings indicate, once the conversation has ‘tipped over’, the communication strategies and practices that helped bring about this development are likely no longer effective. We direly need a faster and more just transition to an economy and society free from green-house gas emissions. To help materialise it, communication practitioners can learn from the cases presented to keep moving the conversation forward. By depoliticising geophysical and social scientific insights about climate change and its impact on humans, they can build the foundation for an informed discussion about different solutions to underpin the controversial political debates needed to make future-defining decisions.