We are in the midst of a transformation of the digital news ecosystem. The expansion of online social networks, the influence of recommender systems, increased automation, and new generative artificial intelligence tools are rapidly changing the speed and the way misinformation about climate change and sustainability issues moves around the world. Policymakers, researchers and the public need to combine forces to address the dangerous combination of opaque social media algorithms, polarizing social bots, and a new generation of AI-generated content. This synthesis brief is the result of a collaboration between Stockholm Resilience Centre at Stockholm University, the Beijer Institute of Ecological Economics at the Royal Swedish Academy of Sciences, the Complexity Science Hub Vienna, and Karolinska Institutet. It has been put together as an independent contribution to the Nobel Prize Summit 2023, Truth, Trust and Hope, Washington D.C., 24th to 26th of May 2023.