The course will focus on how climate science can inform policy and decision making in the context of a changing climate. It will provide an historical perspective and describe how the IPCC process developed, in order to make available the most authoritative information, with respect to climate change, the anthropogenic contribution to it and the necessity (and urgency) to deal with both mitigation and adaptation aspects. The negotiation process leading to the Paris agreement, including the controversies around it, as well as subsequent developments will be presented, and the linkages with sustainable development issues will be studied in detail. The course will present the latest scientific knowledge and discuss how this knowledge could and should inform and encourage action, as well as the need to adjust governance mechanisms. The impact of the Covid-19 crisis on climate change issues, and lessons from it, will be addressed from various angles. The course will conclude by looking at remaining challenges and future perspectives.