This lecture will highlight commonalities and differences of the climate crisis and the Covid-19 pandemic. Both crises are symptoms of dysfunctional unsustainable interactions of social systems with natural systems. In this lecture I will unpack the common elements of these crises and outline lessons learned from the comparison. Building upon a recently published scientific article, the analysis is divided into four sections: diagnosis, prognosis, therapy and rehabilitation. It highlights the role of science in its ability to anticipate crises before they are imminent, for example through projections and probability calculations. The climate emergency and the Covid-19 pandemic are characterized by critical time points, after which certain damages (such as loss of life) can no longer be avoided through adaptation measures. This time criticality does not allow us to wait for the perfect solution. Therefore, early preventative action with available measures is of the essence. Collective action guided by courageous moral stewardship on different levels of governance is key to overcome these complex crises. In closing I will thus discuss our understanding of the differential responsibilities across generations and income groups to contribute to transformative solutions.