How can we predict the next century’s climate if we can hardly predict this weekend’s weather? Is the latest flooding or heatwave due to climate change, or not? Why is it so hard to take action on this problem? Climate change is likely the most complex crisis humanity has ever faced. It is a convoluted scientific problem and involves complicated social, economical and psychological dynamics. In this Hot Topic session, we will try to pin down open scientific questions on climate change and discuss what scientists can do to tackle this problem. The Hot Topic was coordinated and will be moderated by Michele Catanzaro. He is a freelance journalist with a PhD in Physics who writes for Nature, El Periódico, and other media, and he co-authored "Networks: A Very Short Introduction" (Oxford University Press, 2012). His accolades include the King of Spain International Journalism Prize; the European Science Writer of the Year 2016 Award; the BBVA Innovadata award; and the Prismas Award. He teaches and mentors students in science communication at several Spanish universities. He has been Journalist in Residence at the Heidelberg Institute for Theoretical Studies. First part: Facts In the first part of the session, we will discuss the fundamental laws underlying climate change; how mathematics, data, and computation enable predictions; and what are the big open questions for which mathematicians and computer scientists can make a difference. Chris Budd, professor at Gresham College, professor of mathematics and director of the Institute for Mathematical Innovation at the University of Bath, will discuss the mathematics of climate change: how we construct mathematical models of climate and how good they are at interpreting the past and predicting the future. He will discuss what are the frontiers of research in this field and argue for the usefulness of simpler models alongside more complex ones. Sonia Seneviratne, professor at ETH Zurich and IPCC coordinating lead author, will explore how to speed up climate research. She will argue that research is too slow for the magnitude of the problem. We don’t need better models, but quicker ones, in her opinion, and machine learning has a key role to play in achieving this objective. Opha Pauline Dube, researcher at the University of Botswana and IPCC coordinating lead author, will discuss the science of impacts, vulnerability, adaptation, and mitigation. She will explore the frontiers of research in this areas, how mathematicians and computer scientists can help, and provide a much- needed point of view from the developing world on the problem. Tim Palmer, Royal Society Research professor in climate physics at the University of Oxford, will discuss the role of supercomputation in climate change as an essential tool to move forwards in simulating a complex and challenging phenomenon as climate. He will defend that climate change requires computational infrastructures of the scale of the ones used in space science or fundamental physics. The opinions expressed in this video do not necessarily reflect the views of the Heidelberg Laureate Forum Foundation or any other person or associated institution involved in the making and distribution of the video.