The Path to the next IPCC Assessment: Known Knowns and Known Unknowns

We summarize the key findings of the Sixth Assessment Report (AR6) by the Working Group I of the Intergovernmental Panel on Climate Change regarding the physical science basis for climate change. We summarize the empirical evidence of accelerating human-induced changes in the atmosphere, ocean, cryosphere, and land surface as evaluated in the AR6. The interpretation of this evidence has been bolstered by significant advances since the last Assessment in our theory, computational models, and observations of the forcings, responses, and feedbacks driving the evolution of the climate system. We note the impacts of these advances on the levels of evidence and confidence underlying some of the core findings by Working Group I. Despite this progress, many areas of climate science present ongoing research opportunities for physicists where discoveries would materially improve our understanding of past, present, and future climates. We conclude by discussing several of the most important directions for future research.