The World Climate Research Programme maintains a list of Grand Challenges in the area of climate science, with excellent explanations, references, etc.
Check it out for yourself: https://www.wcrp-climate.org/grand-challenges/grand-challenges-overview
We hope this list might inspire new research, e.g. for researchers in the data sciences to work with climate scientists to try out some data-driven approaches.
If one of the topics excites you, but you can't find a collaborator to work with, contact us. We might be able to help.