Changing fields after PhD, master or post-doc? I am not far away from finishing a PhD in molecular toxicology, however with time i have gotten more and more interested in topics such as renewable energy, environmental/climate science and engineering. My education so far is not completely alien to environmental science, but my background heavily oriented towards molecular biology so i lack basic knowledge about things relating to renewables, climate systems and field work. Another big factor is also that non-academic jobs in my current field do not interest me at all.
So what would be the best route for me if i wanted to move towards these fields, get a new master or try to land post-docs incrementally closer to where i want to be?
I don't expect this to be the best answer (I am not from these fields), however what I'd do in your place would be researching websites of environmental science departments and research groups in order to find some topics/projects for which your qualification up to now makes some sense or adds some relevant competence. There even may be postdoc positions, however maybe you can ask for some project or internship work. Maybe also there are some biologically oriented temporary teaching jobs in such departments, which could enable you to get into the community.
In the meantime try to read and learn, and try to get into contact with people. I can't guarantee it of course but sometimes opportunities open up when looking for them in a determined way. And surely try to make use of your already achieved qualifications, try to connect things somehow.