I am a newby with Cartopy, so ....
How can you transform the CF-convention metadata describing the coordinate systems of the data (from your NetCDF file) to a Cartopy's CRS object ?
I was expecting that the API reference would include, in the "input/output capability" section, some entry providing a method for returning, from the CF-compliant metadata section of a NetCDF file (or equivalent in memory structure), a corresponding CRS object, to be used as the transform parameter of Cartopy's high level functions