Re: students can't learn Fortran ?
The students will be busy learning Julia and getting it working to model the climate model, so it's going to be a while before we get to start verifying that the new code replicates the original climate model. However that will be a very good experience for the students and will probably make them very good coders - it will be a good lesson:
println ("hello whirled")
But a FORTRAN programmer would just be writing the original code in Julia, FORTRAN programmers can write FORTRAN programs in any language - that's a traditional joke but the reality is that creating accurate and functional code is determined by the writer, not the language.