Why are most climate models in Fortran?
1. There are thousands of scientific subroutines written in Fortran that are stable and well tested - in fact, there are well established formal libraries of them that go back over 60 years. The researchers know and trust them.<p>2. Despite the sneers and derision that Fortran has been subjected to from non-Fortran programmers over recent decades, Fortran is an excellent language to do intensive scientific and mathematics work. Compilers are optimized for calculation&#x2F;math speed and large intensive calculations. From the outset, it could handle complex numbers, double precision, etc., etc. natively without having to resort to calling libraries&#x2F;special routines as other languages had to do back then.<p>3. Scientific enterprise alongside mainframes and supercomputers have well established and stable ways of working including program and data exchange etc. Essentially, a well established computing ecosystem&#x2F;infrastructure surrounds scientific computing that researchers know and understand well. There is no need to change it as it works well. Moreover, it&#x27;s a stable and reliable environment when compared to other computing environments - Fortran was introduced long before the cowboys entered the computing field, back then the programming&#x2F;computing environment was more formal and structured, this contributed to that stability.<p><i>For the record, Fortran was the first language I learned, and my programming back then was done on an IBM-360 using KP-26 and KP-29 keypunches and 80-column Hollerith cards.</i>