This special issue gathers together papers documenting the development of the Firedrake system, and geoscientific models built on Firedrake.

Firedrake provides a model development system which is both high productivity and high performance. Users write high-level code in Python describing the mathematical formulation of a model. The low-level, high-performance, parallel implementation of the algorithm is then automatically generated by a sequence of domain-specific compilers. The user writes maths and gets simulation. Firedrake provides users with a vast range of finite element discretisations, including the compatible finite-element methods which accurately represent the critical force balances in large-scale geoscientific problems. Other important features for the geoscientific user include curved elements and layered meshes, which are key to accurate atmosphere and ocean modelling.