Mimi.jl – Next Generation Climate Economics Modeling
2019-07-25, 14:30–15:00, Elm B

We will present Mimi.jl, a next generation platform for Integrated Assessment Modelling widely used in climate economics research. The talk will outline technical aspects of the platform, as well as its adoption and impact both on research at universities and in the US federal climate regulation process.


In 2016, the EPA commissioned a report from the National Academy of Sciences on research priorities for improving and updating the Social Cost of Carbon, a metric used by the federal government to account for the impacts of climate change within regulatory impact analyses. One central recommendation from the ensuing National Academies report was to create a common, modular computational platform to better serve modelling work in this area.

Our team created the leading (and probably only) implementation following this call to action: the Mimi Framework. Mimi.jl is entirely implemented in Julia. This talk will present this computational platform, discuss its application, and dive into key design considerations.

The main design constraints for Mimi.jl were that we needed something:
a) computationally fast,
b) simple enough that a lack of significant programming experience is not a barrier for users,
c) that enables a modular work style for distributed, loosely coordinated teams, and
d) that creates a transparent framework enabling easy replication of computational experiments.

We will describe in some detail how we achieved this design using a macro based domain specific language for certain parts of the framework, while at the same time exposing the full power of the Julia language to users. We will also touch on our use of a custom Julia registry as the repository for different modules that different groups can work on, allowing us to use Julia’s package manager to solve the replication problem for computational experiments. We will also discuss a large number of specific design decisions that helped us make the system easy to use for novice programmers.

We will conclude the talk with a discussion of adoption and impact of this platform. We will outline how different groups at a number of leading universities and think tanks have adopted the platform for their work and outline why we believe it will power the next generation of the US federal climate economics work in the regulatory space going forward.