Scott Johnson asks about C-LITE, an ultra-simple version of C-ROADS, built in Processing – a cool visually-oriented language.
With this experiment, I was striving for a couple things:
- A reduced-form version of the climate model, with “good enough” accuracy and interactive speed, as in Vensim’s Synthesim mode (no client-server latency).
- Tufte-like simplicity of the UI (no grids or axis labels to waste electrons). Moving the mouse around changes the emissions trajectory, and sweeps an indicator line that gives the scale of input and outputs.
- Pervasive representation of uncertainty (indicated by shading on temperature as a start).
This is just a prototype, but it’s already more fun than models with traditional interfaces.
The learning curve for all of this is remarkably short. If you’re familiar with Java, it’s very easy to pick up Processing (it’s probably easy coming from other languages as well). I spent just a few days fooling around before I had the hang of building this app. The core model is just standard Euler ODE code:
do while time < final time
compute rates & auxiliaries
The only hassle is that equations have to be ordered manually. I built a Vensim prototype of the model halfway through, in order to stay clear on the structure as I flew seat-of-the pants.