While many of you have voiced appreciation for the models, you have also noticed their limitations and hidden assumptions. What can we do address these concerns? Which assumptions create difficulties? We can find ways to host most models on the site, but we need to identify (or build) those models first. Can you help us do that?

Hi Chris, I don't know how tricky it would be to have that modular approach but it's appealing to imagine clicking on the model and getting to see the machinery inside the box, with perhaps the big pieces further clickable to see how they work (algorithms, references and assumptions?). Not sure I'd understand much of it but this would open it up for more people's thoughts so it's appealing anyhow! I also like your backup suggestion of an assumptions log, which might work nicely with/within the existing page explaining the model, https://www.climatecolab.org/web/guest/resources/-/wiki/Main/MIT+composite+model Particularly interesting for me would be to learn more about the possibilities for how economic growth and emissions cuts are linked. If the linkage could be reversed, so that growth rises as emissions fall then the political game would change, wouldn't it?

I think the core problem is that the model has the user set emission targets, then calculates the cost. I'd like to see something that works in the other direction. My dream model would be something like this: Input one or more energy generation technologies, with capital and development costs, operating cost, emissions per kilowatt-hour, lifespan, and year of introduction. (Values for various technologies could already be included, but should be modifiable.) Input one or more CO2 absorption technologies, with similar attributes appropriate to absorption, plus a maximum potential. Justifying the values of all these attributes would be up to the submitter. The model should simply work out the consequences of the numbers supplied to it. Let the user set a carbon fee, increasing over time. Don't necessarily assume a penalty to economic growth based on the full carbon cost; allow for the possibility of fees returning to consumers or offsetting tax cuts elsewhere. Give source emitters the options of paying the fee, reducing emissions, or paying for absorption, whatever is cheapest. Any of the three will raise the price of energy, influencing conservation by consumers. Take all this and calculate the resulting emissions. The DICE model might be a good place to start. Later enhancements could take into account variations in other climate forcings: methane, particulates, or engineered albedo changes. Ideas for the UI: Make it easy for a user to copy the model and play with it, to see how sensitive the plan is to various parameters. What if a particular technology takes ten years longer to develop, or is twice as expensive? What if we can only get half the initial carbon fee? Etc. Let line items in the model hyperlink to text justifying them.