Sorry for the stupid question, but I have been unable to answer it even after wasting time googleing for a while... I know there are several climate-changes scenarios, and I know the several climatic databases offering surfaces (rasters) with those scenarios. However, I want to try some calculations on my own, for which I am looking for the mathematics behind these models (the different scenarios) or some code (preferably in R). Any suggestion?
As far as I know, climate models are usually not statistical models but models built from first principles that simulate physical laws, so they will probably not be R-based.
Maybe people at earth science.StackExchange https://earthscience.stackexchange.com/questions/tagged/climate-change will be able to give you a better answer. You can also search for climate change modeling courses or books, e.g., https://www.coursera.org/learn/global-warming https://www.coursera.org/learn/global-warming-model https://www.edx.org/course/modeling-climate-change (I do not know anything about the quality of these courses)