I applaud and encourage your engagement with this site, but I don’t see a good case for your proposal. Off-shoot sites work best either when they fill gaps that are off-topic for existing sites or when a sub-topic generates enough momentum on an existing site to sustain its own space. I don't think that either of those conditions is met.
This site started after several aborted attempts to start Meteorology.SE, Oceanography.SE, etc, none of which got enough traction to be launched individually. Despite graduating out of beta in the last year, ES.SE is still a small site on the network compared with other science sites. Eight years after launch there are only ~200 questions tagged as modeling (climate, atmosphere, ocean), that’s ~2 per month, nowhere near enough to sustain its own site. The old Area 51 benchmark for a health graduation out of beta was ~300 per month.
Running IPCC/CMIP type climate models requires large computing resources that are typically provided at the national level by government funding. This means they also have their own, well-established support networks, which is a big reason why we don’t get many technical “how do I...” climate modeling questions on this site. Even more tractable climate models (e.g., WRF) have good user networks that are the first port of call for questions. Now, I’m slightly surprised that there haven’t been many questions on this site about using freely-available climate model outputs (e.g., CMIP6) but, again, that probably reflects the strength of existing support networks outside of this site.
Proposed Q&A site for this site is intended to unite the geosciences and computer science and to help in the creation of competent climate models.
Your proposal doesn’t look very focused. The title says climate modeling, but the strapline says geosciences (i.e., the entire scope of this existing site). Also, as I mention above, the creation of these models is already necessarily well-supported – I'm not convinced there’s a set of currently disparate climate modelers who lack a space to share experience. All those example questions would be in scope on this current site (in fact, most of them have been asked on this site already) and most of them are not particular to climate modeling, e.g., data visualisation, programming languages.
I encourage you to stick with this site for now - your questions are welcome here and trying to start a new site would be a distraction.
