The C13 timeseries data has been stored as a single global value. However, this use doesn't allow the data grid to change. The C14 for CMIIP6 was with three latitude bands, but the CMIP7 data has four., and the code is hardcoded for this handling, and can't easily adapt between the two, or a future more complex grid. It also exposes the data grid to the points where the data is used, rather than have that information isolated to the file handling part. As a first step to moving the data to streams, this needs to change.

The upside is flexibility, readability and code maintenance. The only downside is an increase in memory, but because the memory is scalable this is acceptable.