CHANGELOG

Author: znichollscr

changelog/427.breaking.md

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+Added data with the source ID `FZJ-CMIP-nitrogen-2-0`. This data updates the historical forcing data provided in `FZJ-CMIP-nitrogen-1-2`.
+
+As a result of an issue being found ([#425](https://github.com/PCMDI/input4MIPs_CVs/issues/425)),
+[TODO further details, ozone text below as a template]
+models that rely on exogenous ozone forcing are now required to use different versions of the ozone files for pre-industrial control (and related) simulations and historical (and related) simulations. 
+For all historical (and related) simulations, files with the source ID FZJ-CMIP-ozone-2-0 should be used. For pre-industrial control (and related) simulations, 
+files with the source ID FZJ-CMIP-ozone-1-2 should be used (note that this guidance differs from the email communication sent by the CMIP IPO on 12 February 2026). 
+For details of your options for pre-industrial control simulations, please see the ozone dataset page.
+
+Modelling centres who have already run their historical simulations do not need to re-run.
+Modelling centres who have not yet started their historical simulations should use the `FZJ-CMIP-nitrogen-1-2` data.
+For further details about the error and recommended action,
+please see [the nitrogen deposition dataset page](https://input4mips-cvs.readthedocs.io/en/latest/dataset-overviews/nitrogen-deposition/).
+
+If any modelling centres run historical simulations with both the `FZJ-CMIP-nitrogen-2-0` and `FZJ-CMIP-nitrogen-1-2` forcing,
+these simulations would be of interest to the Forcings Task Team.