Add draft Changelog message

Signed-off-by: Lizzie Lundgren <elundgren@seas.harvard.edu>

doc/ChangeLog

@@ -1,3 +1,65 @@
+Tag name: TBD
+Originator(s): lizziel
+Date: 9 Jan 2025
+One-line Summary: Update to HEMCO_CESM 2.1.0 and introduce new FCSD_HCO tests that pass ERS
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1221
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+HEMCO_CESM includes fixes to allow ERS tests of CAM-chem with HEMCO to pass if restarted on the
+hour. The new tests (10hr) do this, allowing demonstration that the issue with current ERS
+tests (9hr) is understood to be causes by restarting mid-hour (issue #856).
+
+Describe any changes made to build system:
+
+Describe any changes made to the namelist:
+
+List any changes to the defaults for the boundary datasets:
+
+Describe any substantial timing or memory changes:
+
+Code reviewed by: TBD
+
+List all files eliminated: N/A
+
+List all files added and what they do: N/A
+
+List all existing files that have been modified, and describe the changes:
+
+M       .gitmodules
+        - Update HEMCO_CESM version
+
+M       bld/namelist-files/namelist_defaults_cam.xml
+	- Update default hemco_config_file to read and regrid aviation emissions hourly
+	- Change default path of hemco_config_file
+
+M       cime_config/testdefs/testlist_cam.xml
+	- Add ERP_Ln10 and ERS_Ln10 for FCSD_HCO
+
+M       testmods_dirs/cam/outfrq10s/shell_commands
+M       testmods_dirs/cam/outfrq10s/user_nl_cam
+M       testmods_dirs/cam/outfrq10s/user_nl_clm
+	- Add files for new Ln10 tests
+
+M       src/hemco
+	- tag hemco-cesm2_1_0_hemco3_9_0
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
+
+derecho/intel/aux_cam: TBD
+
+derecho/nvhpc/aux_cam: TBD
+
+izumi/nag/aux_cam: TBD
+
+izumi/gnu/aux_cam: TBD
+
+Summarize any changes to answers: bit-for-bit unchanged
+
+===============================================================
+
 Tag name: cam6_4_038
 Originator(s): lizziel
 Date: 1 Oct 2024