diff --git a/bld/namelist_files/namelist_defaults_cam.xml b/bld/namelist_files/namelist_defaults_cam.xml
index fbd64ccd61..0471219ab3 100644
--- a/bld/namelist_files/namelist_defaults_cam.xml
+++ b/bld/namelist_files/namelist_defaults_cam.xml
@@ -2180,8 +2180,9 @@
 <clubb_l_damp_wp3_Skw_squared                     > .false. </clubb_l_damp_wp3_Skw_squared>
 <clubb_l_diagnose_correlations                    > .false. </clubb_l_diagnose_correlations>
 <clubb_l_diffuse_rtm_and_thlm                     > .false. </clubb_l_diffuse_rtm_and_thlm>
-<clubb_l_do_expldiff_rtm_thlm                     > .false. </clubb_l_do_expldiff_rtm_thlm>
-<clubb_l_do_expldiff_rtm_thlm phys="cam7"         > .true.  </clubb_l_do_expldiff_rtm_thlm>
+<clubb_l_do_expldiff_rtm_thlm                        > .false. </clubb_l_do_expldiff_rtm_thlm>
+<clubb_l_do_expldiff_rtm_thlm clubb_sgs="1"          > .true.  </clubb_l_do_expldiff_rtm_thlm>
+<clubb_l_do_expldiff_rtm_thlm clubb_sgs="1" silhs="1"> .false.  </clubb_l_do_expldiff_rtm_thlm>
 <clubb_l_e3sm_config                              > .false. </clubb_l_e3sm_config>
 <clubb_l_enable_relaxed_clipping                  > .false. </clubb_l_enable_relaxed_clipping>
 <clubb_l_fix_w_chi_eta_correlations               > .true.  </clubb_l_fix_w_chi_eta_correlations>
diff --git a/doc/ChangeLog b/doc/ChangeLog
index e267ccd639..78cd2e72fb 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,5 +1,125 @@
 ===============================================================
 
+Tag name: cam6_4_002
+Originator(s): adamrher, eaton
+Date: Wed Jun 26, 2024
+One-line Summary: activate additional clubb diffusion in cam6
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1056
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+Resolves #1041 - cam6 should have additional clubb diffusion activated but it doesn't
+
+. The fix is to set the namelist defaults for clubb_l_do_expldiff_rtm_thlm
+  the same way that defaults were set for clubb_expldiff before tag cam6_3_059.
+
+Describe any changes made to build system: none
+
+Describe any changes made to the namelist:
+. defaults changed for clubb_l_do_expldiff_rtm_thlm
+
+List any changes to the defaults for the boundary datasets: none
+
+Describe any substantial timing or memory changes: none
+
+Code reviewed by: cacraigucar, nusbaume
+
+List all files eliminated: none
+
+List all files added and what they do: none
+
+List all existing files that have been modified, and describe the changes:
+
+bld/namelist_files/namelist_defaults_cam.xml
+. change defaults for clubb_l_do_expldiff_rtm_thlm to be true when clubb is
+  used, except when clubb is used with silhs.  False otherwise.
+
+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: BFB except:
+
+ERP_Ln9.f09_f09_mg17.FCSD_HCO.derecho_intel.cam-outfrq9s (Overall: FAIL) details:
+SMS_D_Ln9_P1280x1.ne0ARCTICne30x4_ne0ARCTICne30x4_mt12.FHIST.derecho_intel.cam-outfrq9s (Overall: PEND) details:
+SMS_D_Ln9_P1280x1.ne0CONUSne30x8_ne0CONUSne30x8_mt12.FCHIST.derecho_intel.cam-outfrq9s (Overall: PEND) details:
+SMS_D_Ln9.T42_T42.FSCAM.derecho_intel.cam-outfrq9s (Overall: FAIL) details:
+- pre-existing failures
+
+SMS_Ld5.f09_f09_mg17.PC6.derecho_intel.cam-cam6_port_f09 (Overall: NLFAIL) details:
+- namelist change for cam6 physics.  No answer change for PORT test.
+
+ERC_D_Ln9.f19_f19_mg17.QPC6.derecho_intel.cam-outfrq3s_cosp (Overall: DIFF) details:
+ERC_D_Ln9_P144x1.ne16pg3_ne16pg3_mg17.QPC6HIST.derecho_intel.cam-outfrq3s_ttrac_usecase (Overall: DIFF) details:
+ERP_D_Ln9.f19_f19_mg17.QPC6.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_D_Ln9_P64x2.f09_f09_mg17.QSC6.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ld3.f09_f09_mg17.FWHIST.derecho_intel.cam-reduced_hist1d (Overall: DIFF) details:
+ERP_Ln9.C96_C96_mg17.F2000climo.derecho_intel.cam-outfrq9s_mg3 (Overall: DIFF) details:
+ERP_Ln9.f09_f09_mg17.F1850.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.f09_f09_mg17.F2000climo.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.f09_f09_mg17.F2010climo.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.f09_f09_mg17.FHIST_BDRD.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.f19_f19_mg17.FWsc1850.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.ne30pg3_ne30pg3_mg17.FCnudged.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9.ne30pg3_ne30pg3_mg17.FW2000climo.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERP_Ln9_P24x3.f45_f45_mg37.QPWmaC6.derecho_intel.cam-outfrq9s_mee_fluxes (Overall: DIFF) details:
+ERS_Ln9.f09_f09_mg17.FX2000.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERS_Ln9.f19_f19_mg17.FXSD.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+ERS_Ln9_P288x1.mpasa120_mpasa120.F2000climo.derecho_intel.cam-outfrq9s_mpasa120 (Overall: DIFF) details:
+ERS_Ln9_P36x1.mpasa480_mpasa480.F2000climo.derecho_intel.cam-outfrq9s_mpasa480 (Overall: DIFF) details:
+SMS_D_Ln9.f09_f09_mg17.FCts2nudged.derecho_intel.cam-outfrq9s_leapday (Overall: DIFF) details:
+SMS_D_Ln9.f09_f09_mg17.FCvbsxHIST.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+SMS_D_Ln9.f09_f09_mg17.FSD.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+SMS_D_Ln9.f19_f19_mg17.FWma2000climo.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+SMS_D_Ln9.f19_f19_mg17.FWma2000climo.derecho_intel.cam-outfrq9s_waccm_ma_mam4 (Overall: DIFF) details:
+SMS_D_Ln9.f19_f19_mg17.FXHIST.derecho_intel.cam-outfrq9s_amie (Overall: DIFF) details:
+SMS_D_Ln9.f19_f19_mg17.QPC2000climo.derecho_intel.cam-outfrq3s_usecase (Overall: DIFF) details:
+SMS_D_Ln9.ne16pg3_ne16pg3_mg17.FX2000.derecho_intel.cam-outfrq9s (Overall: DIFF) details:
+SMS_Ld1.f09_f09_mg17.FCHIST_GC.derecho_intel.cam-outfrq1d (Overall: DIFF) details:
+SMS_Ld1.f09_f09_mg17.FW2000climo.derecho_intel.cam-outfrq1d (Overall: DIFF) details:
+SMS_Ld1.ne30pg3_ne30pg3_mg17.FC2010climo.derecho_intel.cam-outfrq1d (Overall: DIFF) details:
+SMS_Lh12.f09_f09_mg17.FCSD_HCO.derecho_intel.cam-outfrq3h (Overall: DIFF) details:
+SMS_Lm13.f10_f10_mg37.F2000climo.derecho_intel.cam-outfrq1m (Overall: DIFF) details:
+SMS_Ln9.f09_f09_mg17.F2010climo.derecho_intel.cam-nudging (Overall: DIFF) details:
+SMS_Ln9.f09_f09_mg17.FW1850.derecho_intel.cam-reduced_hist3s (Overall: DIFF) details:
+SMS_Ln9.f19_f19_mg17.FHIST.derecho_intel.cam-outfrq9s_nochem (Overall: DIFF) details:
+SMS_Ln9.ne30pg3_ne30pg3_mg17.FW2000climo.derecho_intel.cam-outfrq9s_rrtmgp (Overall: DIFF) details:
+- answer change for cam6 physics
+
+izumi/nag/aux_cam: BFB except:
+
+DAE.f45_f45_mg37.FHS94.izumi_nag.cam-dae (Overall: FAIL) details:
+- pre-existing failure
+
+ERC_D_Ln9.f10_f10_mg37.QPC6.izumi_nag.cam-outfrq3s_am (Overall: DIFF) details:
+ERC_D_Ln9.f10_f10_mg37.QPC6.izumi_nag.cam-outfrq3s_cospsathist (Overall: DIFF) details:
+ERC_D_Ln9.f10_f10_mg37.QPC6.izumi_nag.cam-outfrq3s (Overall: DIFF) details:
+ERC_D_Ln9.f10_f10_mg37.QPWmaC6.izumi_nag.cam-outfrq3s (Overall: DIFF) details:
+ERI_D_Ln18.f19_f19_mg17.QPC6.izumi_nag.cam-ghgrmp_e8 (Overall: DIFF) details:
+ERP_Ln9.ne5pg3_ne5pg3_mg37.QPC6.izumi_nag.cam-outfrq9s_clubbmf (Overall: DIFF) details:
+SMS_D_Ln9.f10_f10_mg37.QPC6.izumi_nag.cam-outfrq3s_ba (Overall: DIFF) details:
+SMS_P48x1_D_Ln3.f09_f09_mg17.QPC6HIST.izumi_nag.cam-outfrq3s_co2cycle_usecase (Overall: DIFF) details:
+- answer change for cam6 physics
+
+izumi/gnu/aux_cam: BFB except:
+
+ERP_D_Ln9.C48_C48_mg17.QPC6.izumi_gnu.cam-outfrq9s (Overall: DIFF) details:
+ERP_D_Ln9.ne3pg3_ne3pg3_mg37.QPC6.izumi_gnu.cam-outfrq9s_rrtmgp (Overall: DIFF) details:
+- answer changes in cam6 physics
+
+SMS_Ld5.f09_f09_mg17.PC6.izumi_gnu.cam-cam6_port_f09_rrtmgp (Overall: NLFAIL) details:
+- namelist change for cam6 physics.  No answer change for this PORT test.
+
+CAM tag used for the baseline comparison tests if different than previous
+tag:
+
+Summarize any changes to answers: This changes answers for all
+  configurations using cam6 physics, except for cam6 with silhs.
+
+===============================================================
+===============================================================
+
 Tag name: cam6_4_001
 Originator(s): eaton
 Date: Wed Jun 26, 2024