diff --git a/config/longrun_configs/amip_target_diagedmf.yml b/config/longrun_configs/amip_target_diagedmf.yml
index e98c886cbd..e5f3a45fd2 100644
--- a/config/longrun_configs/amip_target_diagedmf.yml
+++ b/config/longrun_configs/amip_target_diagedmf.yml
@@ -14,6 +14,7 @@ rad: "allskywithclear"
 dt_rad: "1hours"
 dt_cloud_fraction: "1hours"
 insolation: "timevarying"
+co2_model: maunaloa
 prescribe_ozone: true
 aerosol_radiation: true
 prescribed_aerosols: ["CB1", "CB2", "DST01", "OC1", "OC2", "SO4", "SSLT03", "SSLT04"]