diff --git a/config.default.yaml b/config.default.yaml
index cca71e61..d9376857 100755
--- a/config.default.yaml
+++ b/config.default.yaml
@@ -36,7 +36,7 @@ enable:
 electricity:
   voltages: [220., 300., 380.]
   co2limit: 7.75e+7 # 0.05 * 3.1e9*0.5
-  co2base: 3.1e+9 # 1 * 3.1e9*0.5
+  co2base: 1.487e9
   agg_p_nom_limits: data/agg_p_nom_minmax.csv
 
   extendable_carriers:
diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index e678f669..54419681 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -11,6 +11,8 @@ Release Notes
 Upcoming Release
 ================
 
+* Fix: Value for ``co2base`` in ``config.yaml`` adjusted to 1.487e9 t CO2-eq (from 3.1e9 t CO2-eq). The new value represents emissions related to the electricity sector for EU+UK. The old value was ~2x too high and used when the emissions wildcard in ``{opts}`` was used.
+
 
 PyPSA-Eur 0.3.0 (7th December 2020)
 ==================================