Index: /issm/trunk-jpl/src/m/classes/linearbasalforcings.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/linearbasalforcings.py	(revision 24545)
+++ /issm/trunk-jpl/src/m/classes/linearbasalforcings.py	(revision 24546)
@@ -31,5 +31,5 @@
             inv = args[0]
             self.groundedice_melting_rate = inv.groundedice_melting_rate
-            #self.perturbation_melting_rate = inv.perturbation_melting_rate
+            self.perturbation_melting_rate = float('NaN')
             self.geothermalflux = inv.geothermalflux
             self.deepwater_melting_rate = 0.