Index: /issm/trunk-jpl/src/m/classes/gia.m
===================================================================
--- /issm/trunk-jpl/src/m/classes/gia.m	(revision 14812)
+++ /issm/trunk-jpl/src/m/classes/gia.m	(revision 14813)
@@ -30,4 +30,19 @@
 			md = checkfield(md,'gia.cross_section_shape','numel',[1],'values',[1,2]);
 
+			%be sure that if we are running a prognostic ice flow model coupled with gia, that thickness forcings 
+			%are not provided into the future.
+			if md.transient.isprognostic,
+				thickness=md.geometry.thickness; 
+				%figure out if thickness is a transient forcing: 
+				s=size(thickness); 
+				if s(1)>=md.mesh.numberofvertices,
+					%recover the furthest time "in time": 
+					time=thickness(end,end);
+					if(time~=md.timestepping.start_time),
+						error('if isprognostic is on, transient thickness forcing for the gia model should not be provided in the future. Synchronize your start_time to correspond to the most recent transient thickness forcing timestep');
+					end
+				end
+			end
+
 		end % }}}
 		function disp(obj) % {{{