def check_internal_consistency(self, **kwargs):
        inconsistent_vars = {}
        for variable in self.variables():
            diff_agg = self.check_aggregate(variable, **kwargs)
            if diff_agg is not None:
                inconsistent_vars[variable + "-aggregate"] = diff_agg
            diff_regional = self.check_aggregate_region(variable, **kwargs)
            if diff_regional is not None:
                inconsistent_vars[variable + "-regional"] = diff_regional
        return inconsistent_vars if inconsistent_vars else None