Although scarce can be used as an adverb (scarce more than a bare living), its greatest use in contemporary speech and writing is that of an adjective meaning "infrequently found or seen," "insufficient," "not plentiful": "Pretty women are scarce in this town." Scarcely is an adverb meaning "barely," "by a small margin," "just": "He could scarcely breathe under the heavy covers." Scarcely has a negative sense and should not be used with another negative; avoid such expressions as "didn't scarcely," "couldn't scarcely," and "without scarcely." See also double negative and hardly.
Dictionary of problem words and expressions. Harry Shaw. 1975.